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Exploring the tuning fork idea...


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#1 JimF

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Posted 11 May 2013 - 02:52 PM

I have some bits and pieces and a nice R-Geo kit to use in building a tuning fork chassis. Problem is.........I don't really know what it does. After looking at the various pictures and reading postings regarding the tuning fork......I still don't know enough. I had a general idea of what the concept does of course but just not enough to go on for a serious build attempt. Sooooo..........I took some bits and built one figuring to just slap it on the track and see. I didn't take a lot of time or effort for a super sano build and I didn't use up any of my favorite components, because I think I'll be hacking and slashing on this thing.

 

This frame was built up with a pair of forks in .062 supplied by 'R-Geo' Rick. The rest is an old JK nosepiece, JK bracket and 1/4" X .062 pans.

 

Some details:

  • Forks twist freely in the 3/32 tubing bits. Thus, nothing is holding the front and back halves together.
  • To tie the ends together without changing the character of the fork concept, I added secondary rails of .039 wire.
  • Pans are hung on a bit of .032 wire and form a fixed plumber arrangement.
  • At the mid-rear, there is a bit of 3/32 soldered only to the fork rail. A bit of .047 goes into this to form an up/down stop.
  • The longitudinal flex is more or less as one would expect but the torsion is ridiculously soft.
  • This car is stoopid-light @ 84 gr as shown.

63dd981a-f665-42f0-bc47-2e79b47a4eb2_zps

 

1ac9c16b-107e-4192-9168-464b34a4496c_zps

 

 

Here is how the car will get tested today with weight added as shown to hit 96 gr. Still really light for me.

 

148f6635-06e3-477c-a86d-ed0277a5013c_zps

 

Development thoughts:

 

 

  • Actually, my first thought is that this car won't work at all......but a lot of good builders are using the concept so.......????
  • Brass weights are soldered to the center forks. No effort was made to create any 'suspension' system for the weights.
  • The extreme torsional flex may make the car really tippy and 'bitey'
  • The torsion can be stiffened by soldering the forks into the tubes or tying the fork to outer rails in various locations.
  • The outer rails could also be made of larger gauge wire (like .055)
  • I'll be testing today @ Fast Track Hobbies and this is always a mixed bag due to highly variable conditions.

 


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#2 SlotStox#53

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Posted 11 May 2013 - 03:06 PM

Whether first attempts building & exploring tuning fork chassis or not it looks a class build!

One very clean & sharp looking F1, hope the test goes well & answers some of your questions/concerns . Will definitely look forward to reading your results :)

-Paul

#3 Tim Neja

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Posted 11 May 2013 - 03:14 PM

Take the weights out Jim---be LIGHT and FLEXY!! For some reason--it works!! :)


She's real fine, my 409!!!

#4 MantaRay

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Posted 11 May 2013 - 03:40 PM

Nice Buils as Allways........Did you make and coin the nose piece?


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#5 JimF

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Posted 11 May 2013 - 04:11 PM

Dang.....gonna have to back to work to close up tonight so.....testing is stalled for the moment.

 

 

Timmy.....I hear ya and that's why I built this the way I did for starters.........but 84 gr.? I don't think I could drive an 84 down there let alone up here on our flatter tracks. Still, after some tuning, those weights will drop right right out at the touch of an iron.

 

Ray.....The nosepiece was hacked out of an experimental JK kit build that uhhhh.......didn't work out.


Jim Fowler

#6 Tim Neja

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Posted 11 May 2013 - 04:21 PM

Well Jim---the guys down here are getting 84 gram cars around on the KING track---then it seems we've still gone up to 90 some grams for the flatster!!! The super light--has worked on the King only so far--but who knows?? Obviously the lighter Can Am cars have been going faster too!  So it's inevitable that F-1 is going to move in that direction!! :)  

Nice build Jim!!


She's real fine, my 409!!!

#7 Jim Lange

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Posted 12 May 2013 - 09:59 AM

Don't be afraid of the LIGHT! I have made many nay sayers....Believers!


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#8 Rick

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Posted 12 May 2013 - 10:51 AM

Very intersting, I like the idea for a test. Car should be able to use a harder tire, now to see if it sucks HP or not? I think Jim is correct with changing the propertes with several options, tacking the fork together, torsion wires to pans etc. Can't wait for his test results! The .039 rails should not change the fork characteristics any..................now we wait.


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#9 JimF

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Posted 13 May 2013 - 12:02 AM


Development thoughts:

  • Actually, my first thought is that this car won't work at all......but a lot of good builders are using the concept so.......????

 

 

OkaaaaySoooo......................don't necessarily go with one's first thought.

