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Rear axle noise in a TC

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Rear axle noise in a TC
#1
  This topic is about my 1948 MG TC
jgood67mgb Avatar
jgood67mgb Jim Goodwin
Colorado Springs, CO, USA   USA
1948 MG TC "Cash Eater"
1952 MG TD "Pick Pocket"
1957 MG MGA 1500
1960 MG MGA 1600 "Old Reliable Healey Killer"    & more
Greetings, I've been looking for the source of some noise in my rear axle. I've got a knock, knock noise; not rhythmical like a drum beat, but somewhat random. It's a fairly sharp knock sound and only happens in gear. If I shut the motor off and coast in neutral; no sound. I thought it might have been the pinion bearings so I replaced those but still have the noise. I really can't imagine what's inside the pumpkin that could be giving a sharp knock sound as if something was (occasionally) hitting the inside of the rear axle housing. I've got sealed bearings at the axle ends, new bearings in the pinion carrier and New U joints on the drive shaft.
The bronze pinion bearing retainer was broken into little pieces as you see in the photo. And yet all of the ball bearings stayed in place and continued to spin very smoothly. By holding the pinion carrier assembly in one hand and spinning the pinion with the other hand there was no indication anything was wrong. I washed the pinion carrier assembly in a solvent tank before disassembly and it got "notchy" as the oil was flushed out and would actually lock up and not rotate or only rotate in one direction. I thought, "great, replacing these bearings is an easy fix and my noise will go away!" But I still got that random knock knock. Any ideas guys? Thanks Jim

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Paul J Avatar
Locust Grove, OK, USA   USA
I've never seen a TC rear apart, but if it was mine, I'd pull the case apart and check the whole final drive, possibly one or both of the carrier bearings is shot and allowing horizontal movement of the final drive. PJ assembly.

Mitchman2 Avatar
Mitchman2 Mitchell Andrus
Mills River, NC, USA   USA
I had a knock-knock in a car a few decades ago. Drove us (dad and I) nuts. It was a broken leaf in the spring. Under load it jammed the break together and made contact. In other words, check the dumb stuff too, like the shock bolts, links and their bolts.



Buy a man a plane ticket and he flies for a day,
push a man out of an airplane and he'll fly for the rest of his life.

'30 Model A Ford
'48 MGTC
'58 MGA
'58 MGA

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Melbourne, Victoria, Australia   AUS
Loose or worn splines can make a knock on take off, or in reverse.

Matthew.

petergerard Peter DeBruyn
SARATOGA SPRINGS, USA   USA
Hi Jim -

I suffered a similar noise - the cause was a sheared bolt inside the case -
One of the bolts that holds the ring gear had failed and was occasionally
Being thrown against the back of the case making a disturbing noise.
I replaced all of the bolts w/aircraft quality lock-bolts. Take a look at your
Ring gear - could also be a loose cotter pin floating around ...

Cheers,
Pete

jgood67mgb Avatar
jgood67mgb Jim Goodwin
Colorado Springs, CO, USA   USA
1948 MG TC "Cash Eater"
1952 MG TD "Pick Pocket"
1957 MG MGA 1500
1960 MG MGA 1600 "Old Reliable Healey Killer"    & more
Peter, I think you're on to something. It sounds like you described, like something loose is bouncing around in there and occasionally getting caught in the gears. There looks to be only two bearings in the center pumpkin, maybe a ball has fallen out or there's a broken bit as you surmise. All of the broken pieces from the pinion double bearing are accounted for. I'm going to see if I can fish around through the tiny drain hole and feel if there are any loose bits. Thanks for the ideas guys. Jim

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