924Board.org

[Dutch924-racer]

What is the origineal spring rate of Porsche 924 Turbo front springs/ rear torsian bars?

I now run coil-overs, but way to stiff for street use. Springs I now have:
Front: 90 N/mm = 514 lbs/inch
Rear: 80 N/ mm = 475 lbs /inch
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937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
Fast road camshaft
Forge recirculation valve + boost controller

[Rasta Monsta]

From some oddball place called "924.org":

http://www.924.org/techsection/SuspensionPreparation.htm


rasta

P.S. Your springs are stiffer than those on my race car.
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Toofah King Bad

• WeiBe (1987 924S) - 931 S3
  
• Red (1987 924S) - Pro44/Spec944

[Dutch924-racer]

Great thanks!

So my springs are way of the original, will go and look for something between 160, maybe a bit firmer/ sportier 230lbs

Any tips for 60mm id springs in europe?
_________________
937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
Fast road camshaft
Forge recirculation valve + boost controller

[Cédric]

The ride is highly dependent on the dampers, ive driven a 944 with almost twice that stiffness, it was pretty good on the roads, though it had very well designed dampers, professionally valved(and expensive).

For us mortals with simpler dampers we have to restrain the spring rate a bit. I run 63 N/mm up front and it's pretty good on the roads. If you are more comfort oriented around 45N/mm would be a good middle ground imo. It depends on what you want to use the car for. I used to buy springs from the UK which had motorsports stores with alot of stuff like démon tweaks, faulkner springs etc. However that has ended up significantly more expensive since brexit.
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1980 924 Turbo

[Dutch924-racer]

Just another question, I now had less stiff springs in the rear, the idea was less pressure in the rear to have oversteer on the track.

I read different stories about the spring rate. What I understand is that with the original set up, the torsian bars were a higher spring rate then the front springs.

What will be the best (sport) street setup?
- front and rear the same spring rate
- stiffer springs in the rear
- stiffer springs in the front
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937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
Fast road camshaft
Forge recirculation valve + boost controller

[!tom]

Softer rear springs should promote understeer, harder rear springs oversteer.

Your setup seems backwards.

You may wish to tune this with your swaybar.
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78 924 NA
5-lug

[Dutch924-racer]

I run 30mm sway bar in the front and 20mm in the rear.
_________________
937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
Fast road camshaft
Forge recirculation valve + boost controller

[Cédric]

You have to calculate the actual spring rate on the wheel for a proper comparison, you cant directly compare the spring rates without taking into account the geometry/motion ratio. Google it and you will see how its calculated

Normally a car like ours use a slightly stiffer front than rear, of we talk spring rate at the wheel. But it allt depends on weight distribution and tyre sizes. If you have wide rear tyres for example you need stiffer springs at the rear to make those tyres take up more laod, otherwise you will easily end up with understeer.

As tom says, going softer in the rear will make the front end take up mote of the load, and thus max out the tyre grip even earlier than before. So if you want more oversteer go for softer at the front or stiffer at the rear. If you have adjustable sway bars that's the best option, then you can adjust the balance in just a couple of minutes.
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1980 924 Turbo