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CMF3 1237-series design and build progression

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#76 Rick Moore

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Posted 25 October 2018 - 08:47 AM



I opted to start with the 1262-series design with a configuration that most “resembled” the previous 1237-series builds in structural functionality, in this case a “1262.1”, which has the center main rail (solid attachment), the medial buttress rails articulated aft, and lateral buttress rails articulated fore and aft. I also decided to start the 1262-subseries building “d” dimensioned chassis, instead of the “c” dimensions that were the starting point for the previous 1237-series builds.


First pic is the completed chassis, and also shows two add-on pans off to the sides that were not soldered onto the chassis at this time. I knew going in that this chassis would be under the 100-gram minimum for CanAm class cars; and as the build progressed it looked like the completed car would be about 95 - 97 grams; so I made these two pans which weigh a total of 5.0 grams; they would be trimmed as required and added once I got a better estimate of the final weight for the car. This seemed a better option, keeping the added mass even with the bottom plane of the chassis as opposed to just sticking lead atop the chassis frame…





My last estimate was I would need 3.3 - 3.5 grams more, so, not fully trusting my ability to do simple math, I trimmed the pans down to 3.6 grams total and hung them from the forward edge of the rear motor/drive assembly between the side pans and the lateral buttress rails; in this position they changed the general balance of the car the least, and similar pans could be applied in this same location to other versions in the 1262-series as well.













Pretty weird looking, with a capital W. And the final RTR car came out to 100.4 grams…


Test Run:


Spent most of Wednesday evening at Fast Eddie’s Raceway sorting out the cars for the GRRR races this Sunday (no work, yea!), especially since I hadn’t made it back to the tracks since the Southern Retro Rumble. Once I got some laps on the Oval with the Stock Cars, and blew the dust out of the CanAm Plus cars and sorted them out on the Hillclimb, I finally got around to running the current ten car CanAm stable on the Hillclimb; last year if you were in the 4.5’s you were fast, but this year you better be in the low 4.4’s. Since all the other CanAm’s were in their “race” set-ups, I put a “race” motor in the 1262.1.2-Cd3 and stuck it at the end of the line just to see how it would shake out on its maiden run…


Running it conservatively, the 1262.1.2-Cd3 ran laps in the upper 4.4’s in its first 20 lap stint. On its second stint I drove it harder and dropped into the low 4.4’s… in fact, it ran the second fastest lap of any of my CanAm cars ever, only 0.007s behind the fastest lap time (which was also run last night by the 1241-Cd3, and both were faster than what Jeff qualified the 1241-Cd3 at the SRR…)…


Okay. Well. I wasn’t expecting that. I know I’m not alone hoping a new chassis will just go like a batouttahell when we put it on the track, but in reality I mostly hope it isn’t a disaster. This was especially the case with the 1262.1.2-Cd3 being the first of the sub-series. So, as first runs go, this one was out of the ordinary. But, as always, this was just the first run… Also, I didn’t have time last night to do any runs on the gutter lanes with the 1262.1.2-Cd3, or any of the other CanAm’s, but I’ll probably get some time before Sunday to test it and some others out on Red and Black since the gutter lane performance is a major factor in my determining which car I will race… Who knows, I may have to add another car to my options…


Next up:


The plan for the next builds in the 1262-series would be the 1262.6.2-Cd3 and/or the 1262.9.2-Cd3, and then do a comparison of those three chassis/cars. After that I’d pick one of those to try a 1263 design build (replacing the 1237-based rear assembly of the 1262’s with one based on the 1254), and then…


That’s the short list… all subject to change… change being the only constant…


More cheap thrills. Fun fun fun!


Rick / CMF3

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#77 Rick Moore

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Posted 12 December 2018 - 11:06 PM



“All around the mulberry bush…”


…subject to change... Here we go again.


The “we” above in as far as other than “me” there may be one or two of “you” left reading this who haven’t completely given up on this thread, most others having succumbed or acquiesced to boredom, confusion, consternation, abhorrence, or various combinations thereof toward general frustration; and should “you” suspect “you” may be part of that “we”, “you” may want to do some serious introspection, because I already know what is seriously wrong with the “me” part of that “we”. However, if “you” have already done that center-of-your-mind mucking about and “you” are already cool with all that squishy miasma between the ears, welcome back. Now kick back, read on, beverages optional, and enjoy.


As I noted previously in the post for the 1254.2-Cd3, the 1254 in concept was just a chassis to fill the gap between earlier 1237-series designs and the 1255 through 1258 designs, and envisioned as such should have been a one-and-done thing, but, no, with further testing (and competition) that would not turn out to be the role the 1254’s would take. And, no, I’m certainly not complaining; once I figured out the characteristics of the 1254’s I have to admit I was, shall we say, pleasantly surprised.


That’s part of the inherent nature with any series of chassis designs and builds in as much as it is not some nice clean straight-line linear progression, but a convoluted mish-mash of diverging, converging, and intersecting lines between various points… So, while testing continues, I had to throw in…


The 1259 is a back-track I never intended to build originally, basically the 1254 with the dimensions of the 1257/1258, which is why it is CMF3-numerically out of sequence. Here’s where it fits in and why:


The relative lengths of the single center main rails on the “c” and “d” dimensioned 1241’s, 1254’s, and now the 1259 are:


1241 = 2.00”

1259 = 1.6875”

1254 = 1.375”


So, the 1259 allows me to have a chassis with an intermediate main rail length between the 1241’s and 1254’s, hopefully for further observation noting any contributing factors this may have in the grand scheme of things, and being fully aware it may not matter squat, but if the 1259 turns out to be anywhere near as good as the 1241’s and 1254’s the effort would still be worth it. Or so I was able to convince myself, and stop putting it off.


Opted to build the “c” dimensioned frame first on the 1259, with full intention to build a “d” immediately afterwards… or shortly afterwards… maybe… who knows…


The 1259.2-Cc3:













And, for better visualization, a side-by-side pic of the, left to right, 1254.2-Cc3, 1259.2-Cc3, and 1241-Cc3:





The 1254.2-Cc3 and 1254.2-Cd3 RTR cars came out just over and under the you-know-what 100-gram thing (100.4 and 99.8 grams, respectively); I figured the 1259 should be somewhere around that range. The 1259.2-Cc3 RTR car came out to 100.1 grams… did that Buster Keaton blinking thing… Another example of it being better to be lucky than good.


Test Run:


Wednesday evening, Fast Eddie’s; I got a great poster from Ed showing the winning cars over all the years at the 12 Hours of Sebring (and by coincidence I was wearing my 1991 Sebring sweatshirt). Thanks Ed! This night was going to be good no matter what.


On the Hillclimb, first lap sets on Orange, out-of-the-box the 1259.2-Cc3 not only ran the fastest laps (mid 4.4’s) of all the cars, but ran the fastest laps for that particular motor in any car (previously the fastest lap for that motor was in the 1254.2-Cd3, and I honestly did not expect this motor to even come close to those times, much less be quicker). Not bad. On Red and Black lanes the 1254.2-Cc3 was the fastest of all the “c” dimensioned cars, and within 0.02 s behind the two faster “d” dimensioned cars. Not bad at all. I’ll have to see if this was just a lucky set-up on the first try, or if this car can perform consistently like the 1241’s and 1254’s. Seems to be in the ballpark at least. And, first impressions, the handling characteristics of the 1259.2-Cc3 seems to be “something” between the 1241’s and 1254’s (but time and more testing will show this better). I definitely want to build a “d” dimensioned 1259 now…


“Pop, goes the weasel.”


