sd944s

Hello rennlisters!

I've searched for tips on rear shocks and such and come up with suggestions like the "bounce test," "spring compression," "spring rate," etc. My records from the previous owner don't indicate if / when the shocks were replaced. Also, my rear tires are 17x255x40's (I know, I know, I've heard about how Porsche doesn't recommend them for tracking - but I'm not tracking my car _yet_ and I like how they fill out the wheel well). Which brings me to my problem:

Just over a month ago, during hard (and I mean the accelerate like a madman) right-cornering through on-ramps when I had another passenger, I heard a scraping noise from the left wheel area. This became more common when I had _any_ weight in the trunk area and even happened over rough sections of road when I had ~250 lbs. extra in the car. Now, however, I can get the rubbing noise during hard right-hand cornering when it is only me in the car (and I haven't gained _that_ much weight). Also, it sould be noted that, no matter how hard I try, I cannot get this to happen on hard left-hand turns which leads me to believe the tire size is not the problem.

My initial guess is that the tires are actually rubbing against the wheel well because extended cornering with the scraping sound causes a burning rubber odor. Questions:

Does this require shock replacement?

Spring replacement?

Both?

Recommendations if they do need to be replaced (and keep in mind, I would just like to solve the problem, not go all-out and blow thousands on a race setup)?

Thanks for any suggestions!

Best,
-William

ian

I would try rolling the fender first, but new shocks might also be in order depending on how old they are.

Dave

On a long turn, I doubt shocks would be the cause as your suspension would have ample time to transfer weight no matter what the condition of the shock, a good shock just takes a little longer than a bad one. Perhaps you have just had enough practice that you are able to push the car a little harder on these turns. It has been my experience (and I've heard of others with the same experience) that the left side will rub more often (more easily?) than the right side. I guess these cars are not as symetrical as we would think! Rolling the lip is the quick, easy fix, but if you plan to track the car in the future you may need more than this, I'd say you should look into upgrading the torsion bars and of course the front springs will need to match.
OTOH, you havn't mentioned if your car is lowered. If the rear has been lowered you may just be running out of suspension travel.
Clearly you are aware that the change you made for cosmetic reasons has it's downside, in this case it's that a "filled wheelwell" does not always leave room for the wheel to move with the suspension. If the clearance issue is indeed at the outside of the wheel, switching to rear wheels with less offset would also help.
Also, it's not that Porsche does not recommend them for track, Porsche does not recommend them PERIOD, and further makes recommendations for other mods that are needed for those owners who DO use them.

sd944s

Thanks for the early replies!

Dave: as far as I know, the car has not been lowered. Also, although the rubbing initially came during "long turns," it now happens during hard short turns and even hard acceleration with cargo. Since you suggested that the suspension should have ample time to transfer the weight in a long turn, does the short turn / acceleration problems indicate shock issues? Yes, I am aware of the downsides of the larger wheels but I'm trying to track this specific problem as it progresses.

I found a great thread titled "How to roll the fenders?" that went through a discussion about grinding vs. rolling. The rennlisters also tried to describe the "baseball bat" method but I'm having difficulty understanding the specifics. Google provides some answers but are there any 944 specifics that I should watch out for if I attempt this? Basically the bat handle or a dowel from Home Depot (possibly using a "thick sheet of high density polyethylene" between the bat and fender) placed between the wheel and the fender while the car is rolled front to back? Do I want the fender to come straight "out" or a bit "up and out"?

Obviously, I don't want to crack the paint or give rust a easy starting point. I have plenty of tools and experience under the hood but not much body work experience. It seems straightforward enough but do any of you think I should I leave it to a shop?

Thanks for all the advice!

Best,
-William

Al P.

I take it from your post that the tire is rubbing on the inside of the wheel well not on the outside fender lip. Up-grading your suspension will do little to correct this replacing the worn out ruber bushings on the spring plate and in the trailing arm probably will. Eventually it will rub on a left hander when the other side gets a little sloppier. Most tracks run clockwise (primarily right hand turns) so the body shift toward the wheel usually occures on the left side first. Was this car tracked a great deal in the past? A temporary fix would be to add 1/4 spacers but this would probably cause the tire to rub on the outer lip.

sd944s

Al,

Your post makes plenty of sense! I was never under the impression that the tire was hitting the outer edge of the fender, rather the car was "bottoming out," so to speak. This is also indicated by the rubbing during straightaway driving then hitting bumps with cargo. The previous owner didn't race the car, but I cannot account for the two owners before him...


1/4 inch spacers, eh? I'll search for how to add those as a temporary fix - should it be a pretty straightforward procedure? From the sounds of it, I can replace this rubber bushing on the plate? I'll look into it.

Thanks for the insight!

-William

KuHL 951

I've had the same problem on my 86 with the same size tire/wheel etc. Just a thought: if you have the yellow Koni's make sure the rubber damper in the top of the shock is intact. If this is missing or too compressed you'll bottom out much easier. I've got my rubbing problem reduced to a minimum by rolling the lip and a new damper. If you have the Mille Maglia 17's like I do, the offset is +10 over OEM. I still touch under heavy boost and off camber right turns but it seems to have removed enough tire to solve most of the problem. You could always tape a piece of masking tape inside the fender lip, drive it hard, just to make sure it's not rubbing there. I'm still looking for some 16's to rid myself of the problem once and for all.

Steve

944S2NUT

www.koni.com