Tom in Austin

Isn't there a spec for 'cross-camber' relating to the difference between right and left? That's been my challenge, my left side can't be adjusted enough to get a good cross-camber number. I have Carl's inserts and hope they fix this condition.

FredR

Tom,

Which side do you have a problem with as a matter of interest?

I presume you have too much camber on the problem side- is that correct?

The insert primarily facilitates establishment of the correct adjustment range assuming it is positioned where Porsche intended- the slot also exceeds the length of the stock slot in the cross arm and thus the position of the insert controls the upper and lower extremes of camber adjustment [to some extent].

I did not check this but in theory you could alter the extremes of the range by where you position the insert as long as one does not exceed the limits of the slot in the cross arm. If this was to be the case then even that could be opened a bit more on one end.

In my case I made sure the insert inboard face stayed at the original position. The bolt facilitates a horizontal travel of approx 9mm which I suspect translates to an adjustment range of about 2 degrees of camber and a stock examples in good condition will probably have a capability to give you anywhere between 0 camber and minus 2 degrees.

Considering the above and assuming what I perceive to be the case is correct, unless you have damage to the adjustment shoulders greater than mine, the damage will only account for loss of about 2mm of travel thus does not explain what I experienced. My estimate of the compression of the dog bone bushes suggested they would account for 4mm or 5mm of adjustment, add that to the 2mm lost in the shoulder and that would be 7mm accounted for.

If you want to get some idea of the state of the dog bone bushes simply unbolt the outboard one on the wheel carrier, remove the conical washer and then you can see the bush face in situ and any compression should be evident.

Bottom line-fitting the insert alone will probably not solve your issue unless the shoulder on the cross arm has been "demolished" -and that is most unlikely I would think.

In my case I now have about 1.5 degrees of camber and I am about half way across the adjustment range, whereas previously on one side the lowest I could achieve was 1.7 degrees of camber so mission accomplished in my case.

Now the difficult bit- has the car any accident history on the side you have difficulty with? if the adjustment range cannot be explained by the adjuster and the dog bones then mechanical damage would have to be the other "suspect" - hopefully not the case of course but I have seen this on a GTS here. The owner did something a bit stupid horsing around and he put the car sideways into a lamp post with the B pillar taking the hit. To keep the repair costs down they did not straighten the body correctly and the consequence of that was an inability to get higher camber-it could only make stock setting and the lower end of the range at that.

Trust the above helps a bit. perhaps you can advise what camber measurements you have.

Rgds

Fred

Carl Fausett

Mark - I disagree with your assessment. Not sure how you can ignore the numbers of pictures from the field that show the camber pockets are dented based on knowledge of just one car. Running a steel eccentric on an aluminum wall wasn't a great idea. As to why you haven't seen an issue on the track car: race tracks are smooth and do not have potholes. No shock like a street-driven vehicle.

All - regards holding the given Camber setting once set. Do torque it down as per spec like mark says. DO NOT put any lube on the eccentric or shaft of the bolt. Experience has shown that was a mistake and made it more likely the rear camber would turn when driving.

Fred: there is a multiplier involved caused by the rear bearing carrier. I do not know what it is, but a 2mm difference at the camber eccentric produces a measureable change at the wheel when measured in degrees. Then add the smooshed bushings you had at the bottom (lower link) and the top (upper link) and the camber is really out of range. Good job!

FredR

Carl,

Good point about the lube- I did not mention that I quite deliberately did not lube anything- all was quite clean- a bit of crud on the shaft of the bolt that cleaned off easily otherwise it was spotless.

Before attacking this issue My minimum camber was 1.5 on one side and 1.7 on the other and I could not even get these if the adjuster was turned and the arm moved away from the minimum stop position.

I am currently at about 1.5 degrees mid range. The available travel seems to give a differential of about 2 degrees maybe a tad more. The one thing I could not do anything about was if there was any distortion on the lower bushes. I checked for this and could not see anything noticeable as with the dog bones but it would not surprise me if there was some amount.

Either way I am happy that I can get the camber I currently want which is around 1.25 degrees. Even with my roughly measured -1.5 at the moment the rear end is already much more grippy compared to the train wreck it was previously.

My perception is that roughly a third of the improvement is down to the insert and two thirds is down to the dog bone bush replacement but to be fair, trying to estimate the distortion on the dog bone bushes was a bit of a thumb suck.

It will be interesting to see what range of camber I can now achieve on the alignment rig when I get there. Prefer to do this when I get new tyres on.

On reflection I can believe my camber pocket problem was caused by under tightening as posted earlier - it would be interesting to learn more about the experience of others.

Regards

Fred

mark kibort

Respectfully,, thats a interesting comparison, but not the case. PLUS, my car over 20 years has been street and track . full race only now , even though more than full race duty in prior years plus street driving. hitting birms at 100mph and getting airborn of them and slamming down, is equivalent to pot holes.
never seen any wear in that area of the car, and we are talking 4-6 different 928 racing platforms and street cars. ive even been hit in the rear and it bent the lower control arm. do you know what it takes to bend one of those?????? camber was fine when the new one was replaced and thats a HUGE hit by the way!

the aluminum vs steel doesnt wear the cross member out, its the lack of position tightness. if its damaged or worn, your solution is a great one!! no doubt!

ROG100

Fred - Out of interest when I could not get the camber in line on a couple of local GTS cars we found that it was the lower control arm bushing, towards the center of the car, that had deteriorated. Consensus at the time was that the deterioration was due to close proximity to the exhaust. Once changed out the camber came in line. I do not remember seeing any damage in the area of the eccentric. Obviously damage in this area would require Carl's fix. Just wondered what the condition of your bushes like?

