What is the best setup for a 90 rear axle?

[Matthew]

What is the best possible set up available for a Defender 90’s rear axle?

The Sunday just gone was the last event both my rear diff and half shafts will get to visit! After a brilliant time playing in the Forest at the Shire LRC event at Minstead, Hampshire, my rear diff went bang. I removed the half shafts when I got back to the car park and found the ends of both had twisted about 10 degrees! Following that I removed the rear prop shaft and drove it home (very gently!) in diff lock.

Clearly I need to get my truck back on the road (well off really!) as soon as possible, and obviously I’m going to have to spend some money doing so. The question is what do I do? Do I simply buy a cheap range rover/disco axle, fit it, use it for another couple of events and then find I’ve blown it again? OR do I invest in up-rated half shafts, new axle casing, locking diff etc?

Has anyone any experience in fitting up-rated half shafts? Who makes good quality/the best? How much?

How much stronger is a locking diff compared with a standard Land Rover unit? ARB or Detroit..which is stronger/better?

Is there anything else I need to consider before jumping in and up rating diff’s/halfshafts/propshafts etc? Any adverse effects on other components (like transfer box?)

What would be your perfect rear axle set-up??

Or am I simply not putting enough faith in the good old land rover components??

Thanks for all comments!

[LR90]

what size tyres are you running?

If I was starting from scratch (and didn't want portals) I'd consider a toy conversion but filling the old case with ashcroft parts works well enough for many on here.

[Matthew]

Thanks for your comments,

I’m currently running some 33inch Michelin M/T’s but I plan on going bigger in the future, up to 35/37’s.

Portals would be excellent but I think a little beyond my engineering skills at present! (and that’s before I even look at the costs!)

Could you explain more about the “toy conversion” please?

I’ve heard many good things about the ash croft products, are they the best manufacturers or are there others?

Thanks again!!

[LR90]

toy conversion

Replaces your diff and shafts with something suitable for 37's. If you're starting from scratch this can be cheaper too while if you go the ugraded shafts, then diff, ,, route most of us take it costs more over time and you'll still end up with thinner shafts.

I did the latter, ARB which required different shafts (24 to replace my 10 splines) which I bought from KAM. I then had to have the ARB rebuilt a second time with a KAM 4.75 R&P as my old 4.7 (to turn the 35's) gave up within minutes

Happy with it now but still tempted to move the ARB to the front (already have some ashcroft shafts to suit) and fit a toy centre in the rear but prob not worth it for me as I doubt I'll be going larger than 35's.

Ashcroft's have a very very good reputation but for me they didn't do 4.75s and KAMs shafts came closer to my tighter budget.

[landmannnn]

It does depend on your budget but if you stay on 33" tyres your best value for money would be 24 spline 4pin diff and a pair of halfshafts to suit. Diff you should be able to get second hand and halfshafts are quite cheap.

If you move up to much bigger tyres then you will need to upgrade a bit more, not just the rear but also the front diff and cv joints. Budget £3k for the full kit including locking diffs from Ashcroft, a bit less from KAM but perhaps not as strong.

Plenty of discussion on the International Forum in this area.

[pigster]

ARB's is the best bar far route to take.. however if just playing and not doing things competition serious.. then you can get away with a detroit locker (approx 400 quid) absolutely brill piece of kit, never had a problem with my one and I rarely broke a shaft (10 spline standard LR). If you drive senseibly you can still do the harder stuff, just a little slower.

I assume your on rear disc axles already which is good.

for budget I would detroit, (fit and forget - unless in V8's which from experience smashes them nicely) 200tdi - loves them, as its a different power deliverance.

if you have the money - go to ARB's - a little more wireing and faffing but once in, marvelous bits of kit. I am running front and rear, and never really had a problem with standard shafts.

a 4 pin standard diff - doesn't give you that extra edge for traction, but you will not break it. which I think were about 200/250 quid (but don't quote me) arb's are about 500 for the locker and 150 for the compressor. (again - I think)

It does depend on your budget but if you stay on 33" tyres your best value for money would be 24 spline 4pin diff and a pair of halfshafts to suit. Diff you should be able to get second hand and halfshafts are quite cheap.

If you move up to much bigger tyres then you will need to upgrade a bit more, not just the rear but also the front diff and cv joints. Budget £3k for the full kit including locking diffs from Ashcroft, a bit less from KAM but perhaps not as strong.

Plenty of discussion on the International Forum in this area.

[vinny]

Which LRs were the 4pin diff fitted to as standard??

[Mark90]

Genuine factory V8 90's had a 4 pin rear diff. Not sure what (if anything) else had them fitted, except 4.6 P38's but then they aren't a direct fit anyway.

[darthdicky]

My 2.5 Petrol 90 had a 4 pin rear diff, don't think it was standard so probably a heavy duty option when it was made, still no idea why mine had it though...

From my experience it would be worth checking what you have already!

Richard

[Matthew]

Thanks for all the useful information everyone, for now I have bought a new axle from a late Range Rover to get me back off road as soon as possible. Whilst I’m using this I’ll have to consider my other options and start building the “perfect” axle…ready for when this standard replacement gives up!

I’m still unsure as to which route to take, mainly between the toy conversion and the ARB on LR axle.

I know little about the Toyota trucks and even less about their axles, do ARB make a locking diff to suit and would I need to uprate the Toy halfshafts or are the standard strong enough?

I’ve heard various things about the ARB system, some people claim to never have any problems whilst others complain of constant leaking? Is that simply down to poor installation or are there any specific problems with the ARB system?

Thanks again!

[FridgeFreezer]

Astro_Al knows all about the Toy conversion - he was doing it to his series before he stopped building his series and bought Mog portals and started building nothing whatsoever very slowly

£3k is a LOT of money to sink into Rover axles, sure they'll end up strong (Ashcrofts seem to be improving their already great reputation with their current batch of upgrades) but when you can pick up mogs for ~£500 and run about on 44's without fear of breakage for the sake of some fabrication it seems a bit of a waste.

Consider carefully what you're going to want to do and how far you'll want to go - if you just want to play, then stick with 10-spline at £10 per shaft and £40 for a diff and learn a bit of mechanical sympathy if you want to get serious then before you get stuck in for thousands of squids have a good look at your options. PortalTek have a UK distributor and they will make you any axle setup you can think of - and the numbers don't stack up too badly when you put them next to a Rover setup.