Author Topic: Throw Out Bearing Noise  (Read 920 times)

Offline tom120

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Throw Out Bearing Noise
« on: May 29, 2012, 08:56:00 PM »
my 47 Clipper has a throw out bearing that hums when the clutch pedal is depressed.  been that way for almost 20,000 miles with no change. anybody have the same issue? thanks

Offline bevans6

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  • 1980 MCI MC-5C
Re: Throw Out Bearing Noise
« Reply #1 on: May 30, 2012, 11:36:47 AM »
Not that I have a '47 clipper, or have any idea what kind of gearbox or clutch is in it, but yes, I have had a bad throw-out bearing before.  It can sometimes be confused with a bad pilot bearing.  The pilot bearing is in the tail of the crankshaft and the nose of the input shaft to the gearbox rides in it.  Throw out bearings can go bad such that they "sing" when they are under pressure with the clutch in, and they can hang up so they "sing" when the clutch is out.  The throw out bearing can be fine and the clutch can be bad - the discs can be loose or the fingers can be broken, or the springs can be bad.  Now, in my case (1980 MC-5C 8V-71 Spicer) I found that I had a bad throw out bearing (lack of lubrication, noticeable roughness when spun), an almost seized pilot bearing, some broken springs in the clutch cover and mis-adjusted clutch fingers.  No noise and it all worked just fine, I found it when I took the engine and gearbox out for another reason.  Moral of the story - sometimes you gotta look and see...

Brian
1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Allison MT-647
Tatamagouche, Nova Scotia

Offline tom120

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Re: Throw Out Bearing Noise
« Reply #2 on: May 30, 2012, 07:01:00 PM »
good points all brian. this is a singer when pedal is down. otherwise everything sounds and works fine. will have to take a look i think. thanks. tom