Crankshaft end play = clutch chatter? - Team Camaro Tech
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post #1 of 14 (permalink) Old Apr 4th, 08, 05:42 PM Thread Starter
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Crankshaft end play = clutch chatter?

I've been trying to figure out why my '68 (327/muncie) clutch chatters when it's warm. The flywheel was resurfaced, checks flat, and the PP/disk are new. But while I was checking the flywheel I noticed the crankshaft has .040 of end play. I know this is out of spec, but can it make the clutch chatter?
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post #2 of 14 (permalink) Old Apr 4th, 08, 06:11 PM
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Re: Crankshaft end play = clutch chatter?

I don't believe excessive crankshaft thrust clearance will cause clutch chatter but can cause connecting rods failure or wrist pins to work loose. Clutch chatter from my experience has been more related to high coefficient of friction, bad motor mounts, an incorrectly machined flywheel or faulty pressure plate, spring-centered race disc (aggravates chatter), and contamination (oil, grease, or rust), pilot or input transmission bearing or possibly a misaligned bell housing.

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post #3 of 14 (permalink) Old Apr 4th, 08, 06:18 PM
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Re: Crankshaft end play = clutch chatter?

If Muncie 4-speed, also check front bearing retainer (throwout bearing rides back and forth on this piece). They get worn after years of service. Mine was worn, not much, but worn. I replaced it while fixing a few other things and my clutch chatter is gone.

As noted above, did you check the pilot bushing?

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post #4 of 14 (permalink) Old Apr 4th, 08, 06:33 PM
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Re: Crankshaft end play = clutch chatter?

Right about the Muncie front bearing retainer snout. I've seen friends of mine have them welded and lathed to freshen them up.

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post #5 of 14 (permalink) Old Apr 4th, 08, 06:52 PM
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Re: Crankshaft end play = clutch chatter?

Here's a pic of my bearing retainer. You can't really see that it's worn, but if you measure it..........

I had posted this pic a while back asking if guys thought it was bad. I bought the new cover from Jody at Jody's Transmissions, a great guy to deal with. Good prices too. I bought a new Autogear piece, which seemed to cure my chatter.
Jody Haag at [email protected]


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post #6 of 14 (permalink) Old Apr 4th, 08, 06:57 PM
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Re: Crankshaft end play = clutch chatter?

Jim,
If you really have .040" crank end play, I dont care if its making the clutch chatter or not, its time to pull the engine and fix it. The crank counterweights are just about ready to start hitting the main caps

Bill Koustenis
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post #7 of 14 (permalink) Old Apr 4th, 08, 08:07 PM Thread Starter
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Re: Crankshaft end play = clutch chatter?

Quote:
Originally Posted by BillK View Post
Jim,
If you really have .040" crank end play, I dont care if its making the clutch chatter or not, its time to pull the engine and fix it. The crank counterweights are just about ready to start hitting the main caps
That's what the dial indicator says and it feels like it's moving at least that much. It's a shame as it runs great and has good compression, but the oil pressure is kinda low (10psi hot idle). Is the crank worth fixing or should I just find a good one?

As another poster suggested, I'll check the muncie bearing retainer taper. I had it rebuilt about 200 miles ago though.
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post #8 of 14 (permalink) Old Apr 4th, 08, 10:50 PM
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Re: Crankshaft end play = clutch chatter?

if crank moves that much that is your problem as you push in clutch it moves crank back up into engine and when you release clutch and give it throttle it moves baxk
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post #9 of 14 (permalink) Old Apr 5th, 08, 03:49 PM
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Re: Crankshaft end play = clutch chatter?

Quote:
Originally Posted by go2fast View Post
Is the crank worth fixing or should I just find a good one?

If its a steel crank, it might be worth getting the thrust welded up and reground. If its a cast crank its not worth the trouble. I personally would not start the engine again until you fix it. All you are doing is circulating more metal through it, which will make it even more costly to repair.

Just my opinion,

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post #10 of 14 (permalink) Old Apr 6th, 08, 07:55 AM
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Re: Crankshaft end play = clutch chatter?

Crankshaft end play should be somewhere around .005", according to sources I see. To remove excessive end play, you'd typically need to replace the thrust bearing and that should fix it. Normally the crank would be OK.

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970

Last edited by Chevy-SS; Apr 6th, 08 at 11:40 AM.
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post #11 of 14 (permalink) Old Apr 6th, 08, 11:16 AM Thread Starter
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Re: Crankshaft end play = clutch chatter?

Quote:
Originally Posted by Chevy-SS View Post
Crankshaft end play tolerances are between .005" - .036", so you're not far off.

.040" is a tad loose, but not horrible IMHO.

To remove excessive end play, you'd typically need to replace the thrust bearing and that should fix it. Normally the crank would be OK.
I like this answer better than the others :-)
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post #12 of 14 (permalink) Old Apr 6th, 08, 11:40 AM
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Re: Crankshaft end play = clutch chatter?

I made a mistake, that's the wrong number. .040 is too much and may be a cause of your low oil pressure. I was looking at tranny endplay numbers.

The correct number appears to be around .005 to .008, but I see some advocating .002 to .006. It's been a few years since I last assembled an engine, but I think mine was .006..........

Dave F. in Rhode Island
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post #13 of 14 (permalink) Old Apr 6th, 08, 06:11 PM
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Re: Crankshaft end play = clutch chatter?

Factory end play spec is .003-.007 You can usually get away with up to .010 or .012, but any more than that and its done with.

Bill Koustenis
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post #14 of 14 (permalink) Old Apr 6th, 08, 07:58 PM Thread Starter
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Re: Crankshaft end play = clutch chatter?

Quote:
Originally Posted by BillK View Post
Factory end play spec is .003-.007 You can usually get away with up to .010 or .012, but any more than that and its done with.
Yea, that's what I figured. I took the crank out today. The thrust flange looks OK, so I guess it's the bearing. They don't look terrible, but there's definitely been some trash in there. Guess I either need to get it turned or just buy a crank kit for it. Everything else in the motor looks great.
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