izuzu 12 bolt into a XJ

i have one setting around and im thinking of putting it inplace of my 8.25 rear. ive heard there pretty strong and its got 4.55 gears and disc brakes.

whats some problems i will incounter? my main concern is the differnt lug patern.

They're a pretty damn stout axle. When they changed it over to the Dana 44 a lot of the isuzu guys complained about what a downgrade it was.

Biggest thing is lack of aftermarket and junkyard parts, but on a mild rig with 33-35" tires or so you should be pretty well set.

You might wanna PM Timmay on here for more info, he looked into running one for a while before he decided to just do the 14-bolt.

i need to swap in a new 8.25 b/c mine busted all to hell but while im there i might as well upgrade and i have a trooper with the 12 bolt here allready . im looking to run 33's. so the 4.55 gears will be good and i can slap some 4.56 in the d30 up front. and i want the dic brakes.

it's a stout axle, but with limited locker options (ARB only, I think). It may be slightly narrower than your XJ axle, so you may be able to get back to 5 on 4.5 with spacer/adapters...

so arb is the only locker option. thats not cool lol.

how much work goes into makeing the yoke/u/driveshaft fit?

I'm not sure, since my experience with the axle is the one that was under my Isuzu for 12 years of wheeling... I would think it would be easier to have your shaft customized to fit the stock flange than to mess around with a modified yoke...

I have one. In my MJ. Uh...


You need a flange from a rodeo driveshaft to run a spicer 1310 joint on the axle.


You might run into master cylinder issues with the brakes.


Be aware you can get a 4.77 version of the axle. Hard to find a gearset that can match that.


But yeah, traction aids are the powerbrute LSD (came stock) the ARB, or welding it. Buuuut, the isuzu guys on pirate have been trying to get a lockright made for it.

do you have a pic of your set up

And in that dark mess is a 12B, 2 shocks, a couple leaf springs, a driveshaft, a truss, and one very skrewed brake line (hint, make sure the grounding clamp for your welder is where you thought you put it before using an arc welder to cut something...)

The isuzu 12-bolt has a WM to WM of 59". The lug pattern is 6x5.5. LockRight use to make a locker for this axle but has discontinued it. Matt Brown from Independent4x.com sells axles, gears, 3rd members and the ARB for this particular axle. DirtyMJ is correct about getting the yoke off of a rodeo rear axle in order to utilize a 1310. The "Big Tire Option" yields the 4.77 gears. I'm personally debating running one of these with a waggy D44 up front. They're supposedly a little stronger than a D44.

matt4wheels said:

LockRight use to make a locker for this axle but has discontinued it.

Click to expand...

Sure? I thought they made one for the 10B rear, but it is often adapted to the 10b front. Never had I heard of them making one for the 12B; if they did I might go looking for one.

The Isuzu 12 bolt comes in at least 3 widths.

Early Amigo/Trooper were 58" - 59" WMS to WMS, 3" tubes with disk brakes with an ebrake lever on the calipers.

'92 - '94 Trooper and some '95's use a ~ 61" wide axle w/ 3.5" tubes set up for coil springs. The rear disks changed a bit. They are much bigger and the e-brake is now an internal drum brake inside the rotor.

The '94 Amigo specifically is the earlier width (58 -59), 3" tubes, but with the same upgraded brakes from the Trooper.

BTW, you cannot swap brakes from one type axle to the other. The flange on the end of the tubes is completely different.

Starting in '95 up through '99 or so, Troopers got a wider 63" wide, 3.5" tube axle.

All shafts up to this point are 1.3", necking up to 1.5" at the splines.

In '99, they switched to a "modified" 12 bolt. It's huge. Ring gear bigger than a D60 & 1.5" shafts. No gears available any more (there were some available from iceland a few years ago), but there is an ARB available.

The VX uses the 12 bolt as well. I believe it's the same as the '95 - '99 Trooper.

ARB is the only locker for any Isuzu 12 bolt. There was never any Lock-Rite or other drop in locker. LSD's are available as well.

--Dan

Good info. Thanks Dan.
Do all of those years have a 6 on 5.5 pattern?