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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHVibration from Rear of C4S under high-speed braking
Reported or suspected cause
rear passenger side)
Suggestion or failed attempt
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
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Discussions that suspect a cause
1
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Suspected cause · Original poster
- brake pedal vibration is less noticeable vs the vibration coming from the rear (suspect rear passenger side)
Vibration from Rear of C4S under high-speed braking
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Leading evidence: 'rear passenger side)' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'rear passenger side)' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check runnout' (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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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
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Suspected cause · Original poster
I am experiencing a pretty severe vibration while braking from 100+ mph and suspect a warped rotor but I cannot recall really stressing the car hard enough to do that.
Vibration from Rear of C4S under high-speed braking
Check runnout
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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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
Check runnout to find out which brakes/hubs are out of spec.
Vibration from Rear of C4S under high-speed braking
warped rotor
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 · Original poster
I am experiencing a pretty severe vibration while braking from 100+ mph and suspect a warped rotor but I cannot recall really stressing the car hard enough to do that.
Vibration from Rear of C4S under high-speed braking
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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.
5 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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I am experiencing a pretty severe vibration while braking from 100+ mph and suspect a warped rotor but I cannot recall really stressing the car hard enough to do that. The rearview mirror shakes and there is a pulsating sound. Curious if it is something less obvious before I throw new pads and rotors on the car. Car is a C4S.
- No vibration in the steering wheel - definitely the rear
- tires are Pirelli with less than 2k miles on them - should still be balanced and no vibration other than while braking
- rotors and brake pads are 5+ years old but have 50% life remaining from the looks of it
- car is driven maybe once a month and kept in a garage
- vibration occurs with clutch engaged and disengaged - wasn't sure if it was a motor mount or something
- no noticeable grinding when swerving at high speed - try to rule out wheel bearing
- vibration is barely noticeable if at all when under 90 mph
- brake pedal vibration is less noticeable vs the vibration coming from the rear (suspect rear passenger side)
Appreciate any thoughts or items I may be overlooking.
Simple explaination may be that weights fall off of the wheels all the time as well as the tires will slip on the wheels. Both cause an out of balance. May want to check that first.
Sure, could be a few other things, but start with the cheap simple stuff first.
Real simple, if you have vibration, shuddering, shaking steering wheel,
ONLY
under high speed braking, its your brakes. Check runnout to find out which brakes/hubs are out of spec. Then try and figure out why you developed excess runnout. Sticking calipers are a common cause. Change that brake fluid regularly...
If it was a
tire balance problem the vibes would be there all the time at high speeds
,
not just under braking.
.... Them the facts, tried to explain that on the other recent thread...
jmo
All joking aside, if you aren't a wrencher, find yourself a good indy. As mentioned it could be alot of things. I have had sticking calipers on the track, out of balance wheels, crap stuck on my rotors, bad bearings and everything else you can think of. Never had a hub problem nor a warped rotor even with heavy tracking. But it can happen. Start simple, cross it off the list and move to the next one. Let's hope it something easy and cheap.
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