[Brenno]

Some background:

4.9 gears
Re4 auto
4.11 Maruti ring and pinion
Solid pinion spacer

I am having numerous issues with arb airlocker which I've had from new a few years ago.

I am a bit concerned about how far the floating section that holds the quad seals sticks out, other sierras I've seen don't look like that.

I can't replicate the leak when it's out of the car so it's really hard to trouble find.

It happens only in low range, ie won't do it in high but as soon as I put it in low and go into first, it will start leaking and you can smell diff oil out of the breather and the pump starts to cycle.

I have replaced and replaced the quad seals numerous times. I have reset the side bearing preloaded numerous times and is much higher than where it should be now just to make sure it wasn't that.

Just wondering if anyone else has had this issue and what the problem was. My next option is to change to Sierra 3.9 gears etc to make sure it's not something to do with the Maruti stuff.

[Beery]

Hmmm, my first thought was bearing preload too. If it's only doing it under higher loads then that really suggests the centre is moving around and unseating the O-rings, but I'd of thought it'd have to be pretty sloppy for that to happen. Indeed your seal housing/adjustment nut seem to stick out a little further than usual. Mine sits basically flush from memory. If the locker's been installed for a while, usually the O-rings polish up the surface where they run - does the outer O-ring look to be running really close to the edge? Maybe it's really borderline and high loads jussst break the seal.

I'm a bit stumped, and don't have an exact answer, but here's some things to check that I've come across before:

Check that the adjustment nut for the side bearings hasn't got a burr on it. I've seen this before where the tool slipped out or whatever, it burrs the edge, and then the seal housing doesn't sit flat/flush with the nut.

Also check that the locking tab for the adjustment nut doesn't foul on the seal housing. I know my sierra one did, I had to bend it a little to clear. The seal housing must be able to "float" and it should rotate back and forth a little when turning the diff forward/reverse. it might just be the photo, but the copper line looks pretty close to the crown wheel. Be sure it has enough gap to allow the seal housing to rotate back and forth.

It very well could be the Maruti 4.1's require the centre to be offset a bit more to get the correct gear pattern/backlash compared to other ratios. You could machine the adjusting nut down a bit to get the seal housing to sit further in, if that turns out to be the problem. that way you could keep the 4.1's.

Is it an issue with both diffs?

[Beery]

Beery wrote:

It very well could be the Maruti 4.1's require the centre to be offset a bit more to get the correct gear pattern/backlash compared to other ratios. You could machine the adjusting nut down a bit to get the seal housing to sit further in, if that turns out to be the problem. that way you could keep the 4.1's.

Now that I've said that, it shouldn't actually matter how offset the centre is. Definitely check the bearing is fully seated, no burrs on the nut etc.. something must be making the seal housing stick out further than usual.

[Brenno]

So I did some more testing on the whole system. I removed the crownwheel and placed the seal housing back on and pressurised the system. I move it in and out and twisted it and couldn't get it to leak. I had to move it so far off the end of the shaft you could see the middle of the seal before it blew out.

So I pulled the centre apart and removed the inner seal (pics coming once I'm on a PC) and there was quite a bit of metal shavings inside and a little bit of oil

Perhaps this could be the cause? Not sure why it only does it after heavy load. New seals were provided free as ARB weren't sure how the shavings got into a sealed system...

Will get some more side bearings as they suffered from too much bearing preloaded and I will test again once re installed.

I initially thought something might have a hairline fracture which was leaking after load but couldn't see anything.

[Brenno]

There is a large washer that sits on this gear and as you can see something has been in there munching up the surface...
I removed this seal and underneath I found the below bits of metal. This should only have air behind it and is what pushes the gear into the other side gears to lock it up.

[Beery]

What does your centre crosspin support block (I think ARB call it a spider block or something) look like? I've heard of full float axles chewing into this causing metal fragments.

[Brenno]

funny you say that, I did notice when I pulled the axles out that the inner splines were a little chewed out during its recent disassembly. I hadn't noticed it in previous ones. I'll pull it further down and see what might have caused it.

[Beery]

Yea, the "fix" was to machine out the support block so the axle could slip through it and the crosspin itself would limit axle movement.

I think securing the axle somehow out near the drive flange might be a better option instead of machining locker parts. Maybe a circlip or something, I haven't really looked into it yet.

I only found this out after doing my floater, but it's on my list of things to check/fix.

[Brenno]

The diff is back together (again) and back in the car. It appears to be ok under no load (auto is out at the moment getting swapped out).

The only other thing I noticed was the copper airline has some wear on it near the bulkhead fitting where the O ring seals. This might provide reason why it moves under hi torque as the copper line might be moving around slightly?