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Thanks for the comments!

Going to the track today, hopefully it works as expected. Full report this weekend.

Good luck on the track.

Really cool. Remind me what the deal is with the narrow chassis that is so popular now?

RichieRich wrote:Really cool. Remind me what the deal is with the narrow chassis that is so popular now?

It looks cool I am sure there is a better explanation, maybe something about better balance or something.

chassis flex for more grip

or agreed...looks cool

Track Report:

Well I made it to Trackside Raceway http://tracksideraceway.com/ in Brookfield, WI Friday night for a club race. With the Spektrum race coming the following weekend the place was packed. The surface is black dirt (with possibly some clay mixed in) slightly damp and high-bite. And the layout was simple but very fast with nothing too technical, think on-road with jumps.



Besides testing the new chassis I’m also working on a lightweight transmission setup for 17.5 stock (eliminated the slipper, 64p spur/pinion, aluminum top shaft and narrowed idler & diff gear). Throttle response feels more like a mild mod motor than a numb blinky-stock and carries more speed down straight as well, but I don’t think it will be effective in less than high-bite conditions without a slipper.



On to the chassis, besides getting lots of attention in the pit area it proved to be durable. In my first practice session I drove into the high-speed sweeper too hot, traction rolled, tumbled through the air and went into the boards without a scratch (was quite spectacular). I started with the same setup and tire combo I run with the +8 factory chassis. After I got the new track layout somewhat figured out and got comfortable, the car felt light and agile but the balance was off. The rear-end was locked down and the front pushed pretty hard on corner mid-to-exit, with the old car this was never a problem and I usually had to dial steering out. After trying a few different sets of tires and adding a little weight the car got better and as the race day progressed the track dried out slightly which also helped. Some how I managed to make it into the A-main and finished mid pack, pretty decent for its first time out but still off pace. In hind sight I wish I made the car shorter (+8mm instead of +10mm) and didn’t limit myself to a shorty pack in the far forward position (see version 2.0). I still plan on using it at the upcoming Spektrum race and am confident I can get it to work as good as the factory chassis.

That facility looks killer!

And the "speedy's" cut gears and the slipper eliminator is a great idea too!

My testing drove me to the conclusion that the chassis has to have a good amount of flex with the +10mm

Torsionally the +10mm printed chassis feels similar to the +8mm AE. I made the battery box area extra thick and added a bulkhead behind the battery to tie it together. I’m thinking some of the balance issues the car has is because I moved too much weight forward and the car doesn't want to rotate, the added length doesn't help either.

I lost about 40% torsional rigidity when I narrowed the truck chassis, which really helped the initial turn in, and the length stabilized it after that-

Did you change your setup much from the B4 to the narrowed T4 chassis?

One thing I forgot to mention…

Some of the fastest most consistent buggies in the building Friday were mid-motor Centro C4.2 converted B4s, even after the track dried out some they still looked planted. I’m afraid most of this work was for nothing.

GreenHell wrote:Did you change your setup much from the B4 to the narrowed T4 chassis?

Added some droop to both ends to compensate for the extra chassis movement, kept all the ballast weight the same except the front end, where I increased it to 3/4 oz

I'm ready to see a direct drive 17.5 B4.2.....

That's nice, but have you thought about also running MIP's new 17.5 Pucks system for even less rotating mass. I run those now and they have made a difference. I just picked up some of the Speedy diff and idler gears for my truck and buggy.

I'm ready to see a direct drive 17.5 B4.2.....

I would love to see that and give it a try.

janaya wrote:

I'm ready to see a direct drive 17.5 B4.2.....

I would love to see that and give it a try.

It's the only thing that hasn't come full circle