18 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHSteering wheel vibration under braking
Leading reported evidence
Check pads
Performed · outcome unconfirmed
No successful repair reported for this finding.
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Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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.
Discussions that performed work without a confirmed outcome
1
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.
Leading evidence: 'Check pads' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'tie rod ends' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check pads' (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.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
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.
Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed
I don't find PFC pads are bad for this, but the Pagid pads I've used have been really prone to it, for some reason.
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.
Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed · Original poster
checked at the shop I use for all service - everything tight and good.
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.
Discussions that suspect a cause
1
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Suspected cause
I had a early 911 that at certain speeds and on braking would vibrate the steering wheel and it turned out to be bad tie rod ends, but this sounds like a rotor problem of some sort to me.
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.
Discussions that contain suggestions
1
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Suggestion
+1 or you can switch to a set of very hard metallic pads to "clean" the rotors from any PFC compound for a few miles and retest the new Raybesto pads.
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Suggestion
By the way, the easiest way I've found to clean rotors of glazing and pad transfer is to spray them with water and let them rust, then bolt then back up.
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Suggestion · Original poster
Have been running PFC 97 compound pads for track days, changed out to Raybestos pads with much higher COF, now get severe steering wheel vibration under moderate braking (not as bad under heavy braking), hotter the brakes get the worse the vibration.
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Suggestion
+1 to Sneaky Pete, I read in a rotor prep article once, it suggested washing the rotors, then wet sanding them using an orbital motion where the pad will ride.
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tie rod ends
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
Read evidence and context
Discussions that suspect a cause
1
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.
Suspected cause
I had a early 911 that at certain speeds and on braking would vibrate the steering wheel and it turned out to be bad tie rod ends, but this sounds like a rotor problem of some sort to me.
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.
18 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.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T222516Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Have been running PFC 97 compound pads for track days, changed out to Raybestos pads with much higher COF, now get severe steering wheel vibration under moderate braking (not as bad under heavy braking), hotter the brakes get the worse the vibration. Have had rotors checked - they are good - within .001 TIR - calipers are correctly torqued, wheel alignment done. Put the PFC 97's back in & the vibration goes away. What else could it be?
Thanks for your help.
I'm thinking your rotors are glazed with the PFC compound and your street pads don't like it. Maybe grab some fine grit sand paper or emery cloth and give the rotor surface a rub down. Blow compressed air or brake cleaner fluid on them afterwards to get all the grit off your rotors.
+1 to Sneaky Pete, I read in a rotor prep article once, it suggested washing the rotors, then wet sanding them using an orbital motion where the pad will ride. I followed that procedure then washed them again to remove any metal particles. In reading your post the problem begins with the pad change so clearly any other pursuits should be ignored until that one is eliminated.
Actually it's very common for worn out control arm bushings/ball joints to only exhibit steering wheel shake under certain braking or at certain speeds. Not sure on the 996's but it happens all the time in BMW's.
I had a early 911 that at certain speeds and on braking would vibrate the steering wheel and it turned out to be bad tie rod ends, but this sounds like a rotor problem of some sort to me.
-Jason
Thanks for all the ideas. Installed new (slotted) rotors at the same time as the Raybestos pads so there was no prior PFC pad build up on the rotors. Am told the Raybestos track pads have much higher initial bite than other pads which is why the pad supplier suggested it was possibly worn bushings/ball joints. Will have them checked out. Appreciate all your help. Any other thoughts would be welcome.
Perhaps but the problem began with the pad change, its tough to ignore that factoid in chasing this down. IMO, its a stretch to believe the worn bushings did not previously reveal themselves because the old pad set up doesn't have as hard of an initial bite, that explanation may eventually prove to be cheese.
Had control arms etc. checked at the shop I use for all service - everything tight and good. Seems it is back to pointing to the pads. Any other ideas?
Thanks
This seems to be from track use, so I would guess that it's pad material depositing unevenly on your rotors. I don't find PFC pads are bad for this, but the Pagid pads I've used have been really prone to it, for some reason. I have no experience with Raybestos, so it's just a guess.
By the way, the easiest way I've found to clean rotors of glazing and pad transfer is to spray them with water and let them rust, then bolt then back up.
Take off the rotors and hit the braking surface with 100 grit paper on a rotary sander/polisher. Also hit the pads. If the vibration goes away, then its glazing of the rotors/pads.
If I read this correctly, you're running new pads and new rotors? And the vibration happens under hard braking? Sure sounds like a rotor issue, although warped NEW rotors aren't so common.
Correct, but medium-force braking. I believe his Raybestos pads are leaving deposits on his rotors. When he put the PFCs back on, they cleaned them off. The pad may not be entirely to blame, though. If I'm right, the OP may want to look into a caliper rebuild if his calipers are dragging (and leaving a hot pad pressed into a hot rotor when he parks the car after coming off track).
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