This page is about replacing a broken TD/TF half Shaft via DIY methods.  The basic technique being utilized is mentioned a few times in various TSO articles of The New England MG T Register, e.g., February 1991, Pages 34 -35 under Technical Topics.  To avoid getting into copyright problems with the TRegister I'm going to be using a procedure written up by Guenter Kallies from Germany.  Guenter is a regular contributor to the MG Enthusiasts' BBS.  When the half shaft of his TD broke he solicited help from the members of the UKMGBBS.  As always, Guenter went beyond that which is necessary to get the job done and did an excellent job of documenting his procedures.  He then was gracious enough to provide Ttalk with a set of information to be shared with all.  Here is Guenter's report:

Broken rear axle shaft

Breaking a rear axle on our MG TD has been a steady problem for almost 60 years. If you compare the three shafts shown in the picture you will understand why.

Number 1 (on top of the picture) is the original one, made somewhat in the 50^'s and possible delivered with my TD # 29276 in 1953. As you can see the surface is very poor

 

, some porosity are visible because the surface was not machined.

Number 2 in line shows a replacement, which was installed, may be in the 70^th, when the car was fully restored. It is a very similar shape, but fully machined.

What you not can see is the material specification. Both of them should be made according Factory specification from AISI 1340 carbon steel and heat treaded to a surface hardening of #50 to #55

Good news now!

Mr. Jerry Austin decided to assist TD, TF, and YB owners by eliminating that fragile factory axle and provide an extra-duty shaft made by a company that has produced axles for many, many decades.

 

Those axle shafts are made from high-duty material with other improvements incorporated. The result is certainly a much more reliable axle than the original one.

Number 3 shows you how the new one looks like and here are the further details of this upgraded axle:

The material now is AISI 1541, which is a high Manganese Carbon Steel. The heat treating is by high-temperature induction and it is now done to #62 (which penetrates further to about 1/3 of the diameter).

For further Material details see: http://www.efunda.com

 

The factory shaft was 15/16” in diameter from the splines at the end that fits into the differential and is now reduced to 7/8” the whole length up to where it tapers upward to the axle bearing stop surface. This makes that area a good deal more resistant to failure, as it provides more twisting with the strain of starting out or snapping the clutch. It works in fact as a spring bar. Thus reduce breaking in the typical spot at the end of the splines. (See Gord Clark's text on previous page- Bud)

 

I did not know all of that when my RH rear axle shaft failed. It was a beautiful day in May the weather was great and I finished the seasonal inspection of my car. I decided for a tour around the block to find out if everything works fin. After a halve mile there was a noise like a "bang" but the vehicle works OK so far. At the next corner the next “bang” and now there was no longer any transmission. The axle shaft was broken.

I call my wife to tow me home. In the meantime it’s starts to rain. Isn’t it Murphy? In the garage I remove the RH side rear Wheel, brake drum and bearing housing and get out the broken shaft. Unfortunately but logically the portion inside the bevel gear is still in position.

 

What’s to do? I ask the computer, but more precise the Enthusiasts Experts from BBS and I get a very fast answer and good advises as usual.

Barc Cunningham provide me the information for a special tool to be use to drive out the broken piece. I made this special tool from a length of ½” (12 mm) steel rod about 3 feet long, which was drilled at one end and a 3/16” (5mm) drill rod was glued into this hole using epoxy. It extends about 8” (200mm).

A second tool was a small round magnet attached to another steel rod.

Next step was to remove LH wheel, brake drum and bearing housing to be able to pull out the axle shaft. In the darkness of the axle housing there is nothing really to see. But with a torch and some passion you can imagine where the way for the special tool should be.
A small modification on the tip was necessary. The tip needs some special shape. On the grinder it was flattened to get better access trough the differential gear box. The magnet rod inserted in the opposite axle housing.

The second attempt was successful. With a light blow with a hammer the broken piece came out and was already on the magnet. In the picture you can see the pinion gear pin and the groove in the serration were the tool must go through. There is not too much space.

 

Here is the other end of the axles, the inner portion.
As you can see from the picture, there was high torsion load to destroy the shaft. The other shaft looks like new. There is nothing to see.

I have decided to replace both sides at this time and store the other as spare. I'll get the reinforced version from Jerry Austin as described at the beginning. He offered regularly this reinforced version in Ebay.

With the new reinforced axle shafts I hope never to use the special tool again. Anyway, it was a nice experience and takes me less than 2 hours to make the tools and get the broken parts out.
I like our TD's they are so simple!

Contact to Jerry:
Jerry Austin
4312 Pearl Court
Cypress, CA 90630-2017
jdaustinmg@dslextreme.com

Note: Needless to say that I have nothing to do with Jerry except to be a satisfied customer

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Here's Guenter's image of the broken pieces as he found them

And here is his "Mouse Hole" image of the view into the axle tube: