Cheburator

As per the title, can someone tell me the length of the springs used on our cars or even better, if someone has Carl's kit and is willing to measure it...

Thanks in advance,

Alex

Ispeed

front 8"
rear 12"

Sab

I bought the kit and the car sits almost a factory spec height even though I screwed it all the way down.
I am abit confused why there is about 10 inches of thread on the adjustment and 9.5 are useless...
If I was to screw it all the way up it would sit at 35mm height, kinda like for offroad use...

Jim bailey - 928 International

The shoulder on the Koni 928 shock dictates where the threaded sleeve must sit so all the extra threads must be higher one could easily cut off much of the sleeve to replicate the factory sleeve which might cool the shock better.

Sab

So how can one lower the car any further?

Jim bailey - 928 International

cut the springs (increases spring rate) , get shorter springs ... Fabricate different upper mounts.

Carl Fausett

The ride height adjustment sleeves we manufacture for the 928 are 5" tall.

The following two photographs are from a 1990 P928 with pretty normal curb height. This car is about .5" below spec curb height with these settings.

As you can see, at this setting, there is room to lower the car about 2 inches more and or raise the car about 2.5" inches. The spring perch is just below center on the threaded sleeve.

The threaded sleeve is made from alluminum and hard-coated for anti-corrosive purposes. The 5" sleeve is sweat-fitted onto the Koni shocks and provides a finned exterior to dissipate shock absorber heat quickly, aiding in a consistant shock dampening action.

Shocks that are not cooled are known to get softer during a race as the fluid within them gets hot and less viscous.

These ride height adjustment sleeves only fit the Koni reds. They do not fit Bilstein or Boge shocks.

Carl Fausett

Please be careful lowering the 928. The first thing to hit the pavement in the front will be the alternator and/or the AC compressor. A cracked block is the result - and often a repair that is so expensive it spells the end of the car.

I make protection plates that we strongly recommend to save your motor if you plan on lowering the car.

Okv

Original 1991 928 GT springs:

F: 45 N/mm (257 ib), 340 mm (the spring compresses to a length short enough to not interfere with upper a-arm)
R: 33 N/mm (186 ib), 400 mm

Spring rate and length data calculated from information found in the manual and PET, thus may be inaccurate.

My new coilovers, from Mobeck in Nisse, Bilstein BM5 on modified original mounts:

F: 500 ib, 300 mm (12") (diameter of spring must be small enough to clear inside upper a-arm)
R: 350 ib, 300 mm (12")

I can post an article here about the suspension tuning and modifications if you find it interesting.

Cheburator

I would be very interested to read it, so please post it!

Thanks to all the other who contributed too!

Alex

Sab

+1

Chuck Schreiber

Hey Carl,

Not to get too far off topic here, but in other related news....
Will be looking for a spring/shock combo upcoming for the GTS.

If you look back through Rennlist threads, seems that there are mixed reviews on the Bilstein/Eibach combos (some love em, some think they might be a little harsh on the street) I haven't seen any (maybe I missed something) bad reviews on the Koni/Hypercoil setup. (Dating way back to the Devek Days) I've ridden in some of those cars and they seemed to be planted, but not too harsh. But again, these were "rides" and I didn't have to live with it every weekend.

Question to you, Here is your setup options straight from the website for the hypercoils:
Front Rear
OEM 215 120
Street 300 200
Street+ 400 250
Street/Sport 500 350
Sport/Race 600 400
Race Mod 850 450
Race Pro 1000 500

Devek used to pimp the 600/400 setup for the street. I know there are a decent # of folks probably still running that setup with their externally adj koni shocks. You have them listed as more of a sport/race setup. You thinking that they ARE too harsh for a weekend driver? More of a DE or a race setup?

Give me your thoughts on that one. Again, just trying to get more info as I'll be on that path eventually. Thanks!

Vilhuer

600/400 Leda setup in friends S4 is little too harsh in my opinion. I would go with 450/300 or 500/350 if I would get setup for myself.

Cheburator

Depends on the tyre / wheel combo that you are running too... Have driven a 600/400 set up on 16" wheels with 225/50/16 and 245/45/16 and was sweet. Yet I believe that this would be harsh on a GTS-like 17" set up...

Ispeed

I have the 600/400 and my recently revalved Bilsteins. I am 100% happy with this set up for not-too-rough roads, highway and twisty driving.
The Bilstein revalving is pretty cheap at $65 a corner, and a good solution you get it right and don't care to change it up.

I feel that the Boge and Bilstein shocks are valved for stock springs, and when you go stiffer the dampening is too light. That explains the bouncy ride many complain about with the Bilstein/Eibach combo. So; really only an adjustable shock or a revalved one will be a good match for stiffer springs. This is my opinion.