Rumbling noise ? Differential ?

Friday 13th Jimny loaded up and on the road at 7.15am. Destination Walters Arena to help marshal at the AWDC Driven To The Edge. Once onto the A34 noticed a slight noise from drive train. Not a constant wheel bearing starting to fail noise. Rumble increases in pitch then decreases. Difficult to put into words. Drove all the way to Wales, spent 3 days driving around the site then returned home to North Hampshire. The noise is now getting louder. Today I removed the rear prop shaft and replaced it with a spare unit I have. The noise is exactly the same. Is this noise the result of a differential bearing starting to give up ? Topped up diff oil. Was a bit low but still oil in there. Has anyone else ever come across similar. Appreciate your comments on where to look next.

Oh forgot to say my Jimny is a 2000 model with over 100k on the clock. Transfer box oil level was also checked and is fine.

Mine had a noise from the rear diff. Even got a proper mechanic to sit in the back and diagnose it: he said to put some magic potion in and ignore it until it got too noisy to stand. :whistle:

I swapped the diff out and the "new " one had the same noise. :evil:

Some time later I found that the brake pedal had to be pumped to stop the car, when I jacked it up the front passenger wheel was hanging off, so I fitted a new front wheelbearing and all the noise from the rear diff went. :pinch:


Doesn't mean that your diff isn't worn, but worth checking all the wheelbearings first before you swap it.

Disconnected the rear prop shaft at the transfer box. Jacked up front onto axle stands. Started up with front wheels driving. No noise. Still points to rear diff I think !

As you have axle stands use them to support the rear then run car in 2wd in gear and listen with a stethoscope or even a long screwdriver on the diff case and listen for the noise. A bearing growling should be evident.

Yes I did that yesterday. Got a good stethoscope. Trouble is interpreting the noises. Thanks for the idea.

It only takes an hour to swap the rear diff out if the noise is definitely from the diff.
Make sure that you get the right ratio, as autos are different, and the ratios changed for the vvt.

Thanks for the info facade. Question :- do I have to remove the brake back plate or can I just remove the drive shaft ? Don't intend to replace the wheel bearing and axle oil seal at this stage unless I find oil leak and or bearing play. All the stuff I have read up always states removing brake back plate..... I hate messing about with brake shoes and springs. Once I have removed brake drum is it possible to remove drive shaft ? Probably not as otherwise what retains the drive shaft ? It will all become apparent once I get down to it.

The backplate holds the bearing in unfortunately.

So

remove propshaft.
Drain oil
Take off brake drums
Undo 4 nuts on each axle flange
Undo nuts all round diff
Snatch halfshafts out with backplates (slide hammer is your friend here), they need to pull outwards a couple of inches. If you are lucky, there is enough slack in the brake lines to do this, otherwise you will have to disconnect the brake lines and then you will need to bleed the back brakes on re-assembly.
pull diff out.

It helps if you have a mate to pull the halfshaft outwards against the brake line as you are removing the diff, you only need one mate, as you pull one shaft out then twist the diff, then do the other.

I thought it was something like that. Thanks very much for your information. That will help. Cheers

Well looks like my diagnosis was wrong. After getting hold of a salvage differential (thanks to our Big Jimny friend j999pre) and advice from facade removed the rear drive shafts today using a home made slide hammer, which worked really well, to find that one wheel bearing is worn and the second is suspect. So looks like a visit to the Big Jimny shop. I am assuming the rear wheel bearings are plain roller type so should have no detectable sideways movement ?

facade wrote:
It helps if you have a mate to pull the halfshaft outwards against the brake line as you are removing the diff, you only need one mate, as you pull one shaft out then twist the diff, then do the other.

How is the bearing held in place?