1984 16v 4.7l euro
hi all

i spent saturday adjusting the suspension geometry on my '84 s2 euro. oh boy was it a long way out.

i used the 'string method' - two parallel strings one each side of the car, and then measured using a digital vernier the 'toe in' front and rear, and using a spirit level for reference the camber angle. not the angle but the required offset using trig.

the strings ended up being exactly 1 inch from each front wheel centre, and exactly two inches from the rear wheel centres. didn't know that the track was that different front to rear!

i wasn't able to get my head around how to measure the front castor angle. does anyone have a DIY method for this? using common measuring devices?

i'm sure i read somewhere (maybe one of wally's posts) that the front castor angle can be set at minimum........now is that with the hub fully adjusted forward or backward? at the moment i have it adjusted exactly halfway on the eccentric cam adjuster.

anyone have any ideas?

BTW the car now runs dead straight, and corners on rails.......it was fairly ok before, but much better now.

regards
johnb

 

johnb,

I have found on the 17 928s that I have aligned that the caster usually ends up at the maximum when adjusted to the minimum and the variation from side to side is acceptable.
Turn the caster eccentric until the ball joint is all the way back. The inner end of the ball carrier will now be all the way forward. Be sure to readjust toe-in. Any time that you adjust caster or camber, it destroys the toe-in adjustment. I would be interested in your evaluation of the feel of the car after the change. Do all adjustments without rasing the car or you will have to drive up to 100 miles before you can accurately adjust the toe-in.

I developed and presented at The Frenzy a document that describes everything that you would ever want to know about managing 928 wheel alignment. Every level of owners mechanical ability is covered, from no involvement to DIY at home. I plan to put this information on a web site with pictures, but have been trying to get my GT painted before winter and have not wanted to spend the time right now. I expect to have it up in a month. If you need to start immediately, I could send it to you. The DIY assumes that you have shop manuals. One page is designed to give to an alignment shop that you want to train to do 928 alignment. It is written in Lotus WordPro, but I have converted it to MS, but some of the formatting got lost. Let me know which format you prefer. There are no pictures right now, so it takes some studying to understand.

 

hi earl

many thanks for your response. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

i will be checking the adjustments this evening, so i will readjust the castor to reflect your comments, and then reset camber and track.

i am aware of the lifting issue.

i would be interested in your document, in word (if poss) although any form i can process.

once again many thanks.

regards
johnb

 

earl,

id be interested to read anything you have on setting up the alignement.

appart from an untraceable 'clonk' from the front on cornering and the bent front wheel, something else about it dosent inspire confidance!!

it is lowered, uses bilstein shocks and 'steroid' droplinks. it feels as its best when the gas tank is half empty both in acceleration and cornering, slightly more 'planted'.

at other times, whether its my paranoia or not i dont know, but it feels as if the front might suddenly break away? with a full tank of gas it feels slightly 'vague'.

ive had some work done including replacement steering rack, lower ball joints and upper control arms and its been aligned since, but it just dosent feel right...

cheers,

 

Question, how did the car feel before it was lowered?

There have been bad things said about how 928 react to being lowered. Might this accout for your feelings?

 

drnick,

Some of the cars that I have worked on were lowered. Mine was, and after raising to factory height, I could not believe the difference. All that we raised had the same response. For a road car, raise up to at least the lower factory height. You will love the ride, feel and handling, and save your AC compressor and alternator and possibly engine block from those high manhole covers in the process. I will send you the document. There is an excellent write up on ride height at <a href="http://www.928.org.uk/height.html." target="_blank">http//www.928.org.uk/height.html.</a>

 

ride height on the front is set at 160mm. this was done following the bilstein install and an alignement also, by an official porsche main dealer. the car handled so much better, but it was seriously out of wack before so i cant really compare.

would you expect this ride height to seriously impare handling?

if it was a motorcycle id say it wanted more weight over the front end and a sharper turn in, hence slight lowering of the front. clearly it has four wheels and an altogether different suspension geometry but, well, i thought id try!

at the moment though... well it could all be the bent front wheel (mille miglia 993, i cant find a replacement throughout the whole country), and then there is this strange clonk noise!!

nick.

 

hi guys

well i have completed the suspension alignment, pushed the castor angle right back.

it was actually quite a frustrating job. i took the car for a run between each set of settings, and it was amazing how far they all changed. i took height measurements (fender lip to floor) and they where spot on each time, but the front track angle would invariably be out slightly.

one area of concern is that the rear left wheel is at maximum adjustment for both track and camber. camber fully out, track fully in, to achieve the correct alignment. no signs of damage to suspension or car.....i was very careful to triple check this adjustment.

i checked the alignment again and it seems to of stabalised.

here are the measurements i used:

the alloy wheel rim to rim on my car is 430mm dia.

degrees/mins decimal degs offset in mm
front toe in:15 mins|0.2500|1.88
front camber:30 mins|0.5000|3.75
front castor:3.5 degs|3.5000|26.25
(castor not measured)
rear toe in:10 mins|0.1667|1.25
rear camber:40 mins|0.6667|5.00

using sin = opp/hyp

where hyp = wheel dia (430mm)
where opp = required offset
sin = required angle

therefore offset = sin(required angle) times wheel dia (430mm) (or measuring point)

the string forming the base of the triangle, measured offset = distance from string (at right angles to string), to the wheel rim.

the offset being the difference between the back and front edge of the rim (toe in) and the difference between top and bottom edge of rim against a vertical spirit level (camber)

hope this makes sense!

regards
johnb

 

johnb,

Your numbers look good. Keep in mind that the Porsche specification for rear toein is for each wheel, but the front toein is for both wheels. It looks like, using the string method, that you adjusted the front toein to double what it should be. I use .125 degrees to calculate front toein for each wheel.

I can't answer why the left rear is at its maximum adjustment for camber and toein. Are you saying that you can adjust the camber more negative? When we did Wally's GT, I think we were unable to get the right rear any better than -1 degree camber and did not persue it due to time constraints but thought that it was caused by lower control arm bushing wear. Wally, have you worked on it?

If you are not using turnplates to make the adjustments, I can't imagine how many times that you would have to drive the car and recheck adjustments to get a proper job.

 

hi earl

i hadn't realised that the front toe in spec was across the front axle, i will have to reset the front toe in to half its current set value. thanks for pointing that out. trust porsche to give a different reference for front and rear!

regards
johnb