Rich9928p

I would bet that 90% + of 928s are not within factor ride height specifications.

I was getting tired of my GTS scraping the front chin spoiler over every curb. I also noticed more tire wear on the inside of the tire. My S4 that I purchased 7 months ago didn't have the problem scraping. It was time for a ride height check. I thought that my two previous dealer alignments included ride height settings. WRONG.

FACTORY SPEC for S4 and GTS:
Front: 190 mm (-20mm)
Rear: 173 mm (+/- 10 mm)
Fuel tank should be full. The tolerance towards “too low” spec is permissible on used vehicles, however, this must then be the case for both axles.

For S4 and GTS The height measuring points are
- Front: the wheel contact area (floor) to the measurement surface on rear control arm bearing.
- Rear: the wheel contact area (floor) to the measurement surface on cross member

Earlier 928 specifications may have different measuring points, thus the specs may be different. Check your tech docs for specifics.

My initial measurements were:

RF: 135 mm LF: 131 mm

RR: 147 mm LR: 144 mm

I was WAY under height specification, especially in the front. No wonder why I got a lot of scraping. Ride height adjustment is an inexact science, one adjustment affects the opposite diagonal side. So it took a bit of back and forth cranking.

After a few rounds of adjustment, my final readings were (after a 10 mile settling drive):

RF: 170 mm LF: 167 mm

RR: 155 mm LR: 151 mm

I wasn’t in the car when the ride height was measured so I don’t have a problem with the left being a little higher then the right. The front may settle down a bit more with road miles. It is necessary to drive quite a bit for the car to settle down to its normal ride height between settings and measurements! I'll see if I need another round to bring up the rear to spec.

Each 360 degree turn of the spring perch raised the car approximately 3.5 mm in the front and 1.1 mm in the rear (your results may vary).

Note, your front and rear alignment should be checked after resetting ride height.

Before the adjustment, the front tire was just about even with the top lip of the fender. After the adjustment, the tire looks “centered” in the wheel well since it was raised 35 mm (~1.4 inches). It looks high after seeing SO MANY low 928s.

For earlier 928s that don’t have adjustable ride height, check with your local 928 mechanic. There may be a reliable way to “shim” up the springs in the perches or replacement springs may need to be installed.

There are several added benefit of increased ride height

a) reducing the chance of striking an object that will hit the oil pan, oil cooler (that sits BELOW the radiator in newer S4s and all GTSs) and the A/C compressor. If either of these low hanging objects are struck a VERY expensive repair could be needed. I’ve heard that A/C compressor strikes can break off the ear on the block and replacing the engine block becomes necessary if you want the compressor to stay in place!!

b) improving steering response. When the ride height is set properly, the tie rods are parallel to the ground surface. When the car flexes up and down the toe-adjustment changes the least. If the car is sitting too low, the toe setting varies much more and bump steer can be felt.

Ispeed

Amen to that. I just recently re-checked the ride height on my '89 that has new Eibach springs, and it has dropped in the last 3 weeks since I had it re-aligned. The new springs must be breaking in. Anyways, lots of toe out!!! I raised the height, toed the front in, but I'm not through dealing with it.

Pain in the a$$!!!

Chuck Z

This one hasn't even settled yet. Kinda looks like a "four wheeler" when they're at the factory setting b/f any settling has taken place. Thought I'd like to lower the front a bit until I realized it can't be lowered!

Garth S

Another Amen to proper adjustment: My S4 was also low when received, and I raised it to an even 166mm all around. With new shocks & tires to install, it will be tweaked to 170mm and realigned again.
I recall the rear thread pitch to be 1.5mm, and the front must be close to that - meaning that each turn on the adjuster should only raise the car that amount - but there is the loading , or diagonal effect as noted: on turning the adjuster, the shock is extended, but the spring is not further compressed - so the adjustment should be fairly linear with a settled suspension.

fst951

The shock is mounted inboard of the hub causing the wheel to raise or lower to a greater extent than the shock. Much more so at the front than the rear due to the suspension geometry. Also, progressive springs (928 Spec. Eibach's for example) will not show a positive or negative adjustment as quickly as a single rate spring. There is a lot more give to compensate for.

Dave

Thom

Chuck Z - are you going to drive the '78 or keep it as a garage queen ?

Nice car, by the way.

Chuck Z

Thanks Thom,

Since the car has only 1,400 original miles and is probably one of the last mint original unique 1978 928s left in the world, it would be a crime to put a bunch of miles on this car. Fact is, this is probably one of the lowest mileage 928s in the world of any year. I will drive it some to keep the fuel system clear but we didn't buy it to wear it out. How many opportunities does one get to step back in time and drive a brand new 1978 928?

There are parts on the car you cannot get any longer and some are different colors than the parts currently on the car for example, the interior op-art fabric is not available, you cannot get the intake tubes and the rear drop links are now black.

docmirror

For S4 and GTS The height measuring points are
- Front: the wheel contact area (floor) to the measurement surface on rear control arm bearing.
- Rear: the wheel contact area (floor) to the measurement surface on cross member

Well, I'm out herre trying to set my ride height, and need some hep please. Can someone point to where the "measurement surface on rear control arm bearing" is? I've found the rear control arm bearing(bushing) I think, but it appears to have a contour. Since I'm working in mm, finding the right surface is kinda critical.

Same help needed with the rear measuring point

Thank you!

jserio

section 44 - 3 in wsm. Points right to it.

jpitman2

On the rear metal bridge holding the arm to the chassis, in the centre of the hump is a 1/4-3/8" flat round spot - thats it. Similar round flat spot on the bottom of the rear cross member, under the lower arm pivot fixing.
jp 83 Euro S AT 48k, just BTDT again.

Nicole

I said it before, and will say it again: The ride height adjustment on my car made a world of a difference in both ride comfort and handling. Before, the car was hard to handle in bumpy turns - it felt like it was jumping all over the place. And I'd bottom out all the time, sraping front spoiler and belly pan, or the metal guides on the frame rails. Once the ride height was corrected, the car felt like a newer, better design, more than one class up. It's much more pleasure to drive it as it is now!

onebad928s

well my front spoiler is about 3 inches off the ground so as i take the sharp turns in the autocross it scrapes the ground.My adjustment perches on the coilovers are set all the way down.

Lou
83 928 5speed

justin

Im sorry, I have mine lowered, and it handles better, I would imagine that if you dont run the "good" shocks up front and back, it would be tough to drive.

onebad928s

trick of the trade when you lower the car you must cut the rubber or sponge in the shock assembly otherwise you get what they call "bump steer"

Lou
83 928 5speed

Earl Gillstrom

This is a quote from my alignment website: http://members.rennlist.com/captearlg/
CORNER BALANCING

I have found that when properly balanced, the spring perch adjustment nuts for most 928s are the same height on each side of the same axle. Apparently Porsche springs are very accurate. I therefore recommend that during ride height adjustments, you make the spring perch height the same on each wheel of the same axle. You may end up with the ride height slightly different from side to side, but the car will be close to corner balanced and the difference will not be visible. Keep in mind that the car is not the same weight on each side (passenger side heavier on LH drive cars) and the sway bars may not be perfect. Also, if you have Louie Ott drop links, un-bolt the lower rod end attachment from the lower control arm during ride height adjustments and adjust the length so that the bolts just slip on when you re-install them.