Half-shafts: Information and Issues

[Rick Waters]

Probably fifteen years and 25,000 miles ago, I had a half-shaft snap. Upon examination, it was discovered that a previous owner had welded the old half shaft to the hub, effectively ruining both items.

At that time, Phil Marino was making new half shafts, out of better material, and with a morse taper, which promised to solve a lot of the problems owners were experiencing with shaft breakage and oil leaking. My hubs were sent down to Phil, and I received them back, with hubs machined to fit. At that time, I reckoned that buying a spare shaft was a good thing to do, just in case.

The other day, while enjoying the car, I lost drive, and after having the car towed back to the garage, discovered that the right side half shaft did not connect to anything. I removed the shaft, to discover it had broken at the inboard spline. I made some inquiries, and heard some opinions that although Phil used quality material, the heat treating that was used may not have been correct, and that the shafts were hard and brittle. I've met Phil once or twice, and found him to be a great guy, and very knowledgeable about our MGs.

As it happens, Bob Grunau of this group, makes shafts from 4340, and uses the same taper (Number 4 Morse) as did Phil. So, I've ordered replacement shafts (two), along with the 2 inch hex nuts that he supplies. A 20 ton press was not sufficient to remove the shafts from the hubs, so I'm off to a machine shop with a bigger press to get that job done.

I post this info for the benefit of those who have had similar problems and questions about the troublesome, in my opinion, rear axle used in these old cars. Of course, if any of you have anything to add by way of advice or the benefit of personal experience, please chime in.

[Steve Simmons]

I have a set of Bob's axles in TC8975, along with his hubs, bearings, sealed nuts, etc. The whole package. It was one of the earliest upgrades I made to the car. All I can report is that after about 20,000 miles on them, there are no leaks and nothing has failed. Good product. I believe Roger Furneaux sells a similar kit over in the UK.