 

Got some track time today @ Fast Track Hobbies in Citrus Heights. My first laps were done on the fast Purple Angel track. We don't have a target time for F-1s on this track as yet but it's safe to figure 5-6 tenths slower than a good Can Am and a standard fast time for a very good Can Am is ~~ 5.0 so I'm targeting 5.6 as good and 5.5 as really good. Today, my F-1 that has won on the King @ Eddies the last two time out was @ 5.58 ....so that's a fair guess. Track conditions were poor as even the normally fast orange lane was slick and maybe a tenth or two off.

 

  • Started as shown in the OP with weight in place and Alpha Wonder rubber. Car was loose but reasonably stable and easy. Time was a 5.78 best.
  • Went through the tire options and ended up with JK 8713 untreated. At this point, the car was running a 5.55 best and felt quite forgiving. Still a touch loose and maybe a small amount of wheel hop on turn exit.
  • First modification was to solder a small 3/32 tube bridging the front part of the fork rails (blue arrow). This didn't do much either way. Still easy, maybe a tad less wheel hop.

 

 

79337790-5ec1-4e70-a2fe-26705da58f51_zps

 

  • Solder joint on the short tube cracked pretty quick so a second tube was added at the location of the red arrow. Again......not much different.
  • Almost immediately, I dropped all the weights as shown here. Now the car was running a best of 5.47 and was still forgiving. By this point, I'm pretty surprised.

 

1dd39704-a70c-45b1-91c4-91317024f13a_zps

 

  • Next step was over to the flat track, change the 9-27 for a 9-30 and add back all the weights. Target time would normally be 4.95 but my regular cars weren't that fast today.
  • Best time was 5.05 and the car was much more forgiving than I thought a 97 gr car would be.
  • Next, I dropped the weights. I expected the car to be really jumpy and it was notably quicker off the corners but not as hard to drive (@ 85 gr) as I thought it would be. Best time was 5.00 and the tradeoff here was not worth it. The heavier car was a better race car.
  • Last step was to solder the forks solid within the front tubes (red arrow below). At this point, the character of the car changed notably. The car was much quicker off the corners but also tippy like I thought it would be from the start.
  • I took it back to the Purple Angel to verify and got a similar feeling.....it drove like a light car.

6251313d-bb44-414d-979e-1559a935b430_zps

 

Conclusions and speculations:

 

  • The tuning fork makes the car softer on turn exit as long as the forks are free within the front tubes.
  • With the forks in this setup, the car does not feel light or tippy or nervous. It is not terribly punchy as I thought it might be.
  • Solder the forks into the tubes and this changes for the worse as the cars exhibits the feel of a car that's too light.
  • I think the fork twisting in the tube softens some of the torque transfer from front to back making the car more forgiving.
  • I think surrounding the fork with more conventional chassis rails might negate some of the effect of the fork. (for example, if I had made the rails on this car say 1X .062 or 2X .055 instead of the 1X .039)
  • I THINK, that I think that a lighter and more flexy chassis could make a good combination that you might normally think wouldn't work. (such as maybe a multi rail can am with far fewer than normal rails (like say 4X .039 + a fork vs. say 7X .039)

Uhhhhh............I THINK!!!


Jim Fowler

#10 John Streisguth

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Posted 13 May 2013 - 05:15 AM

I recently built a tuning fork F1 with 055 center rails (soldered in front and rear) and started with 4 rails of 039 on each side.  It seemed way to flexible torsionally, so I ended up with 6 rails of 039 on each side.  No room for pans anymore so I used an 063 wire on each side as the "pan".  The car works really well on a fast king, not quite as well on a more "standard" king.  I would just add a second 039 rail and uncouple those forks again. 

 

Great seeing your experiments Jim!


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#11 JimF

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Posted 13 May 2013 - 11:00 AM

I will change the rail setup to a 2X .039 or a 1X .047 but there are some other things that I want to try first. For sure, the forks are going to be unsoldered....that didn't seem to offer the effect that I was looking for. I'll finish version 1.2 today. The rail change will be version 1.3 or 1.4.

 

The goal for these experiments isn't necessarily to make this car a final form. Rather, it's to see if I can figger out the effects before transferring the findings to a more finished product.


Jim Fowler

#12 John Streisguth

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Posted 13 May 2013 - 11:02 AM

Absolutely...that's why I like your build reports.  One step at a time to see what does what...very informative!


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#13 MikeC

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Posted 13 May 2013 - 12:01 PM

If you think these reports are thourough, you should see his notebook and note keeping.  :D


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#14 JimF

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Posted 14 May 2013 - 02:20 AM

Version 1.2

 

 

Following up on what I learned from the first test round. Goal for this go was to get a slightly tighter feel without losing the forgiveness of the fork design.

