Changing the rear diff, I know this subject has been flogged to death

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SpaceDawg

Active Member
Posts
935
Location
Cowfold, West Sussex
Hi All,

I have a very noisy diff/rear end on my 90 which has been to a couple of garages and they have said "yes you have a noisy back end" with various comments like it could be the tires etc.

Anyway, I have replaced the bearings (knackered), and springs (saggy) so I'm thinking the thing to do now is do the diif, not change all my tires as they all have 12mm of tread (Khumo 71's).

So quick question, are all the rover diffs Defender, Disco 1 the same and I can use a second hand one on the 90.

And having a quick peek at it, it looks like I can pull the drive shafts out and change the diff without needing to removing the tires. Or am I going mad?

Basically I'm going to change the diff and see if the new/old one is better or worse, if its better then job done, worse then I have a very noisy 90.

Any thought or comments.
 
Yes and no.

Stay clear of the Sailsbury ones, they won't fit, you want a standard Rover diff, standard ratio (so don't take one from Mr Modified's truck or you might end up in trouble).

You need to make sure you get the right number of splines, the absolute perfectly certain way to tell is to pull your halfshaft and count the splines, either 10 for early or 24 for late, however you can actually tell by looking at the hubs, the flatter skinnier looking hubs will be the 24spline, chunky more rounded looking things are 10. Other option is get under it and try and find the code = HRC???? part no then back track what it is. Up to 200tdi was 10 spline, what age is yours - never go by age mind you, I have 300tdi axles on a 1990.

Here is the next thing, I have sitting in my workshop a very good diff, I just need to check how many splines it is, its a known good unit and I was going to keep as a good spare but seeing as I have 2 brand new diffs (within last 4/5 years) I think I ought to be OK for now - I was going to ebay it...
 
When you have obtained the right diff, changing them is quite simple. As you say, pull out the halfshafts, no need to remove wheels. Unbolt the propshaft and remove, drain oil and undo the ring of nuts holding diff to axle. Then wriggle the diff over the studs, you may need to lever it.

The new diff is quite heavy when you are on your back under the vehicle. I use big wood blocks to hold it up in the right place, and then work it back over the studs, having already fitted a new gasket.
Do up the bolts, refill the oil, props back on, hubs and shafts in with new seals. Jobs a good un!
 
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If you are looking at a disco diff, then be aware the drive flange will need changing for a defender one, not a big job. but something to keep in mind.

As turboman pointed out the diff is heavy and awkward to manoeuvure, so be carfeul and be prepared for it.

I personally found it easier to have the wheels off so that halfshafts could be remove easier and also for getting under the Landie.

Cheers
 
If you are looking at a disco diff, then be aware the drive flange will need changing for a defender one, not a big job. but something to keep in mind.

As turboman pointed out the diff is heavy and awkward to manoeuvure, so be carfeul and be prepared for it.

I personally found it easier to have the wheels off so that halfshafts could be remove easier and also for getting under the Landie.

Cheers

Wimp!

Undo the halfshafts and pull them out, (you should buy new gaskets or have a cornflakes box and hylomar on hand).

Drop the prop at the diff end and tie it well up out the way, securely or you might end up under the Landy for some time.

Loosen all the nuts then lie under the vehicle with your legs under the axle sticking out the back end, undo your nuts and tap gently/lever (don't damage faces of axle/diff) the diff out and slide it onto your lap, have an old towel on your legs or something if you are feeling fragile, you can bend your knees and lift your legs up to act like a ramp and then lower it down.

Now lower the diff onto a clean sheet or something - someone will possibly take it off your hands for £20 for a refurb exchange unit to save being out of pocket or to rebuild themselves. Someone bought my knackered LT230 for this reason.

Similar for refit; ABSOLUTE cleanliness is paramount, you don't want a grain of sand or a stone or anything going in there, I personally would wash a secondhand diff out with diesel/kero and make sure it is spotless, then EP90 up the crown wheel and pinion gear and spiders gears etc and turn it all over by hand listening for any gritty noises. I also put a big dollop of molybdenum disulphite or Rocol MTLM paste around the gears and things to give them a good chance in life and increase the quality of the lubrication.
 
Be aware some diffs have slightly different thickness castings on two of the lower studs.
 
Wimp!

Undo the halfshafts and pull them out, (you should buy new gaskets or have a cornflakes box and hylomar on hand).

Drop the prop at the diff end and tie it well up out the way, securely or you might end up under the Landy for some time.

Loosen all the nuts then lie under the vehicle with your legs under the axle sticking out the back end, undo your nuts and tap gently/lever (don't damage faces of axle/diff) the diff out and slide it onto your lap, have an old towel on your legs or something if you are feeling fragile, you can bend your knees and lift your legs up to act like a ramp and then lower it down.

Now lower the diff onto a clean sheet or something - someone will possibly take it off your hands for £20 for a refurb exchange unit to save being out of pocket or to rebuild themselves. Someone bought my knackered LT230 for this reason.

Similar for refit; ABSOLUTE cleanliness is paramount, you don't want a grain of sand or a stone or anything going in there, I personally would wash a secondhand diff out with diesel/kero and make sure it is spotless, then EP90 up the crown wheel and pinion gear and spiders gears etc and turn it all over by hand listening for any gritty noises. I also put a big dollop of molybdenum disulphite or Rocol MTLM paste around the gears and things to give them a good chance in life and increase the quality of the lubrication.

Unfortunately PO had a love of tiger seal on any sealing surface, a gentle tap did not cut it to remove either of the hub flanges or the diff itself.
A good application of a pry bar and a rubber mallet were needed.

Cheers
 
Thanks all for the excellent advice as normal, including putting a towel or something on my nuts just in case. I'll have a peek at the car on sunday and find out what diff is has. What I do know is its a 1990 200tdi with drums on the rear, so its likely to be a 24 spline diff, but I'll yank out a drive shaft to check. Discomainia I'll PM you if I can work that out and see where you are etc.
 
I'm watching this thread as I also have a whine coming from the rear end of my 110. isn't there any bearings from the prop to the diff that could also cause a whine if buggered. And would this be the best time to change them or can they be changed without removing the diff?
 
Take the opportunity to renew the oil seal at the flange for the "new" diff. Chances are if it was sitting around for a while the seal might not be in the best condition. In addition, when you remove the old diff clean the axle housing out thoroughly of any fragments and debris.
 
I'm watching this thread as I also have a whine coming from the rear end of my 110. isn't there any bearings from the prop to the diff that could also cause a whine if buggered. And would this be the best time to change them or can they be changed without removing the diff?
Usually I also have a whine in the back of my truck, I have to tell the Mrs to get out or shut up....

There are only uj s on the prop or the diff after the transfer box
 
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