Check-up for Scott's V6 3rd with ARB
(68 low res pics loading)
JAN 21 2009

Scott from Fort Lewis, Washington just purchased a pair of 3rds off the internet. The one shown above right is what this link is about. This is some of Scott's email to me...quote - " I was fortunate to find an ARB in a V6 with precision 4:88ís for an awesome price. I was told that it was set up professionally for the seller. The ARB was set up twice. The first set up broke a pinion which scarred the ARB carrier. The ARB unit was sent to a state side tech for inspection, the damage was deemed cosmetic only." (said the seller).

Something looked a little 'off' when I visually inspected the air bearing with the 2 o-rings.

It's hard to show it in this pic but the assembly seemed to be offset a little. It should sit perfectly level and it should sit at least few thousandths below the level of the journal end.

The brazed copper connection has some separation.

First, to verify that the brazed connection is not a problem by running an air check.

This is my ARB leak tester. This is the 3rd or 4th iteration of my tester. I've eliminated the on/off valve and the 2 rubber hoses. Past iterations were prone to leaks in themselves. This one works beautifully.

Using a compressor, I pump it up between 90 and 100 pounds and see what happens in 5 did not budge... copper line is ok.

The used PRECISION 488 had these markings on them.

Precisions used to be top notch in quality and strength, in my opinion, through the years...but things changed sometime in 2008. I now prefer to work with Nitro Gear from JustDifferentials or Motive Gear.

Make sure the tab is not pushing against the air bearing assembly as that might cause the o-rings to leak air. This one is just fine.

These next 6 pics show the damage near each of the 6 bolts...All I can say is WOW. To me, this is borderline "something needs to be replaced" damage.

The seller said the ARB was sent to a stateside tech for inspection and the damage was deemed 'cosmetic'.

UPDATE---- 1-26-2009 ---- I just got off the phone with the stateside tech...I sent this link to him and neither he nor his co-tech had ever seen this ARB. They were concerned about the shearing forces on the existing 6 bolts/case lid and were concerned about the future of this ARB case.





Before dis-assembly, the ring gear is painted. The drive pattern looks fair...possibly a little shallow.

coast side.

I needed another 'pinion'... so this paint looks deep...deep on the pinion means shallow on the ring.

The wheel on the left is the original adjuster wheel for the air bearing side. It was cross-threaded and damaged beyond use. The previous installer is responsible for this. The brand new adjuster on the right will replace it.

Same thing happened on the other side...the left one is the original and it was also cross-threaded. The one on the right is a replacement I found.

Red Loctite was used on the 4 bearing cap bolts and in the process of removing them, the solid chunks of loctite bunched up and destroyed one of the bolts. Perhaps red is too hardcore for this particular bolt... maybe a medium strength blue would be acceptable. I use none just like the factory.

I found 4 bearing cap bolts in excellent condition that will be used.

That damaged bolt almost destroyed the threads in this particular hole...using a tap seemed to save it. The entire carrier would have been junk if the internal threads had been destroyed.

All the ring gear bolts checked good in the torque department.

With the case out, now is a good time to check the PPL. I measured 5 in/lb which is in the good target zone.

Somebody wheels it in the goopy mud :)

Using the press to push out the pinion.

Even the solid collar could not escape some cosmetic damage.

Some dings on the inside of the carrier bore...outer pinion race seems ok.

I'm not sure how this gap opened up. I can't even guess. :(

The busted pinion from the first break must have done this.

All looks good here.

Here's another shot of the gap.

It certainly wouldn't hurt to press the bearing off and add just a little more shim to push the pattern closer to the ideal. As the painted pattern showed earlier, it was a little shallow.

The original shim is measured and documented.

The original shim added up to .2125 and I will substitute in a shim that is .004" thicker.

Time now to put the pinion assembly back into the carrier. The solid collar shim was perfect where it was.

I know everything will work out nice so I'm confident enough to install the seal now.

I used red Loctite and cranked the nut extra tight. I measured 7 in/lb which is at the upper limit for used bearings. Ding the nut and this end is done.

I can see the wear marks from the rubber o-rings...not as centered as I thought they might be.

Even with all the cross-thread damage to the adjuster wheels, the actual carrier threads are not nearly as bad.

Lots of aluminum based anti-seize on 100% of the threads. This way, 100 ft/lbs on the wheel adjusters is more like 120 ft/lb on dry threads (due to the reduced friction).

The ARB case is installed and the wheels are carefully matched to the threads.

The bolt circled is the one with the damaged threads from the red Loctite. I used the torque wrench and it accepted 70 ft/lb with a good solid feel.

This end of the spanner wrench fits the ARB wheels perfectly. It will not scar the surface in the least and that means the air bearing that gets put on next will set flush and even.

I filed the grade 8 threads to make for a perfect fit in the squarish ARB slots.

Used carrier bearings....and plenty of anti-seize. 100 ft/lbs is plenty for a good install.

I took about 21 readings all around the ring and had a nice .007" for BL.

Drive side with the .004" extra shimming and the pattern looks good.


The pinion pattern looks good also.

All looks good so this lock tab is torqued to 10 ft/lb with red loctite on the 17mm bearing cap bolts, thank you.

Now to install the air bearing assembly.

This happens to the end of the soft copper line when the brass bulkhead fitting is over-tightened and the fat o-ring starts to crush the copper. If this continues, it's possible to almost pinch off the line resulting in the air locker responding slower.

Everything looks much better compared to when I first received this unit....except for that case :)

The jpeg pic is deceptive but the air bearing is more than is past the journal end enough where the o-ring can never pop out.

The retainer clip goes on now...and so does the lock tang (not shown).

The screwdriver pops it in place solidly.


This is the part number from ARB for the fat tiny o-ring.

A new one is smothered in gear oil and pushed in place.

One more air leak test...


It never lost even 1 pound.

I'm sending back the damaged wheels and bolt for Scott to inspect.