Rick / CMF3


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#78 Rick Moore

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Posted 28 December 2018 - 04:04 PM



While I was backtracking, I went off on a side project…


Periodically I like to play around putting different bodies on my cars to see what if any difference it makes, and one recent foray involved the Parma wide and narrow nose Ti-22’s, and, another narrow nose, the Edge Ti-22 (thanks, Bryan!). Both the wide (1041-B) and narrow nosed (1043-B) Parma Ti-22 bodies will fit on my chassis unmodified, but other narrow-nosed Ti-22 bodies, like the Edge, do not fit due to the “square” front wings on all of these CMF3 1237-Series chassis. The Edge Ti-22 does fit if you pull out the front sides, but that deforms the body front somewhat, so I got to thinking…


Here was an opportunity, or a good enough reason in my thinking, to build a 1254 chassis with the front wings built slightly truncated to fit the Edge Ti-22 body. Since the Edge Ti-22 is not legal in IRRA rules but is under SCRRA rules (where the Parma bodies are not… all this gets confusing…), this meant I could build this 1254 car with no minimum weight requirement… Cool. Motivation. This could be fun.


That’s how I wound up with the 1254.2-Cd3-NN:















Besides the lateral forward angles on the front wings, the 1254.2-Cd3-NN has no dynamic pans between the center main rail and the buttress / front axle rails; these pans are built onto my other 1237-Series CanAm frames solely to bring the cars closer to that 100-gram thing, which was not a requirement for this car. As such, the RTR car came out to 94.5 grams (probably on the chunky side for a SCRRA CanAm BPR King car).


Of additional interest to me with regards to the series progression, with the smaller front wheels and a different body this car would be a CanAm Plus class car, so this car also gives me some info going in that direction as well… hint, hint…




More test laps on the Hillclimb at Fast Eddie’s; it’s a dirty job, but someone’s got to do it.


There really are too many variables I had to take into consideration if I wanted to do any comparison between the original 1254.2-Cd3 and this new 1254.2-Cd3-NN: the cars have two different Ti-22 bodies; the square and truncated front chassis wings; and that difference of 5.6 grams of mass, largely by whether they have the dynamic pans or not. So testing the 1254.2-Cd3-NN would mostly be a case of being judged on its own merits or deficiencies.


This thing definitely runs like a “1254”. The first thing that became apparent was the difference in mass; while 5.6 grams may not seem like all that much, it was more than evident in comparison with the other 1254’s. The two earlier 1254’s will launch out of turns faster than anything else, but with less weight the 1254.2-Cd4-NN would come out of the turns like a rocket. Tracking through the turns seemed to be better as well, though I probably should have played around with different tires on this car. It took me a while to get used to this thing, but overall it was consistently faster than any other car on this evening, even on the gutters (but that mediocre driver could definitely use more practice getting it around on Red). All in all, a lot of fun, and very interesting…


But essentially the 1254.2-Cd3-NN is a chassis/car legal for SCRRA racing, and not IRRA racing which is the rule set in these parts. I don’t foresee myself driving to SoCal to give this car a proper thrashing on the Gerding King at BPR any time soon, as tempting as that thought may be. But that doesn’t mean the 1254.2-Cd3-NN can’t go… a 1/24th scale road trip…


Share the fun!


Rick / CMF3

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#79 Rick Moore

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Posted 02 January 2019 - 09:27 PM



Okay, with that little side project thrown in, maybe this wasn’t “immediately afterwards”, but I’ll let this one slide as being in the “shortly afterwards” time frame… relatively speaking… as “planning” goes that was pretty good for my part… even though this is another back-track build... the plan was it was planned after it was unplanned after it was never planned…


To go with the 1259.2-Cc3, a “d” dimensioned version of the 1259, the 1259.2-Cd3:













On the 1259.2-Cd3 the RTR car came out to 100.2 grams, a whopping 0.1 gram more than the 1259.2-Cc3… blink… blink…


Test runs on the 1259.2-Cc3 have been going well enough that the 1259.2-Cd3 had to be built. A few of you may have noted on that 1259.2-Cc3 post why I have such interest in these short wheelbase / long guide lead “d” cars, where I noted on that initial test evening the 1259.2-Cc3 was the fastest Orange lane car, but not the fastest Red or Black lane car where it was beat out by two “d” cars on each gutter lane. Since I already have “c” and “d” versions of the 1241 and 1254 (and 1256 as well), this 1259 “d” was needed to complete the “collection”, for better comparison in testing as well as giving me more options for competition selection.


Side note: The odd thing about all these different dimensioned “c” and “d” chassis frames and cars is whenever I’m doing test runs at the track the first car I put on to “run in” the lane and to gauge track conditions is always the 1241-Cb3… that is not a typographical error, not a “c” or a “d” car, but a “b” dimensioned chassis… and currently the only “b” in the active stable of CanAm cars, and thus far is one of only two “b” CanAm class chassis in the 1237-Series (there was a “b” CanAm Plus class car also). The 1241-Cb3 is just so ding-dang consistent and predictable, which was coincidentally the same thing I liked about the previous “b” dimensioned car way-back-when, the 1229-Cb2. Maybe, just maybe, I keep thinking now, this “b-thing” might not be a coincidence, that it could be inherent to the “b” dimensioned cars… and that maybe, just maybe, I should build another “b” car, maybe a 1254, or a 1259, or… hmmmmm…


No Test Run:


That says it all. I mentioned back in the previous 1254.2-Cd3-NN thread I was playing around with bodies; what I didn’t mention was that activity was spurred on by the need to replace a bunch of the bodies on these cars (if they don’t come off you aren’t driving them hard enough…), so I’ve got some painting to do here before heading back to Fast Eddie’s. Plus, I got in some non-slot-car fun during the holidays, which pushed back items on the CMF3 O-2-It list. Just terrible, right?


Honestly, if the 1259.2-Cd3 doesn’t fall into its expected “nook” relative to the 1241’s, the 1254’s, and the preceding 1259.2-Cc3 then I’ll be surprised, and will make some notation in a later post for future reference for the continued annoyance of those still following this thread after all this time.


Speaking of which, besides being the first chassis to come out in 2019, the 1259.2-Cd3 is the thirty-sixth design/build in the 1237-Series that started, along with this thread, three years ago. If some of you winced after reading that, I can’t say I blame you, since I did the same thing when I wrote it. I really had no idea it would have gone on this long, and for the foreseeable future still be a long way from running its course. Someday I must give up this mad carefree existence… In the meantime…


Best wishes to all of you and yours in this new year! Oh, and of course, make sure you have fun!


Rick / CMF3

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#80 Rick Moore

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Posted 07 February 2019 - 09:16 AM



…change being the only constant… So where was I before I got distracted…


What Was:


Or almost wasn’t. Throwing in the builds of the two 1259’s, though unplanned, now seems like one of the “smarter” things I’ve done in this series progression. What I’ve found is that the relative difference in the center main rail lengths on the 1241’s, 1254’s, and 1259’s is a significant factor to the relative differences in chassis characteristics. The test run(s) on the 1259.2-Cd3, missing from the last post, came into line perfectly as expected compared to the 1259.2-Cc3, the 1254’s, and the 1241’s. It was an epiphany that in retrospect seems all so obvious now.


