61 replies to this topic

[Duffy]

In a week where it seems everybody's arguing and nobody's building, I figure it's a good time to post some thoughts on a class that it seems--nobody's building...But, I'd passed along my veteran GP chassis (Duffy #02 if anyone's counting) and needed a new JD ride for the race this weekend, so I pulled out my brazing rod and went at it. Kind of a nice change from building Can-Am frames.

So as I set up this build, some of the stuff I've been applying to my current torsion-based Retro builds crept in. Here's how that worked:
One thing everybody talks about with these JDs is how fragile they are, how easily out-of-tweak they'll get if you wall 'em. Maybe so...I haven't found mine to be too crooked after a race, but maybe it's just because I'm so d@mned slow!--OR maybe there's something really viable in making these big swoopy gentle-radius bends and staggering 'em, and maybe there's a benefit to rigidity in soldering every wire available right up next to the other. --Making a [bronze & solder] pan, so to speak.
Maybe. Let's try it.

I chose to use the McLaren "Serenissima" bod from Howmet's Bodies For Beer International on this ride, and that's a pretty narrow car, a quarter-inch under the allowed JDGP width; but I want to play with the concept some guys have concerning keeping weight low & close to centerline with these cars; lacking any real width anyway, nor any aero advantage from a wide bod, it seemed like a good time to try narrow & dense.



So the inner run of rails just nuzzles up against the motor here, affording two runs inside the Duffy JD bracket. the inner-est one got a little bend to fetch up against the cheeks just like the forward set does--



--And the outer runs also snake around to keep everything as dense and in-contact as possible. Put 'em all together, and--



--And we get the "Slithery Jungle Tail" in all its glory. What I'm hoping by all this is to minimize any gaps or structural faults that might flex independently, in a sense creating a "pan" of wire. Initial bending tests indicate the idea works, and there's no need for those small right-angle gussets we like to use on Sports Car chasses.
The other thing you see here is the steel hoop I fit into the gap shere the bracket cheeks are; it needed grinding down to the .040" cheek thickness.



While I was doing all this fancy squeezy-narrow junk, I took the opportunity to do my math and stack up all the bits aforehand. A quirk in the Duffy JD Bracket (it's so hard to get quality components these days!) necessitated a droparm stackup of .615" width, so when I made up my droparm central unit I filed away half that loss before attaching the bearing rods, and then filed those to slip-fit. I vainly believe a perfect slip in the droparm is more stable: better & faster racers have pooh-poohed that conceit.



So there's the Duffy "Chillon Castle" GP Jaildoor, as close to a solid pan as I could manage. The droparm is also kept as close to minimum-movement as possible in up-down mode.



A couple of guys (YOU know who you are!) who like to mess with wire and the limits of motion will quickly hip to some interesting possibilities vis-a-vis selective rod grouping and partial-soldering. To those I say only, --it's a bright future.




Here's the body mounted. Livery is totally made-up. My sentimental approach to Jaildoor determined my exclusive use of brushes for the body; sometimes it's fun to be sixteen again.
I really do enjoy painting, I should gear up to do more.



I wanted to save as much of the transaxle as possible--like I say, I intended this to be a celebration 0f 16-year-old Duffy's scale-like leanings...so I spent more time than I should've cutting&fitting&trimming&cuttingsomemore...and even then, the crown gear was jammed. That's when I pulled out my soldering iron and dialed it up to LOW, & gently pulled the box out to clear. I swear, if I'd hipped to that trick before I'd started cutting away...

So that's what I'm taking over to SAL this weekend. I'll report on how well I wrought after.
Duffy

[Mopar Rob]

In a week where it seems everybody's arguing and nobody's building,

I've built 2 chassis this week, but don't want to show any photos. They're a secret Just kidding one's an Aero stock car, but everyones seen photos of them so I didn't post




BTW:


Nice JD build

[slotcarone]

Duff that's a beautiful chassis!!!!! I don't know if it is legal though with the twisted rails in the back like that.

[Pablo]

I give it 2 thumbs up !!!!!!!!!!

[Joe Mig]

Looks great I hope we have a JD race this weekend.

[MrWeiler]

My sentimental approach to Jaildoor determined my exclusive use of brushes for the body; sometimes it's fun to be sixteen again.

I've been doing the (no air) brush thing on some of my vintage bodies too...it's fun and takes a while to finish...

I like the "bundle-o-snakes" chassis...

[Duffy]

Duff that's a beautiful chassis!!!!! I don't know if it is legal though with the twisted rails in the back like that.

...Ah.

Well, that is a concern, innit? The strictest reading of the Rule--
3e. No tapering (or bending of the rails except for the bend up to bracket or axle tube) of the rails, only parallel rails
from the front to the rear connecting the axles.
--would disallow it. I didn't read quite that strict.

I've campaigned cars with work like this back to chassis #02 back in mid-2009:



I have always understood this clause to refer to gross tapering along the whole chassis; what bends happen as the
rails rise up to meet bracket & axle, those don't affect the ideal of parallelism over the length of the chassis.


This didn't originate with me (I've just divined a possible structural advantage here), I've seen it on others' as well.
If there's a problem now, I can think of three cars showing up this weekend at SAL that'll share in it. (Too bad you'll
miss the fireworks, Mike!)

Duffy

[JerseyJohn]

 a MASTERPIECE Duff. love the drop arm !!

[tonyp]

Duffy, Check rules on piano wire rear brace. I believe it states it has to be inside bracket....

[Noose]

This whole bent rail thing has been a controversy even in the sports cars rules. The "intent" of the rule, 3e, which you properly cited was that there would be no "squiggles" in the rails as they went from the motor bracket to the front. The last picture looks OK to me. Your latest one does not IMO.

