Ladies and Gents,

I have an 86 944 Turbo, track ONLY car (racing) and I'm hitting the bump stops.

Specs
86 944T 2650# 400hp
Font 600# with Koni custom valved dbl adjustable
Weltmeister Adjustable Front (set fairly stiff - 3 inchs from rear)
Rear 30MM torsion bar with Koni adjustable
Weltmeister Adjustable Rear(set stiff - 3 to 2.5 inchs from rear)

Tracks
Mid-Ohio
Road America
Black Hawk Farms


The rear is too soft and I'm finding that when I encounter in a bump in the corner it caused the car to wash out (it hitting the bump stops), first goes the front and then the rear. The worst is applying to much throttle in the corner and getting throttle induced oversteer when it bottoms out on the bump stops.

The car is lowered (A-arms parallel to ground on front and zero rake (rear set to match front).

I need to raise the rates in the back (at a minimum), I'm looking to move to coil-overs and remove the torsion bars.

I'm looking for advice for rates for both the front and rear. I'm trying to cut down my development time by starting with a correct set of spring rates. Any help is greatly appriciated.

Thanks in advance

 

what ride frequencies do you want to run?

 

If the shocks can take it I would go for at least 700# springs in the rear.
The car must be pretty understeered in the current setup!

 

I bet that car is tough to drive well.

as Duke indicated
with 600lb front..... should be mated with a coilover in the 700-750lb range

 

Can you fit the rear 968cs helper springs?

 

I'm running 450 in the front and 550 in the rear. I think it worked quite well on Watkins Glen, but if you're running 600 up front I think around 700 would be good for the rear.

 

I run 500f/650r no torsion bars in my car, which weighs about the same as yours, with a little less hp. It is a pretty good balance, same sway bars, but not set quite as stiff. On a couple of club racers I maintain, we run 900f/1100r (moton's)with 10mm torsion bars (basically ineffective, but meet club rules of running a torsion bar), along with welt. sways. This setup is run on smooth tracks. We swap down to 700/900 for rougher tracks like Hallett. With the 700/900's at Hallett's Club Race last weekend, a friend took 1st in saturday's race, and 2 2nd's in Sundays races.

 

For those wonder how the car handles, it is does very well as long as I stay off the bump stops... 245.45.16 on 9inch and 255.50.15 on 10inch with 27/25 cold - 37/35 hot temps look great across the tires. The stiff bar in the back is what makes it work with the 30MM t-bars

 

i think a 3012 Koni rear coil over kit with a 750 spring would be a good next steep. cost is about 1300 bucks not including the solid bushings and other parts you should add if you dont already have them

the next step would be to spend real money on a true racing suspension like Ohlins, Motons, Penske or whatever


what kind of tires do you run? I think your pressures are a little low (hot)

I also need way more spring at least my F/R spring ratio is pretty good. I think most would agree a slight rear bias is the way to go.

 

What tire temps do you suggest Phil? They sound pretty good to me but obviously depends on what tires you're using of course, hence your question.

 

Spike, are you sure you're hitting the bump stops and don't have some other problem (like a bad shock or something limiting the travel)?

My car is heavier and sprung less, and I've NEVER hit the bump stops at any track in the north east - and some are quite rough.

 

p.s. 944s normally have enough rear suspension travel so the plastic rocker skirt pieces in front of the rear wheels scrape on the ground. When I ran a stock suspension, I sanded both of mine down - and STILL never bottomed the car out.

 

^^^^^^^^^^^^^^^^^^^^My thoughts also.

 

for a 2650lbs track only car, running coil overs (no torsion bars), we run 550lbs front and 750lbs rear.


TonyG

 

Our car weighs 2550# with 1/2 tank of gas, no t bars, M030 units in front rebuilt and revalved with 600# F springs, Koni 3012 in the rear with 750# rear. Shocks are set in the medium range, M030 sway bars, RE bushings all around. Car is neutral with 200# driver.