Unusual "crunching" sound
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From: sf ca
Unusual "crunching" sound
Can anyone help with this diagnostic?
Here's my situation. I have a '96 993TT with 11,000 miles and the original OEM S02s on the car. From 1996 to 2001 the car only covered 6,000 miles and was stored without being driven for long time periods.
About 1,000 miles ago I had the euro M030 installed, retaining the original shocks that were "cut down" to fit the M030 springs. I don't excactly know what "cut down" refers to but the work was done by a very reputable shop that does nothing but high end Porsche work and has done this work for many customers before.
After having this work done I discovered that when on the track I hear a very pronounced "crunching" sound that appears to be coming from the left rear wheel area. I never heard this before the M030 work and I only hear it on very heavy left suspension loading (right turns).
There is nothing in the wheel well that gives any indication of any rubbing whatsoever. The fender lips have been turned and we ran a few laps with tape on the fender lip to identify any rubbing that might be occuring and the tape was clean after a few laps during which the crunching sound was occuring. Hence, I know I'm not rubbing the tire against the fender lip.
When we removed the wheel we found that the tire tread had begun to deteriorate about 1/3 of the way from the inside of the wheel. There were small blocks of tread missing throught the circumference of the tire on this line. It is consistent with what you might expect to see if the tire was being consistently poked with some fixed object as it rotated. Again, when you examine the wheel well there are absolutely no signs that anything in there is making contact with the tire.
The car is back with my mechanic and they are going over the car in detail, including examining the shocks. One idea they floated was that the tire could be independently deteriorating and that what I'm hearing is actually noise from the cords in the tire.
Does this seem plausible or does anyone have experience or insight as to what else we might look for. My next track event is about 250 miles from my home and I will hate to get there and have my track time (or worse) compromised.
Thanks in advance for any insight/opinion.
Here's my situation. I have a '96 993TT with 11,000 miles and the original OEM S02s on the car. From 1996 to 2001 the car only covered 6,000 miles and was stored without being driven for long time periods.
About 1,000 miles ago I had the euro M030 installed, retaining the original shocks that were "cut down" to fit the M030 springs. I don't excactly know what "cut down" refers to but the work was done by a very reputable shop that does nothing but high end Porsche work and has done this work for many customers before.
After having this work done I discovered that when on the track I hear a very pronounced "crunching" sound that appears to be coming from the left rear wheel area. I never heard this before the M030 work and I only hear it on very heavy left suspension loading (right turns).
There is nothing in the wheel well that gives any indication of any rubbing whatsoever. The fender lips have been turned and we ran a few laps with tape on the fender lip to identify any rubbing that might be occuring and the tape was clean after a few laps during which the crunching sound was occuring. Hence, I know I'm not rubbing the tire against the fender lip.
When we removed the wheel we found that the tire tread had begun to deteriorate about 1/3 of the way from the inside of the wheel. There were small blocks of tread missing throught the circumference of the tire on this line. It is consistent with what you might expect to see if the tire was being consistently poked with some fixed object as it rotated. Again, when you examine the wheel well there are absolutely no signs that anything in there is making contact with the tire.
The car is back with my mechanic and they are going over the car in detail, including examining the shocks. One idea they floated was that the tire could be independently deteriorating and that what I'm hearing is actually noise from the cords in the tire.
Does this seem plausible or does anyone have experience or insight as to what else we might look for. My next track event is about 250 miles from my home and I will hate to get there and have my track time (or worse) compromised.
Thanks in advance for any insight/opinion.
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Joined: May 2001
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From: Austin TX
Check to make sure it is not hitting the fender liner. There maybe some piece of metal it is hitting to damage the tire. You may have a bad shock that is letting the suspension bottom out. Just a guess. Good luck.
Greg
Greg
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Joined: Jun 2001
Posts: 64
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From: Monroe, LA
You can't duplicate the noise on the street? You have to change the damaged tire anyway, right? Do that, then try to reproduce the sound with some hard righthanders, possibly cloverleafs. If no crunching then you can feel more confident it was just the tire. What did the inside of the damaged tire look like when it was removed? This is pretty obvious stuff but maybe it will help. Good luck. Bill
