Sirocco Posted July 4, 2011 Share Posted July 4, 2011 Afternoon Gents, Recently purchased a Rover diff with a truetrac built in and the PO said all the bearings had been replaced recently. When I finally picked it up for the inlaws place this weekend it all looked fine, but I noticed there was play between the propshaft flange and the 'gearing'. so my simple question is, should this play exist and if so, how much? Its not much to be fair, but I just thought that before fitting it for good I should get it right. If it is too much is it just a case of fitting/removing shims on a trial and error basis? (Yes I have been reading all the threads). Is this straight forward and is there a guide somewhere to do it? Anything else I should check? cheers G Quote Link to comment Share on other sites More sharing options...
moose Posted July 4, 2011 Share Posted July 4, 2011 Afternoon Gents, Recently purchased a Rover diff with a truetrac built in and the PO said all the bearings had been replaced recently. When I finally picked it up for the inlaws place this weekend it all looked fine, but I noticed there was play between the propshaft flange and the 'gearing'. so my simple question is, should this play exist and if so, how much? Its not much to be fair, but I just thought that before fitting it for good I should get it right. If it is too much is it just a case of fitting/removing shims on a trial and error basis? (Yes I have been reading all the threads). Is this straight forward and is there a guide somewhere to do it? Anything else I should check? cheers G the play should be there its call backlash... If you have too little or no backlash the pinion is jammed into the ring gear, this will produce a lot of friction and heat and could lock up your rear axle. If you have too much backlash the pinion and ring gear will be too far apart and will probably chip and strip the teeth of the gears. It can also cause excessive whining. If it was build by some reputable then its most likely going to be correct. hope this helps Quote Link to comment Share on other sites More sharing options...
Sirocco Posted July 4, 2011 Author Share Posted July 4, 2011 the play should be there its call backlash... If you have too little or no backlash the pinion is jammed into the ring gear, this will produce a lot of friction and heat and could lock up your rear axle. If you have too much backlash the pinion and ring gear will be too far apart and will probably chip and strip the teeth of the gears. It can also cause excessive whining. If it was build by some reputable then its most likely going to be correct. hope this helps Thanks for the quick reply mate, appreciate that, settles my mind. I thought the backlash was for something else (internally), so all that now makes sense. I checked the crown wheel and the other bits I could see and it all looks fine. Fingers crossed. G Quote Link to comment Share on other sites More sharing options...
Sirocco Posted July 11, 2011 Author Share Posted July 11, 2011 Ok, I removed my original diff tonight (from my 300tdi) and it is very much tighter than the replacement with the Truetrac fitted I was quite surprised as Im know this is the original diff on 107K miles. The play in the original is almost undetectable so I guess this is still somewhere close to the tolerances I have read about (0.1-0.17mm). I would think that the truetrac diff is out of the tolerance zone. Is there an easy way to measure this? should it be this 'slack' for any reason? Anybody know where I can take it in Bristol or nearby for setting up? Damn. I wanted it all in and set-up in the evenings this week never goes to plan does it! Any help or suggestions most appreciated Cheers, G Quote Link to comment Share on other sites More sharing options...
BogMonster Posted July 12, 2011 Share Posted July 12, 2011 Having recently been setting up a diff to go in the front of my 110 one thing you should be aware of is that the available settings on the locking ring that holds the side carrier bearings in place are fairly limited. When we put new carrier bearings in the 4 pin diff currently in my vehicle, one notch was too tight (no detectable CW/P play at all) but the other one was really a bit too loose, on the basis that the too-tight is bad news for the reasons described above, we opted for the next notch out so there is slightly more backlash than there was in the diff we took out but there was no other option. If you have seen a lot of working diffs you can tell if it is "right" by feel but a dial test gauge is the proper way. I guess if you have the two side by side you could remove the locking pins on the side bearings, loosen the caps and wind the crownwheel side one in by one notch and the opposite one out by one notch, torque the caps down again and see how it feels then when you clamp the pinion and rock the crownwheel back and forth, compared to your other diff. If you're happy its ok, you need to turn it right around to make sure there are no high spots on the crownwheel, which might indicate muck under the crownwheel, but unless you have disturbed the crownwheel (taken it off the centre) it should be OK. Quote Link to comment Share on other sites More sharing options...
Sirocco Posted July 12, 2011 Author Share Posted July 12, 2011 Thanks Bogmonster I think this is all getting beyond my expertise and toolset. I would really have liked to accomplished this, but have backed down and dropped it into Bristol Transmissions, they said the bashlash was 'excessive' and also noted the pinion preload is likely off to. Hopefully they will just inspect and do the backlash and it will come in at an hours labour (£75!). Wish I knew what I was looking at before parting with my £££ LESSON LEARN'T Thanks again for those who gave input, most appreciated. G Quote Link to comment Share on other sites More sharing options...
Sirocco Posted July 12, 2011 Author Share Posted July 12, 2011 Well fair play to Bristol Transmission. I dropped it off at 1300 without booking it in and they were mega busy, got a call at 1530 saying it was ready for collection and would only be an hours labour So I got it back tonight and all fitted, everything back together, topped with oil etc. The last thing I need is the torque value for the nuts that hold the diff assembly to the axle casing. I did a google and only found 1 post with a value of 45nm but even that was skeptical. They didn't take much to break off so I just wound them on with my ratchet and nipped them up using loctite also. My other question is why are 2/4 of the studs longer? I dont have any deep 9/16th sockets so these were a PITA to get reasonably tight. Any help most appreciated. G Quote Link to comment Share on other sites More sharing options...
BogMonster Posted July 12, 2011 Share Posted July 12, 2011 The workshop manual says 41nm for "pinion housing to axle case" (which probably wasn't what you Googled) but TBH it isn't that critical. One grunt on a small spanner would be my torque setting As a self-sufficient Land Rover man you should have a 9/16" ringspanner in the vehicle at all times to whip a propshaft off when a UJ goes bang in the middle of nowhere Quote Link to comment Share on other sites More sharing options...
Sirocco Posted July 12, 2011 Author Share Posted July 12, 2011 I have an open 9/16th 41nm shouldn't be a problem then, excellent. Thanks again BM. G Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted July 12, 2011 Share Posted July 12, 2011 The longer studs are to accept the fitment of imperial diffs, on which the casing thickness varies around the circumference. Where it is thicker, there is a longer stud. Later diffs were the same all the way around I believe Quote Link to comment Share on other sites More sharing options...
Sirocco Posted July 13, 2011 Author Share Posted July 13, 2011 The longer studs are to accept the fitment of imperial diffs, on which the casing thickness varies around the circumference. Where it is thicker, there is a longer stud. Later diffs were the same all the way around I believe ah, makes sense. Thanks for that. G Quote Link to comment Share on other sites More sharing options...
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