 

I put a bit of .047 wire about 1/2" long between the main fork rail and the .039 secondary rail. This is to place a stopping point for the enormous amount of twist that results from the fork design. Forward of this block, there is still plenty of twist flex.

 

69691984-3c22-4308-bede-83b106a283c7_zps

 

 

All hinges and stops are removed from the pans and they are soldered directly to the .039 frame rail. The .039 rail has so much flex that the pans flex totally separately from the center section.

 

The solder joint between pan and rail stops just forward of where the flex block is (between the arrows). At first, I soldered all the way to the back of the bracket but this stiffened up the entire structure pretty dramatically.

 

f09d2b25-81cc-463a-9773-d7285350a9d6_zps

 

This won't get tested now until Friday or Saturday. The whole structure is now slightly stiffer than the original version and some reinforcement has been added in case I decide to race it this weekend.

 

 

 


Jim Fowler

#15 JimF

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Posted 18 May 2013 - 10:32 AM

OK......quickie update.

 

I ran last night @ TNT raceway in Modesto with the 'Forker'. I'm still shaking my head but no longer a disbeliever. With the configuration shown in the last update above and back to the basic weight of 85 gr (no body) the car was stupid fast on the full tuck hillclimb. It needed no additional weight and the pans soldered to the main rails seemed to eliminate the last bit of pan rattle. On the twisty little Korkscrew road course, it was surprisingly good for an 85 gr. car. In this case it needed weight to settle it down but was pretty good the way it was/is.

 

At this point, I can't wait to build up a test mule in Can Am form and an additional F-1 geared more to flat tracks.

 

Reports in this thread as I get those going.


Jim Fowler

#16 team burrito

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Posted 18 May 2013 - 11:42 AM

You still have to renforce those axle tubes; those will bend for sure in race conditions. Just pointing it out. :blum:


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#17 Duffy

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Posted 18 May 2013 - 11:53 AM

Thanks so much for this narrative. We don't see nearly enough of this sort of analysis & thinking out here in the trenches, and it's where lots of us oughta be in our own race programs.

duf


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#18 SlotStox#53

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Posted 18 May 2013 - 12:32 PM

As Duffy so eloquently put it thanks so much for taking the time and effort to put this much time and description into testing the chassis/ideas.

There really isn't any substitute for doing your own testing such as this.

-Paul

#19 JimF

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Posted 19 May 2013 - 12:44 AM

Thanks guys. I find that doing something like this helps my own thinking about this particular frame concept. I think this is a case where I think the jury is still out. These frames have been in use, some with great success. However, I'm not sure that any of us know precisely what the 'fork' does. I don't know precisely myself but I do know a lot more than I did a couple weeks ago.

 

What I have learned so far will help a lot in trying this concept in other forms such as a Can Am or as a more flat track oriented F-1. I'll be sure to report the ongoing developments as I learn more.


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#20 redbackspyder

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Posted 19 May 2013 - 02:27 AM

Russ, why do you need axle tubes at all ? ? ?  The axle tubes add weight up high, and simple ball bearings with aluminum axle spacers will prevent any bearing blow out.....   Don't take my word for it, check out numerous Retro Chassis in the SCRRA,  ball bearings without axle tubes......


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#21 JimF

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Posted 19 May 2013 - 03:20 AM

FWIW.....Russ didn't build this, I did and I used some sorta "disposable" components such as a JK bracket that needs tubes. (you'll notice BTW that the tubes are very short) The reason was that I sorta thought this wouldn't work and and didn't want to use up one of the "good ones" that I ordered from Bryan which are set up for no tube. I'll probably do the same with the first experimental Can Am as well.


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#22 redbackspyder

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Posted 19 May 2013 - 03:43 AM

Beautiful Chassis Jim, Bryan and I have been running the tuning fork F1's very successfully on our King Track.....I was 2nd TQ at the Checkpoint Cup with mine...


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#23 JimF

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Posted 20 May 2013 - 12:25 AM

Mill, I knew that you have had good results and was really the impetus for me to start this project. I just didn't really "get it" about this chassis concept until I started messing with it a bit. This one won pretty handily today in it's first outing so now I have enough to go for the next few stages.

 

I hope to make it down there for the first Retro race @ the "cave" but not sure yet if it's doable.

 

 


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#24 endbelldrive

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Posted 20 May 2013 - 05:40 PM

Hi Jim, I used to use 3 small pieces of .063 OD tube and a length of .032 piano wire on my old cheap and cheerful tuning fork sidewinder scratchbuilds from the dark ages.  I used the middle tube to tune the dampening effect.  Maybe worth a try?

