Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing 1975 Plus 8 Diff noise?

Doug.. yes there is a tag there but I was unable to see any numbers on it.. the choices being 3.31 or 3.58 only.

I'll see if I can loosen that bolt and get a good look at it.

Horror : Thanks ..but mine is 1975. According to the manual its either a 3.31 or 3.58 depending on what gearbox was installed. Problem is that the gearbox has been upgraded to the 5 speed one by a previous owner so I don't know which was the original box.

Anyhow, thanks everyone for pitching in with advice.

I'll keep checking in here. And will re-post with an update as soon as all 4 wheel bearings and seals are replaced and everything fully greased. Then I will know for sure its the diff.

Hi Niels.
The 3.58 was ditched when the 4speed Rover box replaced the Moss box as per Horror in previous post, so with a fair amount of certainty the diff will be 3.31.
Doug
From deep deep down under

Doug, Yes, Chris van Wyk has confirmed its a 3.31. New bearings are on the way. Fingers and toes are crossed - this will be the problem.

The weirdest thing is that I removed the tag, cleaned it up and the only thing stamped on it was "8P1". Yet another Bletchley House moment on my path to deciphering secret The Morgan Code.

OK.. Folks .. here's the update.

I chickened on doing the bearing change myself in case it all went to worms so I took it to my local garage run by a couple of old boys who are able to fix stuff without the aid of an OBD interface.

While removing the rear axle for the bearing change, a piece of differential came out with the axle. This pretty much explained the noise in the diff.

Salisbury 7HAs are difficult to get parts for, let alone to find someone here to overhaul them.

So the solution was to modify a differential from a Holden Commodore circa 1987 and at the same time convert to disc brakes. The advantages are easily obtainable (and reasonably priced!!) parts especially wheel bearings and seals etc.


This was done and it works perfectly, I also had the ratio changed to 3.08 (from 3.31). I am not sure where they sourced the disc brakes from but they had to be smaller and with smaller calipers to fit the old style rims.

Anyhow, the car is back on the road and drives beautifully - the ratio change is a big improvement as are the disc brakes. Maybe its my imagination but it seems to drive a whole lot smoother.

So many thanks to everyone who offered advice.

Thanks especially to Cheshire Dave who gave me a lot of his time on Skype.

Very well done. Just goes to show ..." Where's there's a will there's a way!"

You live in a wonderful area ...perfect for Mogs.

My wife's cousins live there and we just love it too!

Great to hear.

Richard - I'm sure you mean it's great to NOT hear!!!!!

Quite a conversion that. Glad it works