Kolbjorn S

That's my understanding too. My car was delivered with M474 however no M639 is listed. But when inquiring at the P-dealer their tech said the springs on my car appear same as the GT, so hence it seems the ROW M474 indeed comes with stiffer springs. Are there any visual difference(s) between standard / GT springs, how can I tell them apart?

Chris

Two white marks on the springs. From what I can gather 87+ with Boge had white marks.

1 white mark = 6377 ... 6573 N
2 white mark = 6574 ... 6769 N

For Bilstein equipped cars white/green mark.

white/green mark = 6377 ... 6630 N.

Well that is my take from the workshop manuals.

I kept my front springs (two white marks) when I did the koni/hpercoil upgrade just incase they might come in useful in the future.

Chris

khalloudy

The Club Sport Springs for Europe and probably ROW are M637 and they are marked orange. The regular springs are marked brown according to PET. That is where i am getting my info from also the magazines actually

Chris

OK, you got me wondering, so went out to the garage, my old springs have 3 brown marks. My memory is going I guess ....



Then check PET, spring part number = 928 242 511 09, now back to workshop manuals.

1 x brown = 6375-6570 N
2 x brown = 6571-6766 N
3 x brown = 6767-6963 N

I can't find anything on Orange.

Chris

khalloudy

Chris,

I checked the WSM and Springs and went looking around. The White or Green and other marks are actually tolerance groups (one mark, two marks or three marks). The 86- cars had the brown ones shown above (both in S, S4, GT and GTS). The only apparent difference is the shocks Boge (red/blue) or Bilsteins. All the info above is available in the WSM 40-40 under the front suspension section and on. The only missing one is the M637 which is the european CS/SE version with stiffer springs that were developed by Porsche engineers so they can go have fun playing on the racetracks on the weekend apparently and ended up being sold on the market as CS and SE (UK only). The CS/SE are the predecessors of the GT literally - actually the GT seems to be an SE with a detuned springs and wheels which was then retrofitted with advanced traction control and others in 1990.
The question remains how stiff is the CS when compared to the S4 and GT. I apparently have a GT setup right now which is adequate (Boge Red + Brown Marked Springs = M474). But since I am changing the front springs, I would like to keep my options open M474 or M637 (Boge Red + Orange Springs... i have no specs on them, but european magazines mention a 10% stiffer setup).

Sincerely,

928SS

it's soooo subjective indeed. I have the same setup, w/poly bushings and it was fine w/the 16" wheels. w/the 18" wheels, the tire sway is gone, so its more precise, but then it did get to the point where I start dodging potholes. (probably a good idea anyway w/the low slung alt and ac stuff)

just my .928 cents... might try going for a ride w/other listers 1st...

slate blue

Stock suspension is pretty soft, Bilsteins tend to give a jiggerly rig imho any twin tube shock will probably give a better ride than a mono tube.

Rob not meaning to hijack, did you get back to the dragstrip? I think I missed the post if you did.

Greg

Cameron

I went with the CS front springs on my '91 GT. They are slightly noticably stiffer, but good for daily driver. I have read 8% stiffer, and I have read 10% stiffer than stock S4/GT springs. I don't know which. They are also about 1" shorter. Bottom line, my cd player started skipping on my daily drive to work in three places where it never skipped before, validating the seat of the pants difference that I thought I could feel. Now that I am DE'ing the car more regularly, I kinda wish I went even stiffer.

Ketchmi

There happens to be a set on Ebay right now!!!!

C.F.

Khaled
What you are saying there is similar to what I heard about another 928 owner, he didn't like the 'bounce',not major bouncing along the road just not total control.His S4 IIRC only had about 60k miles on it & the shocks were not leaking & he was told by a leading 928 mechanic that they were not worn out & that they didn't need replacing. Still unhappy with the ride he went ahead & replaced them anyway with stock Borg's. He was delighted with the transformation,NO more bouncing , so it seems that even if your shocks don't appear to be worn out just replacing them with new could be the answer .

928SS

not since beating the twinscrew gts I"ve moved on to Autocross stuff and getting my *** handed to me on a track w/curves by 4 and 6 bangers. but suspension isn't the problem as much as the extra 500-800lbs or so these sharks have - and my general incompetence

that bounce might be aggravated by 16" wheels w/higher profile tires too.. I still had some of that even w/my new suspension setup, but it went away w/the 18"s/ lower profile tires...

fwiw, I did get some minor wheel hop w/excessive wheel spin on acceleration that appeared after the suspension upgrades, but that went away after installing the LSD and 140 treadwear tires

imho, I suspect there is a lot of interaction btween tires and suspension - so to only compare suspension w/out a tire context could be difficult/misleading.

khalloudy

All,

thanks for the feedback. I do personally like my D90 wheels (even though they are outdated and 16" when ricers are running stock 18). I really like the stock look of the S4/GT and I want to maintain it as much as possible. I do have brand new Boge red shocks on the car so I pretty much have the M474 Sport Option right now. One thing i have noticed is that the car's ride has improved with raising the height towards the factory setup (this is one of the reasons i am changing the front springs that are sagging now and i max out at 160mm). The car is being shipped to Saudi Arabia this summer so i want to do all the fixes before it goes there. I am planning on bringing it here every couple of years for tuneup and all... but it will be living overseas now
Going back to topic, i like to maintain a stiff ride as i do drive the car fast and hard. I do not however drive it on DE or races on track, so i want to maintain a civilized composure specially when i have girls in it (hey i do put the car to good use )
I have 2 sets in my house right now (404 and 504). The first is the S4/GT/GTS, the second is CS. I am trying to decide really what to go for.

Cameron,

I know you race your car so you need the stiffest suspension you can get. For a daily driver, would you have kept the standard springs or would you still go for the CS? Do bare in mind i will never put this car on the track. You experience is appreciated.

Sincerely,

Cameron

For the street, I like the change to the CS springs plus the stiffer sway bar from 928 Specialists. For the track (DE not race) it would be nice to have even a stiffer ride, but the setup is a good compromise for me. If it was setup for racing, I would need something way way stiffer.

It is very subjective and I don't know what your preferences are. The shock choice will make a difference too. How are the roads where you are? If they are bad, stiffer suspension might just agrivate you.

I would say that if you want to stay 'stock' and want something stiffer, then go with the CS springs. They will firm things up a bit and are a 928 part, the stiffest factory spring made by Porsche for the 928. In terms of real world daily driving, I don't think that the change to CS springs on it's own will mean a lot to you in terms of performance. After all, on the street you are not likely approaching the limits of the stock suspension anyway.

Good luck.

Kolbjorn S

My front springs have 2 what-looks-like orange marks ... but perhaps it's just the brown that looks like orange (CS springs on a 12/86 car seems unlikely), it's hard to tell under there! What does the 6571-6766N mean...? TIA

dom1102

Im having the same bouncy suspension issues every time I go over a dip in the road. The car handles pretty strangely too. Also able to physically bounce the car very easily. The ride height is also very low, the front spoiler hits everything (It has not been lowered) My car has done 100k miles and has sat around allot, guess the springs & shocks are toast. I have tracked down a crashed GTS with 20k on the clock which is being dismantled for parts. I have the option to buy all 4 suspension legs complete. Im told all GTS cars have an orange paint mark (as opposed to brown!) to identify the stiffer springs and should be running "club sport" dampers as standard. Does anyone know if this is correct and how can I tell ?? Are there any other improved suspension parts (over the s4) I should consider taking?