Show full size 924Board.org
Discussion Forum of 924.org
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
 Technical FAQ924 FAQ (Technical)   Technical924 Technical Section   Jump to 924.org924.org   Jump to PCA 924 Registry924 Registry

Spring rate for Porsche 924 Turbo

 
Post new topic   Reply to topic    924Board.org Forum Index -> General Discussions
View previous topic :: View next topic  
Author Message
Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1066
Location: The Netherlands

PostPosted: Thu Feb 18, 2021 5:19 am    Post subject: Spring rate for Porsche 924 Turbo Reply with quote

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
_________________
937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
Fast road camshaft
Forge recirculation valve + boost controller


Last edited by Dutch924-racer on Thu Feb 18, 2021 7:08 am; edited 1 time in total
Back to top
View user's profile Send private message
Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11468
Location: PacNW

PostPosted: Thu Feb 18, 2021 6:52 am    Post subject: Reply with quote

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.
_________________
Toofah King Bad
  • WeiBe (1987 924S) - 931 S3
  • Red (1987 924S) - Pro44/Spec944
Back to top
View user's profile Send private message Visit poster's website
Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1066
Location: The Netherlands

PostPosted: Thu Feb 18, 2021 7:15 am    Post subject: Reply with quote

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
Back to top
View user's profile Send private message
Cédric  



Joined: 27 Aug 2004
Posts: 2100
Location: Sweden

PostPosted: Thu Feb 18, 2021 8:09 am    Post subject: Reply with quote

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.
_________________
1980 924 Turbo
Back to top
View user's profile Send private message MSN Messenger
Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1066
Location: The Netherlands

PostPosted: Wed Feb 24, 2021 6:30 am    Post subject: Reply with quote

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
_________________
937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
Fast road camshaft
Forge recirculation valve + boost controller
Back to top
View user's profile Send private message
!tom  



Joined: 28 Aug 2006
Posts: 1910
Location: Victoria, BC Canada

PostPosted: Wed Feb 24, 2021 8:11 am    Post subject: Reply with quote

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

Your setup seems backwards.

You may wish to tune this with your swaybar.
_________________
78 924 NA
5-lug
Back to top
View user's profile Send private message Visit poster's website
Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1066
Location: The Netherlands

PostPosted: Wed Feb 24, 2021 8:09 pm    Post subject: Reply with quote

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
Back to top
View user's profile Send private message
Cédric  



Joined: 27 Aug 2004
Posts: 2100
Location: Sweden

PostPosted: Wed Feb 24, 2021 9:06 pm    Post subject: Reply with quote

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.
_________________
1980 924 Turbo
Back to top
View user's profile Send private message MSN Messenger
Display posts from previous:   
Post new topic   Reply to topic    924Board.org Forum Index -> General Discussions All times are GMT + 11 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group