littleball_s4

It's in the WSM. Photos there worth a million words.

By the way, lowering the car should not affect ride as long as shocks are ok. It may affect cornering, as the roll center changes, but not ride; as long as you don't hit bump rubber or bottom the pan.

fabric

Sharkskin posted it a while back:

https://rennlist.com/forums/showpost...4&postcount=11

edit:
This seems to get asked a lot:

http://members.rennlist.com/fabric/ride-height.html

RichS 1986928

Wow, 30 replies in one night, Thanks guys!
I tried to keep the subject concise but there's just obviously a lot of
non-definite opinions out there on this subject.

My biggest problem is what I have to compare to. The most spirited driving I've ever
done was in a Chevy S-10 that didn't even have a sway bar. So as you can imagine
the 928 is already night and day. Yes, I waited and saved and actually made the jump
from the pickup to porsche... With this in mind you should know that even the softest
928 would seem like it's on rails to me.

I did get a chance to drive an 85 with Stock springs and Bilsteins.. however I couldn't
really push it, but it did seem a bit harsh for my liking and the shocks were old.

So I'm trying to accomplish two things here. #1 stop the really rough ride, #2 possibly upgrade
and consider a future spring upgrade.

I live in Seekonk MA now but I'll be moving to Colorado soon and the roads are much smoother there, less huge potholes and no frost heaves. I'm running CUP IIs with Kumo 712 tires, 225/45-17 & 255/40-17.

I'm going to be doing the work myself. I'm leaning towards just replacing the stock Boges right now
but for $200 more it's very tempting to have the flexibility of an adjustable Koni.

So to narrow this down: Thoughts on Boge vs. Koni with non-sport stock springs?

SMTCapeCod

Bear in mind folks, the OEM Bilstiens can be rebuilt at Bilstien, last I checked for $65 per. And can be custom valved at that time too....

Jim bailey - 928 International

Perhaps worth noting...."it's very tempting to have the flexibility of an adjustable Koni." that the standard Koni is ONLY half adjustable. The compression valving is fixed and all you play with is rebound rate.

the flyin' scotsman

The WSM pages 44-2b and 44-3 gives the ride heights and pictures of where to measure.

svp928

I have the Bilstein/Eibach combo on my car, and live on some of the world's crappiest roads. I think the Bilsteins could stand a little more rebound damping, but generally soak up the small to medium bumps pretty well. My car is lowered quite a bit, and on really big bumps will contact the 'skid plates' on the pavement. Also need to remember if lowering the car, to cut down the bump-stops on the shock. Bouncing off the bump stop will produce the 'bouncy' ride and porpoising. On the track, the combo works fairly well for the occasional weekend. I think they are a good compromise for street/track, but definitely too stiff for a 'luxury' ride. For comparison, when stock, I was able to get the car to move up and down 1-2" on the suspension by pressing and releasing the front bumper, and the rear above the bumper w/ hatch open. With the new stuff, I can JUMP on it and get nearly zero movement. No bounce at all.
I think my car is set too low for for comfortable street driving, I always worry about breaking the A/C bracket or something against the ground on a hard hit, but, it handles very predictably on the track, and I'm too lazy to change it every time I go.
Just my .02....

Steve

Steve

Garth S

RichS,
I have been very satisfied with the combo described in post #15 - ie linear springs over Konis .... set at 165mm heights: this setup is unperturbed by nasty pavement, very stable, etc. You can sense every pebble without feeling in in your butt - and equally as Steve has noted, I cannot 'bounce' the suspension.
Having stated a preference, many are justifiably very pleased with Bilsteins, generally with progressive springs: I have Bilsteins with progressive MO30s on a 993 ... at a mere 128mm - absolutely great, but perhaps as pointless to mention other than to illustrate that what is correct for a 928 depends largely on your driving style and preferences - and available roads.

Bill Ball

The front ride height measuring point is very hard to get to if you are on the ground. I measured the difference between the point and the lowest point of the surrounding walls of the A-arm bracket as 10mm. It's much easier to put a ruler against the outside of the bracket and add 10mm to get the correct number.

Bill Ball

I must have gotten bad shocks from Koni both times. It was easy to bounce my sport spring suspension up and down quite a ways, although less so with the second set.

fabric

That is true, good tip Bill! I"ve added that info to the page.

jon928se

Taking a mental straw poll from this and other threads discussing "odd" or "unsatisfactory" handling with new shocks, it seems that the common factor is ride height less than factory settings.

Spring "preload" is not affected by ride height, ,the only thing that affects that is the static weight on the spring. So spring behaviour is unaffected.

Got me to thinking that shocks could have different damping rates depending upon whereabouts the "piston" is in the overall stroke of the shock. ie bump damping increases as shock is compressed, rebound damping reduces as shock is compressed and vice versa.

Assuming the shock is designed with the normal ride height "at rest" position in the centre of the stroke, by lowering the ride height so the shock sits at say 4/10ths extended that would change the damping behaviour from as designed, to being more bump and less rebound on initial displacement.

Any merits in this theory?

Bill Ball

Dunno, Jon. All I know is George Sunnen has Konis on his 90 S4 sitting at 120mm with standard springs and the road handling is superb except for those pesky speedbumps.

Tampa 928s

Ready to replace my shocks have Borg factory now; will this require changes to the struts to add add Bilsteins? All the menbers have an idear on the B and K but not much on the Borgs. I'm not going to race this car; will I be happy with the Borgs or go do a change if required, for another type. How about ride hight with the large tires in the rear any problems with this set-up?
Tires
Rear P-255-50zr 16
Front P-225-50zr 16

Bill Ball

What are Borgs? Eh, I know what you meant, but what year is your 928?