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MG MGA - Rear axle conversion to 4.1

I have a 1600 MGA Coupe with wire wheels and the standard 4.3 rear axle. I have the opportunity to acquire a 4.1 rear axle with disc wheels. I would like to install the 4.1 rear axle but with my wire wheel hubs. What do I need to do to accomplish this conversion.

Many thanks

Andy
Andy Preston

Remove an axle shaft from your car and see if it fits into the side gear internal spline of the 4.1 differential assembly.
If the splines match just pull the other axle shaft partially out and remove the differential center assembly and fit the 4.1 assembly.
If the splines do not match transfer the differential side gears of the 4.3 over to the 4.1
Remember that if you take both axle shafts completely out (not necessary) mark them "Left" and "Right". The two shafts are identical when new, but can get a slight twist in them after much use. Putting them back in the wrong side can lead to early axle failure.

Mick
M F Anderson

Andy,

Just to clarify the wire wheel axle is narrower than the steel wheel one. It is important that you either swap differential (pumpkin) assemblies or buy new half-shafts made especially for wire wheels on steel wheel axles (commonly available for conversions).

As Mick says if the half shafts have the same number of splines it's a very simple swap, if not you need to swap over the sun gears.

Your 4.1 axle is most likely 25 spline (Mk2) whereas your 4.3 will most likely be 10 or 26.

Now is a good time to get rid of any rear end knocks due to worn (shaft,hub,wheel) splines or pinion and gear thrust washers.

As always, you can find everything on Barney's site.
Neil McGurk

Andy,

Neil mentions what you can most likely expect, but I never make assumptions with cars that are 50 years old and have probably had many previous owners.
I always go back to basics. Ignore the model year and the ratio stamped on the axle casing. Test your 4.3 ratio by the turning test. Then test the 4.1 the same way. Then physically check the spline matching.
I assume that you know how to test the ratio, it is not as simple as some imagine, the differential system can play tricks on the unwary.

Mick
M F Anderson

The easiest way is to swap pumpkins and the sun gears. A relaxed day's work if you have never done it before. Half a day otherwise. As Neil points out, Barney has it covered. I followed his instructions. Straightforward enjoyable job.

Steve
Steve Gyles

Guys, thanks for your input. I'll review Barny's site and the shop manual. If I have any more questions I'll get back to you. At least it sounds possible and reasonably straight forward and worth pusuing.

Thanks

Andy
Andy Preston

This thread was discussed between 31/10/2009 and 01/11/2009

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