993 Wheel Wobble
Discussion
Mine did this even with what looked to be almost new discs and very decent pads.
When I investigated further the pads were a mess! although they hadn't covered many miles, they were old, and were cracking and falling apart.
I decided to replace both discs and pads for brand new Porsche items and all is very well once again.
It seems it's the washing and putting away slightly damp that causes the problems.
Another possible candidate is the wishbone bushes, however if you only feel the wobble under braking it does suggest you have the same issue I had.
When I investigated further the pads were a mess! although they hadn't covered many miles, they were old, and were cracking and falling apart.
I decided to replace both discs and pads for brand new Porsche items and all is very well once again.
It seems it's the washing and putting away slightly damp that causes the problems.
Another possible candidate is the wishbone bushes, however if you only feel the wobble under braking it does suggest you have the same issue I had.
If its through the wheel under braking and not the brake pedal then (and not continously at higher speed i.e. warped or unbalanced rim) then you would be thinking more in terms of shot bushes in the front A arms. A quick visual inspection should reveal all. They have a habit of separating from the alloy and popping out in places & also check for for regular crumbling and cracking.
Brake problems like glazed pads would be felt quite vividly through the brake pedal IMO
Brake problems like glazed pads would be felt quite vividly through the brake pedal IMO
Edited by jackal on Monday 3rd October 23:32
Could be brake pad residue that has built up unevenly on the discs. My car does this from time to time. Just carry out a succession of hard stops (ver (very hard) from 60mph. About 5 of these should do it. This gets the brakes good and hot, burns off the pad residue and gets the pads seated well against the pistons.
I would try the above before spending time and/or money on anything else.
pp
I would try the above before spending time and/or money on anything else.
pp
Could also be warped discs - there was a batch several years ago which were defective and some may still be around. My brand new discs were skimmed in under 1000 miles and then replaced under 2000 miles. Maybe pattern parts aren't quite as good as OEM. Did you run the discs in gently or hammer them from mile 1? It will make a difference.
Guys, sorry cant keep my mouth shut on this one.
1. Brake discs DO NOT warp.
Sorry but its the biggest car maintenance myth out there. You can get an uneven transfer of friction material onto the disc face which will cause hotspotting and then wheel judder under certain conditions, but that is nothing like the discs actually being physically warped. Just hard braking with the existing setup won't cure this. Your first and cheapest port of call is to try and rub down with emery paper. Failing that, change to a NEW metallic pad and then hard brake the car several times to clean off the disc. As a very last resort, have the discs ground but if the depositing is deep and prolonged enough then the wobble will likley come back.
2. If you can't feel the juddering through the brake pedal as OP states then even in the most remote feeling setups (definitely not a 993 !) the problem will not be brake related. If the brake disc surface is uneven then its night on impossible not to feel it through the brake pedal simply because the hard deposits on the disc will push back on the pads, the pistons, the fluid, master cylinder etc. and then that movement will eventually reach your foot.
1. Brake discs DO NOT warp.
Sorry but its the biggest car maintenance myth out there. You can get an uneven transfer of friction material onto the disc face which will cause hotspotting and then wheel judder under certain conditions, but that is nothing like the discs actually being physically warped. Just hard braking with the existing setup won't cure this. Your first and cheapest port of call is to try and rub down with emery paper. Failing that, change to a NEW metallic pad and then hard brake the car several times to clean off the disc. As a very last resort, have the discs ground but if the depositing is deep and prolonged enough then the wobble will likley come back.
2. If you can't feel the juddering through the brake pedal as OP states then even in the most remote feeling setups (definitely not a 993 !) the problem will not be brake related. If the brake disc surface is uneven then its night on impossible not to feel it through the brake pedal simply because the hard deposits on the disc will push back on the pads, the pistons, the fluid, master cylinder etc. and then that movement will eventually reach your foot.
I had a similar issue on my previous 993C4. Brake discs and pads were changed, but the wobble/vibration under braking returned after only a few hundred miles. The discs were then skimmed, but again the problem came back shortly thereafter. In the end it was suggested that it may be a 'out of true' hub. The car was, however, sold before a solution was found.
jackal said:
Guys, sorry cant keep my mouth shut on this one.
1. Brake discs DO NOT warp.
Sorry but its the biggest car maintenance myth out there. You can get an uneven transfer of friction material onto the disc face which will cause hotspotting and then wheel judder under certain conditions, but that is nothing like the discs actually being physically warped. Just hard braking with the existing setup won't cure this. Your first and cheapest port of call is to try and rub down with emery paper. Failing that, change to a NEW metallic pad and then hard brake the car several times to clean off the disc. As a very last resort, have the discs ground but if the depositing is deep and prolonged enough then the wobble will likley come back.
2. If you can't feel the juddering through the brake pedal as OP states then even in the most remote feeling setups (definitely not a 993 !) the problem will not be brake related. If the brake disc surface is uneven then its night on impossible not to feel it through the brake pedal simply because the hard deposits on the disc will push back on the pads, the pistons, the fluid, master cylinder etc. and then that movement will eventually reach your foot.
On my 993, under light braking - not heavy braking - or simply lifting off the throttle at highish speed, the steering wobbled and there was a noticeable "grumble" from the front. That was with new OE discs and pads (at huge expense....). Skimming cured it slightly but chucking them out and fitting new ones, and now't else, cured it completely. They were changed FOC as there was a known defect causing the symptons I had, and similar to those described by the OP. The discs were clearly, measurably, not perfectly flat and while not "warped" they were something........1. Brake discs DO NOT warp.
Sorry but its the biggest car maintenance myth out there. You can get an uneven transfer of friction material onto the disc face which will cause hotspotting and then wheel judder under certain conditions, but that is nothing like the discs actually being physically warped. Just hard braking with the existing setup won't cure this. Your first and cheapest port of call is to try and rub down with emery paper. Failing that, change to a NEW metallic pad and then hard brake the car several times to clean off the disc. As a very last resort, have the discs ground but if the depositing is deep and prolonged enough then the wobble will likley come back.
2. If you can't feel the juddering through the brake pedal as OP states then even in the most remote feeling setups (definitely not a 993 !) the problem will not be brake related. If the brake disc surface is uneven then its night on impossible not to feel it through the brake pedal simply because the hard deposits on the disc will push back on the pads, the pistons, the fluid, master cylinder etc. and then that movement will eventually reach your foot.
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