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Help me setup my 944s2 race car suspension!

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Old 04-29-2017, 12:00 AM
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floatingkiwi
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Default Help me setup my 944s2 race car suspension!

Hi All


Just got a 944 s2 race car. Still road legal so has lights etc but is fully stripped out interior with cage etc and fiberglass bonnet.


It currently has:


Leda 24 way adjustable suspension. Ride height is very low with spherical bushings in the appropriate places.
The rear shocks do not have spring perches on them yet - I am thinking of doing this to use helper springs (but not get rid of the torsion bars).


Front springs: 350 in/lb
Front sway: I was told it was a 968 bar but only measures 27mm so it does not appear to be the 30mm 968 M030 bar.


Rear torsion bar: 26mm
Rear sway: 19.3mm 968 M030 bar with 3-way adjustment.


Car seems reasonably adjustable but does seem quite soft in corners.


Q's:
1) I have been advised 450 in'lb springs and 28mm torsion.
2) I think I need to find a 30mm M030 front sway?
3) do I bother with leaving the 26mm torsion in and doing the helper spring thing? If so what size spring? Or just go to 28mm (or other) rear torsion.


I am currently getting some parts from leda in the UK so now is the time to modify my rear struts to take helper springs if I go that way. Currently the struts have no perches.


Thoughts??
Matt from NZ
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Old 04-29-2017, 02:08 AM
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beamishnz
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Hi Matt. Sounds like an interesting car. Are you going to use it to race or for road use? If for road use then 350 fronts is plenty hard enough ... especially for NZ roads! I run 400 progressive CupCar/Motorsport springs and that is in my opinion absolute max for road use. 250lb is normally what I'd recommend for 'enthusiastic' road use. 26mm torsion is a bit light for 350lb springs. 28 - 29 would be ideal match but again right up there for road use. I'm suprised you are saying the set up is soft in the corners. with 350/26 set up and the swys you have got it should be very firm. I'd be checking all the sway bushes and also where the Ledas are on adjustment ... maybe they are on full soft.

Re the front sway - Porsche have superceded the 30mm hollow bar with a 27mm solid which is meant to be the same rating. the stock bar on that car would be a 26.8mm hollow. I have a spare 30mm hollow fornt sway but I wouldn't worry about that if I was you at this stage.

Start off by checking all your sway bushes and control arm bushes and check settings on the Ledas and then either go for some 200lb front springs to match the 26mm torsion or get some 28 or 29mm rear torsion bars.

I'm up in Auckland and have a fair amount of knowledge re these cars if you need any help. There is fairly enthusiastic good 944 community and the NZ Porsche Club puts on some good events. Social, gymkhanas, track days etc.

Post up a pic of your car. I'm curious to see it. I know most of them
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Old 04-29-2017, 11:06 PM
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floatingkiwi
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It's Pete's old FIX car, the burgundy one so it's a full stripped out race car, albeit still road legal. It will be a circuit car at this stage, but it can be driven to events. It's certainly not too hard on the road at all currently.


Most off the guys seem to be running 400 ish up front for the circuit work, and I have been recommended to get around a 28mm torsion bar, but I have the opportunity to sort the rear shocks to carry coil springs and I'm wondering whether to do that or not. Certainly the 26mm rear bar is too soft. I can feel it.


Any way to tell if I have the solid or hollow up front?


I'm running the ledas around 4-8 clicks from full hard depending on circuit conditions.


I'm in the rennsport gruppe so lots of guys to ask!
Pic below on full braking coming into T1 at Taupo
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Old 04-29-2017, 11:33 PM
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Originally Posted by floatingkiwi View Post
Q's:
1) I have been advised 450 in'lb springs and 28mm torsion.
2) I think I need to find a 30mm M030 front sway?
3) do I bother with leaving the 26mm torsion in and doing the helper spring thing? If so what size spring? Or just go to 28mm (or other) rear torsion.


I am currently getting some parts from leda in the UK so now is the time to modify my rear struts to take helper springs if I go that way. Currently the struts have no perches.


Thoughts??
Matt from NZ
Really need more info, like static weight of car and corner or front to rear balance...., but,

1)Hmm, we never keep the torsion bar but if memory serves, a budget hot setup used to be 400F and 30mm rear torsion bar. Your car should be understeering like a pig right now with twice the factory front spring rate paired with that current rear tbar and a rear shock with no spring.
2)Yes, pair the 30mmF with the 19mm rear. Good enough for track duty and front of the pack running for a 944.
3)It could be done, but why bother. Ditch the tbar and do the Elephant Racing rear polybronze bushing kit there while gutting. The math to fine tune F/R spring rates is easier with just coil springs on the rear LEDA.
You already have 450F, gut the rear tbar, get the hardware to use rear coil spring and mount 750# rear spring for neutral balance, 700# for bias understeer since you aren't complaining about the front of your car driving like a snow plow, you might like understeer....

T
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Old 04-30-2017, 01:54 AM
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Originally Posted by beamishnz View Post
Re the front sway - Porsche have superceded the 30mm hollow bar with a 27mm solid which is meant to be the same rating. the stock bar on that car would be a 26.8mm hollow.
Not quite.

