Commodore lsd cone damage

[Dazza92VP]

Hey guys diff pinion bearing on my wagon crapped out so stripped the diff down and pulled the carrier apart to clean out but when I stripped the cones out and pulled the spiders away from the cones found metal from the cone had welded it's self to the back of the spider but there is no heat marking at all if it wasn't for these marks on the back you would think it just came off the parts shelf. just wondering if anyone's come across this before. This diff is the original from factory first time apart and never abused at all oil changed religiously no water has been in it at all both of these are splined to the same axle and unable to move independently asked the guys around the workshop and they've never seen it before

[immortality]

That is bloody weird.

I'd clean it up and put it back together.

edit, what does the other side look like? Have you checked the bearing on that axle?

The only thing that springs to mind is an earthing issue with the engine which has resulted in the engine possibly been earthed through the driveline instead.

There was a guy on another forum who had an earthing issue which resulted in the destruction of the thrust bearing for the crankshaft and consequently a stuffed engine.

[VK_3800]

That's common, its where the shim material is placed - there isn't really any heat because the spider gear and the cone don't turn in relation to each other, but this area is heavily loaded when the LSD is working (the cone pushing the spider gear into the centre). I think when things sit for a long time moisture creeps in too and adds a bit of corrosion and pitting to the mixture.

As long as there's still a reasonable amount of flat area remaining on both parts it shouldn't affect operation. Obviously the shims will be stuffed though (and will probably need increasing) so replace those.

[Dazza92VP]

Yea damage is done to both sides. I've got another diff that's stripped down and there is none of the damage like this in it but the cones are worn to small and are hitting on the ends of insides of the carrier so no good to use. This isn't friction material that's stuck to the back of the spider it's hard facing metal from the cone there was no shim in there. I'm thinking just clean it up and refit as it's not a wearing surface and the lsd still worked perfectly before hand

[VK_3800]

You will probably need a shim (or shims) in there now as it won't be as tight as it was new. No there is no friction material, just (usually) hard shims to ensure that the cone is correctly placed in the carrier.

The cones that are bottoming out can go another round by machining the end until it has suitable clearance, should be able to do this at least once and still have ample material left. This face doesn't do anything so in a pinch you can hack away at it with anything to gain the needed clearance, I've used a stone in a drill press before!

[VX L67 Getrag]

Sort of on topic, what's the difference between diff's marked high performance & the just marked LSD?

I have a3.07 high performance out of a vx that doesn't LSD by hand turning, then a VZ 3.08 that is tight as a nun's!

[immortality]

Some diffs got shot peened gears, VN-VS V8 models, I think these had the high performance tags with em.

The label on the side of the diff will tell you if it's LSD, the high performance tag on the filler hole just tells you to use the good oil.

[vs ss]

That's metal fretting,every second one of these suffers from it as the stuff stuck to the gear comes off the cone cause the cone is a lot softer metal than the gear.

I do the same as vk3800 I just lathe a suitable amount off the bottom of the cone then reset gear clearance with a thicker shim.

[immortality]

What type of cutter do you use in the lathe on the cones? My guys at work were a bit skeptical thinking the cones would be made of fairly hard material.

I've pulled a few of these diffs apart over the years and not seen that before like the pic.

[VX L67 Getrag]

Some diffs got shot peened gears, VN-VS V8 models, I think these had the high performance tags with em.

The label on the side of the diff will tell you if it's LSD, the high performance tag on the filler hole just tells you to use the good oil.

That show's how little I know, I thought they had slightly different ratio's to indicate bigger crown's to suit the LSD, so I thought all 3.07 were LSD & 3.08 were standard, obviously not with the diff's I have here!

I've always been worried about rebuilding diff's as if you don't get the crown to pinion mesh correct I HATE the load on/off noises they make!