Thread: Rear Diff Broken

If you can do the gear box then the diff shouldn’t be a big challenge. The manual is excellent for giving the tolerance and there are some good you tube vids.

I had a bad diff on Sid and bought a ‘mint’ new axle only to find a cooked bearing so had to rebuild anyway.

I did document the diff rebuild in my thread

I just rebuilt my diffs on my s3 109 with new r+p, new truetrac carriers, and new bearings. Definitely possible for the backyard mechanic if you're willing to do the reading and understand the process. You need a dial guage, vernier calipers and a torque wrench.

If it's a rover diff then fitting a new carrier is pretty simple, as you adjust the backlash with threaded adjusters, and you can work on it on a bench (or the tray of your ute). Salisbury is harder as you have to use shims to set preload and backlash, and you're installing it and checking lying under the truck.

If the carrier's flogged out then consider that the pinion bearings might need replacing too. If they're in good condition then there should be some resistance/drag to turning the pinion. My Salisbury appeared to be working fine, though the pinion preload was about 0. When I stripped it the carrier bearings were pretty rooted with massive pitting on the races, and the pinion bearings had very obvious visual wear.

Ok, thanks guys.

Cadas, I’ve been using your excellent thread for most of my gearbox rebuild! Will keep going on to the diff.

NZ Nath, I have those tools...I don’t have a press (but do have access to one) and I watched a couple of videos and started glazing over when they talked about pinion height setting blocks and dummy bearings etc 🤯.

Thanks for the confidence! I’ll read a bit more. Probably more questions to come!

Did the diff before the gear box.

There’s a couple of extra tools, a set of fishing scales to measure the rotational drag when setting the backlash and a shop made tool to tighten the carrier nuts. The tool is worth making as it is needed for torquing up the gear box flanges.

Just a flat steel bar with holes drilled for two bolts.

The only thing that can be tricky to get are a set of shims if you replace the pinion bearing. think you can buy packs or find a handful of second hand ones as you need a few, it’s trial and error . I had spare broken diffs.

In my position I would simply fit another complete differential into the axle housing. Good second hand diffs should be readily available, although shipping them would be more expensive than just shipping parts. But then I have a number of "spare" 2as to get parts from!

The only real caution if going this route is to check that both your vehicle and the one you are getting are the same ratio. If yours is standard (4.7:1), while there were numerous changes, the differentials are interchangeable from about 1949 to the end of Series production (but some models had different ratios e.g. V8 & Isuzu) a very few had completely different diffs (One Ton and Series 2b FC) and the salisbury rear axle was optional on 109s at the end of 2a production and standard on S3 109s. And note that while front and rear diffs are interchangeable late model front diffs lack the filler plug in the nose.

The dummy bearings are only really needed for the carrier on the Salisbury. Even though my old bearings were worn I sanded the inner races with a flap wheel and used them as dummies, and the final install with new bearings resulted in the same backlash and similar preload (as measured by whacks with a hammer to install).

The pinion height is set with shims behind the outer race on both diffs, and that isn't too hard to knock in and out to adjust. I made a stab at setting pinion height using the vernier and dial guage, but it's hard to do accurately without the block. However correct pinion height is meant to be fine tuned according to contact pattern, so reusing the old height shims as a starting point should be acceptable rather than setting to the specified height.

If it's a rover diff you would need to check which bearings you'd need as there's different combinations of imperial and metric.

Originally Posted by flyboy

Hi all,
I’ve got my head around putting my gearbox back together, so whilst waiting for replacement parts, I decided to strip the rear axle.
All went well, and on inspection of the rear diff, I initially thought everything looked good, however the carrier has sheared where one of the side bearings sits. I never drove this car, but it seems the half shaft was keeping everything somewhat lined up.
The axle casing has a large dent, where I’m guessing in the past a more substantial diff failure has caused the casing damage.
I noticed i can get a new carrier, but I’m not sure I’m equipped to fiddle with the diff centre...I’m tempted to search for an entire rear axle with diff.
I’m in NSW Southern Highlands. Can anyone advise if Landrover Heaven sells used parts? or if someone has swapped over a carrier on their diff, could you advise on the difficulty.

Thanks guys!
Marcus

hi mrcas i have a complete rear diff brake drum to brake drum from a 86 inch jim

Thanks Jim,
I’ve got it now in bits. Will clean and inspect and work out which way to go.
Where are you located?