Rear Axle

I recently bought my MG and it has a droning noise at the rear constantly. I am presuming it's the diff and am wondering if it is an easy job to put in another diff or easier to replace the complete axle. My car has the semi-floating type fitted and browsing through my workshop manual it doesn't give any details but simply states that this type of axle and diff is "specialised" and therefore a main dealer job.

Has anyone tackled this type of diff and if so is it a job that can be done myself?

I have purchased a good used complete axle in preparation.

Comments appreciated, Russ.

I tried to rebuild mine and I ended up bringing the entire rear end to a pro and let him rebuild it then I put it back on. It didn't seem to hard, but there were certain tools needed to take out the axle that I didn't have.

Afer reading this article I decided to let someone who had extensive experiance do mine: >>> http://www.differentials.com/install.html

:eyeroll: mmm . . . point taken! For the time being, or at least until the new year I think I'm just going to change the oil and add some Molyslip and see if it quietens down a little. Reading other articles on similar subjects, they will howl away almost indefinitely!

You would be astounded by the ability of a B rear axle to operate without ANY lube. For just this moment drop the cover plate and the drain plug and see how much oil is in there. Chances are that it is REALLY low. If you drop the cover, try to wipe out the gunk from the bottom of the case.

Refill to the correct level ( until oil just begins to flow back out of the filler opening ) and go for a drive. Refill SLOWLY to get the accurate level.

As far as fully rebuilding a hypoid final drive is concerned, it isn't rocket science, but it IS tedious and if you are a first timer at it and you aren't in a proper shop environment you will spend a ton of time and still have a 50/50 chance of ending up with a noisy axle. All of that grief revolves around getting the pinion and crown wheel gears set perfectly.

Replacing the thrust washers in the diff cage and replacing the axle bearings are another matter, much less involved.

Jack

Jack,
Is the procedure for "All of that grief revolves around getting the pinion and crown wheel gears set perfectly." explained somewhere?

Not specific to MG, but a general sorting of the issues here:

http://www.differentials.com/install.html

Russ

If you have a real problem it might be easier and cheaper to just get another diff, they are usually bullet proof though.
Recommend Jacks advice first.

Ron

Besides the above, you can replace the thrust washers (two sets of two) easily enough. Some people get noise to go away doing that. If you don't have a slide hammer for getting the one axle out, you can use the sledge hammer hooked t o achain and then swing; it pops the axle out as it follows the sledge head.
I just took the car to have the pinion seal replaced and a new crush bushing installed at the same time as I do not do that end of the diff; the clunk is now gone!
So, clean, replace thrust washers, replace pinion seal and crush bearing and you should be noise free!

Don't rule out the drive shaft as "most" of my noise was in the U-Joints and a worn slip joint. My joints were worn in the yoke, not the t ypical joint wear. I ended up replacing the entire shaft as an assembly from Moss and so much noise was gone that I decided to live with what is left (which I beliieve to be the pinion). Also, make sure its not the outer axle bearings before replacing the entire rear end.

Just my $.02 worth and trying to give back to the list what I get out. :)

If you are going to replace the complete diff you do not need to do anything with your brakes. Remove the brake drums,then the hub (one nut 1 5/16) and the 4 bolts that hold the backing plate. Leave the backing plate hang on the steel brake line and do not remove the lines and let brake fluid out. Once thats done you have 4 driveshaft bolts,8 nuts on the U bolts and anthing attaching the steel brake like and flex line to the diff. As i recall remove the passenger side rear spring shackle and get that diff out of your way! (with assistance I think you can remove it without dropping the one shackle.) Reassemble in reverse order but put your new pinion seal in while its on the floor! Its not a hard job unless your U bolts are rusted and the threads strip out. That could hold you up if you need to order new ones. Good luck on the repair. Bob

Thanks for all your advice. I'm going to take Jacks advice first this weekend if it ever stops raining here in the UK and see what the oil situation is like. Many thanks, Russ.

Hi Russ

I've got a similarly problem with my GT right now. The diff is making some noise. I'll get around to replacing it next year I think. The folks at my local MG club told me to check the oil and keep an eye out for leaks. But, as people have noted already, I'm told the diff is pretty solid and likely to go on making noise for some time without any probs (other than the noise...) I recall reading somewhere (prob on this forum?!) that the axle on the MG was part-shared with the much larger and heavier Sherpa van, which prob explains its robustness.

Anyway, I noticed from your profile pics that you don't yet have the plastic wheel arch protectors fitted. If you're using your GT as a daily driver (as your profile says), then IMVHO you should definitely invest in a pair! Especially with all the rain and salt we have on the UK roads right now. They are easy to fit and prevent water from sneaking over the splash panel and rotting away your car... Moss UK (no affiliation) sell them, but you can no doubt get them elsewhere too!

take a look: http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=5585&SortOrder=1

T