What Now:


So, after the backtracking with the 1259’s (and side-tracked with the narrow-nose 1254, and the Asp), it was time to get back to the 1262-series. The time between not only gave me a much better insight into these  chassis, but also afforded me more testing on the 1262.1.2-Cd3 (which continues to perform with the 1241’s, 1254’s, and 1259’s), allowing me the opportunity to reassess what I wanted to do next…


I opted to build the first 1263 chassis next, rather than, as I had planned before, other versions of the 1262. Here’s a quick outline of who’s who:


1262: rear assembly design based on the 1237 / 1241, with a resulting “c” or “d” center main rail length of 2.00”;


1263: rear assembly design based on the 1254, with a resulting “c” or “d” center main rail length of 1.375”;


1264: rear assembly design based on the 1259, with a resulting “c” or “d” center main rail length of 1.6875”;


So, having already built the first 1262.1.2-Cd3, “the plan” became to build the same “.1.2-Cd3” version of the 1263 next, and then to be followed by the same version of the 1264. I figure after comparing the same versions of the 1262, 1263, and 1264 I might have a better idea how I want to progress in the 1262 sub-series… the key word being might… as in maybe… as in subject to change…as in I have no friggin’ idea…


Confusing as all heck, don’t ya think?


The 1262 sub-series, part 2, take 2: the 1263.1.2-Cd3:













Crazy looking.


Because of the drastically shortened mid-section (main and buttress rails) there was not enough room on the 1263 for the variable spring wire boxes. That was okay, since I rarely if ever adjust them anymore; I just like to still have the option. On the just-for-fun Competition Asp chassis build (just prior to this build), which had some space restrictions of its own, I experimented with some changes to the articulations, and to using just the spring wires directly soldered to the chassis; so on the 1263 I already knew that the spring wires could and would be directly soldered to the framing without the control boxes.


As on the 1262.1.2-Cd3, the 1263.1.2-Cd3 had add-on pans made up during the chassis build that were trimmed down to my estimated 3.6 grams total and added after the initial RTR set-up to bring the car to that minimum weight thing-a-ma-bob; in the end the RTR 1263.1.2-Cd3 came out to 101.0 grams… I guess I still need to work on my guessing math…


Test Run:


Another evening at Fast Eddie’s Raceway, toiling away testing slot cars… So much hard work for a bunch of little toy cars, right? It’s a dirty job, but someone’s gotta do it.


The big question was would I see similar chassis characteristic differences between the 1262 and 1263 as I’ve noticed between the 1241’s and the 1254’s.


In a word, yes.


On this maiden test run it appears the characteristic differences between the 1263 and the 1262 are not as pronounced as they are between the 1254’s and the 1241’s, but they are definitely there. More testing to come. Even got Ed to run the cars some, affording me the opportunity to step back and watch them, confirming my previous observations, and letting Ed do some of “the work” too.


Now What:


Last time I said what I was going to “do next” in this thread it got drop-kicked in the gonads. I have a list of “chassis to build” sitting here that has been rewritten pretty much constantly of late. Ideally the next chassis I should build would be the same “.1.2-Cd3” version for the initial 1264 chassis in the sub-series, which for all intents and purposes is what I’m intending to do at this moment. After that I can think about the other configurations of the 1262’s, 1263’s, and/or 1264s that I can build and test, probably a “.6.2-Cd3” and “.9.2-Cd3” to start…


…But that’s not taking into consideration any other CanAm class chassis I’ve got on the “O-2-It” list, one being another “b” dimensioned chassis… And there are chassis for the other classes on the list as well… Will the madness never end?


So many chassis, so little time…


I do this for fun, right?


Well, yeah… I actually do… could be worse… in fact, it’s not bad at all, really… Okay, sure, maybe when I keep dropping stuff and have to crawl around looking for it I’ll question life, the universe, and everything, but that’s really the idiot-with-the-fingers’ fault…


Cool beans.


Rick / CMF3


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#81 Bryan Warmack

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Posted 17 February 2019 - 01:59 PM

  The 1254 car profiled earlier in this thread did make a little trip to the West Coast recently as Rick sent it out to me to see how she'd run on the BPR King track!  The original plan was to run it this month on the King, but I decided what the heck, let's see what she'll do on the Flat track and ran it last weekend at the monthly Flat track race!








  I didn't have any opportunity to do any testing before the day of the race so I just threw on a little insurance weight to bring it up to 113 grams and put in a decent FT motor and tried it first with some JK Premium tires.  I put on some JK 8703's and it really liked these better and it didn't do anything wrong and was really smooth and hooked up and I deemed it totally raceable after running some very good times on the difficult red lane.  We only had 9 guys so we didn't qualify and I started slowly to get the feel of the track and the car and soon saw it could be driven harder and harder with no problems!  It ran a VERY respectable 303 laps to 2nd place and I'm going to run it again next month to try and better the lap total!  All things considered an excellent first outing and I'm going to go back to the original plan of running it next weekend, 2/23, at the monthly race on the King track. Should be interesting and I'll certainly report back here with the results!  :)



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#82 Rick Moore

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Posted 07 March 2019 - 10:44 AM



The third installment in the 1262-series, the first 1264 built in the same dimensions and version as the previous 1263 and 1262. The 1264 has a rear assembly and center main rail length based on the 1259 (versus the 1263/1254 and the 1262/1241).


The 1264.1.2-Cd3:













Looks weirdly familiar. All put together with the add-on pans it came out to 100.5 grams.


The question being is the 1264 relative to the 1262 and 1263 as the 1259’s are to the 1254’s and 1241’s…



Yep. The 1264 was pretty much what I expected. First impressions are the differences between the 1262, 1263, and 1264 seem to be less pronounced than they are with the 1241/1254/1259 comparisons; need to think about that. Unfortunately last night’s testing session had other priorities, so I didn’t get to run the 1264 on the gutters yet, but, as always, there is more testing to come.


At this point I have a ridiculous number of CanAm class cars; and that’s just the ones in “active” status. That is not to say there are not more on the drawing board, but, criminy, this is probably indicative of some mental health issue. And tires… holy moly, do I go through a boat-load of tires…


Whatever. I’ll do some more comparative testing between the 1262.1.2-Cd3 (currently on vacation), the 1263.1.2-Cd3, and 1264.1.2-Cd3 before deciding how I want to move forward in the 1262 sub-series. In the meantime…


I’ve got no control…


Rick / CMF3


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#83 Rick Moore

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Posted 13 March 2019 - 11:29 PM



Stock car time again. Yee-haa. I’ve been dragging my feet on stock car builds, largely because the 1244-D3o, which was built well over a year ago, is so freaking good there just wasn’t any hurry. To say the least, there is a log-jam of stock car chassis designs piling up…


First in seemingly forever is a 1254 version of the 1244-D3o, the 1254.23-D3o, another asymmetric frame for left-turn-only oval racing; hence the “.23” designation denoting L-R asymmetry, the “2” as 1241-left, the “3” as 1250-right. Got that? No? Good. Try not to think about it. In fact in most cases you’re probably better off just skipping the next couple of paragraphs and going on to the pictures. Besides, I don’t think anyone actually reads anymore these days anyway, do they? Rhetorical question; the answer is no. Anyhow, I just wanted to write a sentence with anyone, anymore, and anyway in it. But just in case you’re bored, or a glutton for punishment…


