rear tire wear and broken sway bar

[Alkem]

During routine inspection on my 02 996 C2 Targa, prior to taking it in for a 30K service, I noticed that the rear tires were worn heavily on the inside shoulders on both rear wheels. The outside shoulders still had good tread. The tires looked good at the last service at 27K miles last year. The front tires are wearing evenly and still have good tread.

I took the car in for service and the mechanic called me to say that the rear sway bar is broken. Would this have contributed to the uneven wear? Or should we be looking for some other problem. The mechanics are going to check and realign everything once the new sway bar is on.

[bhussung]

The wear of your back tires is typical of the 996. This is due to the toe-in and camber of the wheels. Depending on the type/brand of tires, you should expect 8-12k miles per set of street rears. You still can't go wrong with an allignment.

[wross996TT]

During routine inspection on my 02 996 C2 Targa, prior to taking it in for a 30K service, I noticed that the rear tires were worn heavily on the inside shoulders on both rear wheels. The outside shoulders still had good tread. The tires looked good at the last service at 27K miles last year. The front tires are wearing evenly and still have good tread.

I took the car in for service and the mechanic called me to say that the rear sway bar is broken. Would this have contributed to the uneven wear? Or should we be looking for some other problem. The mechanics are going to check and realign everything once the new sway bar is on.

Yes this will indeed create the wear problem (or at least exagerate it). In fact it doesn't have to break. The stock drop links (I hope this is the right name) are rubber and they can be effected by hitting bumps in the road...they can actually become misaligned quite easily. I plan on putting some aftermarket drop links to fix this in the spring. I have one of the rear tires with more wear on the inside as just one of the links was "out".

[perryinva]

It is virtually impossible to break a sway bar mounted on the car. Are you sure it wasn't a broken drop link to the sway bar? As wross said, that would have the effect of, if bent, adding more pressure on one side over the other and cause uneven wear on one side. If the link was broken, it would not affect wear unless you did a lot of cornering with it broken, which would be near impossible to do without wondering "WTF is wrong with this car?" Somethings not right here.

[Alkem]

It is virtually impossible to break a sway bar mounted on the car. Are you sure it wasn't a broken drop link to the sway bar? As wross said, that would have the effect of, if bent, adding more pressure on one side over the other and cause uneven wear on one side. If the link was broken, it would not affect wear unless you did a lot of cornering with it broken, which would be near impossible to do without wondering "WTF is wrong with this car?" Somethings not right here.

No, I am not sure. The shop rep said it was the sway bar. He said it looks like the bar snapped when I spoke with him on the phone. I haven't been out to the shop yet to see the damage, so I am not sure. I will ask when I get there. The shop is a motor sports oriented shop that specializes in Porsche, so I assume they are reputable though this is my first dealings with them.

I have noted that the car rides rough, but truthfully, I haven't been driving it hard. I've only put 3K miles on it since I got it 18 months ago. I haven't tracked or auto crossed it.

[PorschePRH]

During routine inspection on my 02 996 C2 Targa, prior to taking it in for a 30K service, I noticed that the rear tires were worn heavily on the inside shoulders on both rear wheels. The outside shoulders still had good tread. The tires looked good at the last service at 27K miles last year. The front tires are wearing evenly and still have good tread.

I took the car in for service and the mechanic called me to say that the rear sway bar is broken. Would this have contributed to the uneven wear? Or should we be looking for some other problem. The mechanics are going to check and realign everything once the new sway bar is on.

I just don't see how the sway bar has anything to do with alignment.

And I don't see how you could snap a sway bar. They are made of substatial metal.

Porsche does have some unique ability from an engineering perspective to screw things up, but I would still have to see it to believe it.

What's your alignment specs?

[SH-GT3]

I think I'd find another shop, starting with an alignment shop. If your tire wear is even, it sounds normal. Get it up in the air and take some pictures.

[Alkem]

During routine inspection on my 02 996 C2 Targa, prior to taking it in for a 30K service, I noticed that the rear tires were worn heavily on the inside shoulders on both rear wheels. The outside shoulders still had good tread. The tires looked good at the last service at 27K miles last year. The front tires are wearing evenly and still have good tread.

I took the car in for service and the mechanic called me to say that the rear sway bar is broken. Would this have contributed to the uneven wear? Or should we be looking for some other problem. The mechanics are going to check and realign everything once the new sway bar is on.

I just don't see how the sway bar has anything to do with alignment.

And I don't see how you could snap a sway bar. They are made of substatial metal.

Porsche does have some unique ability from an engineering perspective to screw things up, but I would still have to see it to believe it.

What's your alignment specs?

I got the car back and all seems well.

The old sway bar broke at the point where the connecting link bolts to the main bar. The shop tried to order a new OEM sway bar, but it took to long to come in, apparently from Germany. So they asked me , and I agreed to install a "used sway bar" off the shop owners GT3. It was almost new and they gave me a good discount. It is adjustable. They installed it at the second setting from the rear (looking forward). I'm not sure how that would affect handling compared to other settings.

They also installed a new set of Potenza RE50 Pole Position tires on the rear. While the same size size spec, 285/30-18, they look like they are higher profile than the tires they replaced. These tires also have a pronounced ridge that runs along the inner circumference where it meets the wheel. As a result the tire appears wider than the old one. The old tire looked like it sloped in from the wheel.

Now that I've driven it a bit, I believe the ride is smoother, and my wife commented on the smoother ride too. I suppose that is mostly due to the tires, but I am not sure. Any way, I'm happy to have the car back and running great.

[perryinva]

Well smack me up and down and call me batter. There's a first for everything. I'm glad I said "virtually impossible". HAD to be defective from the factory. I know how it's great to be back on the road. I didn't notice you were in Virginia, or I would have offered you my OE one I took off for free. (I'm in Richmond). I put the M030 ones on mine. The GT3 bar is a far stiffer & better bar. Since you still have the OE front bar, I'd have put the rear on full soft, as it would still be way stiffer than the old bar was.

[Alkem]

Well smack me up and down and call me batter. There's a first for everything. I'm glad I said "virtually impossible". HAD to be defective from the factory. I know how it's great to be back on the road. I didn't notice you were in Virginia, or I would have offered you my OE one I took off for free. (I'm in Richmond). I put the M030 ones on mine. The GT3 bar is a far stiffer & better bar. Since you still have the OE front bar, I'd have put the rear on full soft, as it would still be way stiffer than the old bar was.

Thanks for the tip and offer. The car has the factory sport suspension. Does that include a different sway bar? In looking at the Pelican parts web site, I didn't see a bar for the sport suspension for sale.

Since I use this car more for Grand Touring as opposed to track use, I appreciate the smoother ride.

I just finished reading the latest issue of Excellence and the two articles about the autocross cars were really interesting and inspiring. I'd love to have a project car like those.