Measure it with the weight of a driver in the driver's seat and see what you see. Car level then?

 

Something I'm hearing from Bill's posts is dissatisfaction with the way the wheel fills the arch. This is one place where, I think, the designers and engineers didn't coordinated the results. My guess is that the wheel is supposed to be higher in the arch for styling, but with stock ride height there's a 2" gap.

The selection of shock and spring doesn't change the geometry of the suspension. Once the ride height is set to a specific number, the gap over the wheel will be the same with any shock/spring combo.

I run my car at 155mm all around. Really too low for street use. Won't be long before the spoiler is splintered. It does look good and handle well and I don't mind that it limits the approach velocity to driveway ramps.

 

You are right Glen - I am not happy with how the wheel fills the arch. More importantly, I am not happy that there is a mismatch in how the car sits higher on the drivers side than the passenger side. I am sure, as Thaddeus suggests, that the car will sit a little lower with 200+ lbs of me in the drivers side, but if I had a passenger of similar weight than the car will not sit correctly again - i guess I would be surprised if Porsche deliberately engineered the car that way. I guess I am curious if other owners have this same issue - i have seen a lot of pics of other 928's that don't show that large of a gap.

Maybe a better question would be: How do i change the gap between the tire and fender lip without altering the ride height?

 

Bill, any sign the car was ever wrecked and/or resprayed?

 

I need to check/adjust my ride height soon. Let's say you knew you knew how far things needed to be adjusted. Could you simply mark the current position on the collar, and then adjust and check the travel on the collar? In other words, does a 10mm movement in the adjuster equal a 10mm movement in ride height? I know this seems like an elementary question, but I'd hate to find out that it's not a 1:1 ratio and go do something stupid (like that's never happened before... doh!).

 

Andrew;
From my experience with ride height adjustment, 8 turns = 12mm of ride height = 25mm of body lift (as measured at the fender lip). At least these were the figures I experienced on the front of my car.

Garth's note on the adjuster thread pitch jives with my field experience...1.5 pitch x 8 turns = 12mm. This is good to know and makes perfect sense.

So, I would think that you could indeed guesstimate the number of turns for a given ride height adjustment. As always, measuing to the factor ride height reference marks are best. But if you want to check things from the fender lip, then remember that this measurement will be 2x the ride height ones (1" ride height increase/decrease = 2" body height difference at the fender lip).

Regards,
SteveCo in St. John's

 

Thanks Steve. I will indeed measure form the factory marks, but may need to remove the wheel for better access and stuff - so i wanted to be sure I could move the adjuster by the amount needed and call it good. Of course, I'll recheck after driving the prescribed 50 miles, but it's good to know this stuff before you do the job.

 

I've danced this dance a few times, and have to remind myself regularly that adjustments made with the car either on the ground or in the air will not show up accurately until the suspension has been flexed by driving the car. I have a closed-circuit loop of local roads with 15 MPH speed bumps, I rip[ through them at a screaming 30 MPH a few laps, them come back up to the house and measure again. If I have had the car up, no measurements are valid until at least 50 miles of road have been covered, and that's after the laps of the speed-bump course. The suspension bushings and the shocks seem to have a pretty high breakaway friction.

Best way to get the car's load sttraightened out at this point may be a real corner balancing. A year or two ago, there was a pretty brutal crash on my local mountain playground road. the car had been recently upgraded to Bilstiens and Eibachs, but the ride height was just roughed in. Weight transfer left or right caused the car to shift fore and aft, since the car was really sitting heavy on two opposite corners.

If you can't do a real corner balance, at least start off with the same number of threads right and left on each pair. Adjust the front pair to the same number of turns up or down from there, and do the same on the rears. Not same turns front and back, just same turns left and right. From there, you'll have at least a reasonable starting point for balance.

Reading that one side is way high and one low on the front probably means that the rears are the opposite to get the car at least close to level right-to-left.

Be aware also that our 'used' cars aren't always perfectly square and true. You'll make the compromise settings that have the fronts as close as possible with the rears as close as possible too. Both may be a bit off, but in opposite directions.

I kick myself for mentioning now seven years ago that the fender lip height is a good indication of height. It is, but it's a rough indicator, more to see how badly the car has drooped over the years. It's not a definitive method by any means.

 

Bill,

It's nearly impossible to lower the fenders without lowering the car. You'd have to mod the fenders or frame to do it.

