Rear Diff, should I be worried?

[Lightning]

I would be tempted to change the oil and leave it.

Monitor from time to time but only take it apart if it gets noisy or develops excessive play, you won’t be able to re build it yourself anyway without special tools.

The rear diff was “moaning” on my 110 TD5 when l bought it on 56,000 miles.

l changed the oil (and have changed it again since) but it’s now done 114,000 miles and is no worse.

[monkie]

I'm going to get some magnetic drain plugs from Nige. 

[lo-fi]

Good call, but no special tools needed to pull the cover plate and have a nose.

What I'd do:

Pull the cover. Chock front wheels and raise one rear wheel enough to spin, put transfer case in neutral, take hand brake off and get a mate (or use your foot) to spin the wheel. Look for chunks missing from teeth on the ring gear, listen for rumbling or clicky sounds. Repeat with the other wheel. Use a pry bar and check the diff carrier isn't moving in its bearings and have a good look at the gears inside. If nothing obvious, pop a brew on, button it back up as Lightning suggests and see what happens next oil change. Might not be the worst idea to pull the half shafts and check them too, which is only six bolts a side and a couple of gaskets. 

[Snagger]

I’ve done it with a spreader and without.  It doesn’t make a world of difference - you just have to keep the diff “square” as it comes out without a spreader or it’ll bind in the bearing mounts.  You’ll need two good pry bars.

It is a little easier if you have the spreader.  You can fabricate a better version that the shown special tool that has lugs which locate in the circles either side of the rear cover (that’s what they’re for) and uses a screw jack above and below the housing to push the lugs apart - the type I borrowed was two sturdy square bars that sat above and below the casing with vertical threaded bar and nuts to compress the casing vertically, which bulges the case laterally.  That is simpler to fabricate and less likely to get in the way or slip off the casing in use, and I suspect less likely to damage the casing.  The amount of distortion must be kept minimal.  By using the spreader, you won’t need pry bars, but you do need to slacken it off to check end float and should slacken it between jobs to avoid permanent distortion of the case.

[monkie]

I'm absolutely amazed at the apparent flexibility of what I thought to be a solid chunk of metal. 

I'm initially going to buy some magnetic plugs, drain it and take the cover off and the half shafts to see what's going on before I try to take anything apart. 

[Bowie69]

Sounds like a thoroughly pragmatic plan

[Snagger]

Yep, sensible first step.

[monkie]

That's the easy part, I've now got to think of a way to get my wife to take the kids out for a day so I can get on and do it 

[cackshifter]

Just an observation - the spreader can only widen the aperture by a gnat's nadger. Why the blue blazes didn't they just make the case that little bit bigger - it's not exactly svelte now.

[landroversforever]

It is just so the diff can be taken in and out more easily. It's all got to sit snug when assembled so they can't just make it wider. The salisbury doesn't have the adjuster rings that a rover type has, so the bearings need to be shimmed around.

[monkie]

I've got some chunky angle iron and M18 threaded bar. I'm going to make my own axle spreader. I'll post a pic of the results

[Ex Member]

You don't need M18 bar.  It is not a lot of pressure.  You need to be very careful not to spread too much.  In fact, there is a very clearly specified maximum spread that is allowed to prevent the damage.  You are only spreading enough to remove the side gear preload.

Read this: https://www.randysworldwide.com/wp-content/uploads/2017/02/Dana_Spicer_Housing_Spreader.pdf

No more than 0.015" housing spread.

Edited October 30, 2019 by Red90

[monkie]

30 minutes ago, Red90 said:

You don't need M18 bar.  It is not a lot of pressure.  You need to be very careful not to spread too much.  In fact, there is a very clearly specified maximum spread that is allowed to prevent the damage.  You are only spreading enough to remove the side gear preload.

Read this: https://www.randysworldwide.com/wp-content/uploads/2017/02/Dana_Spicer_Housing_Spreader.pdf

No more than 0.015" housing spread.

Thank you for that. Very interesting information. I will use a dial indicator to ensure I'm not over doing it

[Ex Member]

It is also in the workshop manual.  It says 0.030 mm (0.012") maximum.

[Snagger]

In practice, nip the spreader nuts up, and then apply just enough tension to get the diff out without a struggle (other than its weight).  Don’t go tightening the nuts until the diff is loose in the casing!  You won’t need to measure the spread, just turn a nut half a turn at a time and pull on the diff - it doesn’t come relatively easily, you need another half turn.  Slacken the nuts off once it’s out; don’t leave the casing distorted for extended periods.  In short, don’t be brutal, but don’t overthink it!