Ride height adjustment: Check the nice write-up / procedure on Tony's website:
Ride height adjustment
A while ago, someone posted what correct ride height is at the wheel arches,
when using factory size wheels / tires. I believe it was 27" front, 24
rear. Is that correct? Also, some mention was made of how many turns
the spring adjustment would change ride height a certain amount. What is
that number? I would measure 1" worth of threads if they were
the collars are so far down that I can't see the threads to measure them.
( sitting pretty at 26" front, and 24.5" rear)
Chris, the proper ride height is 27" front, 24.5" rear. Looks like yours is an inch lower in the front than recommended. Also, if you're running 17" wheels, correct ride height would be 1/2 " higher all the way around, 27.5" front, 25" rear.
(nit-picking, while watching the "Power TV" guys doing a nitrous installation.......)
Another aspect I encountered when setting ride height was that doing an
adjustment on one corner changed the ride height at the opposite corner, so
their was no direct corresponding relationship between turns of the
adjuster and ride height. 1" may = 1" for the first shock, but
opposite corner is now being compressed/expanded. By the time you work
your way around the car, the ride height will have changed on the first
shock you adjusted.
Anyone else experience the same?
'88 S4 A/T
Dear fellow sharksters:
The proper measurement locations are: Front - use the lower control arm rear pivot, and rear - use the cross member bracket that allows the trailing arm to pivot. Both locations have tabs from which the measurement should be made. (This topic is well covered in the service manual.)
The allowable measurements are: Front = 190 - 20 mm, and rear = 173 +/- 10 mm. Also, the left to right measurement should be within 10 mm.
Make sure the car is on level ground and that the tires are properly inflated and not badly worn. Also, the fuel tank should be full. If you really want a near-dynamic height setting, ask someone that weighs about the same as you to sit in the driver's seat while checking the height.
Once the height is properly set, then take a height measurement from the fender wells. It will facilitate any future ride height checking, but it will only apply to YOUR 928, as no two 928s are identical. YMMV.
Question is for all those who have been down this path. I just upgraded my
MY85 to the Bilsteins and Eibachs. I also replaced the lower ball joints, tie
rods, upper ball joint boots.
My initial settings on the shocks were to set the rears half way up adjustment range and the fronts just 2 turns up from lowest setting.
I left the lower a-arm mounts loose and bounced the car to get to settle quickly as possible. It came down to normal height quickly and here are the initial heights:
LF 150 RF 145
LR 169 RR 171
I want to set as follows:
LF 163 RF 163
LR 175 RR 175
Question is does anyone have any idea how many turns of adjusters on Eibach springs is the equivalent of 5 mm/10mm of ride height change? I remember reading that for the factory springs, 6 turns is equal to 13mm of ride height adjustment.
The geometry is about the same. The spring is already compressed by the body weight. There might be some, minor, variation, but you're about right. From what I recall, it's 12 turn per inch. That be about...um.. 6 per 13mm!
If this tip ain't old: cut some sticks to length (163,175) and use those to gauge the height.
I am thinking of setting the ride height about 25mm lower than the factory
around 26" for front (ground to fender lip) and 23.5" for rear (ground to fender
This does reduce the ground clearance by 1", I am curious how much of an issue the 928 list thinks this will be?
I don't recommend it. My GTS had these measurements, it was way too low in
RF: 135 mm LF: 131 mm
RR: 147 mm LR: 144 mm
I had it adjusted up to
RF: 170 mm LF: 167 mm
RR: 155 mm LR: 151 mm
Before the adjustment I was scraping on every curb and low dip in the road. Now I don't need to worry. It also reduced the odds of hitting something that can punch a hole in the OIL COOLer that sits below the radiator, the oil pan, and rip the A/C compressor tabs off of the block (no repair possible)!!
When the front is low you also have the problem of bump steer, because the tie rods move at a different arc then the suspension.
It may not look as cool, but you'll get there in better shape.
Thank you, I am worried about scraping stuff of the road as well.
