Engin

After driving my 964 at its original SUV height for around 8 months, I have opted for new (original) shocks and a set of Eibach lowering springs.

Although the car handles a lot better/neutral (I have also changed camber and toe-in settings to achieve that) it is really too stiff for day to day driving. I have looked in the catalogues, but did not find any lowering springs that have a lower rating.

Here comes the suggestion:

I am in the process of manufacturing softer lowering springs, (that will achieve the same effect of the originals, just shorter). I wanted to find out whether I am the only one to think like this or would there be anybody else interested? If anybody is interested, I can supply info on the material, manufacturing process, the actual rating of the springs in a couple of weeks, since I plan to be out of the country on a business trip next week; maybe even manufacture a few extra sets once I am satisfied with the solution on my car.

Kahdmus

I find my H&R 965's and Bilstein heavy duty struts to feel more comfortable over the stock setup 90% of the time. The exception only comes when I encounter a road in very bad condition or the car hits a pothole (my wife drove the Porsche for the first time with the new suspension last week and drove straight into a rabbit hole on the road, ouch!)

Engin, what type of spring rates are you thinking about?

BGLeduc

My experience with Bilstein HD's and H&R (the 964 not 965 progressives) matches Howards perfectly.

For virtually all situations, the overall ride quality is actually better. Then again, I live where the roads are usually pretty good. I don't know what the road quality is like in Istanbul, so it may not be a valid comparison.

My stock set-up had about 50K miles when I did the update. It has been my experience in the past that when gas dampers begin to age, they actually seem to be stiffer and are less compliant, so perhaps its a damper thing.

If all you want to do is lower the car with stock components, an old racer's trick (when rules required that parts not be upgraded) is to have the springs heated and collapsed. The spring rate will remain unchanged, but the ride height will be reduced.

Disclaimer: I have never actually done this, nor do I know anyone that has....but I have read of this process.

Out of curiosity, are the Eibachs progressive? Again, a progressive spring would normally be softer for the first bit of wheel travel, and should be able to improve the ride quality versus a standard rate spring.

BGL

Engin

Howard,
I do not know the spring rates of the originals (Adrian also doesn't provide spring rates of the originals in his book). The guy who is going to manufacture the new springs has them and will provide me with the rates next week. Perhaps I'll experiment with something between the Eibach and original rates.

BGL,
You are right, Istanbul's roads are not the greatest. On the other hand it should not be a damper problem, as the dampers are all new (but stock items).

Kahdmus

Engin, did you replace the struts with new ones when you changed out the springs? If not how old and what type of struts do you have? --H

Bill Gregory

This was in the March PCA Pano in the 964 Track Preparation article:

89-91 C2 and C4 Front: 158 lbs Rear: 189 lbs
92-94 C2 and C4 Front: 169 lbs Rear: 189 lbs

91-94 Option M030 Front: 169 lbs Rear: 263 lbs (progressive spring working rate)
93-94 RS America
91-92 Turbo 3.3

1992 Carrera RS Front: 247 lb Rear: 440 lb (both progressive spring working rate)
1992 Carrera Cup USA

Carrera Cup Racing Front: 200-600 Rear: 240-800

If you're going with shorter springs with stock shocks, you may force the shocks to work outside the range they were designed for, which can shorten shock life and affect ride. When you change spring rates, to get the benefit of the new rate springs, you should ensure your shocks are matched to the springs.

To give you some idea of shock rate differences, here are the Bilsteins:

964 to 1990, Front: 332/104 Rear: 274/122 (note HD shock)
964 1991 on, Front: 332/104 Rear: 277/124 (note HD shock)
964 RS, Front: 259/84 Rear: 415/237
964 Cup, Front: 220/67 Rear: 379/172
964 3.8 RSR, Front: 237/96 Rear: 402/216

Those values are read rebound/compression.

Kahdmus

Bill, any idea what the H&R 966 and 965 springs are?

Bill Gregory

Aren't those listed in the Performance Products catalog? I don't have an H&R listing handy, sorry.

Kahdmus

ooh, I have one (in the bathroom I believe!LOL!) <runs and gets it>

yup, looks like it (nice one Bill!):

964: 190-225F 220-265R
965/RSA: 250-275F 270-295R


Cheers,

--H