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Second Opinion Needed - What's That Noise in My Rear End?

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Second Opinion Needed - What's That Noise in My Rear End? #1
malargent Mark Largent Holt, MI, USA Sign in to contact 1973 MG MGB GT	Topic Creator (OP) Apr 24, 2014 09:06 PM Joined 15 years ago 337 Posts

I'm sure that this will attract a few wise cracks .... but I'm hoping to get a few good second opinions, too.

'73 BGT

I hear a distinct whirring or grinding noise when I am going 40 mph. It is definitely coming from the rear end, and it is louder when I remove the battery cover. It's loudest at 40 mph and fades when I go faster or slower. The noise is the same whether I am coasting with the clutch in or out or accelerating with the clutch out. I first heard it last year, and it has slowly grown a little louder over the last year.

I have narrowed it down to two possible sources: the pumpkin or the wheel bearings. I am inclined to think that it is the wheel bearings - or, perhaps it is more that I hope it's the wheel bearings because I have a new set of bearings that I can install.

Maybe it's something else. Any suggestions?

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Re: Second Opinion Needed - What's That Noise in My Rear End? #4
33EJB Tim C LS, Eastern Ontario, Canada Sign in to contact 1969 MG MGB	Apr 25, 2014 09:33 AM Top Contributor Joined 12 years ago 3,237 Posts

A grinding noise in your rear end eh?... sounds like a visit to your proctologist is in order... moon

Sorry... back to the topic...

Probably wheel bearings, but - have you checked the oil level in your diff lately? Many people ignore this check and strange rumblings can result if there is insufficient or no oil in the diff. Worth a look.

Even if the oil level is OK, draw a little out with an eyedropper or a small syringe and have a close look at it in the sunlight. If you have a diff problem you might see some tiny sparkly metal flecks floating in the oil from the worn parts grinding inside.

One other possibility that comes to mind is a worn or dry u-joint. They can make a noise similar to the one you describe too.

Good luck.

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Re: Second Opinion Needed - What's That Noise in My Rear End? #5
fireball61 ted openshaw lipscomb, AL, USA Sign in to contact 1975 MG Midget 1500 1992 Jeep Wrangler 2000 Nissan Xterra	Apr 25, 2014 09:41 AM Joined 10 years ago 252 Posts

i cant answer....its toooooo funny......good luck with your car.....\

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Re: Second Opinion Needed - What's That Noise in My Rear End? #6
Dave Braun Georgetown, TX, USA Sign in to contact 1952 MG TD "Tommy" 1970 MG MGB "Maggie" 1974 Triumph Spitfire 1500 "Sammy"	Apr 25, 2014 09:51 AM Top Contributor Joined 12 years ago 3,502 Posts

If it was gear lash the noise would be most apparent when lifting the throttle at any speed. I let a diff get low on oil and toasted the gears once. Won't make that mistake again!

dbraun99 LLC www.dbraun99.com

dbraun99 LLC no longer offers Carburetor Bench Services on SU Carburetors. See www.dbraun99.com for helpful pictures of carburetor rebuilds.

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Re: Second Opinion Needed - What's That Noise in My Rear End? #7
BumbleB74 William Milholen Tidewater, Tidewater VA, USA Sign in to contact	Apr 25, 2014 01:07 PM Joined 18 years ago 8,982 Posts

probably didn't smell too good either did it?

1974-1/2 Roadster, "Bumble Bee", Corvette Yellow - in shambles, wire wheels
1976 Roadster, "Virus", Sandglow - "driver" condition (stock + 32/36 Weber DGEV, cast iron header, 25D distributor), bolt on wheels, ON the road!

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Re: Second Opinion Needed - What's That Noise in My Rear End? #8
RAY 67 TOURER Ray Marloff Fort Bragg, CA, USA Sign in to contact 1967 MG MGB "My Girl"	Apr 25, 2014 02:21 PM Top Contributor Joined 14 years ago 17,488 Posts

If the rear axle oil level drops dangerously low, the case hardening will be worn off the faces of the ring and pinion gears. This will produce the sound that you have described. Here's hoping that it is something else entirely. RAY

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Re: Second Opinion Needed - What's That Noise in My Rear End? #9
mac townsend Fairfield, CA, USA Sign in to contact 1973 MG MGB MkIII	Apr 25, 2014 02:54 PM Top Contributor Joined 18 years ago 24,294 Posts

Rear wheel bearing replacement requires a press. It's not something you can do in the driveway.<G>

1973 Pale Primrose Roadster. A nice 10-footer!
SUs, Datsun 5-speed

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Re: Second Opinion Needed - What's That Noise in My Rear End? #10
Whidbey MG Smile'in Joe Coupeville, WA, USA Sign in to contact 1951 MG TD "Sorted/Sold" 1952 MG TD "Our Wedding Gift To Ourselves" 1953 MG TD "Enjoying/Mellow Yellow" 1958 Chevrolet Nomad "TOO Big/Sold" & more	Apr 25, 2014 03:26 PM Joined 10 years ago 94 Posts

I took my shaft and new seal and bearings to my local garage. HECK, I've already put the owner/mechanics grandson through college I figure, with the bills I've run up there over the years. He did it all for free. Did the last one for free too. I'll give him a couple pounds of coffee next time I see him...always pays to be nice to your local garage and mechanic.

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Re: Second Opinion Needed - What's That Noise in My Rear End? #11
malargent Mark Largent Holt, MI, USA Sign in to contact 1973 MG MGB GT	Topic Creator (OP) Apr 25, 2014 08:59 PM Joined 15 years ago 337 Posts

Thanks to all of you for your advice and suggestions. I'll crawl under the car this weekend and check the oil level in my diff. I suspect it is the wheel bearings.

Can someone please point me to a good source for advice about how to change the wheel bearings. Also, what other "might-as-wells" should I being doing at the same time?

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Re: Second Opinion Needed - What's That Noise in My Rear End? #12
vem Vic Myers Hollister, Ca., USA Sign in to contact 1974 MG MGB 1975 MG MGB "SuperCharger" 1975 MG MGB MkII 1975 MG MGB MkII "Fredo"	Apr 26, 2014 01:54 PM Joined 19 years ago 608 Posts

While you are under and in there, consider a clunkectomy. It won't add more than 1/2 hour to your work. Cheers Vem

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Re: Second Opinion Needed - What's That Noise in My Rear End? #13
malargent Mark Largent Holt, MI, USA Sign in to contact 1973 MG MGB GT	Topic Creator (OP) Apr 26, 2014 08:55 PM Joined 15 years ago 337 Posts

Ok, help me out ... What's a clunkectomy?

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Re: Second Opinion Needed - What's That Noise in My Rear End? #2
joron Michel Joron Roxboro, QC, Canada Sign in to contact 1977 MG MGB "Victoria" 2018 Jaguar XE "Meghan"	Apr 24, 2014 09:46 PM Joined 10 years ago 2,989 Posts

Re: Second Opinion Needed - What's That Noise in My Rear End? #3
Whidbey MG Smile'in Joe Coupeville, WA, USA Sign in to contact 1951 MG TD "Sorted/Sold" 1952 MG TD "Our Wedding Gift To Ourselves" 1953 MG TD "Enjoying/Mellow Yellow" 1958 Chevrolet Nomad "TOO Big/Sold" & more	Apr 25, 2014 06:09 AM Joined 10 years ago 94 Posts

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