Drive Train Advice!

okay, i will do a little intro..

I got a GU 4.2 2006 about 18 months ago and just started spending some money on it...
owned it since 150,000 (ex BHP vehicle) and ive racked up 60,000 on it.. so its just hit 210,000.
Just got a new turbo from united fuel injection, loved it that much that i just ordered the BIG intercooler... :smileyvault-cute-bi

however... my fourth gear has just started crunching as i shift into and out of it.. read a few posts on here as what to do but as im probably not capable of striping down the gearbox.... I went to Perth Gearbox Differential & Clutch Centre in Belmont and spoke to them this morning.. there gonna strip down my gear box and do a rekon it. (while there at it, gonna get a new HD clutch in it)

thing is now im thinking of the "to do" list i have. so im thinking of going back in tomorrow and speaking to them about putting ARB air lockers in front and rear and asking for a 43% reduction for low range.

i recently put some slightly bigger tyres on it, 285/75 (i think are 33's?) and as i seem to be doing everything over... i was thinking about which diffs to get? should i change the ratio? to accommodate for the bigger size while im getting my diffs re-built into lockers?

i should mention that i use this vehicle for work use as well as "play time" :)
it weighs a constant 3.8 tonne (i know the GVM is only 3.4)
and tows a 2 tonne trailer 90% of the time over very long distances all over WA and then bounces down railway access tracks when it arrives! (best job ever) haha

on a separate note... has any 1 installed the Air on Board systems and what do you think of them? easy enough install? Thinking of sticking one of them in to power the lockers (already have an ARB compressor, but don't rate it as the heat it builds up is mental! and dont wanna be stranded some where with 4 deflated tyres and no compressor!)

any info i could get would be greatly appreciated
and hopefully all will be complete for the dwellingup meetup!

hey mate, you are going to love the lockers when in, as for the diffs, most people don't bother changing ratios for 33's and the guys on here that have reduction gears seem to have gone for the full 85% and love em! I think bigrig and ben-e-boy has them.

X 2 on ratios wont need to change anything, Air on board will take best part of a day to install, but wow will you be impressed. HP air instantly and
enough to power rattle guns, air ups in seconds not minutes.
Have you looked at the pro Locker?? If you're putting in reduction as suggested go 85% reduction and 15% reduction on overdrive,
33" muddies, f/r lockers and reduction gears will see you near un stoppable.

Also you'll need to up grade your GVM as well, read Cuppa's thread on mods required etc.
Someone will put up link for me I hope

If you don't go "air on board" fit a one gallon tank to inside of left chassis rail for lockers

Would the 85 reduction be to much for driving in sand?

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Thinking momentum is your friend on sand , don't think crawling would help.
Others would know better

I reckon the 85s would be too much for sand driving.

look at your compliance plate and determine what diff ratios you have now? i bet you have 3.9s? if this is the case then going to a 4.11 or even a 4.3 will be a big help, especially if you do allot of sand work.

i would also be thinking of 305/70R16 tyres next time too mate, same size as the 285s but a little wider ;) good for sand.

Yeah reduction gears are only good when you've got a lot of traction. Definitely not good for mud, I can't comment on sand but agree with threedogs, momentum and a light touch is the key

FanTapstic!

Judging by the compliance plate... I'd say I have 4.1?

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yes you have 4.1s which should be ok. If your running very heavy all the time and tow allot then upping to a 4.3 set will make a bit of difference for sure. Dont think you need to go to 4.6s. 4.3s will be heaps.

4.3s and 45% reduction and your on a winner. IMO. even with the 45% reduction you might find that your doing all your sand work in low 4th or low 5th to keep the momentum up.

The reduction gears go into your transfer anyway and i dont think you need to remove the whole gearbox to fit those so you could even wait and see how it feels with the diff gears and lockers.

What gear are you doing all your beach work in now mate? If your using low 3rd and low 4th then you will find the reduction gears a pain in the butt! Diff gears is all the help that you will need IMO.

The ARB Compressor will be fine for the lockers mate, you wont want or need the endless air for that. the Lockers need you to hold the solenoid open with pressure to hold the lockers on, you dont want the endless air to have to do that the whole time. you could fit a tank and non return valve though, that would sort that.

I rate the ARB Hi Output compressors very very highly mate, simply the best 12v compressor on the market. if you have the coin then the Double header ARB are awesome.

Cheers mate, think I'll up it to 4.3 as you suggest... Just ordered the air on board system, comes with tank and manifold etc. I have an ARB atm, but it just gets so hot when pumping up 4 tyres.. Especially in summer!

Can't wait to get all this installed.. Heading up to Murchison 4x4 park in 4 weeks, when I was there last time I had skinny tyres no lockers. It's gonna b like driving a different car!

Can't wait to find a cruiser bogged somewhere :) although they never accept a snatch!

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Bigger turbo,
Bigger Intercooler,
4.3 diff gears,
Front and rear Air Lockers,
285/75 tyres


You WILL be driving a Different car mate ;)

See whats the biggest tank you can fit. You can then charge $2 a tyre to re inflate your mates
and recoup some monies. LOL

sand driving is better in h4, with bigger wider tyres you will smash the sand easily in H4, L4 is to torquey & tends to dig in more on the soft stuff, reduction gears are for L4 so have no affect in H4, as for reduction gears with twin lockers, I would go 45%, fit 85% if doing a lot of rock crawling, rock climbing, it will climb all day over any rocks, your fuel bill will go up a bit with the diff ratio changes but you will end up with a bullet proof truck that will do anything anytime, doesn't get better than that in my book