Classic cars forum & vehicle restoration.

[ukdave2002]

Hi all
My MGA rebuild has now hit its 20th year ! and given most of the hard work has been done I am determined to get the car back on the road this year.

For the first time I have had a close look at the diff; initial observations are that the crown and pinion look in good nick, but the pinion bearings are very worn, the easy option is to take the diff to someone like Moss hand over a load of cash and get an exchange unit, however the engineer in me wants to buy some new bearings and rebuild the diff myself, this is why my restorations take so long as I have an obsession with doing stuff myself! I have a suitable spring balance gauge, clock gauge and engineers blue…......So; I am after some down to earth guidance on the practicality and sensibility of a diy diff rebuild any comments views or opinions welcome!

Dave

[peter scott]

Hi Dave,

I'd support the DIY approach!

http://www.scottpeter.pwp.blueyonder.co.uk/new_page_2.htm

Peter
_________________
http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[Jim.Walker]

The well equipped workshop way is to use a dummy pinion and crownwheel, which allows shims (or adjustable setting) of the replacement crownwheel and pinion to be established before assembly. Not always satisfactory with used parts.

The harder way is to assemble the parts and use engineers blue to check the meshing of the teeth of both parts to get even central contact on both. This involved juggling with pinion fore and aft and crownwheel side positions to get correct meshing and backlash. A DTI is normally used at a tangent to a crownwheel tooth outer edge to check backlash. I THINK, usually about 5 thou though it differs with bevel and hypoid and IT IS a long time since I did it. A good workshop manual should give the figure.

I am pretty certain your MG will be a Hypoid Diff. Fom a whine or noise point of view, they are less sensitive than Bevel Diffs to noise if not set up quite right.
Don't forget to add pinion shims to pre-load the taper roller bearings.

Not very comprehensive, but I hope this gives you an insight into the procedure.
Good Luck, Jim.
_________________
Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then!

[pryantcc]

Hi Dave, I am like you. DIY hard-core and far to mean to pay anybody to do anything.

I had a monstrous pain in my rectum trying to do this job. I spend weeks building & dismantling my diff adding or removing one little shim at a time. I stil don't know if it's any good because I haven't finished the car yet, so never driven it!

I had no guages, so the way I set it up was a good even contact area on the engineers blue (only bothered with drive side of teeth!) and the tiniest detectable backlash.

It did literally take me weeks to get it right. I had a good page showing the different contact patterns and which way to move crown/pinion to rectify them. PM me if you would like a copy.

Good luck, persevere and don't short-cut it.

Paul.

[ukdave2002]

Thanks, to all the responses, its given me some inspiration and a clearer insight to what is involved and the pitfalls! I'll have a go myself and keep you posted! may well be back for advice

Dave