Diff overhaul - DIY?

**Warb** · 20th November 2011, 08:22 AM

My Haynes manual states that overhauling a Land Rover diff is not a DIY job, because of the special tools required. These tools seem to be the pinion bearing pullers and drivers (both for shells and bearings), and also the pinion height gauge - though my 1963 manual shows a different gauge that works with feeler gauges, whilst the later manuals show a dial-gauge based system. There are a couple of other tools that would seem to be easy to work around, like the flange clamp/spanner and a c-spanner to adjust crownwheel backlash.

The bearing tools, and indeed the pinion height gauge, are still available. They are expensive (AU$300 or so, without a press), but I suspect cheaper than having a pair of diff's rebuilt by a specialist.

Is a DIY rebuild of a LR diff a viable prospect? Which of the special tools are needed, and which can be worked around?

Alternatively, is there anywhere that these tools can be hired from? In a previous life I was involved in a club (not LR) which had gathered various tools and would rent them to members for a nominal fee. Does such a thing exist for LR's over here?

**PhilipA** · 20th November 2011, 09:02 AM

I recently overhauled a Range Rover diff without special tools except a dial gauge.

The biggest hassle is setting the pinion bearing preload , for which you MAY need a set of shims and a fish scale.

To remove the bearings simply cut them off with a Dremel and reinforced cut off wheels. You have to be careful with the inner cone, so cut down to close to the pinion or carrier and then give the cut inner track a whack with a cold chisel. you then use the split old inner bearing to drive the new bearing on.
If you are using the old crown wheel and pinion, the pinion depth will be correct.( in fact you should leave the depth the same even if not ideal as the diff will be very noisy if this is changed.)

More of a problem with new ones. I found that the dial gauge magnetic base will "sorta" sit flat on the pinion and I got a measurement on the carrier that looked sensible, so you do not really need blocks etc for a Rover diff.

The only thing left is the carrier preload and that is really easy on a Rover diff . You do not need a c spanner. Just tap the carrier adjuster ring around with a punch, while checking the backlash with a dial gauge.
Regards Philip A

**chazza** · 20th November 2011, 02:59 PM

As Phillip says it is an easy job to do.

Have a search through the three Series forums - I posted a photo of the tools I made somewhere - sorry I don't have a link,

Cheers Charlie

**Tank** · 20th November 2011, 04:20 PM

Get yourself a REAL Factory Workshop Manual, Regards Frank.

**Warb** · 20th November 2011, 05:03 PM

Originally Posted by Tank

Get yourself a REAL Factory Workshop Manual, Regards Frank.

I have three manuals, an Autoparts, a Haynes and a first edition Land Rover Workshop manual from 1963. The Land Rover manual tells me exactly how to do the job (though differently from later Land Rover manuals) but makes use of various special tools as noted above. Now I know it can be done WITHOUT those tools!

**rovercare** · 20th November 2011, 05:20 PM

Originally Posted by Warb

I have three manuals, an Autoparts, a Haynes and a first edition Land Rover Workshop manual from 1963. The Land Rover manual tells me exactly how to do the job (though differently from later Land Rover manuals) but makes use of various special tools as noted above. Now I know it can be done WITHOUT those tools!

You need a machined boss, to fit between the pinion head and a dolly that goes between the carrier bearings, feeler gauges and dial indicator

**Blknight.aus** · 20th November 2011, 05:38 PM

pfaffle...

you need a tube of bearing blue and some patients.

**rovercare** · 20th November 2011, 06:19 PM

Originally Posted by Blknight.aus

pfaffle...

you need a tube of bearing blue and some patients.

If you want to waste your time, or try and overstate something which is actually a relatively simple process

**Warb** · 20th November 2011, 06:31 PM

I have two sets of detailed instructions.

The first (LR Manual 1963) shows the items that rovercare mentions, i.e. a dumbell shaped "height gauge" together with a slip gauge that sits on the pinion. The distance between the two components is measured with a feeler gauge and the shims changed to give the correct gap.

The second version, a scan of what appear to be a later LR manual, shows the use of a different gauge which is used to preset the height of a dial gauge fixed to a magnetic base. The base is then stood on the pinion, and the relative height of the lowest part of the bearing bore is measured. Again, shims are then fitted to make the measurement correct (nominally zero unless the crownwheel/pinion are marked for an offset).

The second type of gauge is available commercially, I have not managed to find the first style.

Are the two methods interchangeable, or do they relate specifically to earlier or later diffs? The second method of presetting a dial gauge does not really require a special tool (other than for ease) as any block of known size can be used as long as the difference between the known size and the correct size is factored in. However the first style of gauge with an associated slip gauge can only be "faked" if the sizes of the gauges are known.

Of course if the assumption is made that the diff is correctly set up before it is dismantled, it should be possible to replace the bearings and reassemble using the original shims to give the same adjustment....?

**rovercare** · 20th November 2011, 06:44 PM

Originally Posted by Warb

I have two sets of detailed instructions.

The first (LR Manual 1963) shows the items that rovercare mentions, i.e. a dumbell shaped "height gauge" together with a slip gauge that sits on the pinion. The distance between the two components is measured with a feeler gauge and the shims changed to give the correct gap.

The second version, a scan of what appear to be a later LR manual, shows the use of a different gauge which is used to preset the height of a dial gauge fixed to a magnetic base. The base is then stood on the pinion, and the relative height of the lowest part of the bearing bore is measured. Again, shims are then fitted to make the measurement correct (nominally zero unless the crownwheel/pinion are marked for an offset).

The second type of gauge is available commercially, I have not managed to find the first style.

Are the two methods interchangeable, or do they relate specifically to earlier or later diffs? The second method of presetting a dial gauge does not really require a special tool (other than for ease) as any block of known size can be used as long as the difference between the known size and the correct size is factored in. However the first style of gauge with an associated slip gauge can only be "faked" if the sizes of the gauges are known.

Of course if the assumption is made that the diff is correctly set up before it is dismantled, it should be possible to replace the bearings and reassemble using the original shims to give the same adjustment....?

The only difference in diff's is the carrier bearings change size, so one dolly doesn't fit all, I machined up blocks to known size, all your doing is getting the pinion head offset to carrier bearing centre line, they are matched/lapped together, so any offset should be stamped, easy really................unless you want to fit it, blue it, disassemble, change shim, repeat 4298420times till you get it right

If its merely changing bearings, I wouldn't bother checking the height

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