 

ch_07.jpg

 

ch_chap2g.jpg


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#25 JimF

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Posted 20 May 2013 - 08:59 PM

Bob:

 

Thanks for those pics. This application of the concept would violate the universal interpretation of the "no center hinge" clause that is present in most national rule sets. Your two main forks are offset to either side of the centerline and thus avoid the current rule interpretation. (plus) they aren't hinging in a tube anyway so it would be OK regardless. However, it looks like the 1/32 wire is actually turning within the three tubes and is on the centerline thus, this would be a "center hinge"

 

Honestly, I wouldn't be surprised to see some re-consideration of the current rules interpretation. My design and the ones that I used for guidance (like the Warmacks) are legal by virtue of the center rails not being precisely on the centerline but are actually fractionally offset to either side. I'm not 100% sure either way that this should be legal or not. However, currently it is......and so I'm going to continue to play with it for a while.

 

The car shown in this thread was an easy winner yesterday in it's first race outing. I don't know that it will be a game changer in other applications or not. If it is, then I'm going to have to address the situation as to whether to allow the concept or come up with a ruling to outlaw it. I'm also cognizant of all the national organizations and their interpretations. While I'm a little more restrictive than IRRA in some areas (for example bodies), I do pretty much follow what they and So-Cal do for chassis regs. While the jury will be out for a while, it wouldn't be a total shock that some form of this design might be a game changer and thus, might be something that we want to re-consider vs. the original concept of retro racing.

 

Back to your pic, that gets me brain spinning again. I have a lot to do in experimenting with the F-1s and starting to play with the Can Ams but I hadn't thought far enough ahead to the anglewinders yet. (or geeeze....the 1/32nd) I really like your design there and will likely try to get one similar going before our next coupe race.

 

Thanks for the brain teaser....awsome work as always.


Jim Fowler

#26 Duffy

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Posted 20 May 2013 - 09:45 PM

The other part of the much-discussed "no center hinge" rule that applies to these chassis concerns the part detailing the "connection" between bracket and front pan - and since this F1 sled clearly has that (the outer wires), the rule has been satisfied. Any rotation in the tuning-fork part doesn't constitute a "hinge" since there's a solid join somewhere.

Or so I read it.

This same question came up when TonyP and I started playing around with what we called the "Wallenda" chassis (basically, moving all reaction mass inboard and pinned down at the centerline up on the front pan), but in that case any possible "hinge" was specifically dedicated to actuating the pan or pan periphery, and pan hinges aren't center-section hinges no matter where they are.

Or so other, influential, guys read it.

And that's a valid argument; just like your app here proposes a valid app of the same rule. That may be a simpler interpretation than the one here, but I personally wouldn't think so.

 

We have a rule in place, concerning the limits of motion in a chassis. Like any good rules set, there will be discussion that nibbles about the edges of the wording of the rule, and there will be decisions on that discussion. This is what makes for a healthy organization.

And, like any discussion, there'll be considered opinions regarding the wording.

So my lead-off line is not the decision: it's the amicus curiae brief.

 

Duf


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#27 Rick

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Posted 20 May 2013 - 09:50 PM

Goobly-Goop! The rules say: " no centerline hinges".....................Period.

 

You and Tony can spin it any way you like, it's illegal and has been since day one. But rules are made to be broken and revised........................................


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#28 Duffy

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Posted 20 May 2013 - 09:51 PM

Ohhh, Goobly-Goop yourself.


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#29 JimF

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Posted 20 May 2013 - 10:04 PM

Duff and Rick:

 

I know that mine fits the rules as they are written and currently interpreted everywhere. No questions there (from me at least). My own question or concern is whether or not these rules should be written and interpreted the way they are. I'm just not sure.

 

I am sure that this car ran exceptionally well. Like really well. Not too many different chassis concepts that I've tried (and that's been a few) really did anything notable.....this one did. Again, I'm not sure whether the concept will play in other classes (Can Am) or on flat tracks, or even on other classes such as Stock Cars or 1/32 anglewinders (whatever). If the results come similar, then it seems that maybe it's not the best idea in the world given the original concept of retro.

 

As I said earlier, my Jury is out and I'm not advocating either way.....just aware that the genie may be pushing at the cork.


