Defect in tires/short pss9 review...
12-09-2003, 06:24 PM
#1
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Defect in tires/short pss9 review...
I recently installed a pss9 suspension and RS bars on my car with the phone help of the infamous Viperbob. For any of you attempting this install, talk to someone that has done it before and set aside more time than you think it could possible take you. I am very slow, but in total it probably took me 15 hours divided up into 2 days.
I just got back from getting the car corner balanced and aligned. I had it set a RS ride height, which is not at all too low in my opinion. I have not had a lot of time driving the car but so far it is great. I have the shocks set at 5 and the ride is firm but actually not that much firmer than stock in my opinion. It controls the absorbtion of bumps much better. The handling is great just from the couple of offramps I took on the way home. If you are considering this modification, do it, you will not regret it. My camera is out of batteries but i will post pictures eventually. Once I get more experience with the setup I will post a more detailed review.
One thing that is ruining my fun enjoying the car is the fact that there is something wrong with my rear tires that is causing the car to pull very badly to the right under power and off of power. The mechanic who worked on the car is very experienced with Porsche and suspension setup and says there is no doubt in his mind that the tires are the problem. The reason this bothers me is that the tires only have 1500 miles on them, the previous owner put them on 100 miles before I got the car. The tires are Michelin Pilot Sports. Does anybody have any experience with warranty claims for this sort of thing with Michelin or am I just stuck buying 2 new tires?
I just got back from getting the car corner balanced and aligned. I had it set a RS ride height, which is not at all too low in my opinion. I have not had a lot of time driving the car but so far it is great. I have the shocks set at 5 and the ride is firm but actually not that much firmer than stock in my opinion. It controls the absorbtion of bumps much better. The handling is great just from the couple of offramps I took on the way home. If you are considering this modification, do it, you will not regret it. My camera is out of batteries but i will post pictures eventually. Once I get more experience with the setup I will post a more detailed review.
One thing that is ruining my fun enjoying the car is the fact that there is something wrong with my rear tires that is causing the car to pull very badly to the right under power and off of power. The mechanic who worked on the car is very experienced with Porsche and suspension setup and says there is no doubt in his mind that the tires are the problem. The reason this bothers me is that the tires only have 1500 miles on them, the previous owner put them on 100 miles before I got the car. The tires are Michelin Pilot Sports. Does anybody have any experience with warranty claims for this sort of thing with Michelin or am I just stuck buying 2 new tires?
Last edited by TrackJunke; 12-09-2003 at 06:54 PM.
12-09-2003, 06:48 PM
#2
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It would be cool if you could borrow a set of rear tire/wheels (Viperbob maybe?). Just swap them out, go for a little drive, and see if the problem remains. If the problem remains, it aint the wheels. If not, check the wheels for true, and/or get a new set of rears.
Chris
Chris
12-09-2003, 06:50 PM
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I live in SC and Viperbob is in California, so that would be tough. I was thinking the same thing of switching up the wheels to see if that was definately the problem but I could not figure out where to get a set. If anybody lives near the Greenville, SC area and would be willing to switch rear wheels (18" turbo twists) or all 4 other size for a test drive, that would be great. The mechanic also seemed very confidend that the tires were the problem.
12-09-2003, 06:55 PM
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FWIW: From 993 Suspension article from Excellent:
"The 993 and later 996 have an uncommon alignment adjustment that many shops do not know about. It's called Kinematic toe, and it's the angle of the lower control arms, side-to-side.The goal is to have the control arms level when the car is at rest, regardless of ride height. This will ensures the suspension will deflect equally under load. If the diference from side to side is too much, the car will have a tendency to steer under acceleration. In addition, it will increase tire wear and may cause premature ball joint falure due to excessive thrust loading."
"The 993 and later 996 have an uncommon alignment adjustment that many shops do not know about. It's called Kinematic toe, and it's the angle of the lower control arms, side-to-side.The goal is to have the control arms level when the car is at rest, regardless of ride height. This will ensures the suspension will deflect equally under load. If the diference from side to side is too much, the car will have a tendency to steer under acceleration. In addition, it will increase tire wear and may cause premature ball joint falure due to excessive thrust loading."
12-09-2003, 06:56 PM
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Maybe I didn't read your post carefully enough, but was it pulling before the suspension work or only after? If only after, then I doubt it is tire related. It sounds like an alignment issue, including the kinematic toe. If it pulls before and after, it may be a bad tire.
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12-09-2003, 07:16 PM
#8
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You've likely tried the following to help isolate the problem, but if not:
- swap L & R rears to determine if that results in any change in behavior,
- have a decent tire shop check wheel/tire balance, trueness of wheels & if a tire is out of round. It is best to use an "authorized" Michelin dealer to facilitate any eventual warranty claim.
The Michelin Tire Warranty is for the earlier of 6 years from purchase (or from date of manufacture if no proof of purchase) or the "life of the original usable tread."