Like their similarly numbered CanAm counterparts, the “D” designs also vary by the rear assembly and center main rail length; however, with the stock cars having a RAX-GPC of 5.25” (WB = 4.50; GL = 0.75”) and a 3.00” maximum width a recalculation and slight design modification was required. As illustration, and for reference, the center main rail lengths of the “D” designs are:


1237 / 1241 / 1244 / 1262  = 2.25”

1259 / 1264                        = 1.875”

1254 / 1263                        = 1.50”


So this 1254.23-D3o is the “short” main rail version. I decided to keep the stock car chassis build sequence similar to the CanAm sequence, having built the longest (1244-D3o) main rail frame first, now the shortest (1254.23-D3o), and, as currently planned, the mid-ranged frame (1259.23-D3o) would be next; at that point I might have some idea as to what I’d like to build as far as a 1262-series stock car frame… We’ll see if any of that pans out… Don’t hold your breath…


Speaking of pans, like the 1244, the 1254.23-D3o has all the pans on the left side. And I’ve decided this 1254 stock car chassis, and probably all subsequent oval and road course stock car chassis in the 1237-series, will be framed using 0.032” wire; to some slot car geeks the 0.032” wire seems radically small for a stock car frame, but testing and racing the 1241-D3o and 1244-D3o have shown them to be much stronger than I or anyone would have thought, so…


The 1254.23-D3o:















I had forgotten how complex the 1244 build had been, so going into this 1254-D I had to sit down and think over again the entire build sequence before even starting. Since I had the experience from the 1244, this one wasn’t as “thought intensive”, but it was definitely a fun challenge nonetheless.


The completed RTR 1254.23-D3o car came out to 114.5 grams… that’s 0.9 grams less than the 1244-D3o started out, and, of course, well under the 120-gram doohickey, but as before I’ve got pre-cut weights to go on those left-side pans for the oval racing left-turn bias… and, as I found with the 1244, it may very well need not be all that much over 120 grams…




First runs were out-of-the-box, with lead ballast being added subsequently. As with the 1244-D3o, I was surprised how well the 1254.23-D3o handled more than 5 grams under the class minimum weight, and a boat-load lighter than most cars run in the class.


And, just as with the 1244, I saw no reason to go tacking on any more lead to the left side pans than was necessary, bringing the mass up to 120.3 grams (okay, I got carried away). The extra mass did not hinder the car’s performance, and in either configuration ran excellent laps and virtually equal. It was smooth and fast, was the quickest of the Stock Cars this evening, on Orange, Red, and Black, and clocked in better times than the 1244’s maiden run. Not bad.


I used to wonder why I took so long to build the 1244-D3o, and now I’m wondering why I waited so long to build the 1254.23-D3o… but then I remember… how if not why at least… but, considering the input I got from all the other chassis in between, I’m kind of glad I did.


I am in no way even going to hazard any comment as to the expected date of the next Stock Car class chassis, except maybe…


Sooner or later.


Have fun, kidz!


Rick / CMF3

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#84 Rick Moore

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Posted 04 April 2019 - 08:02 AM



Well, I hemmed and hawed over which chassis to build next, at that time a toss-up between a 1259 version LTO Stock Car chassis, or another CanAm chassis using short “b” dimensions. Recent testing and racing results were such that either would have been a good choice in the progression, but I can only build one at a time, and when push-came-to-shove…


Here’s that “b” dimensioned CanAm chassis I wanted to add to the current stable of frames. Since the 1241-Cb3 was the only active “b” chassis still in the boxes, I decided to build it a “b” cousin, the 1259.2-Cb3…


A short refresher of CMF3 chassis designations for WB / RAX-GPC / GL:


c =   3.875 / 4.875 / 1.000

d =   3.750 / 4.875 / 1.125

b =   3.750 / 4.750 / 1.000 …


So “b” is the “short” chassis.


The design consideration that has to be made with making a “b” version (and parenthetically in particular to the 1259) as opposed to a “c” or “d” is how to translate the relative dimensions of the chassis components; there are three main options:

1) Keep the length of the center main rail the same (1.6875”) and shorten the rear/drive assembly 0.125”, or;

2) Keep the length of the rear/drive assembly the same and shorten the center main rail 0.125” (to 1.5625”), or;

3) Change both equally and shorten the rear/drive assembly 0.0625” and the center main rail 0.0625” (to 1.625”).

I can make arguments for and against each. In this case, since the 1259 design layout is based on mathematical points of intersection, the third option of proportionally shortening the chassis components made more sense (a loosely used term)…


In any case, I have “c”, “d”, and “b” versions of the 1241’s, and, now, also of the 1259’s.


For your perusal, the 1259.2-Cb3:













As I’d mentioned in previous posts, I’ve been playing around with bodies of late (see “Other Tidbits”), and one body was the Parma Ti22 Short Narrow Nose (1050B). I had assumed this body would not fit atop any of my chassis without truncating the chassis’ square front wings (as on the 1254.2-Cd3-NN with the Edge Ti22 body), so I was surprised when I found the 1050B would easily fit any of my 1237-series chassis with no alterations. After some convoluted reasoning (is there any other kind…) I opted to mount the 1050B S-NN body on the 1259.2-Cb3.


The 1259 “c” and “d” versions had just come out a tenth or two over the 100-gram whoopdeedoo, and my guess was the “b” was going to be about one or two grams below, and in actuality came out to 98.9 grams… dead-lead weight added to dynamic pans, 100.0 grams, western civilization saved…


Test Run:


I’d mentioned in a previous post that for any given set of test runs for quite a long time now the first car I always run is the other “b” car, 1241-Cb3; it’s predictability and consistency has made it my “test mule”, giving me a feeling for the track conditions, making controller adjustments, and pretty much setting baselines for testing. When you have a lot of cars to test, this is extremely helpful. As far as testing was concerned, any expectations for the 1259.2-Cb3 frame were more a matter of satisfying curiosity, as I really just wanted to see if the 1259.2-Cb3 fell into place relative to the other “b” chassis, the 1241-Cb3 (1241 vs 1259), and with the other two 1259’s, the 1259.2-Cc3 and 1259.2-Cd3 (b vs d vs c). In the long run, I’d be perfectly happy even if it just becomes a second “test mule”.


Test mule it isn’t, at least not on this first run. The 1259 “d” was still in its race set up from ten days ago (see “other Tidbits” again), and this new 1259 “b” easily handled just as well, possibly better, and was definitively quicker with a “test” motor that had not run that fast in any other chassis previously, and that was on Orange, Red, and Black. This might be a case where I find a “lucky” set-up on the first go, so, as is the norm, more testing in different configurations are to follow (this “test” motor is going into the “for later” bin), but as first runs go this one was pretty easy to call. Test mule my, uh, donkey.


Other Tidbits:


Way back around the 1256’s or so I started debating and testing the V-shaped 0.055” wire spines at the forward-center of the rear/drive assembly used on the 1254’s but not on the 1257, 1255, and 1256’s. Subsequently the 1256.2-Cd3 would have one added, and the 1263, 1264, and 1259’s would get them. Finally the jury came out last month and the 1257, 1255 and the other 1256 now have V-spines added to those frames as well.


