coolrcdad

I'm helping a new young racer at our track with his HPI RS4, a gift from another driver. It's the original chassis, like the Rally, but with ball diffs and graphite decks. I'm looking for carpet set up tips, especially shock oil, springs and mounting position. He has a used set of good tires and a pair each of green and blue springs. So far the car traction rolls like crazy.

Thanks for any help.

popsracer

coolrcdad;

Traction rooling is usually caused by 2 things. TOO high of a ride height and TOO soft of springs.

Lower the ride height to between 4mm & 5mm first then try some stiffer springs at both ends of the car.
You can also install some limiter spacers on the outside of the shock shafts, but I would try the other two things first.

futureal

If I remember correctly, the original RS4 is not the full 190mm wide, either. That will make it roll much more often.

You could take some of those spacers that come with HPI wheels and use them in the wheel hex areas to offset the wheels by a couple of milimeters on each side. That might help a bit.

Also, it is often easier for a new racer if you take some of the steering out of his radio and maybe even change the throttle exponential until he gets a feel for the track and how the car handles. Then, gradually add it back in as he becomes more accustomed to it.

Cole Trickle

If the car got droop screws, those will effectively stop traction roll, by limiting the the downtravel.

I cant recall the complete Dr. Diff starting setup for carpet, but I do remember this: HPI White and Yellow progressive springs (yellow up front) and 60 wt oil on all four shocks. Piston nr. 3.

There are several blue and green springs, so it's a little hard to guide. However, they got different length, so if you go to www.hpiracing.com -> option parts -> spring chart, you should be able to identify them. If the current ones are close to the progressives I mentioned, then you probably should get some stiffer ones.

By the way, it's a good car.

coolrcdad

Thanks for the help. Good suggestions. I will try them.

Tom

i still run a rs4

track is out netball courts high grip very fast and open with some hair pins

setup

shocks
40wt all round
#4 pistons
hardest springs u can find

front
8 deg caster
1deg camber
0 toe
top arm in lower position
0 kick-up
ride hight 5mm
midle shock mount on arm

rear
camber 1 deg
1 toe in
outer shock mount on arm
inner on tower
arm in the outa most hole on the hub

tires ellegi 40f fronts and 37r rears(there foams)

for carpet try 50wt shock oil

coolrcdad

I need suggested gearing for the RS4 Pro using 48 pitch gears for a GM3 motor. Will probably use a 96t spur. Thanks!

Tom

i run an orion core with 32.5mm roll-out

i think thats to much for the gm3

start at say 27mm roll out and work ur way up in 1mm levels

make sure you can hear the motor reving out before going up

Cole Trickle

This depends a lot on the track.

A rule of thumb, are that the should reach top-end at 3/4 of the longest straight.

If the motor gets too hot, you should gear a little lower. It's good, if you're able to keep your fingers on the motor for at least 10 seconds.

As far as I know, the GM should be geared 2-3 teeth (pinon) lower than a P2K (talking same car, track etc.)

coolrcdad

Thanks. I finally figured out the what the kit 64p ratio is and I'm transferring that to 48, with lower gearing the GM3. The kit is 122/35 in 64p, which comes to about 96/28 in 48p.