D(iff)-Day

So yesterday was D-day when I swapped the rear diff. I've been putting this off for a while, and to be honest having do the job I'm not sure why!.

A productive day yesterday, I probably got more done than I have for ages. Partly because I have accepted that its unlikely that I'll get the gearbox rebuilt in time, so I should fix everything else and get an MOT sorted.

So the other source of problems has been the rear diff, which has been very worn and leaking alot. I'd previously tried replacing the pinion seal, but that didn't help much, due to the shaft itself being worn.

e-bay turned up a second hand series one diff, which seemed ok though on closer inspection yesteday the pinion has some fore and aft wear - lets hope it's ok!

Fitting a rear diff involves the following

Jack up and place on axle stands.
Remove rear wheels, you remembered to loosen the wheel nuts before jacking up, right ?
Remove 3 coutersunk screws holding each brake drum on
Back the shoes off and remove the drums

Now depending on what else you plan to do you can either

a) remove the bolts holding the hub and backplate to the axle, leaving the brakes complete and avoiding having to bleed them
or
b) remove the brakes, disconnect the brake line and then remove the bolts holding the back plate and hub to the axle.

method a works if you have enough brake line to allow the half shaft to come out about 2 inches or so, that is enough to get the splined end free of the diff.

method b allows you to remove the half shat and hub assembly completly, not needed for this job normally but I had to adopt this method

So what happened ?

Well removing the right hand drum revealed the brakes were covered in oil. My first though was that the seal had failed, which I had a lot of trouble with when I first got it on the road. Given that I didn't really want another job, and especially one which was a compete pain last time, I was somewhat relieved to see that the problem was that the collar which is pressed on to the half shaft to hold thing in the right place had come loose, sliding down the shaft enough to let oil past the seal.
I happened to have a spare collar which seemed a tighter fit and for belt a braces I cleaned everything up and smothered the inside of the collar with lock tight, which hopefully will all help to keep thing in place.

Back to the diff replacement .

Once you have either removed the half shafts completely or slid them out of the way, unbolt the 4 bots hoting the prop-shaft to the diff
Now remove the nuts holding the diff to the casing and with the aid of a jack work the diff off trying not to damage any studs.
Be warned the diff is heavy, so I tried to maneuver it off with an old land rover seat base underneath so that it didn't fall onto concrete.

Replacing it really is the reverse, as they say in the Haynes manuals, start with a new gasket and remove all traces of the old one.

I found that to lift the diff back into position, lying under the car, was hard, so I used a series of blocks, bricks, wood etc. to gradually get it close in height and then moved it across onto the studs without having to lift it in one go. You may have more brute strength than I and not need to do this.

Once in place, tighten up in the usual manner, working round in a star patten, don't tighten it right up on any one stud until they are all at least finger tight.

Replace the half shaft/hub assembly, this requires some wiggling, especially on the log (left hand side ) to get the splines into the slots on the diff, I found rotating the pinion with my foot helped to line things up!

Then all that remains is to replace the drums and reconnect/ bleed the brakes, however since the one side of mine was covered in oil. I've left the drums off at this stage,and I'm about to get new brake shoes.

I took the opportunity to replace the universal joints in the prop-shaft too. So all round a pretty productive day, lets hope there is an obvious difference when driving it.