As for the Parma Ti22 bodies, if there is any discernible difference in performance between the 1041B (wide nose), the 1043B Narrow Nose, and the 1050B Short Narrow Nose, I have not been able to quantify it with my testing of the 1237-series CanAm class cars on the Hillclimb at Fast Eddie’s Raceway. This is not to say you will not find one body to be better than the others on other chassis run on other tracks, you’ll just have to test for yourself as I’ve nothing to offer in this regard, at least to date. For my esoteric purposes though I have recently taken a preference to the 1043B Narrow Nose as the initial body to put on my 1237-Series CanAm cars; it just seems to mount “squarer” for some unknown reason (might just be my not-so-good eyeballs), and I’ve found I prefer mounting the “sissy bar” I use on the 1237-Series CanAm chassis using the 1043B NN body; switching to the 1041B or 1050B bodies does not require any adjustment of the sissy bar. Admittedly this is a highly subjective observation that, since no one else uses sissy bars, has little applicability to anyone else. Aesthetically I like the 1050B S-NN. Your results may vary.


For you competition freaks out there, I’ve been ignoring this aspect of posting in this thread for a while, since the redundancy with the race reports elsewhere on SB and other social media just seemed sort of obnoxiously self-indulgent. For the design and build sequence I’m more interested in test data (of which there is way too much to even begin to start posting… and, yes, I have spreadsheets... I have no life...). However, my result in the CanAm race at the most recent GRRR event at Fast Eddie’s was such that it is heavily influencing my thoughts for the 1237-Series builds at this time (and one of the reasons I built this 1259.2-Cb3 at this time). I ran the 1259.2-Cd3 (with the 1050B S-NN) to second place, three laps behind first place DZ who ran a class record 304 laps (!). More significantly for me, I drove “conservatively” (mediocrity being my normal driving capability) turning those 301 laps, which were also better than the previous class record of 300 laps, and a whopping six laps (!) better than my previous best (295), a notable improvement. A monkey could have driven the thing. Now the monkey needs to do more building and testing, and figure out why…


Also influencing my thinking, the 1254.2-Cd3-NN has returned to “The Other Left Coast” after its sojourn to “The Big Left Coast” where it went through trials on the BPR Flat track and King under the expert auspices of Bryan Warmack. The info Bryan was able to garner for me was enlightening, to say the least, and saved me a boat-load of gas money making the drive to SoCal to do it myself (which, along with a lot of other raceways, is something I’d love to do…). It definitely has me thinking about various possible design elements, options, and alterations. Way cool. Thanks Bryan!




Who knows… I’m still mulling over the possibilities… Stay tuned… same Bat-time, same Bat-channel…


Rick / CMF3


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#85 Rick Moore

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Posted 18 April 2019 - 11:16 AM



Get the meds out, this is about to get even more confusing…


The 1265-series, another sub-series in the 1237-Series, which includes the 1265, 1266, and 1267 designs, are adaptations of the original 1237 concept using a single center main rail with lateral articulated buttress rails, where the articulations of the buttress rails are gone, instead being solid soldered frame junctions, and structurally making the 1265-series chassis have three main rails. Based on Bryan Warmack’s testing of the 1254.2-Cd3-NN on the Gerding King track at BPR, there was a desire to build frames with greater rotational stiffness, and this was the obvious way to move in that direction. The 1265-series chassis were created to fill a gap in the design progression that was about to occur with the proposed building of the “.9.” versions of the 1262-series frames (which will also be non-articulated and having a five main rail structure; more on that if-and-when I get there...).


The 1265-series chassis are still based off the original three base designs for rear assembly and main rail length, where the 1265 is based on the 1241, the 1266 is based on the 1254, and the 1267 is based on the 1259. I decided the first to be built would be the 1267, having a main rail length in-between the longer 1265 and shorter 1266, figuring any desire to move toward more or less rotational stiffness could be ascertained and accomplished better from this starting point.


Another bit of weirdness in the thought process was to start the 1265-series builds with short “b” dimensioned chassis, the thinking being the “b” frames are inherently, if only negligibly, stiffer to begin with; that, and the testing of the 1259.2-Cb3 also had me thinking along those lines.


The 1265-series chassis, as was established early in the 1237-Series for all chassis, will still be framed using 0.032” wire… Some might point out that using thicker wire for the framing, and/or using more wires in each of the rails would be the easy way to make a “stiffer” chassis. While this is true, it would not be in keeping with my intentions for the 1237-Series design and build progression. The desire is to incorporate changes through adaptation of the chassis design, as opposed to just using “heavier” wire.


And that, long-suffering readers, is how I wound up with the 1267.2-Cb3:















Besides the elimination of the buttress articulations transforming them into main rails, the 1265-series chassis, as evidenced here with the 1267.2-Cb3, have much less movement of the “side pans”; all previous incarnations in the 1237-series use side pan restrictors that are 0.055” wire in 1/8” square tube, while the 1265-series chassis are 0.055” wire in 3/32” square tube.


The total mass came up to 99.2 grams, canine flatulence, and with additional ballast on the dynamic pans was brought up to 100.0 grams. 


Test Run:


The big problem at this time for the 1267.2-Cb3 is track testing.


There is just no way to accurately determine if this chassis will be any good on a Gerding King by testing it on an Oglivie Hillclimb; in this case a very fast Hillclimb it is, but it does not impart forces on the chassis anything approaching those that it would experience on a King that would have a much greater degree of banking in the turns (all of them) to properly analyze the chassis dynamics.


However, I do have the 1254.2-Cd3-NN in its last set-up Bryan used on it for the BPR Gerding King, so the thought was I might be able to some extent compare the handling characteristics of the 1254.2-Cd3-NN relative to the 1267.2-Cb3; however for that comparison I would also have to take into consideration the former is SCRRA legal while the latter is IRRA legal.


So, using the 1254.2-Cd3-NN as my baseline, the 1267.2-Cb3 exhibited the same handling characteristics and performed as predicted. That’ll do for me… for now…


Okay, “now” is over. Time to get to “next”.




Rick / CMF3


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#86 Rick Moore

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Posted 15 May 2019 - 11:42 PM



There are a lot of “stiff” jokes that could be made here, ranging from drinks to corpses to anatomical protuberances, but I’ll forego the temptation and just say that this is another “stiff” chassis.


As was the initial intention of the 1262-series, I wanted to explore the changes to chassis dynamics of the same design(s) in the sub-series by changing various framing combinations of the six intersections of the five main/buttress rails, the “VIV” layout, as either solid-soldered junctions (main rails) or articulated junctions (buttress rails). For any one of the three (current) designs within the 1262-series there are nine possible symmetric configurations (also a tenth still in the design concept phase, and seventeen more asymmetric configurations). The initial 1262-series builds were “.1.” versions, which have the fewest solid soldered junctions, with four articulations for the lateral V-rails and two solid junctures for the single center main rail, By contrast, the “.9.” version has no articulated junctions, basically making the “.9.” version a 5-rail “VIV” main rail frame. For that reason I decided to build a “.9.” version to compare against the previous “.1.” version, as they should show the greatest difference in chassis dynamics and handling characteristics.


This build also comes after the first build of the 1265-series, the 1267.2-Cb3. The 1265-series chassis are intermediary designs, all non-articulated, essentially tri-rail “/ I \” main rail frames, as opposed to the penta-rail “VIV” main rail of the 1262-series “.9.” version.


