Clutch chatter is a shudder or vibration as the clutch engages, usually felt when pulling away from a stop or reversing. Common causes are oil or grease on the disc, hot spots or warping on the flywheel or pressure plate, worn engine or transmission mounts, a glazed disc, and some performance discs that chatter by design. A new clutch that chatters may simply need its break-in period.
Common causes of clutch chatter
| Cause | Clues |
|---|---|
| Oil or grease on the disc | Chatter plus slip; a leaking rear main or input seal |
| Flywheel hot spots or warping | Chatter after heavy slipping; blue marks on the flywheel |
| Worn mounts | Engine rocks noticeably on take-off; see engine mount symptoms |
| Glazed or worn disc | Chatter with a high engagement point |
| Performance or puck disc | Some chatter is normal with aggressive discs |
| Improper break-in | New clutch chatters after hard early use |
Chatter at idle, in reverse or when hot
Chatter in reverse is common because reverse has a low gear ratio and engagement happens at low speed, which exaggerates any unevenness. Chatter that appears only when hot points to heat-related warping or glazing. Noise at idle with the pedal released is more often the transmission input bearing than the clutch; with the pedal pressed it is often the release bearing; see transmission noise.
Clutch chatter on a new clutch
- Follow the break-in instructions, usually a few hundred miles of gentle engagement.
- Confirm the flywheel was resurfaced or replaced to specification.
- Check that no grease from the input shaft splines reached the friction surfaces.
- Make sure the disc type suits street use; see stage 1 vs stage 2 clutch.
How to reduce chatter
- Engage the clutch smoothly with a little more throttle when pulling away.
- Replace worn mounts.
- Fix any oil leak and replace a contaminated disc.
- Resurface or replace a hot-spotted flywheel.
Diagnosing chatter
Note whether the chatter is worse cold or hot, forward or reverse, and whether it comes with slip or a burning smell. Have a helper watch the engine during a gentle take-off: excessive rocking points to mounts. If the clutch is due for replacement anyway, inspect the old disc and flywheel for oil, glazing and hot spots to confirm the cause.
Is clutch chatter bad?
Occasional chatter with an aggressive disc is not harmful, but chatter from contamination or a warped flywheel usually comes with slip and gets worse, and the vibration stresses mounts and driveline parts. See clutch slipping and signs of a bad clutch. Our ACT clutch kits list their disc type in each listing, such as the sprung street discs in the ACT kit for the 2003-2006 Evo ($853.00).
More guides: car won’t go into gear · dual mass vs single mass flywheel · organic vs ceramic clutch discs · clutch break-in.
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