I do not think bump steer is an issue in a car that is lowered only 1 inch though. Esp. seeing that the factory manual states in a new car the ride height can be as low as 170 mm, I am guessing 160 mm or so has negligible impact as far as steering is concerned. Wheel offset is of course another story.
It looks like I will set the ride height at 160 and call it a day. I think at stock ride height the 16 inch front wheels look goofy in the wheel well ;-)
By the way, does anyone know what the height increase/decrease is with one turn of the threaded shock collar?
As strange as is sounds, I observed about 3 mm change per turn up front and 1
mm per turn in the rear.
Yep. German FSM, p. 40-45: A 5mm change of the adjustment nut will cause a
ride height change of appr. 10 mm.
Bora: You cannot determine ride height by measuring at the fender lips. My car is right on spec, but looks like it was raised an inch or so. When cornering hard, the front spoiler still almost touches ground, as some photos from a local track show. If you want to lower it, I think at the very least you'll need much stiffer springs than stock.
I'll answer your specific questions below. It should be noted that 928 suspensions, especially in the front have a huge amount of friction in them and it can be rather difficult to get them to settle easily. You can make yourself really crazy trying to do one axle at a time because of this, but the steps I outline below will get you close the first time around.
As a data point to be passed on to ANY alignment shop, raising the front end during an alignment will completely defeat what they are trying to do because most cars will hang up as much as three inches high in the front until driven enough for settling. They can be bounced back down, but you won't know if they're completely bottomed unless ride height is measured before the car is raised, then after it's back down on its tires. FAILURE to do this WILL RESULT in front toe settings so far off that they will wear out a new set of tires in only a few thousand miles. So if you ever have your car aligned, it's really best to find a shop that will do "rolling compensation" rather than lifting the car. It can be hard to find such a shop.
While the above might sound slightly off topic, it ain't. Raising and lowering the front of a 928 WILL affect the toe setting. If you have raised or lowered the front of your car any significant amount, you owe it to yourself to have the car aligned lest you say bye bye to those expensive Michelin Pilots. The reason toe is affected is that the steering rack is attached to the body and the tie rods attach to the steering arms at an angle. When you change ride height, the tie rods will pull or push on the steering arms which are directly connected to the wheels, resulting in the toe change.
> I am working on getting the ride height set on the front of my 85. I cranked the front on both sides up a lot and set the car back down.
> The measurement was 20 MM above the max. After driving the car for about a mile I measured things again and found the car is back down to below the setting points by at least 30 mm - maybe more. The rear of the car is still too high by about 20 mm.
> The question: How much does a single turn raise the height of the car
Threads on a 928 spring adjusting sleeve are 60 x 1.5, with the latter being the pitch of the threads. This means that a one thread change will move you up or down 1.5 mm.
An inch is 25.4 mm, which is a LOT of ride height change. Remember the advice in the opening paragraphs.
> Second question: Should I continue to set the front and ignore the rear or should I set the rear down to spec first.
Doing it without corner scales is simply a trial and error process. Drive the car at least three miles (I believe the FSM specifies five km) to make sure the suspension has completely settled. Then, without lifting the car, measure ride height and write down the variances for all four corners.
Then do what you have to do in order to wrap a piece of masking tape around the threads at a point that will mark the distance you want to raise or lower the car. Then do what you have to do in order to crank on the adjustment collars until they are even with your tape markers. When all are adjusted, drive the car the required mileage and check your ride height again. You'll be pretty close at this point, maybe not for a racer, but easily close enough for a street driven car. Remember that you really must have the front toe checked, not because of any small differences, but because any change in ride height will affect it.
> Third question: Is there a quick way to insure that one side is not holding up the opposite side by too much without going to the trouble of corner balancing.
Probably not. All four corners mutually affect each other. The larger the differences among the four corners, the greater the chance that you'll have to fine tune your settings before you get them right.
I hope this helps. No reason not to do this much at home, but you need to know the effects one aspect has on others.