The nagging question was which 1262-series design, 1262, 1263, or 1264, to build first in the “.9.” configuration. There were good reasons for each. The 1263 design would make the stiffest chassis because it has the shortest main/buttress rails, an “omega” data point. The 1262 design, having the longest main/buttress rails, would make the least stiff chassis, but would effectively demonstrate greater characteristic differences between the sub-series’ configuration versions. The 1264, with the main/buttress rails of intermediate length, would allow for a compromise between the 1262 and 1263 options, and be a good point from which to determine if slightly more and/or less rotational stiffness should be explored (along with other ensuing configurations). Decisions… decisions…


I’ll assume no one’s head has exploded at this point, though some of you may just be staring at the screen transfixed and having no idea what you just read. Snap out of it, throw some cold water in your face, and look at the pics.


Let’s just say, after one recent Wednesday evening of test runs at Fast Eddie’s Raceway, I smashed the proverbial rearview mirrors, put on the blindfold and threw a mental dart to make an executive WAG, and opted for the 1262.


The 1262.9.2-Cd3:













Okay, maybe the pics don’t make things any better. Even I still think these 1262-series things are weird looking.


The 1262.9.2-Cd3 was set up with two body options, the Parma Ti-22 narrow nose (1043B), and the Parma Lola T163 (1036B) for which there is some renewed interest and I just happened to have one still around from back when I was using them. After the mandatory mathematical WAG, then trimming and soldering on the add-on pans, which added about 3.0 grams to the chassis mass, depending on combinations of the runny-bits and body, the RTR car came out to having a range of 99.8 to 100.8 grams (compared to the 1262.1.2 at 100.4 grams, and the previous “stiffy chassis 1267.2-Cb3 at 100.0 grams)…


Test Run:


Not really. The “.9.” has much more rotational stiffness than “.1.” version of the 1262. I just gave the 1262.9.2-Cd3 a quick run of about twenty laps on the Hillclimb at Fast Eddie’s to see if it ran as I expected, in particular versus the 1262.1.2-Cd3. It did. Tore it down, reset it, and sent it to join the 1267.2-Cb3 on vacation. That’s that. At least for now.


But even after those laps it got me real curious about building an intermediate version. I’m thinking the “.6.” right about now. We’ll see. More later. Try to contain your excitement.


The fun never ends…


Rick / CMF3


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#87 Bill from NH

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Posted 16 May 2019 - 07:57 AM

Rick, did you catch the recent post that there was a king track moving to the Tampa area? I forget where I saw it, but there was no who, when, or where info posted. If I come across it again, I'll post it here.



It was a Jeff Chamber's May 14th post on here. "This track has been sold going to Tampa Florida bill and his wife are opening a brand new store we wish them success!! "

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#88 Rotorranch


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Posted 16 May 2019 - 10:21 AM

Rick, did you catch the recent post that there was a king track moving to the Tampa area? I forget where I saw it, but there was no who, when, or where info posted. If I come across it again, I'll post it here.



It was a Jeff Chamber's May 14th post on here. "This track has been sold going to Tampa Florida bill and his wife are opening a brand new store we wish them success!! "


Nope, it wasn't me!


It was Jeff Chalmers.



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#89 Rick Moore

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Posted 16 May 2019 - 12:50 PM

Hey Bill! No, I’d missed that one. Thanks for the heads-up! Looks like a nice track. That post was two days ago; I’m a bit slow on the uptake. Didn’t hear any word of it last night at Fast Eddie’s, but I’m sure all the FL slot car geeks will be listening for this one. Should make some of these guys happy to get a King in FL again; it’s been a few years. I wonder if when they say “Tampa” they mean Tampa, Hillsborough county, or Tampa Bay area. Hasn’t been a slot car raceway down here in Tampatown proper for a really long time (I doubt it would be in my immediate stomping ground, South Tampa, $’s too beaucoup…). But, hey, this is FL; an hour drive is “in the neighborhood”. I guess time will tell if, who, where, and when. Cool beans!

#90 Rick Moore

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Posted 26 June 2019 - 10:01 PM



Back at it, and here we go again…


A rethink led me to consider another back-track to build another short “b” dimensioned chassis, this time a 1254.


The last short-frame 1259.2-Cb3 was initially thought to be something I could use as another “test mule”, with the current mule being the 1241-Cb3, but that turned out not to be the case, not by a long shot, as the 1259.2-Cb3 will rocket around the Hillclimb at Fast Eddie’s even better than the ”c” and “d” 1259’s, and that’s quite an accomplishment for which I can affirm any contribution by my part was purely accidental. I’ve run the 1259.2-Cb3 in a variety of track conditions, from freshly cleaned/glued to heavy rubber, and like the 1241-Cb3, the 1259.2-Cb3 has been extremely consistent regardless. At some point I had to make the WAG there just might be something going on with these “b” dimensioned cars, or not, but in either case it warranted building another “b” chassis…


Since I already have “c”, “d”, and “b” versions of the 1241 and the 1259 I decided to complete the triple trifecta by adding a “b” build to the current “c” and “d” versions of the 1254. As noted previously, the major difference between the 1241’s, the 1259’s, and the 1254’s is the relative length of the single center main rail, with the 1241’s having the longest, the 1254’s having the shortest, and the 1259’s mid-way between.


The 1254.2-Cb3:













More of the same, just different. Like the other two active 1241 and 1259 “b” cars, this one also got topped off with a Parma Ti-22 Short Narrow-Nose body (1050-B). The total RTR mass came up to 98.1 grams before the mandatory banal ballast was added to meet the apocryphal 100-g minimum, bringing it to 100.2 grams.


As a matter of bringing the one or two of you still following this thread up-to-date, with the addition of the 1254.2-Cb3, the current active CanAm stable is now twenty cars… which even I admit is a ridiculous number of cars no matter how you try to spin it, especially for one class (not to mention trying to keep motors and tires going for this many cars…). The present roster of active CanAms: 1241-Cb3; 1241-Cc3; 1241-Cd3; 1241-Cd3/2; 1241-Cd3/3; 1250-Cc3; 1251-Cc3; 1254.2-Cc3; 1254.2-Cd3; 1255.2-Cc3; 1256.2-Cc3; 1256.2-Cd3; 1257.2-Cc3; 1259.2-Cb3; 1259.2-Cc3; 1259.2-Cd3; 1262.1.2-Cd3; 1263.1.2-Cd3; 1264.1.2-Cd3, and now the new 1254.2-Cb3. As I said, ridiculous. Testing has become a rather regimented and lengthy affair, but, considering the levels of performance and test information I’m getting, I’m not complaining.


Test Run:


For this evening’s test-n-tune run the more focused comparisons here are, of course, the 1254.2-Cb3 versus the other two 1254’s, the 1254.2-Cc3 and 1254.2-Cd3, and also in relation to the other two “b” frames, the 1241-Cb3 and (notably) the 1259.2-Cb3.


