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MG MGA - Shaft axle specifications

Inspecting the rear axle I found that the shaft axle has an excessive wear at the ends where the bearings are, my question is if the shafts can be repaired in the machine shop (welded and rectified) I think so, but what are the specifications for that shaft (MGA ´60), diameter basically! Any source of information? Thanks.

R Garcia

Where exactly is it worn? The outer axle shaft itself does not contact any wear surface, bearings or oil seals. It is connected to the hub(bearing carrier) by the flange on the end. It should not be worn at all!
Art Pearse

Art,
Probably you are refering to the propeler shaft, my problem is in the Shaft of the rear axle (steel wheel car) seats in the bearing of the hub (at near the end of the shaft closed to the wheel) and the bearing of the differential (close to the spline).
R Garcia

Art is correct the rear axles do not touch bearings at either end. Your question is confusing. Do you have a picture of what is worn?
R J Brown

Yes, agree, rear axle doesnot touch bearings, but the shaft inside the axle does.

See the imagen attached

R Garcia

The two areas you show do not normally contact anything! Unless a bearing has failed drastically I cannot see how it could. Do you have a picture of he wear?
Art Pearse

Art,

Yes, regards, Raul

R Garcia

Raul,

Could you wipe the oil off the shaft and get a clearer photo?
If you look a the area that you call worn it appears to have a very straight edge and the narrow section appears to be radiused at each end. It would not wear like that, it appears to be machined.
If it is exactly the same on the other end I would bet that it has been machined.


Mick
M F Anderson

Mick,
The shaft is almost clean, except at the groves there is no oil, the wear part looks like machined, I do not know if must be or not, but as you suggest the other end looks like machined and wear also.
The hub bearings are not smooth in the inside surface, seems to me that the play was too much between the two parts.
R Garcia

Raul,

Did you take both axle shafts out?
Are they both machined on each end?
It is not wear, they were machined. If done in a lathe you could probably see the grooves from the cutting tool (very faint). If ground you would probably not see the grinding marks.
Even if the bearings were in extremely poor condition that part of the axle would still not touch anything.

Why was it done? There is a theory, which I do not believe, that reducing the diameter near the loaded ends of a shaft reduces stress and stops a shaft breaking at the ends.

If you take both axle shafts out you should mark them Left Hand and Right Hand. New shafts are identical, but used shafts get a bit of a twist in them over the years and can break if they are put in the incorrect side.
On wire wheel cars if the hubs are put on the wrong side the wheels can come off as you drive.


Mick
M F Anderson

Looks like someone tried to balance? or straighten the shafts. Machining the ends so that it could be rotated on two v-blocks?

In any case, if the shafts are otherwise OK I would leave as is. Otherwise it would probably make much better sense to buy two new shafts than try repairing.
Neil McGurk

This is factory machining to get rid of the rough cast finish. Looks like it was not complete. Micks reasoning is good - smooth surfaces are less prone to cracks. Don't worry about it!
Art Pearse

Mick, Neil, Art,
I will check both shafts and bearings asap (hub and carrier). I will let you know my findings, thanks all!!
R Garcia

Mick, Neil, Art, for your information:
I removed the Right Shaft (I attach pictures)
Looks a little different from the Left Shaft at the carrier side, there is no excesive wear as the left shows, the wear at the hub side looks the same in both shafts, seems normal to me!

The dimensions are as follows:

at the hub side:

Left Shaft 1.772"
Right Shaft 1.774"

At the carrier side:
Left Shaft 0.982" and .0972" where the worst wear shows
Right Shaft 1.000" and 1.020" where the wear is. Is not very strange?

Question: Somebody knows what are the inside dimensions of the hub and carrier bearings?

R Garcia

Sorry, I have more pictures,

R Garcia

The last one!!!

R Garcia

These are non-critical dimensions you measured as these areas do not mate with anything. The outer wheel bearing fits over the axle casing. I think it is 40 mm ID bearing, interference fit to case.
Art Pearse

Now I think the machining looks like part of the manufacturing process.
Neil McGurk

Why did you remove the axles in the first place?
Have you got the diff housing out of the rear axle housing (you will then see how it fits together)?
What sort of fit are the wheel bearings on the axle housing? Were the nuts loose (LH & RH threads- special socket needed)? What sort of fit are the bearings in hubs?
Mike
Mike Ellsmore

Mike,
My car is been with me for more than 30 years, garaged for 15 and now I am in the process to restore it, I do not know if 100%, so I am disassembly some areas for inspection and that is what I found in the rear axles. Regards, Raul
R Garcia

Art, also Mick, Mike and Niel,
You are right, I commit a mistake of apreciation, the shaft seats as you said in the inside of the diff housign and the bearing seats outside of the housing at the same level or distance from the outside.
So, does not touch any bearing as you said at least in the outside, what about inside close to the carrier, where rests the shaft?
R Garcia

See image attached.
The inner axle spline item 41 fits inside the internal spline of gear item 22.
Gear item 22 fits inside the carrier item 21.
The carrier is supported by bearing item 18.
Bearing item 18 is held by item 13.

The inner end of the axle shaft is supported at the spline only by the internal spline of gear item 22.

Mick

M F Anderson

Mick,
Thanks for your time, I just can say that I learned other issue and solution, today I opened the differential case where the part 13 is and found that the bearing cap was losse and the bearing had some play, that caused the excesive wear in the half shaft.
Thanks all for the contribution!!
R Garcia

Raul,

You still have it wrong. It is not wear at the ends of the axle shaft. Forget wear.
The axle shaft cannot touch anything.
If as you say the carrier bearing 18 is loose in the housing 13 (see my previous image), this can cause expensive damage to the crown wheel item 25 and pinion item 31. Any misalignment of those two items is serious. It could also cause some wear at the inner axle spline item 41. BUT NOT THE AXLE SHAFT.

I don't think that I can explain it any more clearly.
If you cannot understand it then I give up.


Mick
M F Anderson

This thread was discussed between 09/08/2009 and 11/08/2009

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