Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Replacing diff oil.

Hi guys. Greetings from down under after a bit of an absence.
Not knowing the service history of my ‘74 4/4 four seater I thought I should perhaps replace the diff oil.

There is a drain plug underneath, a filler/level plug on the side at rear and what appears to be a filler on the top to which a previous owner has fitted a ? filler pipe with what looks like a grease type nipple on the end ( not sure why )

Would this be a Salisbury diff and if so what oil should go in there? Top up or completely drain and replace?

Thanks for any help, Neil.

Hi Neil

The diff oil is very specific and you must fill with correct oil, the level of oil is usually up to the plug on the side definately not fill it up to top...

Thye GoMog website is a good bible for any work on your morgan and lists the oils required.

see here

https://www.gomog.com/allmorgan/axlefilling.html#SALISBURY

It would be a Phase 2 Salisbury 7HA axle.

Its quite a long lived unit capable of tolerating a lot of abuse! Spares other than bearings, gaskets and oil seals are a bit of an issue.

I've a championship winning competition car in my workshop at the moment having is axle rebuilt at 188,000 miles!

A good quality branded 75/90 oil would be best.

Drain through the bottom and fill through the one in the diff cover until you can't fill it any more! I don't know whats been added but by its location I'd guess its some kind of breather

A couple of pointers:

If possible, drain the old oil off into a white plastic container, if it comes out looking like gold or silver paint then you have a problem.

Make sure the breather hole in the axle tube is clear, this is an 2mm hole on the RH axle tube, make sure thus is clear as if it is blocked the axle will pressurise and leak past the seals onto the rear brake shoes

The fill/level plug sometimes works loose so a couple of turns of PTFE tape wouldn't go amiss here. I always drill the fill and drain plugs for lock wiring but thats just me!

Keep an eye on the front oil seal as they do leak and a bit of a pain to remove and replace with the axle in the car


Arwyn

Great advice as always Arwyn wasnt aware of the 2mm breather hole can you identify where this is please?

Check you can get the filler plug out BEFORE draining! You don’t want to drain it then struggle to get the filler open.
Same for gearbox oil change.
My 4/4 had the breather hole on the RHS . If I remember correctly it faced towards the front of the car on the side of the axle tube, not far ( 3-4 inches in) . When greasing that area you look for a worm of grease coming out to indicate enough. Keep the hole clear!

Sospan: are you referring to the hole that is opposite the grease nipple at the end of the axle by the hub?

Probably! It was 7/8 years ago but you may find some details on gomog.
https://www.gomog.com/
It is in the section on “gearboxes, differentials and axles” and is the Salisbury Axle section for greasing. Nipple on either end according to that.
I definitely remember the RH side as I did some work on the fuel pump in that area as well.

Thanks for all the valuable advice guys! As ever this site is such a mine of useful info and experience. I can never hope to contribute as much as I have gained. Stay safe and continue to take care.
Cheers, Neil.

Arwen,
No sign of a 2mm diam breather hole in the right axel tube. Maybe that’s why there is a flexible tube mounted on the top casing of mine. But why no standard hole in the axel tube?...... mystery. But then again no more so than with a lot of other Morgan “mysteries” haha.
Cheers, Neil

Took me a lot of digging around to find mine - it was well plugged up and used a drill bit (by hand) to clean it out.

Your flexi-tube may well have been a modifcation - I know on my Land Rover, the Salisbury had brass vents, and they were often replaced with hoses for wading.