First off, I probably put the wrong motor in this car for a first test run, as the motor had noticeably less brakes than the others tonight, but rather than change it I decided to see how it would handle it anyway. Not bad at all was the verdict in that regard. Despite this, the 1254.2-Cb3 was the fastest car on Black this evening, not so surprising since the 1254’s in general are good Black lane cars, but somewhat surprising considering the lack of braking going into the Lead-On and the Dead Man. On Orange and Red it ran easily with times comparable of the best as well (it was a tight spread tonight). As for handling characteristics, I was happy to find the 1254.2-Cb3 was to the 1254’s what the 1259.2-Cb3 is to the 1259’s. And as for the “b” cars in general, I know it is common anecdotal wisdom that shorter wheelbase cars are “fast but harder to drive”, but for all three it seems the fast part is true, but they’re easily as forgiving to drive on the Hillclimb as any of the other cars, if not more so. Just goes to show you, you never know until you build it. The new 1254.2-Cb3 and not-as-new 1259.2-Cb3 are both top-tier performing cars, which is making me think I should do some set-up work on the 1241-Cb3 instead of just keeping it constant as my “test mule”…


More stuff to test. More stuff to build. Later, Gators.


Rick / CMF3

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#91 Eddie Fleming

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Posted 27 June 2019 - 06:58 AM

Rick call me crazy  :crazy:  for trying to half follow some of this, but would you refresh me on the measurements of the A's B's and C's and all that.

Eddie Fleming

#92 Rick Moore

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Posted 27 June 2019 - 07:43 AM

Hey, Eddie! No problem. An abridged long-to-short list of CMF3 chassis designations, in inches, for:


        WB  /  RAX-GPC  /  GL


a =   4.000  /  5.000  /  1.000

e =   3.875  /  5.000  /  1.125

c =   3.875  /  4.875  /  1.000

d =   3.750  /  4.875  /  1.125

b =   3.750  /  4.750  /  1.000


There are a bunch more, but for comparison purposes I just keep to these basic numbers…


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#93 Rick Moore

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Posted 24 July 2019 - 10:46 PM



Time for the next installment of the 1262’s.


The 1262.1.2-Cd3, the “flexiest” version, is an excellent car on the Hillclimb at Fast Eddie’s. By contrast the 1262.9.2-Cd3, the “stiffest” version, is much more suited to the “punch-bowl” Gerding King tracks, and even made a showing at the Retropalooza at Port Jeff this year driven by Jeff Bonanno (thanks Jeff!). I have driven the 1262.9.2-Cd3 on the Hillclimb, and I can say it is definitely not a good choice for this track, and I can pretty easily imagine the 1262.1.2-Cd3 would have been equally lacking to be run on the Gerding King. Sure, you could probably get them to work, but that’s not what the comparison of different versions of this design is about, but instead to examine the relative aspects of the handling characteristics inherent to the chassis. The idea now is build an intermediate version of the 1262 design, do the test runs and see more precisely how it compares to those two more “extreme” alpha-omega versions.


I decided previously to build the various versions using the 1262, instead of the 1263 and 1264, largely because after testing all of them I made the WAG that differences between the versions would be more noticeable on the 1262, possibly due to its having the longest center main rail of the three designs.


So you don’t have to torture yourself scrolling back through this miasma of a thread to find the info, a quick refresher on the 1262-series frames: The main (solid, or non-articulated) and/or buttress (articulated) rail system can be visualized as a “VIV”, with the top and the bottom of those letters representing forward and rearward on the frame respectively. There are a total of six connection points, three forward and three rearward.


On the 1262’s six connection points of the “VIV” rail system:

a) the 1262.1.2-Cd3 has a total of four articulations at the lateral-fore and rear “V”s, with a solid soldered “I“ center main rail (including the medial-fore points of the “V”s);

b) the 1262.9.2-Cd3 has all six connection points solid soldered and no articulations;

c) the 1262.6.2-Cd3, this build, has all three forward connection points and the rear center main rail solid soldered, and only two articulations at the rear of the “V”s

(And if that doesn’t make your head spin, consider that, besides the three I’ve listed so far, there are six more possible symmetric versions I can make… you don’t want to know how many asymmetric versions there are…)


Without further ado (or a-doo-doo), the 1262.6.2-Cd3:

















No matter how many of these things I build, they still look weird. Of course, that is probably one reason why I enjoy building them.


Pre-minimum RTR mass estimated about 96.0 grams… so after the add-on pans were secured in place the assembled 1262.6.2-Cd3 car came to 100.3 grams. (I was aiming for 100.4, so I might be getting better at this… knock on wood…)


Holding the three 1262’s in your hands it is easy to see and feel the chassis differences. Cheap thrills. I need to get a life. Anyway, all that doesn’t matter squat until you put them on the track.


Had to skip a week going to Fast Eddie’s while recovering from the dentist ripping what was left of one of my “wisdom” teeth out of my jaw, always a fun time, an event I had been putting off for too long. And last week was the Test-N-Tune Wednesday just prior to the GRRR races this past weekend, which due to work scheduling at the hospital I was unable to get the weekend off from work to attend. I thought as a matter of courtesy and pain medication it would be best if I just stayed home and out of the way of all the other slot car geeks.


(After that work scheduling cluster I made sure with my super I definitely get the weekend of Sep 28-29 off so I can attend the 2nd annual Southern Retro Rumble at Fast Eddie’s. Last year’s inaugural SRR was a blast and crazy fast. Ed Hoffman put on a great event, no surprise there, and this year promises more of the same. If you can get the chance, and you know you want to, make the trip on down to “The Other West Coast” in FL, hang out with some of the Sunshine State’s wild, or some older and not-so-wild-anymore, creatures, and join the festivities and fun!)


Test Run:


A day late and a dollar short… actually a week late and a dentist bill / tooth short…


It really only matters how the 1262.6.2-Cd3 can run on the Hillclimb versus the 1262.1.2-Cd3…


The 1262.1.2-Cd3, my point of reference, and to update the few of you still following all this nonsense, is consistently one of the better CanAm cars in the Team CMF3 stable, running right along with any of the other current fastest cars / set-ups. With a couple months and lots of laps it has become apparent the 1262.1 is a different animal when it comes to driving/handling characteristics. It never really looks like it is going that fast; rather deceptively it just kind of looks like it “lopes” around the track. It will also make up for a lot of brain-to-finger mistakes, as there have been countless times I was sure it was coming out of the slot, but it just kept on going, albeit with a little slower lap time. By contrast, if the 1262.1 “lopes”, then the 1262.9 “snaps” and is a handful to drive on the Hillclimb, as it should be, requiring the exact right set-up and your constant attention while driving to hit your marks…


The thought was, and best case scenario would be that the 1262.6 would keep the forgiving stealth-fast qualities of the 1262.1 while acquiring some of the edgier quickness of the 1262.9…


And that is exactly what it did. Lap times for the 1262.6 were right there with the 1262.1, a little quicker, and both dropping into the upper 4.4’s on Orange with test motors, the 1262.6 running the fastest time for that motor. The same was true on the gutters, Red and Black, which surprised me as I was thinking the 1262.6 might give up a little on the gutters, but that was not the case. Not bad at all…


More testing to come, of course. As for what’s next with the 1262 Sub-series chassis, there’s a lot to consider… Maybe another version (I’m thinking a “5”, or…), or maybe a shorter “b” dimensioned 1262 chassis, or maybe…


You never know where you’re going till you get there. Enjoy the ride!


Rick / CMF3


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#94 Rick Moore

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Posted 24 July 2019 - 10:53 PM





It’s been a while; it was time for a Stock Car chassis build. That weekend off from work (not the one for the GRRR races I wanted, but still nice to have the time off) allowed me to get into a second chassis right after building the CanAm 1262.6.2-Cd3, so I cranked out this 1259.23-D3o Stock Car chassis in the CMF3 Skunkworks…


After building the 1254.23-D3o LTO Stock Car chassis, which seems like a million years ago but was only just back in March, and comparing it to the 1244-D3o, it was no surprise it became a “necessity” to build the dimensionally intermediate 1259.23-D3o. And if it falls into place for the Lefty-Stockers as the 1259’s have in the CanAm cousins, it will be a welcome addition, as well as giving that “same” triple-option of chassis between the 1244 (ex 1241), 1254, and 1259 for the LTO Stockers.


