byrdman454

I have an alignment issue with my nephew's '85 US 928. When I was getting it aligned at a reputable shop that I have used many times on all my other 928s (same tech, same machine), he was telling me that he ran out of adjustment on the driver's rear camber. The adjuster is maxxed out, but the alignment is still going to wear out the inner portion of the rear tire (negative camber). I have not gotten it up in the air to take a look yet, but I wanted to get some input on what part might be causing issues. I know the stock adjuster can "wear" a groove and limit the adjustment. 928 motorsports has bolts with larger eccentrics and also steel channel plates to correct this. What other components would cause this condition so I can inspect and replace?

Tom in Austin

Wear in upper arm bushings will cause some of this. On my car, I gained about 0.5 (e.g. from -2.0 to -1.5) by replacing them and, if the parts are still available, it's pretty easy to do. I also had the opportunity to change the lower arm bushings where it attaches to the crossmember, but this did not have any measurable effect on camber in my case.

I think wear to the adjustment slot in the crossmember must the primary cause for camber that can't be adjusted back into spec. I have a pair of the channel plates and someday plan to see if they are the fix.

FredR

Tom has pretty much summed it up. I have thread showing what I did when fitting the camber pocket kit. Replace the bushes on the upper arms and that will also gain a bit.

Carl now has adjustable upper arms available- no idea how well they work but they are available and could be the answer but you do need the camber pockets such that the adjuster is in total contact no matter the rotation.

I now have my rear camber down to -1.3 degrees and that suits my needs - I figured that were I to replace the lower bushes might explain the rest but interesting that in Tom's case it still did not do this and if not one has to wonder why.

I never had this problem on my S4 but then that was some 15 years old when I lost it- my GTS is now 25 years old so more degradation presumably.

What camber are you seeing as a matter of interest?

Carl Fausett

Link to the adjustable rear camber links:

https://928motorsports.com/parts/rear_camber_link.php

Carl Fausett

Your problem sounds like the rubber bushings are finally so out-of-round that you cant bring the alignment in to range with them any more.

Or the aluminum pocket for your camber bolts is worn. I've seen both.

Before I do the links above, I'd install a set of polyurethane bushings (we have) and inspect your rear camber pocket in the cross-member for this damage:

https://928motorsports.com/parts/rea...er_pockets.php

GlenL

Something I had was the bolt for the eccentric corroding to the sleeve inside the bushing. The result was the turning the adjuster rotated the rubber bushing and the arm didn't move as it should.

dr bob

Remember also that the camber goes more negative as the suspension compresses. Cars that sit below the factory-prescribed heights risk seeing camber changes that are not completely correctable with the factory adjusters.

Suggestions:

-- verify the rear ride height is where you want it. Adjust as necessary, and let the suspension settle again for a while before measuring camber again.

-- Remove the upper dogbone links and inspect the bushings, adjusters and sleeves, and the pockets in the crossmember casting where the adjusters live.

. -- Replace the bushings. Factory bushings are readily available. You'll probably want to use a press to change them. Local auto parts/machine shop will do it for you.

. -- Make sure the adjusters are free to turn correctly. Make sure the adjusters are still intact too.

. -- Look for grooves worn in the suspension crossmember casting by those adjusters. Carl has a repair kit that adds steel to the wear areas if that wear is significant.

-- Reassemble with grease or anti-seize on the bolts where they pass through the metal sleeves.

-- Make sure that you tighten the bolts correctly after adjustments are complete. The adjustments are maintained by the tension and clamping from the bolts; the "adjusters" are there to help you get things into the correct position, but shouldn't be holding the adjustment once tightened.

Carl Fausett

With respect, not in all cases. Some were NLA at the time I was developing our polyurethane replacements. I went to purchase brand new ones as part of my study process, and could not get them and in one case, bought the last one they had.

dr bob

The dogbone bushings?

byrdman454

The dogbone bushings are available. I already checked. The lower control arm ones might not be.

byrdman454

The ride height is within spec. I do not lower the cars I work on.

I will be checking the adjuster first to see if I need to order those parts from Carl. It is only the drivers side that cannot be adjusted into spec, but I plan to change both sides.

chart928s4

I had this exact problem on my 91 S4. Seems disturbingly common and also perversely tough to find using search.

Today on the first alignment since I got the car, my LR camber adjustment could only reach -1.4. All the other adjustments on all corners were fine. It was aligned on a new Hunter machine by a good technician. Ride height is at 180mm RR and LR. Suspension totally settled, no raising of the car. New shocks and height adjuster sleeves/nuts, new 265/35-18 tires replacing the stock size.

5 possible causes showed up in several Rennlist posts including this one. 3 dirty lengthy jobs requiring a press: Camber adjuster pocket wear, dogbone link bushing wear, camber adjuster sleeve corroded/seized to bushing. Also wider tires (no fix possible but seems unlikely), and height changes (at spec).

So, in the highly unlikely case someone might ignore this issue to get higher priority jobs done, how much worse is -1.4 than -.8 on the tire tread? On the handling?

Charlie

FredR

Charlie,

The rear camber does not seem to be too hard on tyre wear but then I do not drive high mileages in a straight line and like to push the car in bends where camber is an advantage.

Having stiffer suspension, I run the ride height a bit lower but keep the factory spec front to ride height differential as I believe way too many 928's run with their "nose in the dirt and *** in the air" a bit like a Bloodhound and that is the last thing a 928 needs.

I did the rear camber pocket repair [very neat/easy to implement] and replaced the rear upper control arm bushes and this gained some adjustment but not as much as I expected. I can now run with my target rear camber of minus 1.3 degrees.

As Dr Bob quite rightly states, running the rear end at the lower end of the acceptable range must also change the adjustable range limits because when the car sits lower the camber increases but how much that factors into the equation I do not know.

I do not think wider wheels can or will impact the setting but then I have not even considered that possibility yet alone tested for it.

Bottom line- modern rubber width for width is stickier than the rubber that was available when these cars were designed. Stick wider rubber on them and the suspension bushes are going to take a beating when pulling the likes of 1.2g lateral acceleration as my 928 gets when I have the opportunity. Such wheels/rubber like more camber- technical fact. Push them hard and for long distances in a straight line and invariably there is going to be differential wear. This might be more of a problem in places like the USA where most roads are long and straight to get from A to B but not in places like the UK or where I live where most of my driving is in and around the capital area with some real nice twisty roads around/through the beautiful scenic mountains that run down to the coastal plain that generally is only a few km wide and quite often the mountains run down to the beaches.

Rgds

Fred

chart928s4

Thanks Fred. That is helpful. Sounds like I can leave it alone for now.

Mike, apologies for hijacking the thread somewhat. Curious - what value were you seeing at max adjustment?

byrdman454

What is the trick with pressing in the new rubber bushings? Is the middle metallic insert removable? If I try to press it in all together, it gets about 1/2 way and the metal insert balloons the rubber and stops.