Thread: blown front diff? 99 rangerover

In the absence of P38 owners - I've recently acquired a RRC, and it's viscous seems to be a bit iffy - So, to figure if yours is good/bad/ugly, first find out if your front diff is gone completely. On level ground, rear wheel chocked, N for neutral, jack up a front wheel off the ground.

Try to rotate the wheel with your hands in either direction. If it spins freely and makes a grinding noise - well that confirms that the diff is cactus at least.

If it moves a 1/4 of a turn then becomes tough ( Not impossible) to rotate - diff isn't completely toast, and the VC (Viscous coupling) seems to be doing it's job.

Get an assistant to rotate wheel and watch what the front prop shaft is doing. (Of course, unless you use a jack stand, don't get under the car to do this)

If the prop shaft stays still whilst your assistant rotates the wheel - then your diff is well and truly busted - and you'll have to get under the car ( remember to use jackstand / similar, or lower jack and use max ride height) and try to rotate the prop shaft.

Same deal as above - if it rotates a bit then becomes stiff, then the VC is at least somewhat operable. If it's stuck, that's a bad thing.

thanks langy will now climb under and check it out, as Ive already had a recond diff fitted so I didnt really want to use it much until I found about the coupling and blow another diff what would be all I need thanks again Ill let you know what happens

Right just tested my viscous coupling and all seems ok, an old landrover mechanic told me of a easy way to test it. with a drivable car in a large area or roundabout, put vehicle in full right lock and go around for at least a couple of turns, if the front diff starts to bind up or wheel start to lock up, viscous coupling is shot, and could become a very costly exercise, so hope this helps someone

There was an issue with P38 front diffs. Not sure if anything about it on these forums but do a search on Range Rovers and you will find info.
Cheers

Andrew

Did some more research, ( The above advice I gave I can't edit, and it's a little vague) The technical test for the Borg Warner viscous unit is thus:

At the front propshaft flange, propshaft off, handbrake on, using a torque wrench on the flange nut clockwise. Components ambient temp (ie not hot) ( or VC by itself in a vice)

No resistance - unserviceable

Exert 20nm of torque, and should rotate 25-30 degrees within 60 seconds.

Longer time or higher torque means a fail.

The other value is 60 ft/lbs on front wheel nut whilst one wheel jacked up. 1/4 turn in 60 secs.

Originally Posted by LOVEMYRANGIE

There was an issue with P38 front diffs. Not sure if anything about it on these forums but do a search on Range Rovers and you will find info.
Cheers

Andrew

It's the LM Range Rover (model after P38) that chewed out shafts & diffs. Nothing wrong with P38 diffs (apart from just being Rover diffs).