Also, Tony is correct regarding the piano wire rear brace.3h. A piano wire U-brace may be used inside the motor bracket to reinforce the bracket and protect the crown gear and a single piece of straight .063 piano wire is allowed to be used inside the 3 piece drop arm hinge.

Now, will you be banned from this on Saturday? Only if Mistress Irene decides to cut the party short. Run em for fun. We'll have a protest claim afterward.

[tonyp]

How much, Maybe Ill protest it....

[Marty Stanley]

{snip}
Livery is totally made-up. My sentimental approach to Jaildoor determined my exclusive use of brushes for the body; sometimes it's fun to be sixteen again.
{/snip}

Duffy,

Isn't that the philosphy that originally created the "1966 Rod & Custom" type of cars?

I remember one of the old timers here making a statement one day. That statement was, "Back in the 60's we went to the raceways to run our cars. Today we go to the raceways to race our cars."

To me this category of slot car can be a real hoot ro race. They don't handle as well as the more technical cars - which to me is a good thing. Of course many folks today tend to like the easy way - high banks, lots of positive camber and such to make it easier to negotiate around a track. Once they spend the time to learn a technical track, sll of a sudden they really start to appreciate that type of track. I think the same can be said for the types of cars.

Yes, a car like you have might be more susceptible to damage - I know I saw a car - not mine - make contact with the outer wall in a banked turn one day. A new car had to be constructed. Prior to the incident, all the rails were compliant with the 'straight rule'. After the incident they kind of resembled your wonderful 'bed of snakes' type of configuration. H'mmm, isn't that quite prototypical? I mean if you watch a Formula 1 race, when a car contacts the wall, it is usually finished?

I think we really need to have more of this type of racing as it is fun and enjoyable for many of today's racers.

Just my opinion of course.

[Pablo]

I postulate the clever Duffmaster chose "Scratchbuilding" forum vice "Retro" forum for this build because he well knew it was beyond the envelope

[Noose]

The JD GP cars, are as the Sports Cars, lots of fun to run or race. The GP cars are quite the handful though as compared to the Sports cars that's for sure. The Falcon 2s are as fast as you want to go with these.

Resoldering a front axle tube seems to be commonplace after one of these takes one of those Sarti flying leaps. Keeping them sliding an not sticking is the trick.

[Duffy]

I love these "astringent" moments, these little bubbling-ups of "I Wuzz WWRONNNG..."
I mean it, there's something really delightful in learning that I've goofed gloriously (and nobody's hurt, and no money or property lost--these disclaimers also need to be present to fully savor the fun). A mistake of ignorance carries a gift of clearer thinking. I really mean that.

So: awww shoot, all that cleverness and it's DQ'd fair and square.

Tony's spot-on with the steel hoop, under is not inside (and yah, Marty, I've had dates like that too).
On reflection, I recall not doing this in an earlier build, for precisely this reason. My bad.
And Noose has declared: squiggles past the threshold of the bracket, as part of the upward bend, legal; bends while in transit to the upsweep, not legal.
Okay then.

And I had a ball building this one this week & I'll see how it fares on the track, and now I can build another one too! Is this a great hobby or what?

The bad news is, I may not be getting over to run this on Saturday: got a situation that may not resolve by then (see my wailing & hand-wringing over in the "SAL Up Next!" thread). Stay tuned, though, I'll be sure to document a slightly-less-Slithery tail in this thread, soon.

Duffy

[Duffy]

And: "Aww Shoot" ch.2:

Now I gotta go search the 'Net for a whole 'nother background-pic "Dungeon" to name the new chassis after. I tell ya, Medieval castles are few & far between these days. You guys're making me work too hard.

Duf

[tonyp]

Duffy, see what happens when you think too hard. You don't want to damage that pink cauliflower thats already leaning off kilter inside your head.

[Marty Stanley]

Well, since you can't race it, have you thought of using it as a replacement for a 'lava lamp'?

You might want to put some mood music on and really test it to see if it would work.

I'm thinking it might just start a new trend.

[Noose]

He can race it this Sat if he makes it.

[Tex]

You can race it. Just cut the dang gear guard OFF and replace it with one INside the bracket.

[Duffy]

Naah. I'm not in control of where I'll be Saturday (and anybody who says different is selling something!) but it's got nothing to do with this. Marty makes a good point: this car's to RUN and I had a ball building it. There're a couple new JD chassis coming, race-legal. I'm gonna keep this around just like it is, it'd be more trouble than it's worth to modify it at this point.

Part of what I do with my threads (since I can't lather my immense racing chops on y'all) is to provide experiential anecdotes that Weejuns like myself might draw from. I hope this is entertaining as well as instructive.

Duf

[Prof. Fate]

Hi

What he isn't telling you is that on the phone, I am no help. No local JD class, no interest, however, every Friday, several of us get together and race survivors we have from 1966. Even with the class motor, none of them would be legal because of how they were built, but that is the experience I have!

That said, locally, people have had me build replicas of locally well known cars of this period, and we have had some relatively large fields. But as Mike said, no prizes, money or anything. Among the core group, one of the cars, a pianowire chassis under a Pactra '66 Ferrari has dominated most of the races since it was built.

No one is heartbroken. We are just playing with the cars.

Fate

[Mike Patterson]

Duffy,

NEAT chassis! Just looking at that motor bracket makes my brain hurt.

[Duffy]

Ohh yah, the bracket's the LEGAL bit!! You'll see more of that, I'm already plotting even sexier and snakier and legaler bendies.

[JohnnySlotcar]

Trade it to me!!! I want it. John