- swap L & R rears to determine if that results in any change in behavior,
- have a decent tire shop check wheel/tire balance, trueness of wheels & if a tire is out of round. It is best to use an "authorized" Michelin dealer to facilitate any eventual warranty claim.
The Michelin Tire Warranty is for the earlier of 6 years from purchase (or from date of manufacture if no proof of purchase) or the "life of the original usable tread."
12-09-2003, 07:51 PM
#10
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I'd hope that the alignment shop used a laser aligner like Visualign 3D and printed out the results for you so for use in your warranty claim.
BTW, I'm no tire expert, but that diagnosis surprises me. Can't wait to hear what happens when you swap left & right wheels!! (btw- do it even if the tires are unidirectional; it won't hurt them on a short drive)
BTW, I'm no tire expert, but that diagnosis surprises me. Can't wait to hear what happens when you swap left & right wheels!! (btw- do it even if the tires are unidirectional; it won't hurt them on a short drive)
12-09-2003, 09:04 PM
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If it pulled before the new suspension/alignment, and you're confident that your shop really knows what they're doing, then it could be the tires. But you've described a pull on and off power. Does that mean it's fine at a steady cruise? If so, then you've got bad bushings somewhere, and your alignment is changing as the load on the suspension pieces change.
If, however, you have a pull at a steady cruise, then you should, indeed, try swapping rears to see if that changes anything. I have "fixed" a mild pull in other cars before with a simple tire swap. Hope this helps
Edward
If, however, you have a pull at a steady cruise, then you should, indeed, try swapping rears to see if that changes anything. I have "fixed" a mild pull in other cars before with a simple tire swap. Hope this helps
Edward
12-09-2003, 09:29 PM
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Steve,
They told me that they can adjust the kinematic toe but when I went there he did not have the tool. He told me that he has used the tool many times on the cars lowered to RS height and every time they just had to max out the kinematic toe on each side. The main reason I went to this place was because they said they had the guage. There was not anything I could do at this point other than trust their experience, the guy sets up some of The Racer's Group racecars. The kinematic toe before the new suspension and alignment was maxed out on one side and was neutral on the other. It had the exact same symptoms of pulling then than it does now which makes me think it is not the kinematic toe. Can you adjust the kinematic toe without screwing up the rest of the alignment settings?
Edward,
The car still pulls a little under neutral power but not near as bad. Another symptom is that when you are hard on the gas and let up it feels like the car shimmeys to the left a bit and then goes to the right. What bushings could this be? The car only has 26000 miles on it and I just put the suspension in and did not see anything that looked extremely worn out or anything.
They told me that they can adjust the kinematic toe but when I went there he did not have the tool. He told me that he has used the tool many times on the cars lowered to RS height and every time they just had to max out the kinematic toe on each side. The main reason I went to this place was because they said they had the guage. There was not anything I could do at this point other than trust their experience, the guy sets up some of The Racer's Group racecars. The kinematic toe before the new suspension and alignment was maxed out on one side and was neutral on the other. It had the exact same symptoms of pulling then than it does now which makes me think it is not the kinematic toe. Can you adjust the kinematic toe without screwing up the rest of the alignment settings?
Edward,
The car still pulls a little under neutral power but not near as bad. Another symptom is that when you are hard on the gas and let up it feels like the car shimmeys to the left a bit and then goes to the right. What bushings could this be? The car only has 26000 miles on it and I just put the suspension in and did not see anything that looked extremely worn out or anything.
12-09-2003, 11:55 PM
#14
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when you are hard on the gas and let up it feels like the car shimmeys to the left a bit and then goes to the right
I will defer to the experts here, but this doesn't sound like any tire problem to me. Bad bushings "can" lead to some funky characteristics on and off load, but at 26K on your car, I think it's unlikely yours would be toast...unless there is some physical problem with a link, bushing, or the installation?? Perhaps then it is, indeed, the Kinematic setting, and they're balking. Now since you've invested a bit of time and money in the shop's labor toward your car, I'd swap the rears tires, record your findings (I doubt that it will cure what you just described) and take this back to the shop and ask for a reasonable explanation, while respectfully declining to accept the "bad tire" reason. Let us know; I know I'm curious!
Edward
I will defer to the experts here, but this doesn't sound like any tire problem to me. Bad bushings "can" lead to some funky characteristics on and off load, but at 26K on your car, I think it's unlikely yours would be toast...unless there is some physical problem with a link, bushing, or the installation?? Perhaps then it is, indeed, the Kinematic setting, and they're balking. Now since you've invested a bit of time and money in the shop's labor toward your car, I'd swap the rears tires, record your findings (I doubt that it will cure what you just described) and take this back to the shop and ask for a reasonable explanation, while respectfully declining to accept the "bad tire" reason. Let us know; I know I'm curious!
Edward
