BARC 2020 GT3 Chassis V3

[BARC 1]

I continue soldering together ideas for the 2020 GT3 qualifying run. This attempt is wire and brass in a sidewinder configuration. Bearings on all axles with independent front wheels and a lightly sprung drop arm have resulted in a smooth consistent runner that I cannot flip in testing. Not sure what others think, but my reason for the drop arm is this chassis has no pod, and the thought is a drop arm allows some degree of the same thing a pod offers a car. I.e some movement to allow better handling.

Wheels are 50 year old Cox magnesium rims, with NSR rubber glued on

Chassis has an adjustable wheelbase, and motor mount to easily change motor and gear set ups.

[williamg]

Hmm,
Adjustable, indy front, drop arm, side winder.
Can't get much more exotic Dan

[chrisguyw]

Hi Dan, A great start !!!...........a few suggestions if I may.

It looks like you a running a 14T or more tooth pinion on the car ??......most of the quicker cars in the proxy will be running 3:1 (ish) and numerically higher ratios depending on the motors chosen, so , unless you are running a 42T spur (it does not look like it ;) ) you may want to consider dropping a few teeth on the pinion.

Drop arms basically disappeared from competitive slot car chassis design by 1967/68, as they do not allow the total weight of the chassis (and its associated components) to provide downward pressure on the guide, keeping it in the slot (which is a good thing) . While a few of the European rally track /trials folks still incorporate drop arms, you will be hard pressed to find one in a competitive track/circuit car.

Cheers
Chris Walker

[slothead]

Nice work Dan. Those wheels bring back memories - loved the fat rears on my Cox Ford GT.

I'm all for independent front wheels, so kudos for that. I'll just listen in on the drop arm discussion - good perspectives on both sides.

My question for anyone reading this is about the length of the guide flag. Your's seems a tad too long, and I've always thought a longer guide creates more drag in the slot. Thoughts?

[BARC 1]

Thanks for the tips on gearing Chris. I was planning on replacing the nylon pinion with a brass one. .I noticed in the group 5 cars there are some cars sub 3 in the gear ratios.

Not sure if you can see it in the picture. The drop arm has thin piano wire incorporated into its structure. When sitting flat on the track the weight of the chassis is transferred down to the guide as the front axle assembly sits on the piano wire transferring the total front weight to the guide. This is something new I am trying out, and it seems to work well keeping the guide down in the slot on acceleration. I will see if this drop arm transfers to the entry I decide on.

I have an NSR Porsche on the way to try an reduce top weight as much as possible.

[BARC 1]

Re guide length

This is a slotting plus guide that you cut down to whatever size works best for you. In the picture it is at its full uncut length.

[CJR]

Dan, looks great to me and I will follow this build.
Chris