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MG MGA - Rear axle problem

Hi Folks. This seems to be a year of constant problems and repairs for my MGA 1500 roadster! I was driving the vehicle, when a car pulled along side and the passenger stated that my driver passenger side rear tire was "wobbling a lot" I checked the tires, and didnt see a problem, and also checked that the rear axle is firmly attached to the leaf springs. (It is.)
I took the car home, jacked up the rear end , and then wiggled the road wheel and tire side to side, and up and down. When doing this, there is very noticeable, and feelable slop in the axle!! Additionally, I can feel the opposite end of the axle shaft (splined end) banging around, deep inside of the rear axle housing. Can anyone offer any insight as to what has crapped out in the rear end, and the best course of action to repair the problem? I have never had any problems with this rear axle up until now, and it is the original axle!
Thanks, Glenn
Glenn

Correction: passenger side rear tire was wobbling a lot. Glenn
Glenn

Characteristic of rear wheel/hub bearing failure.
FRM
FR Millmore

I would also consider your thrust bushing inside the diff. Although I do not think they would display ,wheel wobble, there would be a considerable amount of free play when the wheel was rotated from and back. If you rae going to open the diff do yourself a favour and take the time to repalce them. it is very easy to do. Gord
Gordon Harrison

Glenn, the symptoms you describe sound like a broken half shaft with the exception that the axle will drive the car. Usually with a conventional differential a broken half shaft will result in a lot of engine racing and no movement. Is it possible you have a limited slip diff installed? The movement at the axle end does indeed sound like bearing failure as FRM says, but the banging you describe deep in the axle housing really sounds like the broken end of a half shaft.
Bill Young

I'm with Bill. Broken half shaft leading to worn bearing on the wheel end.
JohnB

Surely a broken half shaft removes all drive to the rear wheels?

Steve
Steve Gyles

Steve gets the prize. The banging is because the shaft moves in and out, since the BEARING isn't locating it correctly.
FRM
FR Millmore

Glenn

Get out that manual and pull the half shaft out. It's so easy you'll wonder why you posted the question!

If the half comes out in one piece it ain't broke.
If the bearing is all wobbley, replace it.

Let's hear about what you find.

Pete
Pete Tipping

Hi folks. I did as suggested and pulled out the half shafts. THe half shafts are in excellent, almost pristine condition, with very little wear. The halfshafts are the early 10 spline units. With the halfshafts pulled, it seems that there is some noticeable play in both rear hub ball bearings. Additionally, the driver side ball bearing seems to NOT be a tight fit in the hub! The hub can be pulled in and out while the bearing remains firmly in place on the axle. I assume the bearing is loose in the hub, and should not be? So what is the cure for a bearing that is loose in the hub? Is a new hub required, or iis some kind of slick fix possible? Thanks, Glenn. PS. Mr Millmore: you stated that: The banging is because the shaft moves in and out, since the BEARING isn't locating it correctly. Would you care to expand on that thought please?
Glenn

MGA with disc wheels use a spacer in the rear hub for the outer bearing race (spacer not used with wire wheel hubs). If the spacer is left our of the disc wheel car the bearing hub (and wheel) can move in/out about 3/16 inch on the outer bearing race, which would also lead to rapid wear of the bearing mount diameter in the hub. If your car is missing the outer brace spacer, go find one before you drive it again.

Bearing loose in the hub can be fixed with bearing set adhesive. Try Loctite 609. This stuff is designed to fill a small gap, as much as 0.005 inch diametrical clearance (or up to 0.015 inch maximum for other adhesive type). It is an anaerobic adhesive (cures in the absence of air) similar to thread adhesive.

See http://loctite.com
Click on Products, Assembly Products, Cylindrical Assemblies (Retaining), General Purpose, 609

Beware this stuff has a high shear strength when cured, so it may be tough to remove the bearing next time you need to change the seal in the rear hub.

Loctite 641 can be more easily disassembled, has slightly lower strength, and takes a little longer to set.

These same products are also good for setting and sealing a SpeediSleeve on the axle housing for seal surface repair.
Barney Gaylord

Hi Barney. Thanks for the additional insight. The bearing spacer was in fact there. I should have said with the halfshaft and bearing spacer REMOVED, the hub could be pushed and pulled in and out with a fair bit of slop. The balls inside the race seem highly polished, but there seems to be considerable slop in the bearing. if a pocket knife blade is gently pushed between the balls, the balls seem to move quite freely and move sideways a fair distance. (@ one eighth of an inch) I assume that this is not normal, and that the balls inside the bearings should not "travel" this much when poked, and that the bearing should have little or no appreciable slop? I think perhaps both my hubs and bearings are worn, and I am in the process of looking for replacement parts. I dont suppose anyone has a good used set of rear axle hubs and bearing they would want to part with at a reasonable cost? ;-)
cheers, Glenn
Glenn

Something similar happened to me years ago. It turned out that one night I hit a curb with my rear wheel (steel wheels at the time). The impact slightly bent the axel housing extension that the outer bearing rides on. At the time that it happened, I only thought the steel wheel rim was bent and replaced it. After about a year, looseness developed in the rear hub and wheel and I started losing gear oil into the brake drum. When I removed the large nut holding the hub on, the hub slid off easily. That's when I discovered the bent housing extension since it had noticable wear marks.

I don't know if something similar happened to your car, but your symptoms brought back these memories. I eventually had to replace the entire rear axel housing. That's when I converted to wire wheels and a 3:91 rear end from a 1967 MGB.

Steve
Steve Brandt

Glenn, I might have what you want - hubs plus s/hand bearings. I bought new ones they are SKF4208ATN9, from Motion Canada (used to be MBS bearings). Cost about 60 bucks each, not cheap. The old ones are not too bad shape, no slop. Email me if interested.
Art

Hi Art. Thanks, will emai you. Cheers! Glenn
Glenn

Back after 6 days with no phone/computer service - thanks Verizon!
Glenn,
This axle design is what is called a 3/4 floating unit. Common semi floating designs have the weight of the car supported by the halfshaft, 3/4 take radial loads on the bearing directly, but need some stability or longitudinal location through the shaft; full floating designs (trucks) have all loads through the bearings, with the shaft driving only. On BMC axles, the bearing takes all radial and thrust loads, with only some stability against "wobble" from the shaft, kind of a 7/8 floating system, with the great advantage that when the shaft breaks the wheel stays on. If the bearing is good and correctly located on the axle and hub, there will be no movement of hub or shaft either radially or axially. The original bearings are a doublerow ball race, with bronze cages. When old and worn, the cage breaks, giving the ball movement you see. Cage beakage is usually a result of wear on the races causing excess spreading loads on the balls.
FRM
FR Millmore

This thread was discussed between 09/09/2006 and 20/09/2006

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