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#30 Rick

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Posted 20 May 2013 - 10:55 PM

Jim,

 

What you built is totally legal by any rules set I have read. This is a new system you are exploring now. It seems to be working from the first chassis down this road. I guess if it is a game changer, which I don't believe it will be, that is something to deal with down the road. I never understood from back in 2006, why a center hinge should be banned???! I always figured if it was the bees knees, we could all use it. But the powers to be kept the rules as written, until...........................:)

 

IMO, there will be a fine line between being better and not. I am just going by what my brain says back to me when thinking about the tuning fork deal. I think, it keeps the rear tires planted on the track with no real lifting, WHEN IT IS CORRECT, but too little stiffness or too much stiffness will negate any of this. Did you stumble into a great combination of wire size and torsional Rotation that is just right or ?????????????? You have a pair of .062 tuning fork rails also, so that will prove to be informative how they work too, ......................down the road. I think there will be a very critical tuning feature in where one would put a solder joint on the wires leading into the tubes or where you solder solid the wires where they meet the motor box. This all remains to be tested and seen.......................


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#31 endbelldrive

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Posted 21 May 2013 - 04:25 AM

Technically it's not a center hinge because the three tubes are soldered up solid with the middle tube soldered in the "sweet spot" that stiffens the frame lengthwise without affecting twisting and rolling action.   I guess it could be seen to violate the spirit of the original rules because it was designed to be wire and brass equivalent of the 1990's Eurosport chassis which was an improvement over the 1980's center hinge.

 

I think we're building chassis that are far superior to the standard center hinge concept anyway.  Solder on, gentlemen! :)


Bob Suzuki

#32 JimF

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Posted 21 May 2013 - 11:46 AM

Jim,

 

 Did you stumble into a great combination of wire size and torsional Rotation that is just right or ?????????????? You have a pair of .062 tuning fork rails also, so that will prove to be informative how they work too, ......................down the road. I think there will be a very critical tuning feature in where one would put a solder joint on the wires leading into the tubes or where you solder solid the wires where they meet the motor box. This all remains to be tested and seen.......................

 

Rick:

 

Good points. This one is the .062 fork set that you made up for me. After this, I'm scratching my head about .055. Right now, I can't see the need for more twist flex than this. I do think that the outer frame rail (1 X .039) in this case, can be a major factor here. The first Can Am example will use 1 X .047 and the next F-1 which will be aimed at flat tracks may as well.

 

In the very first go round, I did exactly what you suggested with a joint to bind the front pair right before going into the tubes and also one right where the fork squares out to form the box. I didn't make the joints very long in either case but they didn't seem to do much. That's very easy to do....then undo....then re-do again so I think you're right, it's a valuable tuning feature. I also like the potential for tuning via the suggestion from Bob in the old anglewinder shown in his post above.


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#33 JimF

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Posted 04 June 2013 - 03:25 PM

Continuing the theme of developing the tuning fork F-1, I did extensive testing @  "The Cave" raceway in So-Cal over last weekend. This is a club type setup but with an absolutely top notch commercial flat track in a semi-private setting. This is one of the more technical flat tracks in Kalifornia and has been prepped with GT-12/Eurosports in mind. As such, tuning of retro cars was a setup challenge.

 

In short, the last iteration of the TF F-1 was very very good throughout the testing process. I had to add lead and brass at every available location in order to help with driveability but even so....the car was less than 110 gr. All through the testing process, this car was really fast and should have been a contender to win the inaugural race on Saturday.

 

However, this weekend showed the fatal flaw in the 1.0-1.3 versions.......it can't take a major hit.

 

I had a controller malfunction and that led to a full speed wall blast right as practice closed. I pulled the car off, went back to my pit and started work on the controller. I didn't notice the damage and so I qualified with a severely dinged car (and a funky controller). Another racer noticed how different the car was in qualifying and pointed out to me how wrecked the car was. Long story short, I raced something else that I threw together at the last minute and did so with a poorly performing controller and basically got what I deserved. Fortunately the Can Am race turned out better.

 

So.....what I've learned so far........

 

  • The tuning fork as I built mine is drastically softer in twist flex than others I've seen.
  • This frame works on high speed tracks as well as flatsters given weight and tire tuning.
  • The single .039 frame rail does not offer enough support for the structure and a hard hit is the end of it.

 

So......what I want is to maintain the very soft twist flex while beefing up the strength of the overall frame.

 

  • I think that the main frame rail has to be stronger than the 1x.039.
  • I think that surrounding the fork with conventional frame rails will negate the effect of the fork.
  • Thus......1x.062 or 2x.055 might take the fork out of play.
  • Next car may be a 1x .047, 1x .055 or 2x .039 mail rail frame.

 

The next version will be Tuning Fork 2.0 and will be started up in a new thread.