The NLA factory 30 mm hollow bar was replaced by a 28.5 mm solid bar. And the stock sway on his S2 would have been a 25.5 mm bar, unless the car was specified with the M030 sport chassis option.
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Old 04-30-2017, 01:57 AM
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Yes it is understeering a bit but has quite an aggressive front alignment to counter this from previous I would suspect, about -3.5 deg. Rear about -2.2 deg.
The car already has a polybronze bushing kit installed.
I understand that the body shock mounts need to be modified to get rid of the TB?
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Old 04-30-2017, 01:58 AM
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I understand that the car has an almost 50/50 perfect weight distribution front to rear. I have not measured it though. Weight is unknown but would be on the heavier side of race cars as it has a stripped out interior but still full glass all round and lights in front. fiberglass bonnet is the only weight saving as far as bodywork goes.
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Old 04-30-2017, 02:01 AM
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Originally Posted by floatingkiwi View Post
Any way to tell if I have the solid or hollow up front?
Put a set of calipers on the sway...25.5 mm = turbo/S2 standard bar, 26.8 mm = turbo/S2 M030 bar, 28.5 mm = 968 M030 bar, and 30 mm = 944 M637 bar [or aftermarket replica].
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Old 04-30-2017, 02:33 AM
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It is 26.8mm.
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Old 04-30-2017, 07:25 AM
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Originally Posted by mel_t_vin View Post

Not quite.

The NLA factory 30 mm hollow bar was replaced by a 28.5 mm solid bar. And the stock sway on his S2 would have been a 25.5 mm bar, unless the car was specified with the M030 sport chassis option.
You are right ... the new M030 bar is 28.5 not 27 ... brain fade. However you are incorrect re stock front sway bars being 25.5. S2 bars were 28.5 hollow on both std and M030 cars.


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Old 04-30-2017, 07:43 AM
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Originally Posted by floatingkiwi View Post
It's Pete's old FIX car, the burgundy one so it's a full stripped out race car, albeit still road legal. It will be a circuit car at this stage, but it can be driven to events. It's certainly not too hard on the road at all currently.


Most off the guys seem to be running 400 ish up front for the circuit work, and I have been recommended to get around a 28mm torsion bar, but I have the opportunity to sort the rear shocks to carry coil springs and I'm wondering whether to do that or not. Certainly the 26mm rear bar is too soft. I can feel it.


Any way to tell if I have the solid or hollow up front?


I'm running the ledas around 4-8 clicks from full hard depending on circuit conditions.


I'm in the rennsport gruppe so lots of guys to ask!
Pic below on full braking coming into T1 at Taupo
Attachment 1160402
Nice car! My comments were assuming that you were using the car on the road. If it is mainly for track days then your front springs should be fine, and yes the rear would feel soft in comparison. Just need to match up the rear which can either be done with spring assist or a chunkier rear torsion bar. I'd have thought 30/31 would suit your application. Alternatively you'll need to work out what springs will bring 26mm up to around 350lb to match the front. I'd have thought circa 160lb would be right.

I personally wouldn't go past 350lb. The Porsche Turbo Cup cars ran 160-400 progressive and Michael Neville who is leading the Porsche Series Class B is running around 350lb and his car handles very nicely!

If you are in the RG ... Steve Rasmussen is extremely knowledgeable on the set up of the 944 platform.
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Old 04-30-2017, 09:47 AM
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Originally Posted by floatingkiwi View Post
Yes it is understeering a bit but has quite an aggressive front alignment to counter this from previous I would suspect, about -3.5 deg. Rear about -2.2 deg.
The car already has a polybronze bushing kit installed.
I understand that the body shock mounts need to be modified to get rid of the TB?
Camber looks about right for track. Ultimately will be dependant on the tire choice and then fine tuned to driver preference but you are in the ball park.

If you have the threaded rear LEDA already, you should already have the lower shock mount bolt, no other modifications necessary.

Are you absolutely certain that F is 450#....?

Car sure looks to dive excessively on the brakes.

If that pic is of you and you are new to track, you tend to over brake until you clock more hours in the seat.

After you sort F/R springs, most important thing is going to be corner balance.

For all you know, one corner may be carrying too much load which affects F or Rr on opposite side.

T
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Old 05-01-2017, 01:58 AM
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No the springs are 350# in front, not sure where 450 comes from?
I'm not new to the track, have been tracking my 997 for the last 3 years.


Yes I need to corner weight the car asap! but first get the *** sorted. I have been suggested by the guy that built the car to go for 28mm TB rear but I think that's way too soft.
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Old 05-03-2017, 12:39 AM
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Originally Posted by beamishnz View Post
However you are incorrect re stock front sway bars being 25.5. S2 bars were 28.5 hollow on both std and M030 cars.
Where is it stated that stock, and M030, S2 front sways are 28.5 mm?

The factory only introduced a 28.5 mm bar not 2 years ago...as a replacement for the NLA 30 mm 944 M637 bar.
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Old 05-03-2017, 11:26 AM
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Originally Posted by floatingkiwi View Post
No the springs are 350# in front, not sure where 450 comes from?
I'm not new to the track, have been tracking my 997 for the last 3 years.


Yes I need to corner weight the car asap! but first get the *** sorted. I have been suggested by the guy that built the car to go for 28mm TB rear but I think that's way too soft.

Ahhh, still heavy understeer bias though.

As stated above, your rear Tbar is probably factory balance for for a mere 150-160# front spring and even so, anyone with a good feel for these cars will tell you that there is a built in slight understeer from the get go.

From the braking nosedive picture, you definitely need to go another 100 on the front. IMO, the 30mm bar is a good neutral match for 400# F.
If your springs are 350#, then yeah, maybe 28-9mm. That won't resolve the nose dive though.

Still, what is total weight of car....?

My son races a top of the field 944 in PCA SP2 that I setup completely myself.

400# F. It's my belief that the 1000# spring setups that some people race on these cars is way excessive, his results prove that out, but again, my opinion.
The suspension has to be allowed to work and do it's job and at these high rates, all you have working is the sidewall of the tire....again, my opinion.

I can share other setup data off line....

T
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