Again, without further, or much, ado (a lot of that ado around here tonight; watch where you step), the 1259.23-D3o:















No big surprise on this, as the 1259.23-D3o looks like a slightly shrunken rear assembly / somewhat elongated center main rail version of the 1254.23-D3o. The predictability of building a design series, which is much more fun for me than all you poor suffering readers.


(I included the RTR pics of this 1259.23-D3o and the previous build/post 1262.6.2-Cd3 just to add a little “color” to the pics for a change, or maybe I was just bored or something; please try to contain your excitement…)


Test run:


On the previous Stock Car builds I would test the car at its less-than-120-gram out-of-the-box ready-to-run weight, then add the lead to make the 120-minimum and run again… Having already done this on previous Stock Car chassis, and particularly the 1244-D3o and 1254.23-D3o, I assumed there was no need to do this on the 1259.23-D3o and added the pre-cut lead right off; the pre-lead car mass was 112.7 grams, and the post-leaded car is now 121.1 grams.


The 1259.23-D3o ran just as it was supposed to, with a test motor hitting mid-lane 3.5’s on the Oval on its first set of runs; ran Black and Red just fine too. Handles every bit as good as the other two…


So that gives me the three LTO Stock Cars I wanted, the 1244-D3o, the 1254.23-D3o, and now the 1259.23-D3o.


With all the CanAm’s and the Stock Cars I ran tonight, that was a lot of test laps… And plenty more to come.


Think I’ll build another slot car chassis while I’m at it.


What a long strange trip it’s been.


Rick / CMF3


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#95 brnursebmt


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Posted 25 July 2019 - 09:16 AM

Awesome build, Rick.  Look forward to seeing you in September!

Bobby Robinson RN

"Nobody rides for free." - Jackson Browne, 1980

#96 Rick Moore

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Posted 14 August 2019 - 09:16 PM



I haven’t built a GTC for about a year-and-a-half, and haven’t even thought about them since the Southern Retro Rumble last year. Then, very late one night on break at work I got the idea to build another purpose-built GT Coupe class chassis using the 1262 design. Like most things one might think of around 3 AM, anyone with any inkling of intelligence (and/or not drunk) would probably engage in some strong reconsideration before acting out on “good” ideas one might conjure up at that ungodly hour… So, that rules me out…


I mentioned on the post for the previous purpose-built GTC chassis, the 1241a-Cd3, how much I do not look forward to tacking on slabs of lead to a chassis, for pretty much any reason, much less solely to get it up to the 110-gram minimum weight for the GT Coupe class… I can report nothing has changed my opinion in this regard, and we’ll leave it at that… anyway…


In my wee-hour epiphany, what I wanted was to get the handling characteristics of the 1262.1.2-Cd3 CanAm into a GTC car; as noted previously, the 1262.1.2-Cd3, as I can best describe it, sort of “lopes” around the track, never looking like it is going fast while cranking out quick laps, and at the same time making up for a lot of brain-farts as well. Definitely a car suited to my masterfully mediocre driving abilities. The idea for this class-dedicated GTC chassis was to use that “.1” version of the 1262 frame, also keeping it in the “d” dimensions of the previous CanAm class chassis builds and still framed in 0.032” wire, but, instead of using “small” add-on pans as on the CanAm chassis (to get to the CanAm 100-gram minimum) I would incorporate “full” add-on pans filling the space between those same chassis rails to get the weight to…


My mathematical guess was it would hit about 108 – 109 grams, which would still be a gram or two shy, but that’s not so bad when I consider some of the CanAm’s I’ve built in the 1237-Series have been more than that below their minimum, so, what the heck, at least it should be in the ballpark…


The 1262.1.2a-Cd3:















The 1262.1.2a-Cd3 doesn’t look any less weird with those bigger pans…


As you can see, the GTC chassis is the same as the CanAm chassis with the exception of the significantly larger add-on pans between the lateral buttress rails and the side pan rails. Additionally, I made two changes to the runny-bits from my previous GTC’s:

1) Instead of the JK fronts I typically use on my GTC’s and CanAm’s, I opted for a set of the very nice Samson Classics ball-bearing fronts I had laying around here; the Samson-bb’s weigh about two grams more than the JK’s (including the collars, axle spacers and solder I use), but on the GTC, where I need the extra mass anyway, I figured it was worth a try; and I can always change them easy enough if some reason should arise, though I doubted that would be the case;

2) And, as a matter of aesthetics more than anything else, I also opted to top this car off with the Red Fox Chevron B16 body (RFD341C), instead of the Parma Lola T70 Coupe (1039B) I’d used previously, or the very similar Red Fox Lola T70 MK3B (RFD340C); I was happy to see the RF Chevron would fit my frames without any alterations to the front wings (as had been the case in the past with the OS Chevron), so all three of these bodies are interchangeable on my chassis, and I can even use the same “sissy bar” for them…


(And if I get ambitious later I can always do comparison tests of these three GTC bodies as well, like I’m doing on the RF Charger RT for Stock Cars, and the RTR McKee MK-14J on the CanAm’s, but for now…)


All put together the car came out to 109.3 grams, so when I factor in the Samson fronts, it meant my math had been a little higher than actual. Still, close, but no cigar. I decided to hold off adding the (expletive omitted) lead until I got some baseline laps with the car, and then decide how to go from there…


Test Run:


Obviously the 1262.1.2a-Cd3 will be compared to the other purpose-built GTC, the 1241a-Cd3, but I was really curious how it would compare to the almost identical 1262.1.2-Cd3 CanAm class car/chassis, so much so I considered mounting a CanAm body on the GTC car for better comparison… but not this time… I got lazy… Still, I definitely wanted to see how much of the desired driving/handling characteristics of the 1241.1.2-Cd3 CanAm carried over into the heavier 1262.1.2a-Cd3 GT Coupe… Picking a pony for the 1262.1 GTC was easy enough as I used one I already had data for the 1262.1 CanAm…


First test run was abbreviated (wing guys practicing for races this Saturday, and track was just rubbering in after being cleaned), but sufficient to see this chassis was headed in the right direction. The 1241a-Cd3 GTC always drove like a heavy 1241-Cd3 CanAm, but this was very much less the case with the 1262.1.2a-Cd3 GTC relative to its 1262.1.2-Cd3 CanAm counterpart, as the extra mass (we’re talking about 10% more, which is a fair chunk) was nowhere near as evident. Good. That’s what I was looking for. I’ll get a better assessment with additional test runs, but all-in-all it looks promising (knock on wood).


At least that gives me another GTC option heading toward the Southern Retro Rumble at Fast Eddie’s on September 28 & 29. At some point I’ve got to blow the dust off my F1’s and try getting them set up for the Oval (instead of the Hillclimb), which ought to be crazy fun. I’ve got some new F1 designs that have been hanging around here for some time now… And I’ve got another idea for a GTC… And there’s another Stock Car chassis I want to build… And…


So many chassis… so little time…


Rick / CMF3

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