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#34 redbackspyder

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Posted 05 June 2013 - 12:39 AM

Jim, after the last King Track race, where I TQ'ed with my Warmack Tuning Fork @ 4.14, and then finished second to Duran, the new mods that Bryan made definitely made it the fastest car on the track...  I threw away the race myself, but I had a faster car than even Duran, and the car handled much differently, especially taking away the slight bruppp that it used to do on the lead on... Give Bryan a call, he can tell you the mods that he did, but it drastically changed the dynamic of the car, and my car can easily withstand a hit....

 

The tuning fork will be tried on the BPR Flat track this weekend, with weight added, and I think that it may really be good....


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#35 Gator Bob

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Posted 05 June 2013 - 01:31 AM

Goobly-Goop! The rules say: " no centerline hinges".....................Period.

 

You and Tony can spin it any way you like, it's illegal and has been since day one. But rules are made to be broken and revised........................................

 

I just walked into this.

 

 

Wow Rick, Not cool.

 

You need a better look at those chassis' ....  then consider an apology ... cause it really sounds like you're saying they're cheating.

 

Didn't need a tuning fork to hear that.


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#36 Rick

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Posted 05 June 2013 - 09:14 AM

Bob, you need to read better or more. The tuning fork chassis are legal in every way, they are not center hinge cars. Now you can apologize.

 

Duffy and TonyP are building real center hinge cars and those are the ones referred to, as being illegal..................


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#37 Gator Bob

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Posted 05 June 2013 - 10:47 AM

Bob, you need to read better or more. The tuning fork chassis are legal in every way, they are not center hinge cars. Now you can apologize.

 

Duffy and TonyP are building real center hinge cars and those are the ones referred to, as being illegal..................

 

Sorry Rick.


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#38 JimF

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Posted 05 June 2013 - 05:50 PM

Mill:

 

We talked about the "forkers" a fair bit at "the cave" (missed you BTW). I also looked over Tims TF cars while there as well. The amount of twist flex that mine have got raised eyebrows from Bryan and from Tim. I think this concept has legs on any track surface. I had a tuning fork Can Am that was faster than the the car I ran to win the race. I just chose not to run it b/c I was more than a little gun-shy after completely tacoing the F-1. Besides, the Can Am I raced was more than good enough anyway. I think I had the fastest lap on every lane and I also think that I could have driven the car way better than I did. Still.......the tuning fork was decidedly faster but by then I was totally  spooked about folding it up with a solid hit.


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#39 Randy Tragni

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Posted 05 June 2013 - 09:56 PM

Maybe someone has already said this but "torsion rod" suspension certainly comes to mind with the center hinge design. Maybe we can attribute this to Colin Chapman?

Randy



#40 Rick

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Posted 06 June 2013 - 12:50 AM

Jim F, I understand the gun shy feelings. The Zee Rail cars are also not as robust as straight rail cars and don't handle hard hits usually either. It seems with every plus there is also a minus. So do we roll the dice?....................


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#41 redbackspyder

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Posted 06 June 2013 - 02:16 AM

Jim, I was helping Phil Nyland put up a Patio Cover so that we could get his track up and running, and we were at it all day, sorry I missed out seeing you... Could you post a picture of your Can Am tuning Fork Car ?  I would really love to see it, and I just had an idea about a Z Rail Tuning Fork that I am going to share with Bryan this weekend, and I love the testing and tuning that you are doing, this is what the blog is all about, the sharing of great ideas...  My F1 car is pictured in the SCRRA race report, and you can see what Bryan did to mine, at it is like a freight train on the track, flexible but will take any solid shot....  

 

This is what is interesting for Bryan and myself, seeing an idea come to fruition, seeing how something works, and why


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#42 JimF

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Posted 08 June 2013 - 01:46 AM

Here are a couple of  kinda poor shots of the Tuning Fork Can Am that I had with me. It worked, was fast, but needed a little more tuning and as I mentioned, I was a little leery of taking a shot anyway. The other cars that I had were both good so I picked between those two and quit working on this one. This one uses an .062 fork (hinged) and an .047 main rail, is 109 gr with the lead shown, and is noticeably stiffer than the now deceased .039 rail F-1. I'm not going to change this one and will leave it as a baseline.

 

I think the next Can Am will be completely different as shown by the drawing below. I think this will be stiffer than the first one. If I think it's too stiff, I'm going to try letting the tripod rails turn in a tube out front as well. Then of course I'll have to throw a couple of .032 or .039 "tie rails" in there somewhere in order to be legal.

 

4a4520a7-f83b-4c2f-8372-5dd71dc27cb2_zps

 

e0233872-8071-4fc7-a298-3c5067881fd4_zps

 

f0cddb6e-2c77-4b76-9587-e10a927e7bfc_zps


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#43 SlotStox#53

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Posted 08 June 2013 - 08:00 AM

Awesome looking design drawing Jim. Really neat and simple nose piece design, the tripod rails with the fork should keep the flex under control.

