Diff Talk

[Donie]

Earlier, while working on the SU pump I had noticed that there was oil from the diff thrown up around the battery box, so I knew that I would have to face replacing the diff pinion oil seal.

Today, while I'm waiting on the oil seal to arrive, i decided to have a proper look under there, and check the level of the oil.

I notice the remnants of a twin strap on a backplate bolt, to the right of the oil filler bung.

Of course it's covered in oil and dirt, but it doesn't feel like a steel braided strap. The bolt securing it to the diff is 9/16, when the rest, all but another one, which appears to be 9/16 as well, are 1/2" .

Now to the preferrred procedure for removing, and replacing the diff pinion flange.

Mark the flange, to put it back on the same spline, and the nylock nut, and pinion shaft, to merely pull the nut up to the same mark to preserve the collapse washer tolerance.

What is the significance of counting the nut turns when removing?

Surely when putting it back on, it will start at the beginning of the thread ( and only there) and by slowly screwing it up until it begins to bind up against the flange, and then pulling it back to the scribed mark, does the job? Am I missing somethig there?

[Charles Farran]

If your car is a late RB that has / would have had a straight rod the rod across the car attached to each of the hand brake lever arms on the rear of the drum brakes,then it is the remains of the strap that holds the handbrake cable that passes by the diff on it's way to the rectangular frame that the rod is fixed to. . These straps split over time - mine did. They are not easy to replace as originally installed, which would have been done as the whole brake cable & rod assembly was affixed to the car at the factory. It is possibly by detaching the rod from the rear drums & sliding it on, but not easy. I cheated by putting a new strap on the diff & then using a rubberised cable clip round the cable and then putting a nut & bolt through the eye of the cable clip & the eye of the strap.
Cheers,
Charles

[Donie]

Charles,

Thanks for the information, I will study it, with your plan in mind.

[Vic Butler]

If the axle is a Salisbury (diff cover at rear.) changing the oil seal is a specialist job as there's a collapsible spacer which must be renewed and collapsed to the correct spec. A 250 ft lb torque wrench is required to start the collapsing. Counting and marking the position of the pinion nut and other methods described in the workshop manual do not work. This subject came up on the Series 2 Land Rover club forum recently as Ian Fozzard will testIfy If the pinion nut is not tightened correctly (there's no specific torque figure unlike the banjo diff), then either it comes undone and the propshaft and flange fall off by onand flail around or ethe diff seizes, the propshaft breaks and then flails around. Imagine that at motorway speeds. In South Africa a Land Rover had the oilseal replaced on a Salisbury axle and the pinion nut was tightened incorrectly resulting in the diff seizing, the propshaft broke at about 70mph flipping the vehicle over and killing all 5 occupants. The spacer is collapsed while the effort to turn the diff without half shafts is measured until it is the specified figure. This is of course not shown in the workshop manual.
A few years ago I came across a Land Rover where the propshaft and pinion flange had come undone after the owner had the oil seal replaced on the Salisbury axle and the correct procedure had not been followed. Fortunately no damage or accident resulted and he removed the propshaft and drove off in front wheel drive after engaging 4 wheel drive. I haven't seen him or the Land Rover since.
The Land Rover owner on the Series 2 forum took it to Hardy Engineering in Leatherhead for the work to be carried out professionally.
It's not a job for the home mechanic. If the leak isn't serious leave well alone.

[Charles Farran]

Hi Donie,
Following on from my post in 8 July , i believe your car is a 1978 GT so should have the same handbrake set up as mine.
See attached photo which shows my solution for holding the handbrake cable.
Cheers,
Charles

[Charles Farran]

Photo of new strap in location before adding clip to go round cable.

[Donie]

If the axle is a Salisbury (diff cover at rear.) changing the oil seal is a specialist job as there's a collapsible spacer which mus.

Hello Vic,
Thanks for your caution.
As you can tell from my post I was not taking the course of action lightly, without serious consideration to the pitfalls.

I can well remember back in the very late 60's in an early B, the diff beginning to hum loudly, and being very aware of the possible consequences of what might happen if it locked up.

With the banjo axel it was a simple procedure to change crown wheel and pinion.

Those who change the seal on the Salisbury, (and there appear to be many) are they just lucky with ;ulling the flange nut back to exactly where it was previously?

[Donie]

Charles,

Thank for your photos of the handbrake cable securing strap options.

They are a great help in a work-around to removing the cable to fit a strap.

My my, doesn't that diff in the photos look clean.

[Charles Farran]

Donie,
I understand it is possible that once you detach the fixed rod from each brake drum & remove the brake cable clip from the bottom of the battery box frame;then you can slide the diff strap over the near side end of the rod , over the connecting frame & then over the cable & longer side of the rod along side each other till the end of the rod & then slide it back to where it needs to be just on the cable to fix it to the diff. (Seems an awful lot of unnecessary work , not to mention swearing & stretching the strap - makes sense to me to do what i did & wait until the brake cable itself needs replacing at some point in the future / if ever).
Diff nice & clean as i refurbished the rear suspension etc as required 18 months ago including painting the rear axle & diff! (Fortunately i have no oil leaks at the rear of the car, although an awful lot had been thrown back from the front over the years , the biggest culprit being the rear tappet chest- since resolved).
Cheers
Charles

[Vic Butler]

Donie.
I reckon it's virtually impossible to get the pinion nut on e Salisbury axle back in exactly the right position. Owners who try it that way are very lucky.
I had thought briefly that if there was a device that could measure the torque required to undo the nut then that figure could be used to retighten it but I don't think that would work because the new oil seal would be a slightly different size due to the old one being compressed and a new nut is recommended. This would result in the pinion nut not being tight enough.
After 2002 Land Rover reverted to fitting heavy duty Rover axles in place of the Salisbury. A reason given for a Salisbury axle being fitted to later MGB's is because the propshaft is lower because it enters the diff lower down and the pinion "slides" on the crown wheel and that's why EP spec oil is essential for a Salisbury axle.