Rob Edwards

Old pics, worth dragging out (again):

Front:


Rear:


Dr. Bob- inspired high-tech measurers:

Captain_Slow

Yes. I thought the PB Blaster helped because it made it easier to turn the adjuster collar, but it was simply making it easier to spin the fused collar/sleeve on the shock body nubs.

Dr. Bob, I've been measuring at the points shown in Rob's pics, but I hadn't considered the front points were behind the front tires. Good point. So I think I probably had a full tank of gas when I measured in th fall, and I'm at about half a tank now. Could even be tire pressure is low.

I'm going to measure the distance from the bottom of the adjusting collar to the inner ring/sleeve. Looking up from below last night, after seeing the WSM picture posted above, I thought the collars/rings setting looked identical to the WSM picture (inner ring set flush with top of collar).

This leads me to agree with Ivan...It could all be due to tired sagging springs.

Captain_Slow

Distance from bottom edge of collar to inner ring is 1.5 cm (a little over half an inch). Does anyone who has assembled these know if this close to factory specs? If "yes", then the springs have sagged.

DR

Jon,

Not sure if you have tried this but after soaking in the PB Blaster trying turning the adjuster with the coilovers loaded, i.e 928 sitting on the ground. Yeah it is a pain to reach the adjusters but I have unstuck a few doing it this way. Sometimes the extra pressure of the weight of the car will be enough...sometimes not, but it is worth a try.

Cheers,

Dave

Captain_Slow

Dave - You read my mind, but I couldn't imagine getting the C-spanner on the collar AND my body in a position to pull on it I'll give it a try...I'll turn the wheel to right and left in search of the best access to the collar.
Thanks

dr bob

Just a couple thoughts--

Dave has a good idea trying to adjust with some load on the adjuster. At 165 front height, I can easily reach around the tire to get the spanner on the adjusters.

The TPI on the adjuster doesn't match the net effect perfectly. The shock has a slight incline that reduces the ratio some, while the position of the shock connection on the lower control arm means the ratio is increased some.

My original springs sagged just from sitting it seemed. I ran out of adjustment on the front trying to maintain 175mm so I could get in and out of my driveway, a slow losing effort. With Eibachs in front and new stock rears it's been easier to keep stuff from dragging. Springs do get tired and saggy over time, in spite of some theory that says it shouldn't happen.


IIRC, there is a right-side-up on the threaded part that sits on the nubs on the shock. Installed correctly, it actually slides over the nubs a bit.

mark kibort

understand that 1" of spring perch change can make 5" of ride height. (something close to that in the front). also, you wont know what you have for a long time of driving on it to have it settle.
150mm front and rear is a good setting for street performance. race set up is near 110mmft and 130mmR

Bertrand Daoust

150 mm front may look good but was to low for me.
Bottomed the car few times at that height.

Now I'm at about 170 or so in front and very happy with that.
New (to me) adjusters from 928 Intl. and new Boge shocks.

The ride is way better.

The old adjusters were seized in place. Nothing to do with them!

mark kibort

got it.. yep, as long as its around a finger or a finger and a half, from tire to fender lip, im ok with the looks. that could be around 150 ish..... 180 is just too high, huh!!

supercedar

I like the 170 in front for a smooth ride, I am old.

dr bob

Factory knew nothing about suspension geometry when they designed and built the cars. No reason to follow their guidance, which allowed sag as low as 170mm in front before the dealer was instructed to restore original design height. Follow MKs guidance, using precision fingers between bat-rolled fenders and non-stock tires on odd offset wheels. That will give you maximum amount of bump-enhanced steering effect, a most desirable trait. Plus the shock damping is maximized when they are compressed that far, making for a more go-kart like ride quality. It's the way they should have done it at the factory.

mark kibort

I drive supercars almost everyday, as well as the 928.... the 928 handles better, and rides better than any car I've driven. its the EASIEST car to drive, it tracks better than any of the new cars i drive daily...... Ive also had these same cars at the track. the 928 is more planted and takes less effort to drive than any of them... hmmmm wonder why???? sure, i wont be putting chains on the 928 that the ride height from the factory allows but not many of us need that feature.

it does it because it makes perfect sense. first of all, the 928 ride height is set to meet general Federal transportation requirements. (euro is always lower than US for this reason) this shoots down your first objection.
you seem to not even understand what bumpsteer is. it just means that there will be an accentuated amount of toe, because of the angle of operation when lowered. However, because the ride is stiffened, the amount of movement for the modified car , is MUCH lower than stock (which is generally much too soft). so, it's effects are canceled out.

the ride is smooth, whether race prep or with street sport shocks. still, much softer than any new BMW performance car, or Aston martin for example.
"Dr" Bob... really, because the 225 sized tires on 16s, on all 4s, thats the best for our car? my god...what has happened to you??????

I dont know where you get the information .... but the mods ive done make the 928 much much better in handling, ride and in performance. NO WONDER all new cars are doing the things ive modified my car to have. rolled fenders that look bone stock.
much much wider tires and wheels
wider positioned wheels on the hubs
stiffer suspension and springs and sways to lessened the need for stiffness and keep body roll at a min for street sport set ups.

I will put up any car i have set up, against any stock car , any day of the week over any terrain, except one of those 4x4 bumpy test tracks.

ive been driving the stock 928 with street sport suspension , with 17" 245/275 tires sitting at 140ish front and rear ride height for years and it is one of the best riding 928s ive been in. The only think you can say about this set up is how good it rides and by the way, tire wear is possibly even better than normal. never had any wear issues..... even with my race car on slicks driven 1000s of miles to and from race tracks.

so bob... get your head out of the stock manual... nothing stock works very well from the 80s.

Whitesands

I haven't sorted the front low ride height (153) on the car yet but after reading all the comments, would I be better off lowering the rear (175) to give a more even stance? This would raise the front a few mm?

dr bob

Mark, your thoughts make perfect sense for you and the way you use your car. I'm not arguing that. I don't track my car. I just used as daily driver for a lot of years. Most days that included getting into and out of my driveway without scraping, but only after the ride height was restored to 170mm in front. The streets I drove on included raingutters, where the car needed at least the 170mm front height to avoid scraping even at low speeds.

I recognize that you are the reigning king of track driving in norCal. My hat is off to you for that. Meanwhile, I do happen to know just a tiny bit about suspension design and geometry, including a shred of knowledge about the dynamics of steering under various body-roll and compression/extension conditions. You know a lot about your slammed 928 with stiff shocks and higher-rate springs that virtually no others use on their street cars.

The folks who are asking here are suffering from sagged springs with worn shocks, adjusters that are stuck together and loose on the tubes. Consider that as you shell out advice. You stick with advising on cars that have the same equipment and use conditions that your car enjoys. I'll work with the other 99% who's cars and setups are closer to original, except perhaps with sagging springs and worn shocks.

dr bob

I recommend that you focus your efforts and attention to getting the front adjusters freed so you can restore the front ride height.

Lowering the rear won't gain you much at all in front. I'm not close enough to the car to help with the tape-measure math, but you can do it yourself. Measure forward of the front wheel center to the point where your car will hit the ground first. On my car, this is the bottom rear of the front spoiler just where it is connected to the front lower wheelwell liners. Thinking that's somewhere around 16". Now measure the wheelbase in inches, and divide the wheelbase by that front 16" (or whatever) dimension. I'll take a wild guess that you end up with a number of about 6. So it will take 6mm of rear adjustment to get 1mm of change at the low spot on my car. I suspect that you don't have enough rear adjustment available to make any real difference in that front height. Sorry!