Look forward to seeing it built :)

#44 JimF

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Posted 25 June 2013 - 02:20 AM

After some more building, testing and racing, here are some updates on the concept. Note: the V-2.0 F-1 is updated in her dedicated thread so I won't comment on that one here.

 

The general feel of the tuning fork concept has proven to me to feel like the car exits the corner exceptionally flat. I attribute this to the center section flexing so independently from the rest of the frame that the rear section follows the track with a better distribution of torque. I have done these two Can Ams so far and the parallel rail frame is very good and is worth developing. OTH the "tripodey" one is quite a bit stiffer in torsional flex and while it's fine, it just feels like a "normal" car......hence no advantage.

 

3547a175-65a2-4ce5-bea4-3cfe81577ad5_zps

 

This next batch of pics show an anglewinder used for our big dog "pro coupe" class. This car distributes the considerable power of the big dog motor really well and it raced successfully in it's first outing even given a sub par motor. This car just drives smooth as glass and that's a rarity for this class given that the motor is a little overpowered for what we are running it in. The pics below show the main motor box (blue arrows) that form the core of the build. This is a one piece box of .062 wire. The forks are also .062 wire while the outer frame rail is .047. The car is stripped down here for some repairs but as shown and with running gear, it came in at 98 gr w/out body. I race this car with a soft Big Dog @ 8-40 and Koford soft wonders narrowed by about 1/8" If I put one of my faster motors in this car, I will probably add maybe 5-6 grams of additional weight in the back via my usual brass weight tabs.

 

8818baf5-075e-4534-b895-c16a2c5b0b59_zps

 

5a12befa-c7b2-4f44-8433-29e19eab2a1e_zps

 

07f92cbe-0b98-4ce2-a8b4-c91acf681894_zps

 

Next up is going to be a little more serious stab at a Can Am (inline of course) but built with the above anglewinder in mind.


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#45 Tim Neja

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Posted 23 July 2013 - 05:31 PM

Hey Jim----how'd the "Angle winder" wishbone car work??   I'm curious how it handled --- I"m working on a new whishbone but without any pivot points.  Soldered in .055 wire in the basic straight chassis configuration like yours above!! Would be very simple to build.  And you can rattle--plumber--or hinge the pans any way you like because now there's no additional hinges on the chassis! 
 


She's real fine, my 409!!!

#46 JimF

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Posted 23 July 2013 - 10:45 PM

She won the race first time out @ Modesto and did so with a pretty modest motor. The car was really planted and after tire tuning, easy to drive. It was a little light but worked really well. I may get to go out tomorrow and test @ Vallejo and that track runs very differently than Modesto so......we'll see. In general, the wishbones have almost all worked in F-1 along with a single 4 1/2", and single Pro Coupe. The Can Ams have been a mixed bag with up and down results. The last one with no frame rails is the most promising yet. I really built that one as a speedway car and I want to test it tomorrow @ Vallejo as well.

 

Interestingly, each variation does not work well everywhere. For example the F-1 that won the race handily @ Modesto is not that great on the MTT @ FTH. The Can Am that you saw run well @ the Cave, has been up and down around here.

 

I haven't posted here lately because I just don't have any firm conclusions.


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#47 Tim Neja

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Posted 24 July 2013 - 09:54 AM

Yeah I saw that one pic of the can am with ONLY a wishbone???  That seems like it wouldn't stand up to any wall hits?? But it worked well huh?  I agree that the wishbone's seem to have a mixed bag?? Maybe we have to try different wheel bases/ guide lengths for different tracks? I'm not sure why one has been REALLY good and another nearly identical only so-so on the same track!! But it's fun exploring!! :)  Also--how we either hinge the pans or have a shaker?? Lot's of variables!! :)


She's real fine, my 409!!!

#48 JimF

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Posted 24 July 2013 - 10:52 AM

I think one of the biggest reasons for the variable results is bite conditions. Smooth, even bite from expert track prep (like the cave for ex) and those cars seem to run smooth as glass. Dirty tracks with spotty glue, uneven rubber, and dust and dead flies.........they seem to chatter violently on startup. I have had similar experiences with "Z" rail cars as well.

 

While the "no rail" car is probably somewhat vulnerable.......the rear portion of each pan is controlled by a small rear hinge much like the F-1's that Bryan and Mill have been working with. That car that I pictured has that hinge in .032 wire within a 1/16" tube. If the car runs well @ Vallejo, then I'm going to replace that with an .062 wire - 3/32 tube combo and get a little more bearing surface in the rear solder joints. This is the only "torsion" car that I've had much promise out of. I built that one so that I can easily drop in - drop out frame rails without taking anything apart so that will be a future test. I can always hinge the pans later except right now with no frame rails......there's no place to hang the hinges............ :shok: 

 

FWIW.......that car took a couple of decent hits on Sunday and was fine. I didn't expect much on a flat track but It really was the best car in the race but...............that "danged kid"............. :D.


