Thread: Axles, Diffs, CV's & Hubs... what to do?

I'm apologizing upfront for this question, I've searched thread after thread after thread and still cannot find a concatenated response, so I'm *hoping* to put it in one spot, in case other RRC owners who want to (or have done this before) increase their O/R capabilities, or are investigating larger diameter tyres or engine swaps (or both)

Data:
1. vehicle is a completely standard Oct 1991 build RRC. i.e. no mechanical mods.

it has:
3.9L v8 with 14CUX injection
4HP22 automatic
BW VC centre diff
Standard front & rear differentials.
Springs are standard/unknown. Dampers are Koni. Boge load leveller is still in place.
standard 16x7" ET33 3 spoke wheels with LT225/75R16 cooper ATR's


Desired outcome:
33-35" tyres without the vehicle looking like a jacked-up land-bruiser.

improvement in articulation if possible (superflex arms do not seem to be available for the RRC)

Understood that a body lift & small increase in spring length req'd. to fit the larger wheel/tyre combo, as well as et-25 rims and flares.
(but is this all that is req'd? - i.e. LRA's 'kit')

For the moment, discount the engine swap stuff, I started a thread in the tech section for that stuff.

However, pending the outcome of the engine/gearbox swap and the fitment of larger diameter tyres, I know that the OE axles/cv's/hubs etc may not be up to the task.

So the question is:
1. do I find a complete pair of live axles from something else; or
2. do I upgrade the internals of each to cope with the increased torque & larger diameter tyres.


I've looked at these 24 - 35 spiline hytuff axles etc, but there is simply too much information and conjecture - everyone does stuff differently in their vehicle, so I just do not know what the best solution is.

Also, I really do not have a desire to fit locking centres to the front or rear. Sure, they may be perfect for some, but I would much prefer to install some ATB centres, than to use a full locker. I feel that overall this setup would be far more useful than a locker, and would be a better setup for the on-road driving - which is about 70% of the current use.

So everyone rubbishes the RRC's axles & cv's from what I have gleaned from hundreds of threads - I'm wondering if it is simply a case of misuse & abuse or poor quality. The vehicle I own has been really well looked after, and despite having 312000km on it now, it still drives as-new. (maybe this is due to the service history @ Graeme Cooper ??)

So let's get down to brass tacks....

Either I find a front end and rear end from a disco etc... or I rip out the internals from the RRC's axle housings and replace with all-new beefed up stuff.

Let's assume I take option #2, what I'm planning would be something like the following:

24 spline (or larger) axles
upgraded CV's
new swivels (teflon coated??)
new hubs (questionable - strength versus axle sizes?)
new atb diff centre, rather than a locker.
'pegging' (if required?) or would a different centre carrier be better?
camber / caster modifications to the front housing (good idea or not?)

Someone suggested using ford 9" housings with the RRC's tubes. I don't know if this would work, but I suspect it was for ratio availability?

Also salisbury versus banjo housings on the rear .... surely the sensible thing to do is keep the banjo, or is the salisbury simply that much stronger, that it is a far better option?

I'm no stranger to modifications, but they have to be done properly, and provide a decent advantage over a standard part with 'an upgrade'.

So the advice (or examples) I am chasing are those which make the drivetrain more or less 'bulletproof' for using 33-35" tyres, and to at least maintain the articulation or better it, without significant detriment to the on-road driveability.

bear in mind, I'm no rock crawler, no winch competitor and no hardcore 4x4 park driver... All the RRC will be doing, besides towing boat/ camping trailers, is stuff like the tele track and the vic high country (examples) and maybe strezlecki later next year.

In the past, the patrol needed lockers for the tele and money was spent on lifts & diffs, but it was crude.

I'm hoping the modifications required on the RRC will not turn it into a jap truck.

So for those out there with the experience, please provide your perspective, what worked for you, what modifications would you deem mandatory and what is optional.

It's a pretty big upgrade, but at the end of the day, I want the mods to work as a package and not just like some riceboy aftermarket parts sticker-truck.

thanks in advance.

Originally Posted by Mercguy

This is interesting. I had not thought of this as a viable option.

Apart from welding the BJ mount, what other fab is req'd to fit them in... spring perch mods etc. or does everything line up exactly?

You can change the spring mounts or use 80 series springs in the front and change the shock towers to the ones with twin shock capability and use those mounts to the standard GQ shock mounts.Other than that the front is a straight swap.

'assuming' a GQ front diff was fitted to the RRC, would it then be possible to use the superflex arms or is that still a no-go because of some idiosyncratic RRC thing? For some reason superior do not do a superflex for the RRC but will do it for Disco 1 ?

RRC and D1 chassis are the same, the superflex arms that fit the D1 fit the RRC, some members on here have them in their RRC, check out the superflex arms thread in this section. As for the GQ superflex arms, I haven't looked into that as I don't have the money to even think about that.

I'm figuring that if I have to pull a complete axle housing out, then I may as well overhaul them completely (that is my intention anyway) so naturally the bits that attach to the axle will also come under scrutiny.

That is what I am doing in my D1, I have an air locker for the front and a detroit locker for the 80series in the rear and both will have all new bearings and seals when the lockers get fitted.

The main issue is to examine whether or not it is worthwhile spending the additional $ upfront, or to delay wait until before the next big trip north.

It's one thing to do the diffs, but since the suspension needs modification to fit 33-35" tyres, then I have to look at the whole cost. So the ashcroft/maxidrive axles/hubs/cv's are a sound idea. Not sure if I can source ATB centres for an 80 series or GQ, and my guess is they would probably be more expensive. However, the GQ front axle housing is pretty damn strong, which is an added bonus. BUT, I think maxidrive/ashcroft axles etc would be a bit stronger than OE nissan / tojo.

If you don't wnat lockers just limited slip diffs, you can reshimm the 80 series, I had this done to my 75 series troopy (same diff centre) and the GQ diff can be fitted with an MQ/K rear limited diff centre.

For lift, I have gone with the LRA body lift and a 2" spring lift and cut guards and flares so the 35" tyres will fit.

I did this on a price only basis, as the jap diffs where cheaper than the ashcroft set up, but I do lose a little ground clearance due to the larger diff pumpkin on both diffs.

As for strength, I have had a 75 series troopy for 16yrs and have not broken a CV or axle and mine has the smaller (hilux type) diff, so I don't think I will break a GQ one.

It all depends on what you want to do with your truck, my D1 is a pure bush truck.