FredR

Roger,

In all truth I cannot answer your logical query accurately - all I can say is that I did not see any appreciable deformation but then in reality was not looking for any because I did not have a solution "in the bag of tricks" as it were.

Common sense should tell us all that after 25 years of use rubber bushes "owe us nothing" and ideally should be refurbished as a job lot. The trouble with this type of age related deterioration is that it is progressive and any deleterious performance is not really noticed as such other than at extremes of performance and for most of us that rarely if ever happens.

I have had my late S4 flat out a few times and the handling was stellar but that over 10 years ago and local legislation today is a different ball game than it was then as is the traffic loading. Add to that my accident in the S4 plus 10 years of personal decline and nowadays my speed related ambitions are "significantly lower". Thus in the strictest sense "I can live with less".

On this example, I have not felt any degradation of handling performance until recently, most of which I put down to the need for new rubber and the rest due to alignment issues, my suspicion being too much camber. This "problem" has been with me since I acquired this example, initially I had no idea why it was happening, all I knew was that during initial alignment set up I would not get the camber down to sensible numbers so i knew something was wrong. The damage to the camber pockets was evident but even when we manually placed the camber in the minimal position the lowest number we could get was 1.5 degrees - a bit more than I wanted but I decided to live with it.

I posted about the problem a few times and eventually the dog bone bushes came into the equation and that made a lot of sense to me. Thus I acquired new bushes a couple or so years ago and have just got round to fixing them.

I reasoned that the lower bushes probably do not take the compressive hammering the dog bones do so less likely to be damaged- true or false remains to be seen. I know for a fact the camber issue has improved significantly- whether it is back where it should be remains to be seen but as long as I can achieve an adjustment range of minus 1 to minus 1.5 camber it will be "mission accomplished" as it were. at half range of travel I am minus 1.5 and it will be interesting to see what the camber is at "minimum stop". Given the factory acceptable range is 40 minutes plus or minus 10 minutes [60 minutes = 1 degree] then logic suggests the range should cover something from zero upwards. Add to this the range of travel gives about 2 degrees differential adjustment suggests we should be able to see anything from zero to minus 2 degrees [if I have this right].

Given what I have done to date if I cannot get to zero then in all probability I would put this down to distortion in the lower bushes as being the logical explanation and this is also something that Tom will need to consider on his GTS. I saw the dog bone option as a relatively easy fix, the lower bushes requiring removal of the complete lower arm. Something that has to be contemplated sooner or later I would suggest.

Trust the above makes sense.

My next project is likely to be the front suspension with refurbed lower arms, upper bushes and upper/lower joints on the menu.

Trouble is I do not like to take on too much at once but in reality it is probably the best way to go.

Rgds

Fred

Carl Fausett

That sounds about right. And what Roger said too... if the bushings in the lower link are also out-of-round, they contribute to the same problem.

When I started with polyurethane replacement bushings in the rear suspension, I couldn't correct the camber until I had replaced all the lower link and upper link bushings with new ones that were concentric again. All the old rubber bushings had taken a set to one side...

Anyway - we now offer polyurethane replacement bushings for the whole rear suspension. Our bushings are graphite-impregnated and do not squeak like the cheap bright red and blue ones that you see.

Carl Fausett

Mark,

I think some of the damage is done to the aluminum pocket when turning the eccentric to adjust the camber. Porsche has instructed us to align the vehicle with all the weight on the wheels... turning the camber eccentric in one direction is crazy easy as the weight of the vehicle contributes to the twist.

BUT, if you have to go the other way, turning the eccentric in such a way as to reduce your camber, you are literally trying to stuff the tire back under the car and lift the car via the eccentric. That's when I see the most damage done to the aluminum by the steel eccentric.

ROG100

Fred & Carl,
My own experience at that time (maybe 8 to 10 years ago) was to change all the bushes. However I found that I wasted my time and money on all of them except the one near the center of the car. The originals were all good except that one. Older cars would certainly benefit from new bushes.
Roger

FredR

Roger, Carl,

Just measured the old bushes that came out of the upper link [dog bone] and everyone of them showed a permanent set of 2mm. Thus each side had lost 4mm of lower end adjustment. Add to that the two mm due to damage of the adjustment pocket and it is not hard to understand why the minimum camber I could get was minus 1.5 degrees if the total range of adjustment is 9mm [about 2 degrees].

If I cannot get the adjustment down to zero camber then that would probably be because of some permanent set in the lower arm bushes.

Rgds

Fred

mark kibort

thats an interesting perspective. maybe guys at home or on lifts, are wrenching on the adjusters against the friction of the entire car. its a huge leverage point , but on the sliders on the hunter machine, there is very little friction, and thus force to twist the adjusters. certainly, my moves have always been to give more camber, and thats the "easy direction". So, if there is damage, you certainly have a cool solution.

Lets put that brain power to work for the NA cars and figure out how to make a intake that gives near the HP as the CF intake. with all the designs and experience you have, we should be able fab something. I still think modifying something from stock, might be the answer. use the stock S4 or S3 intake, cut it at the runner mounts and mount something fabulous on top of it. maybe adapt it to the vet, M3 or even aston vantage intake .

Now, not to digress.... back to the adjusters!

Carl Fausett

I have designed two intakes, one for 16v and one for 32v motors.

The write-ups are both available for download here: http://www.928motorsports.com/install.php

in the "articles" section (top of page)