Diff change

Ok my current problem is a noisey diff on an A reg Series three which I am told is 24 spline because of the age.
Do I just change the rear Diff with the iddentical item or Do I change the diffs for a different ratio diff to increase my top speed and fix my noisey problem.
Question is If my Landy is 24 Spline. What Diffs can I put in without modifying anything?

well thats entirely up to you what ratio you want isn't it ?

Its 24 spline outers IIRC and 10 spline inners so will have to be a 10 spline diff unless I'm mistaken

Ok Im baffled already. I just want a quiet diff and a little more speed.

3.54 for more top end speed then

You can forget the spline issue, the 24 splines on yours are at the hub end, the inners/diff is 10 spline and any series/range rover classic/ early disco diff will fit. Your diff is currently 4.7 to 1, the range rover and disco diff swill be 3.54. Some people like the swap, some don't, have a search about re 3.54 diff. If it's a 109 things are harder as you'll need a 3.54 Salisbury diff from an early 110.

Do NOT change just one diff - catestrophic failure will result at some point if you do. .

What noise is it? I found three things on mine were making it whine and grind. The grinding was due to a PO not fitting the split pin in the input bearing nut which was allowing the bearings to rattle. I adjusted most of the whining out by faffing with the bearing carrier adjusters inside. Also a good strip down an clean out was required as there was a lot of oil, mud, crap and sludge in there.

I've got 3.54's on mine now but that's with a tuned engine. With the engine in standard trim I found it was a bit too low on torque which meant needing to be in a lower gear on anything more than a slight gradient. What engine have you got?

The other option if you have free-wheeling hubs is to swap the front and rear diffs as the front will have done a good bit less work than the back. You may need to sort out a filler hole though as the front ones don't always have one in the casting.

As previous posters have said you must swap both if you go for 3.54's!

I had this issue with a whine and a replacement diff made a world of difference, get a good used 10 spline as has been said, and just swop it out with new gaskets. Drain oil, pull half shafts out of old diff, unbolt prop, unbolt diff, prise off carefully, clean faces, put new diff on a jack, jack up into place, use gasket seal, bolt up as per manual torque settings, halfshafts back in and oil in.
Make sure new diff has a filler plug or on your casing! Forget 3.54 unless you have a strong petrol engine.

Just to add my pennyworth. Forget 3,54 diff unless you have a really good engine. 2.25 doozle wont pull em. Been there done that and now back on 4.7.
Count the teeth on any diff you get to make sure you are fitting correct ratio. Divide pinion teeth into crownwheel teeth. IE 4.7 has 47/10 3.54 46/13

This is great. Lots of good advice. Im running a 88" Petrol on a new weber and electronic ignition, my engine runs sweet, so I might go for the 3.54 disco option. What i would like is to be able to cruise at 60mph at lower revs and better economy. Am I being realistic?

Curveking said:

This is great. Lots of good advice. Im running a 88" Petrol on a new weber and electronic ignition, my engine runs sweet, so I might go for the 3.54 disco option. What i would like is to be able to cruise at 60mph at lower revs and better economy. Am I being realistic?

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i used to get 80 on motor ways with a favourable wind ,just change rear to start with see what you think ,most petrols feel more right with 3.54 diff rather than 4.7

Rattlegun said:

You can forget the spline issue, the 24 splines on yours are at the hub end, the inners/diff is 10 spline and any series/range rover classic/ early disco diff will fit. Your diff is currently 4.7 to 1, the range rover and disco diff swill be 3.54. Some people like the swap, some don't, have a search about re 3.54 diff. If it's a 109 things are harder as you'll need a 3.54 Salisbury diff from an early 110.

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Great advice

jamesmartin said:

i used to get 80 on motor ways with a favourable wind ,just change rear to start with see what you think ,most petrols feel more right with 3.54 diff rather than 4.7

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This sounds like the route im going to take. Much more useable.

Cruise at 60mph ! There is an old thread somewhere asking for our speeds. In my experience with a 2.25 diesel that runs well now after a rebuild and a lot of faffing with pump timing, 46/48 is a nice cruise. 50/55 it just to loud and shows lack of mechanical sympathy. On standard diffs you get good driveability and hang on to fourth gear a lot. 3.54 diffs without say a 200 tdi up front you will be in third a lot and these boxes are usually poor for lots of down changes.

or with patience you can hunt down a pair of 4.3:1 diffs which give a NOT massively noticeable difference in gearing and easily allow you to still pull away in second gear whilst lightly loaded plus should allow you to maintain fourth gear on all but the steepest of hills

with even more patience you might be able to find a pair of 3.9:1 diffs which i'd love to have in my 200tdi'd 109 (presently fitted with 3.54:1) with the overdrive to try them out

there's no problem with fitting just the one diff into the rear axle of a Series landrover for test purposes just so long as you don't attempt to use 4x4 on hard packed surfaces, you can still use low box (i know that's 4x4) as long as you have FWHs fitted to disengage drive to the front wheels, i've run my 109 for the last two years with a 4.7:1 front diff without any problems, i've even used 4x4 and low box when needed on loose or slippery surfaces, tarmac or hard packed surfaces are a definite no-no though

just other options to give you something to think about

std 2.25 petrol will happily live with 3.54 diffs