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Reported cause
On other cars that have had pad wear more quickly than normal I've found the calipers to be hanging up, some more than others but always it was the caliper pistons getting gummed up/rusted/corroded, causing pistons to not retract correctly keeping pressure on the pads/rotors wearing them out faster then normal.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion
Maybe buy/borrow an infrared thermometer to make it easier, but you might be able to tell a difference just by checking the temperature of the rim by holding your hand near it.
Leading evidence: 'caliper pistons getting gummed up/rusted/corroded, causing pistons' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'caliper pistons getting gummed up/rusted/corroded, causing pistons' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check temperature of the rim by holding your hand' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed · Original poster
On my 99 C2 with auto trans and traction control the rear brake pads have been replaced three time in about 50k miles while the front pads have not needed replacing.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion
Maybe buy/borrow an infrared thermometer to make it easier, but you might be able to tell a difference just by checking the temperature of the rim by holding your hand near it.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion
If you still believe its TC doing this,, Could always pull the TC/abs fuse and run like that for a time to see if wear stops.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Check temperature of the rim by holding your hand
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Suggestion
Maybe buy/borrow an infrared thermometer to make it easier, but you might be able to tell a difference just by checking the temperature of the rim by holding your hand near it.
Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed · Original poster
On my 99 C2 with auto trans and traction control the rear brake pads have been replaced three time in about 50k miles while the front pads have not needed replacing.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
On other cars that have had pad wear more quickly than normal I've found the calipers to be hanging up, some more than others but always it was the caliper pistons getting gummed up/rusted/corroded, causing pistons to not retract correctly keeping pressure on the pads/rotors wearing them out faster then normal.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
19 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
1 acknowledgements have no verified action link; they do not establish a repair result.
On my 99 C2 with auto trans and traction control the rear brake pads have been replaced three time in about 50k miles while the front pads have not needed replacing. Is this normal? If so, is this from the traction control operation? The brake work fine, I am just puzzled by the difference in wear rates
I'm not specifically familiar with the traction control system on that vintage of Porsche -- mine does not have that option. But I'd say no, that is not normal by a long shot. Rear pads should greatly outlast fronts. Try gauging the temperature of the front rotors vs. the rears after a longer drive. Maybe buy/borrow an infrared thermometer to make it easier, but you might be able to tell a difference just by checking the temperature of the rim by holding your hand near it. If the rears are hotter than the fronts, you have a problem.
Interesting situation. May be a result of traction control with automatic trans and no LSD with the rear brakes working overtime to stabikize the rear wheels. May be the need to rebuild the rear calipers. Love to know the answer when you find it.
I have heard that PSM causes excessive rear brake pad wear, but if yours only has traction control, it makes no sense for the rears to be wearing faster than the fronts.
There is none. Its kinda built into the abs valve.
Its the psm causung the wear but in your case ita a little extream. I know when u tow with an suv the tc avtivates the rear breaks more. Its kinda whats happening here but it shouldnt be.
On a wild possibiliity.....i have seen threads where service was done to an abs unit and the hard lines were hooked up wrong. Just something to rule out.
OK, That is true for a PSM equipped car and on none PSM, Porsche has a few terminology names such as brake metering valve or pressure regulator beside what normally used in the field the proportioning valve, on none PSM car this could be your issue. PSM equipped car is built into the PSM control.
1999-2001 Porsche Pressure Metering Valve PCG-955-305-00 | Sunset Porsche Parts
look here for location between master cylinder and ABS on non PSM
dC Automotive
I measured the temperature of the rotors when I got home this evening. After about 30 miles of freeway driving in stop and go traffic near the end, the front rotors where 155 �F to 160 �F and the rears where 125 �F to 130 �F. So it does not seems that the rear brakes are dragging. The proportioning valve also seems ok based on this data. Wouldn't the rear brakes be hotter if they were doing most of the work?
Is PSM the same as TC? I have only seen the TC indicator light come on a few times. Does the TC work in the background without lighting the indicator light?
Its going to use the brakes to stabilize the car. Dont know what is shown and when on the dash. Bet there is an ancient thread somewhere on the 996 Forum that talks about the details. I believe that PSM was the next generation stability management.
I found a review of the TC and PSM functions on Rennlist. The link is below. My car does not have PSM, only TC. Based on my experience with this car and the description of the TC system, I doubt the TC gets activated frequently. If my car had a manual transmission and I drove it more aggressively, maybe the TC would intervene more often. With the automatic trans and good tires it seems like it has more traction than power. For what it's worth, I don't try to do burnouts or get sideways on purpose.
https://rennlist.com/forums/997-gt2-...c-and-psm.html
Maybe burning thru rear brake pads before fronts in an automatic with traction control is common. You can always go to a different rear pad that is more durable and see what happens.
Just spitballing here for a second, but the other thing to think about is that you may just need to get you calipers rebuilt. Maybe the fronts arent working as well as the rears hence the excess rear brake wear. They are over 25 years old. While it costs money if you cant DIY it yourself, does give you an opportunity to refresh the parts and paint.
Good luck with getting to the bottom of it.
Currently I've got a 6sp 996.1 without T/C or PSM, also got 996.2 with psm with tiptronic. Neither one burns through rear pads. The front wear out way before the rear on both. On the street pads last a long time for me on both cars. My 996.1 with 36,000 miles is still on original pads front & rear, and rotors & pads look like new still... 996.2 probably will needs brakes soon at 37,000 miles on original pads still but they are at least half worn out.
On other cars that have had pad wear more quickly than normal I've found the calipers to be hanging up, some more than others but always it was the caliper pistons getting gummed up/rusted/corroded, causing pistons to not retract correctly keeping pressure on the pads/rotors wearing them out faster then normal. The o-ring groove gets dirt/gum behind it and holds the pistons from moving freely.
Might be time for 25 year old caliper rebuild and fluid flush.. Couldn't hurt and the rebuild kits are cheap...
Doubt its TC doing this, as TC should only come on when the drive wheels loose traction and the dash light should at least flicker on/off. Then the first thing TC does is decrease power to the slipping drive wheels, if that doesn't stop the traction loss only then will the brakes be applied. I'm sure if this system is not working correctly from bad sensors/etc, then it could be the problem, but the TC dash light should come on.
If you still believe its TC doing this,, Could always pull the TC/abs fuse and run like that for a time to see if wear stops. Yank the ABS fuse on my 996.2 will deploy the spoiler and disable PSM/TC for good. goes back to normal with fuse back in.
jmo
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