It's a lot of PITA work to get the height adjusted right. Measure, adjust, drive, repeat. I'd pick some target values for the measuring points that will work for you. (160mm front and 170 rear?) I don't suspect that anyone will notice if the fender gaps are different.

One thing to try is to put a level across the strut tower bar. That should be level or have the same slope as the floor. Most garages aren't too flat.

 

Bill,

Having just gone through this adjustment, I can say that it requires a lot of patience to get it right. The car has to settle after each tweak, and that involves about 50 miles of driving... like another poster, i have some back roads that I use for this. If you do not settle the front suspension, you will be adjusting for infinite things which you will have no way of keeping track of..

If you want to fill the wheel well, get wider tires on properly offset rims..

I posted a pic a few days ago that has the front wheel wells filled up with a 285/30-18 front tire on 10 inch rims...

HTH,

 

Thanks again for all the suggestions guys. To answer your question Dave - neither of my 928's have been wrecked - I am positive of that. Also, I have taken both cars out for some very spirited driving to settle the car, so I think it is about as settled as it can be. I guess what is strange is that both of the cars have the same behavior - the driver side collar is all the way down, but there is still a larger than acceptable (IMO) gap between the wheel and fender lip, while the passenger side still has some downward adjustability, but the gap is less pronounced. Maybe I am being **** about this, but it just doesn't seem right.

So, I am going to experiment this weekend and swap both the shock and spring combo on the cars and see what that does. If my assumption is correct, and I don't adjust the collar on the shocks, than the behavior should transfer from one side of the car to the other, right? If that is the case, than the spring tension is probably the culprit. Otherwise, it has to be something intrinsic to the way the body and the A arm fit together. I will keep you posted...

 

Bill, that eliminates one possibility... I thought there was a left & right to the shocks... or is that just the rear?

 

Another tip to make ride height adjustments much easier. Don't know about any but Koni and hypercoils, but for those, get some shock "bearings". Chris Alston's Chassisworks is where I sourced mine for the race car. He also has available some cool little wrenches to turn the adjustment collars..These bearings, they are thin(about 1/4" max) with roller bearings beween two stainless "races" You place em between the spring perches on the shocks and the bottom of the springs that normally sit directly on those "collars" or perches...You can simply crank away without even jacking up the car, or more realistically, it makes it much easier to turn the adjusting collars/perches..These bearings are especially useful if you have full heim-jointed shocks that can't spin at the top..saves undoing the whole package for each adjustment..
Don Hanson

 

Blimey lots of myths and old wives tales.

The only way you can get ride height correct is using the factory measuring points. If any one here has refitted a front fender they'll know how flexible they are and how much you have to bend them to get the panel gaps to be straight.

175mm all around is a good starting point for a street car.

Its probably a 3 stage process measure all 4 corners first on your flat garage floor ( left too right slope the same at both ends doesn't matter much neither does fore and aft slope so long as you don't have both.)

Then disconnect the sway bars on both sides (The rubber bushings on the sway bars act like springs so you have to disconnect both sides unless you have greasable polyurethane sway bar bushings).

Then jack the car up remove all four wheels and free up the adjusters having first noted where the adjusters were. Once they are moving adjust the front in the ratio 1/2 adjuster movement on the shock body to the amount you needed to get that corner correct. 3/4 adjuster movement at the rear to get that correct. I'll say that again - 1mm adjuster movement at the front makes 2mm ride height movement. 3mm at the rear makes 4 mm ride height.

Then put it back on the wheels and go drive it hard for 30 miles of corners and hard braking. It won't be correct but hopefully it will be a lot closer. If it is still miles out measure all 4 then jack up and adjust as before. If it is close adjust without jacking up then go and drive it like you stole it again. The do the final fine tune.

As others have said above if diagonally opposite corners are one low one high then maybe take out half the error at one end and half at the other, then recheck.

It aint rocket science just perseverance.

I'm trying to picture how much space there is to measure the the ride height with the car on the ground but I can't - I never found it a problem cos I am tall (6') and thin (150lbs) with long thin arms. I don't think it was so tight that somebody with arms twice as big as mine couldn't get too it.

Jon in NZ

Done this about 4 times now on the SE exactly as above but without the wheels off - I made sure the adjusters on the Bilsteins wouldn't get seized when i put them on.

 

try adjusting the rear pass side up a little, to see if that has an effect. (rocking table theory)