Muncie goes fap fap fap

Allison Winn

Veteran Member
Jan 10, 2021
401
I have rebuilt many Muncies in the past. Just got a M20 done and fresh install in a 70 Camaro. All new clutch parts, decided to try LUK. Surfaced GM iron flywheel. New throwout and pilot. All fit and seemed fine as usual until I started the motor. Got a loud fap fap sound concurrent with engine rpm. Has a thin sheet metal slapping sound to it, not like heavy parts banging around. Only thing changes the sound is loosening up the clutch adjustment a LOT. Until it no longer works. So I yanked the trans back out - dont see any marks so far like something was hitting something else. Got any ideas?
 

mallard

Veteran Member
Oct 3, 2013
1,880
SK, Canada
Other than the noise does the clutch work properly? Does stepping on the pedal change anything? Feel any sensations through the pedal?
 

Allison Winn

Veteran Member
Jan 10, 2021
401
Never drove it. Started the engine, made a terrible noise, shut it down. Loosened the clutch rod some, got a little better but by then the adjustment was all the way out.
 

Allison Winn

Veteran Member
Jan 10, 2021
401
Took off the bellhousing tonight - no signs of anything flying around in there or any evidence of parts rubbing. I do notice my throw out bearing does not have the usual roll pin that keeps it from spinning in the fork. I believe I used a Hays high performance part
 

Twisted_Metal

Administrator
Staff member
Lifetime Gold Member
Feb 26, 2004
31,233
Bloomington, MN
Something smacking the inside of the backing plate?

Do you have any pranksters who would sneak a zip-tie unto something while you weren't looking?
 

mallard

Veteran Member
Oct 3, 2013
1,880
SK, Canada
Took off the bellhousing tonight - no signs of anything flying around in there or any evidence of parts rubbing. I do notice my throw out bearing does not have the usual roll pin that keeps it from spinning in the fork. I believe I used a Hays high performance part
I'm thinking it may be your release bearing. It would have been interesting to see what happened if someone stepped on the pedal a little to see if the noise changed.
 

Allison Winn

Veteran Member
Jan 10, 2021
401
I have a new Hayes TO bearing and new bearing retainer on the way. Be here Monday. I opened up the trans just for a quick check and all looks and sounds good.
 

Allison Winn

Veteran Member
Jan 10, 2021
401
Update
So here are some throw out bearings. The unknown brand on left is the one that was in my car. The center is a Hays self aligning. The right is a Brute Force. The left one I took out is slightly taller than the other 2. Maybe that was the problem?
 

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