rear prop shaft

[dan9090]

Hi all,

You may have seen my earlier post. Ive got a virbation noise coming from somewhere along the drive train (i think). Very loud dry/graunching noise when moving (both when clutch in and out). I dont get noise when at a constant speed on a flat road going in straight line.

Most noise is when the truck is lurching forward or back (say when accelerating or engine braking). At this point is sounds like somthing is about to drop off.

So, this weekend (for the first time! ) I've changed my axle oils and greased UJs/prop shafts. Having discovered the my back axle only contained about a pint of muck i was hopeful that this would solve problem. It hasnt.

Sympton 1) Anyway, i have noticed that the rear end of the rear prop shaft (where it connects to the diff) can move vertically up and down by about 1 - 2 inch. The diff doesnt move, just the shaft.

Sympton 2) After a short drive today I came back and noticed that the area around where the rear prop connects to diff had been sprayed with muck (much like that I took out of the rear axle). Presumably this has been sparyed by the prop spinning whilst driving but dont know where the liquid muck is coming from.

Oh, and i heard some "squelching" noises from the undercarriage whilst driving today.

Ideas welcome..... (i am a complete novice though so please go easy on me....)

[101sean]

I'd say the pinion bearing in your rear diff is seriously shot, the liquid muck is a mixture of oil and ground up bearing coming out of the diff through the failed seal. If it's a 90 you can put a new or s/h diff in quite easily. If a 110, easier to change the axle. I wouldn't drive too far in it's current state.

[sean f]

I would have to agree with the above, time to do some serious work.

If the rear axle is the rover type then a second hand diff is the best solution (or new if the budget goes that far).

If it is a Salsbury axle (bolt on cover when looking at the axle from the back of the vehicle) then a second hand axle is the answer.

Either type of diff could be rebuilt but this is a fairly specialist job and if you are not sure best left to others.

All the brakes etc could be swapped from your old axle (assuming they are OK!). Its actually not a difficult job just a bit heavy so make sure every thing is supported securely.

Axles and diffs come up for sale fairly often and there is usually a few on E-Bay although due to the size and weight you would want to find one as local as possible as paying some one to deliver is likely to be expensive.

In it current state it could sieze up or fly apart at any time so it realy would be best not to drive the vehicle until it is sorted out.

[lrfarmer]

Sympton 1) Anyway, i have noticed that the rear end of the rear prop shaft (where it connects to the diff) can move vertically up and down by about 1 - 2 inch. The diff doesnt move, just the shaft.

from your write up it sounds like the rear uj's have gone.

take the rear prop off put it in diff lock drive it, if that stop the problem put new uj's on and put the prop back on.

if it dosen't sort it i'd look at the rear axle again

[sean f]

from your write up it sounds like the rear uj's have gone.

take the rear prop off put it in diff lock drive it, if that stop the problem put new uj's on and put the prop back on.

if it dosen't sort it i'd look at the rear axle again

Definately worth a try but that much play in a UJ would almost certainly mean the yoke had serious damaged and a new prop would be needed.

Always the problem trying to diganose a problem from some one elses description.

You really need to have another look underneath and see if the movement is in the universal joint or the nose of the diff / imput flange ie which side of the four prop bolts is the movement on. Often this is easier to see with no weight on the prop, chock the wheel and take the handbrake off then see what moves around.

Good luck

[dan9090]

thanks for all your replies.

i noticed the vertical movement in the prop before driving it yesterday at which point it was at least 1 inch movement.

having read your replies ive checked this morning and movement is now only 2-3mm?!? BUT, that movement deffinitely comes from further back than the UJ (the round peice which i guess is the flange behind the UJ is moving when i move the prop).

if its the UJ/prop that needs attention then i would have a go myself next weekend but if its a case of the axle/diff coming off then i dont think i'm up to that.

[Les Henson]

If it's the round disc that the prop bolts also pass through on the nose of the diff, then it's the differential pinion bearings that have worn. You need to remove the driveshafts, crownwheel, and pinion to replace the bearings.

This is the drive flange - any play in it is the pinion bearings.

Les.

[dan9090]

Thanks Les. hope you don't mind, ive annotated your pic to show what i can see moving when i move the prop up and down...

would worn differential pinion bearings explain the vibrations and the muck coming out?

trying to work out if i can do this myself. when i bought my first 90 (3 months ago) id never done ANY mechanics. since then ive changed alternator, starter and water pump but a little nervous of the 'big important bits' underneath.

how difficult is removing the driveshafts, crownwheel, and pinion? does this mean removing the axle/diff?

do any of your useful "HOW TO's" cover this job?

thanks, dan

[Les Henson]

On the rear axle it's a lot easier to do than the front. Pop the driveshafts out and if you have the Rover axle - drain the oil and then undo the 10(?) nuts that hold the diff assembly to the axle case. The whole thing will then lift out - it's damned heavy though. The diff can be rebuilt on the bench then.

Best add - undo the drive flange nut before stripping the thing out - they are mental tight.

Les.

[dan9090]

thanks for all your replies. diagnosis was correct - knackered diff pinion bearings.

i decided it was a little soon for me to me playing Mr Ametuer mechanic with important stuff like differentials so the friendly folks down at 4x4 R Us in Warwick have fitted me a second hand diff for £90 + an hours labour.

to make up for wimping out of this job I will be tackling speedo cable, power steering pump, and winch isolator switch at the weekend.

thanks again, dan.

[Martin90]

Hi there all, is there an acceptable level of movement in the shaft or should there be no play at all? I fear I may have the same problem but need to get the prop off to be sure!

Thanks,

Martin

[Les Henson]

On a reasonably used truck you would expect some slack in the diff, identified as some free rotation before the wheels turn. Of course there should be none at all, but a certain amount is acceptable (1/8 turn max I would say) There should be no play in the prop U/J's or sliding joints as wear at these points rapidly deteriorates. If you get a clunk whenever drive is taken up, then you need to fix the problem sooner rather than later.

Les.

[Martin90]

On a reasonably used truck you would expect some slack in the diff, identified as some free rotation before the wheels turn. Of course there should be none at all, but a certain amount is acceptable (1/8 turn max I would say) There should be no play in the prop U/J's or sliding joints as wear at these points rapidly deteriorates. If you get a clunk whenever drive is taken up, then you need to fix the problem sooner rather than later.

Les.

Thanks Les, how about movement up, down, left and right if I was looking at the flange? Should there be any play here and what would the likely diagnosis / cure be if there was? ... I think there is!

Cheers,

Martin

[Ex Member]

Thanks Les, how about movement up, down, left and right if I was looking at the flange? Should there be any play here and what would the likely diagnosis / cure be if there was? ... I think there is!

Cheers,

Martin

There is not supposed to be any play as the bearing are preloaded.

First check that the pinion nut has not loosened off. If it is tight, you need new pinion bearings. Despite what was said above, it is fairly involved as it requires a press and preload, pinion height and backlash need to be set properly.

[Martin90]

There is not supposed to be any play as the bearing are preloaded.

First check that the pinion nut has not loosened off. If it is tight, you need new pinion bearings. Despite what was said above, it is fairly involved as it requires a press and preload, pinion height and backlash need to be set properly.

Thanks for that, I'll check the nut is not loose first then!

Martin