BDSharp's Show-Me Showdown project

[bdsharp]

I've decided to take a stab at the Showdown. I don't have a 1/32 track and this will be my first scratch-build, but I thought that building for a fun-run rather than a race would be a good place to start. So here goes nuttin'.

I ordered one of the wheel/tire/motor package specials from SCC, as well as the other bits to complete a rolling chassis. I plan to make it wheelbase-adjustable, so I'll settle on a body a little later. I'm going to lean heavily on the garage section projects as well as your currently posted builds, and I'm paying close attention to Slothead's newbie thread.

I have a question about axle mounting. I understand that if the motor shaft engages the flanges of the crown gear, that's all that's needed to limit the axle end play. If it doesn't, end play is set by the length of the axle tubes, right? In that case, the inner hub of the wheel bears on the end of the tube, correct? Is this ok, or should there be a better bearing surface than that? And, I suppose, this applies to the front axle too, except for the part about the gear flange.

I've looked over last year's entries and you guys play hard, but it looks like fun. (Can anyone link me to the awards thread?) Thanks for your insight, and I'm looking forward to seeing how all this turns out.

-Brian

[btaylor]

Brian, You will have fun with this series of cars. they are fun to build and race. To answer your axle question, most guys like the motor shaft engaging the crow flange, but it does not have to. you can use the axle tubes as you said, and use axle shims from Slot Car Corner to act as a thrust washer. if you have a lot of space, you can use do-bro locking collars as well.
http://www.slotcarcorner.com/SCC-Axle-S ... -p456.html
http://www.slotcarcorner.com/SCC-Axle-S ... p1261.html
Hope this helps! and good luck

Bob

[slothead]

Brian

Hello and welcome to newbie-land. I've been playing around with chassis thoughts all week and loving it. My ideas have gone from wild to mild and now mine will be very similar to the others shown. Chicagoland Hobbies is getting me all the brass stock off the Stinker Chassis build post, and I still have to order the SCC package (I'm holding out to finalize my list of other stuff to add - axles, gears, motor bracket, etc.).

Please note Harry's comment on my Newbie thread about the motor bracket available at SCC - the motor shaft won't quite reach the crown gear. So I'm figuring out how to take the play out of the axle too. Guess I'll need to get 3/32" axle spacers 'cause all the ones I have are for 1/8" axles. Or, I may go with a different motor bracket that will solve this problem. If anyone has a suggestion let us know.

Slothead

[bdsharp]

I have a idea for the motor bracket, but I want to get one in hand and see if it has any merit before I spout off about it. I'll probably have more fun with the chassis than with the shiny side.

[btaylor]

Guy;s, don't know if this will help, but this is what I use. I like to be able to shift the axles to suit the body and of course set the rear gear spacing. The PM motor bracket is good, but it does not engage the crown flanges. it does work fine as far as the pinion to crown goes. here is a link to the collars I use.
http://www.ebay.com/itm/Du-Bro-3-32-Pla ... Sw0HVWEawA
http://www.ebay.com/itm/Du-Bro-3-32-Pla ... SwMmBVsRJb
Bob

[HomeRacingWorld]

[waaytoomuchintothis]

DuBro collars also enhance low center of gravity, which is always a good thing. In the old days, there were guys in 1/24th who wrapped lead around their axles, and maintained bushing contact with the DuBro collars on each side.

[bdsharp]

I plan to do some soldering today, and I have a couple of design questions. When locating the guide, how much clearance should there be between the bottom of the horizontal braid surface and the track? Braid clearance, in other words. And it should be as far forward as possible, yet under the body, correct?

Also, all else being equal, will independently-rotating front wheels make a faster car, or does it mostly just add to the coolness?

[HomeRacingWorld]

[bdsharp]

Ok, thanks. I probably would have put too much weight on the front tires, and I'll stick with a solid axle.

But just for discussion, let's apply the independent concept to the rear axle on an oval-only chassis. When the car goes around a turn, the outside wheel wants to turn faster than the inside wheel because it is traveling a larger radius turn by the dimension of the car's track. But with a solid axle, it can't, so one tire or the other has to slip a little. That's scrubbing off speed, right? What if you built a car that only drove the right rear wheel (on a counter-clockwise oval)? That's where the weight will go, better planting that tire, and the left side will be allowed to freewheel at a slightly lower speed. Driving the right side only might also help push the car around the left-hand turn. Think it would make a difference, or am I just splitting hairs over something the timer will never show?

[strangebrew]

Don't forget ......You still have to go STRAIGHT the other half of the track......I'm afraid you'd be close to a spin out when you
put the power down on the turn exit. Also consider braking at the entrance to the corner....one tire would be on
lock down while the other free wheels. If your car's rear drifts only slightly to the left, your way out of shape
getting in the corner. (Just like the 1:1's......good entry means quick exit)
My cars last year had a softer left rear tire. (A minor disadvantage on the straights, but an advantage in the corners)
These cars have kind of a high CG & I fought a tipping problem in the corner. It seemed like a harder right rear
kind of counteracted too much weight transfer to that side & eliminated SOME of the tip problem,
You might consider a slight rear wheel stagger (smaller left rear) or a different compound for each of the rears.
I like my cars to brake straight or with the rear SLIGHTLY hanging out to the right. At that point you're ready to
pick up the power with the car in the correct attitude for the corner. For me braking is the key to fast corners.
Testing different setups is important. My track surface is different than Harry's, so for me it's still a "crap shoot".
BUT......a GREAT DEAL depends on your car's driver......We all run differently.
GOOD LUCK

[HomeRacingWorld]

Like I said, can of worms.

Simply put, you want both rears making contact and providing grip. What you may think you gain in the corners, you will lose in the straights. We sometimes forget about those pesky straights, and concentrate on those corners.

On my track you need BALANCE for that fast lap. Stability not just in the corners, but down the longer parts of the track.

There is more time gained by picking your braking points and that "sweet spot" to lay the hammer down coming out. In other words the DRIVER dictates more for time than we give credit to.

[bdsharp]

Both of you make perfect sense. I was mostly just musing out loud, and as usual, got into trouble. KISS.

[HomeRacingWorld]

Not at all, I like musing. I would do it more often, but have not perfected the art of rambling.

Seeing your interest in this event/build is actually quite refreshing.

[waaytoomuchintothis]

I've noticed an odd thing on one of my early scratchbuilt chassis. This discussion reminds me of it. I was experimenting with copper-clad fiberglass (circuit board material), and when I finished it, the front axle was a little out of square, as if it were made to turn right all the time. I ran it several times around the track, and it was very fast in left turns, no matter how tight or broad the turn was. I assumed it was because the chassis was "turning in" the way a 1:1 car hangs its tail out on dirt tracks. I corrected the angle error and it never was as fast in left turns, being equal for both right and left turns thereafter. I think about it from time to time, and I never have gotten around to building another chassis that had that angled front. One thing that is connected to this... I can't stand a car that doesn't roll its front wheels. I'd much rather the car was slow than ever build a true tripod, although, like Harry, I do try to have very little traction up front. (I've run Harry's cars here twice, and his setup is just like mine.) So the only time my fronts are making a strong contact, it is in the turns, particularly in braking.

I still wonder if there's something to this. Has anybody else ever tried this? (I'm an expert rambler- my nickname is Nash).