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#49 JimF

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Posted 25 July 2013 - 12:40 PM

Here is an update on some of the tuning fork designs that I've been messing with over the last weeks. Each has some positive attributes and in some cases, they will become my #1 or #2 race cars. I do think that these cars are pretty dependent upon conditions. (certainly more so than some more basic designs) However, each has the potential to be faster on any given day than more conventional stuff assuming the right conditions or the ability to adapt.

 

Most of these cars have been run on at least one track before yesterday. Yesterday, I was able to test pretty extensively on the King @ Eddies Slot Car World in Vallejo. The track was heavily rubbered but the bite was good so the speeds were perfectly acceptable for testing. I know how fast each car class has to be for this venue. Pics taken w/lead wires off for clarity but weights listed include them.

 

---------------------------------------

 

Pro Coupe: This class runs a Big Dog motor and a coupe body such as Lola T-70C, Porsche 908C etc. The motors can be "built" This frame was pictured in detail above. This car was raced to a win in June @ Modesto with a fairly soft motor.

 

Tested with a pretty good Big Dog motor @ 8-42. Started with JK 8713 p

 

  • This car was very fast but a little tippy/chattery (just too light for the heavy build up on the track) Best = 4.68
  • Added weight tabs as show by arrows. Added ~~ 5.2 gr (now 101) much better, still a little tippy....Best = 4.59
  • Changed tires to JK 8763 PT....all better and more consistent. Best = 4.52 (very good time)
  • Tested Porsche 908C, Porsche 917C bodies but no notable difference.
  • This can win as is so it goes into the box. Guessing that I may have to narrow the tires on race day.
  • This chassis does not seem to need further development

 

4a7c9aeb-87bb-451f-b892-1446a3fd15fc_zps

 

 

4.5" Stock Car: This class runs the S7 Mini Brute and stock car bodies as typified by the O/S '68 Charger....etc. This frame is is a 4-hinge car (meaning front and back) with .062 forks, .062 outside rails (red) hinged @ rear, and .039 inside rails (blue) to hold it together. Weight as shown with added lead is 112g. I didn't test this a lot b/c we are not racing these here in our next race. Started with the weight shown and Alpha Pirahna

 

  • This car was a little chattery in the heavy rubber but pretty good nonetheless. Best = 5.76
  • Tried Koford wonder soft and dumped the chatter but a touch loose. Best = 5.70
  • Tried Hermanator big huge hubs and got fast but a little too much bite. Best = 5.58
  • Narrowed the Hermanators by about .080 and got through the donut better. More consistent Best = 5.60
  • Parked it.

 

a2520094-15e5-4283-9164-b41885ee649b_zps

 

This R-Geo Samurai was featured in a "build it" article. As shown here with the added weight, this car is 109 gr. Tested on a flat track....this was not happening. But.....on the King.....different story. Started w/JK 8713 P, Parma Lola 163 and no weight.

 

  • First laps outta the gate were fast & tight, flat on turn exit good everywhere but critical. You were either in......or you were gone.....no middle ground. Best = 4.86 (exceptional for a Can Am)
  • Went to JK 8713 PT better in terms of predictability but slower at a best of 5.04 (still good)
  • Added the weight shown (~~ 7 gr total) Equal to above, more predictable but no faster.
  • Went to Koford wonder soft narrowed. Improved in the exit from the donut and on the leadon. Best = 4.98.
  • This frame has fast potential but I suspect that I'll replace the fixed forks w/hinged forks.

 

2db5045c-b335-4a8a-bf4c-67aed7b93d81_zps

 

This goofball idea has turned out really well so far. JK plate, .062 forks, no frame rails, rear of the pans (torsion setup) is controlled by small hinges on the small rear outriggers. This car is 98 gr as shown. Testing on this car was rather brief. Started with JK 8713P and Parma Lola 163.

 

  • First lap on this car was 5.10, second was 5.02, next 6 laps were 4.94-4.98.
  • Put it away.

 

07728d5b-9cc5-428d-b8fb-58b2ea92bdbe_zps

 

 


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#50 Tim Neja

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Posted 25 July 2013 - 11:59 PM

Thanks for posting all the pics and feedback Jim!! I'm going to work on the rail-less wishbone and see how it works for me!! :)


She's real fine, my 409!!!





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