High pinion centers

[darnoldrs]

Just curious as to what is required to make a standard diff Center into a high pinion Center and if the ya and Gu centres (and carrier) are the same. Thanks. David

[darnoldrs]

Stupid auto correct.
Gq and Gu Center the same?

[joshy]

Gq/gu centres are the same. Just put a front centre in the rear and lift the oil fill hole.

[darnoldrs]

i thought the would just swap ends but didn't think about the oil level plug height. Thanks for that. Off on the search for some gears

[joshy]

Edit: may have over simplified. Need a front 3rd member with a rear centre as the fronts are 31 and rears 33 spline.

[darnoldrs]

I will be fitting ARB lockers at the same time so that should be no problem.

[joshy]

Yep easy as then

[A.J.]

Rear high-pinion:

-Front third member
-Rear centre (Air Locker etc.)
-Front gears (Will run reversed)
-Raise filler plug about 2"-3"

I have had this setup on my GU for around 2 years, in which it has also done a fair bit of daily driving.
No issues at all.

[darnoldrs]

After looking at the diff/drive shaft clearance it doesnt look to be much of an advantage for ramp over as the radious arms are about the same. I was mostly after it to minimise the change in uni joint angle after the 4 inch lift.
Overall is there much advantage to be gained?? This is just a tourier but thought when buying another center to change diff gears and fit lockers it might be worth doing at the same time, maybe.
Given there is more oil around the crown wheel, is this likly to use more hp to drive(fuel ecconomy)? Anyother pitfalls?
thanks

[darnoldrs]

After looking at the diff/drive shaft clearance it doesnt look to be much of an advantage for ramp over as the radious arms are about the same. I was mostly after it to minimise the change in uni joint angle after the 4 inch lift.
Overall is there much advantage to be gained?? This is just a tourier but thought when buying another center to change diff gears and fit lockers it might be worth doing at the same time, maybe.
Given there is more oil around the crown wheel, is this likly to use more hp to drive(fuel ecconomy)? Anyother pitfalls?
thanks

[ezzman]

It gets the tailshaft further away from hitting on rocks etc. you do need to run same oil levels as in a front diff to keep the pinion lubed. I've done it on my shorty comp truck and it has helped heaps with clearance. On a street driven rig it will also get rid of any uni vibration (normally only in a shorty) associated with a 4"+lift.

[ar3nbe]

Ok, so just to confirm. I have the following parts and want to get this hi pinion rear set-up within the next week or two.

Front thrid member complete with correct ratio gears
Rear ARB locker.

From my understanding that's all I need apart from raising the fill level? Anything else to watch out for while I do the conversion? Any tricks?

Will the stock swaybar still work? Either a GQ or a GU one?

[joshy]

Off the top of my head yea that's it. Duno bout the sway bar, pretty sure ajs gu one still fit ok.

[A.J.]

Yep, swaybar works fine!

Just check where you're the bulk head for the air locker should be positioned to clear the sway bar.
But I'm pretty sure you could get a right-angle adapter for the air fitting in case you have an issue.

Mine worked out fine.

I will post a pic or two in a minute

EDIT (pics):




The blue strap is holding the swaybar up because I didn't have links fitted at that time.

[ezzman]

My rear air locker went in the front carrier no dramas. Whole swap was just a bolt in deal. I didn't bother with raising the filler plug, I just fill it from one side jacked up.

[A.J.]

Good to hear it all worked out.

As you said, it's actually a pretty easy conversion.

[SBL]

Yep, swaybar works fine!

Just check where you're the bulk head for the air locker should be positioned to clear the sway bar.
But I'm pretty sure you could get a right-angle adapter for the air fitting in case you have an issue.

Mine worked out fine.

I will post a pic or two in a minute

EDIT (pics):




The blue strap is holding the swaybar up because I didn't have links fitted at that time.

Gday guys. Just looking at these pics the raised filler plug seems a lot higher in this diff housing than what it is in the front diff housing. Is this done just to "make doubly sure" or does it actually need to be higher in the rear? I did mine the other day and fitted the new filler plug (after lots of measuring from many different angles) about 10mm higher than the front diff plug. It seems to run ok but does feel a bit hot after a run on the freeway.

[SBL]

Probably should also mention that I had to change the flange as the rear is bigger than the front. (09 GU) Easy as, everything just swaps straight over.

[SIM79]

It seems to run ok but does feel a bit hot after a run on the freeway.

Did you previous diff fell cool after a hwy run?

[SBL]

No idea mate, I never checked it so have nothing to compare it to.

[A.J.]

Oh, yes indeed, I forgot about the flange

I just made the filler plug sit about 75mm higher, no real measuring or reason

You don't have to fill it right up to the top, just put about 5liters in it and it should be fine.

I've pulled mine out the other day, bearings and all are still like new, works well.

[SBL]

Thanks mate, mine is running 6 liters which probably doesn't make a huge difference in oil level once it runs out to the end of the axles and all. It's been running up and down the freeway since Friday with no nasty pinion noises so all is good. Thanks for all the info on this page.

[joshy]

Closest correct amount of oil would be what the front diff normally takes.

[ar3nbe]

I did mine a month or so back. Works well. Used an ARB centre and everything just bolted up bar the pinion flange.

I raised the filler about 75mm and ended up putting 5.5ish l of oil in there. Everything seems to work thus far.

Easy job overall.