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4ZUA787
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Discussion Starter · #1 ·
when i go around a right hand turn i get a type of grinding noise from the rear right i believe, it sounds like a bearing when they start to go bad is this the sign are opels give us when the bearings are starting to give out??? jus wonderin what i should look at since i left the car back end up and spin the wheel no noise only around right hand corners. any help, ideas, are welcome.
 

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What year rear axle do you have? If it is a 1971 or later with the ball bearing style wheel bearing then you may be correct; however, usually damaged rear wheel bearings will rumble all of the time. If you have an early axle with the cylindrical rear wheel bearings, then this is likely to be a differential bearing going bad. This type of axle handles thrust with the side bearings in the differential.
 

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4ZUA787
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Discussion Starter · #3 ·
i have a 72 gt with what i believe to be the origanal rear end, never been messed with, well today it started making noise when i made hard right or left turns, im thinking of opening the diff up and lookin but it doesnt leak oil right now and i no if i open it theres that chance when i re seal it it will leak and then i gottta do the whole seel all over, the noise is a grinding maybe could be described as a rumble.
 

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If you're talking about a noise when you are making sharp corners at low speeds, that sounds like the side gears in the differential. You need to open the cover on the differential immediately. Is the oil level correct?
 

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It could be the torque tube mounts. If they have never been replaced, I would try these first. They may look good, but you can't tell a good one from a bad one until you remove them. There are 2 mounts and a top bumper. Replace all three. I had the same noise and it went away after I replaced them. It beats replacing the rear bearings. Just my 0.02
 

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Old Opeler
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Grumbly

If there are grumbles coming from the diff it probably has not been looked at for a long time. A through check is indicated. A noise that gets cyclicly louder and quieter while weaving from side to side is usually rear wheel bearings. It is not too onerous a job to check them:


1st: Jack up the rear of the car and place on solid jackstands or wooden blocks with the wheels off the ground. Grab a tyre in both hands and turn the wheel while applying outward pressure to load up the bearing. You should be able to "feel" any roughness in the bearing.

2nd: It is not too difficult to now remove the wheel and brake drum ( It is probably time to check the rear brakes anyway!). Once again apply pressure to the axle flange while turning it to load the bearing. Feel for any roughness.

3rd: If indoubt, remove the axle from the diff and hold the bearing outer race in one hand while turning the axle with the other - feel for roughness.

A visual inspection will tell you if the bearing seals are still doing their job at keeping the diff oil in - should they be leaking or show roughness then the wheel bearing needs replacement. You already have the axle out ......

A check of the torque tube rubbers at this time is also probably overdue.

It is very seldom that inner diff carrier and pinion bearings fail unless no oil overheating or pinion nut coming loose has occured. If either of these things have occured the diff will be "singing a song" rather than "moaning" as the side load goes on during cornering.
 

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4ZUA787
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Discussion Starter · #7 ·
i no my rear brakes are ok since ive looked at those the last time i rotated the tires, and i redid the torque tube donut and stuff about 2000 miles ago im thinking i may jus need to pop the rear diff cover and take a look, it doesnt use a gasket right its jus silicone that u put inbetween the rear acces plate and the diff?? and if i pul the axle out to check the bearing it is very easy to put back in, i would assume u would just turn it till it slipped back into the grooves.
 

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Old Opeler
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Wiggle

Yes, the axle will go back in very easily with a bit of a wiggle to line up the splines on the inner end. Just be careful with the rubber "O" ring around the outer race of the wheel bearing as bits can be sheared off this as it goes back into the axle housing - and it is there to keep the oil inside the diff.

The centre diff cover usually has a paper gasket in there. Maybe RTV will do the job but don't get too much of it inside! A thin bead of it on an oil free surface and you should be AOK.
 

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4ZUA787
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Discussion Starter · #9 ·
well today i jacked up the rear end and took the fill plug out of the diff it appears to have atleast if not more then enough oil in it, and the oil didnt smell burned or look to dark in color, also i tried the idea that was suggested of turning the wheel while appling pressure from side to side, no noise made, also i tried doing donuts both left hand lock to lock and right hand lock to lock, it doesnt make the noise if ur doing a circle or donut but when u go to make that sharp right hand turn out of say a driveway onto a busy street and u gun it it makes the noise, will investigate more in the am.
 

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I had a 71 kadett that did that. No noise while moving straight ahead or around normal curves in the road. I always heard it at low speeds (under 10 mph) while making sharp turns. I never bothered to check it out but I was convinced that it was side gear wear in the differential. The side gears only do work when one tire is going a different speed than another, like making sharp turns. I would suggest that you pull the cover off the differential and check out the gears. If every thing looks good I wouldn't worry about it unless it gets worse. (starts making noise while driving on the road). Differential cover gaskets are available through typical auto part stores. I ordered three from Autozone. Got them the next day. As I mentioned in an earlier post, rear wheel bearings typically make noise all the time. The sound changes with speed. Because the 72 and later style rear axle relies on the wheel bearing to take axial thrust load, in theory the sound might change while cornering, but I still maintain that it will still make noise even on a straight-a-way.
 

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4ZUA787
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Discussion Starter · #11 ·
i will go to auto zone in the am and see if they have one in stock if so the back cover will be coming off, i jus cant have my car not working for more then half a day right now.
 

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4ZUA787
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665 Posts
Discussion Starter · #12 ·
what is the part number for the rear diff seal from autozone or if anyone has one for anthor retailer, jus trying to find this gasket.
 
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