Rear diff trouble

[88lux]

1988 Hilux d/c 2.4 diesel (LN65)

I've been getting a bit of vibration through the drivetrain lately, and found there was a scary amount of slop in the pinion bearings. Realising this was only a temporary fix, I pinched up the pinion nut a 1/4 turn to take up the slop, and the problems reduced significantly

...for about 2 weeks.
Driving home last night, the diff started making some noises that sounded a lot like "rebuild or replace me".

My problem is I have never had to do anything with diffs before and don't know what I'm doing. I've heard a lot of people say that diffs are very hard to set up the freeplay and preload, and I'm not sure if I have the tools I'd need to get it right. I'm also not too sure if I buy a complete diff (without housing) what other bits like seals etc I would need to replace when installing it.

I've got 4.88:1 ratio diffs, which combined with the 33's work out to be the right ratio for my crappy 2.4 diesel (was awful until I got the 33s). Unfortunately the 4.88s seem to be rarer than hens teeth in an LSD (which I currently have).

Should I take the diff out and see what's what, or is that the point of no return at which I can't put it back together and drive it down to a mechanic if need be? Is another option to find a 4.88 open diff and stick an auto locker in or do the LSD and open diffs not share the same housing?

I'm a bit concerned this could quite easily blow out into a very expensive fix, so any advice as to what I am likely to be able to do myself and what is best left to the pros would be much appreciated. Also feel free to try and sell me that top condition 4.88 LSD you have sitting out in the garage haha!

[Heath]

If you are confident in removing the rear axles (if its a full floater rear even easier), removing the drive shaft, draining the oil and then undoing the 12 (or whatever) bolts that hold the diff head into the diff tube. then you can put it back in. The set up/repair of the diff (backlash etc) I'd leave to an expert. Then you just reverse the process to reinstall (okay you may need new oil and a gasket / gasket goo as well) and save some $$$.

But if you can do the first part take it into a diff place and they'll sort it from there. Save yourself the labour costs for removal / reinstallation and put it towards that locker...

Of course if you dont have another vehicle then drive in/drive out unfortunately.

[pradon35s]

what area are you in mate?

my rear pinion bearing colapsed few months ago.

nigel at lineside automotive (chch) is a good bugger I pulled my head out gave it to him and he gave it back 5days later fully rebuilt and with a warrentee..

he would sort ya out

[88lux]

Well I'm in Auckland (nth shore), so that might be a bit of a hike to get it down to chch. How much did that set you back if you don't mind me asking?

[Mongoose]

I did the same last weekend to get rid of some driveline vibration, does tightening up the pinion nut accelerate or worsen any issues in the diff?

[88lux]

Obviously I'm no expert, but I believe the preload on the pinion to crown is quite critical, and set by tightening the two bearings together with a crush tube in between. If you are having to tighten the pinion nut, you have to ask yourself why. Probably the bearing is worn, and if you have noticed it has enough slack to tighten it, then probably it has worn quite bit. If there is no longer a spacer tube pressed hard against the two bearings, then the loading on the bearings will be at least a little bit off axis and thus the rapid demise of my diff bearings. I will try to get the diff out tomorrow and call around to see if I can find someone who knows what they are doing.

Does anyone know if I'd be okay to pull a Richard Hammond and drive it in fwd a few kms with the driveshaft out? Otherwise I'll get a mate to give me a lift

[gimmemud]

The lsd centre can be replaced into an open diff if you can't find an lsd. Did it with mine. Try diff and rear axle repairs in otahuhu for a price on fixing/fitting.

[88lux]

Cheers for that. I'll give them a go

[Heath]

Well I'm in Auckland (nth shore), so that might be a bit of a hike to get it down to chch. How much did that set you back if you don't mind me asking?

Give Motortech 4x4 a ring and they'll point ya in the right direction (or may do it for you). They're on hillside rd 444 4633.

[Heath]

Obviously I'm no expert, but I believe the preload on the pinion to crown is quite critical, and set by tightening the two bearings together with a crush tube in between. If you are having to tighten the pinion nut, you have to ask yourself why. Probably the bearing is worn, and if you have noticed it has enough slack to tighten it, then probably it has worn quite bit. If there is no longer a spacer tube pressed hard against the two bearings, then the loading on the bearings will be at least a little bit off axis and thus the rapid demise of my diff bearings. I will try to get the diff out tomorrow and call around to see if I can find someone who knows what they are doing.

Does anyone know if I'd be okay to pull a Richard Hammond and drive it in fwd a few kms with the driveshaft out? Otherwise I'll get a mate to give me a lift

Not sure of the diff type you have but unless it has floating rear axles you wont be able to drive it with the centre removed. The inner end of the axles are held nice and stable by the side gears. without the diff they would flail around in there and might damage themselves and the diff inner housing. I could be wrong though.

[88lux]

Good point Heath. I have taken the diff head out now and have decided it's going to be replace, not rebuild. There are a few too many parts inside with pinion gear shaped teeth on them (like the bit that holds the spider gears). At some point I'll take it apart and try to figure out how all that happened, but I think it's safe to say I'd better give up on any plans to reuse this head, if only cos it'll be way out of balance with all the missing metal. Guess I'm lucky it didn't blow and take the housing out with it.

I was going to put the shafts back in and sit it back on the wheels so that I could wheel it back into the garage, but the hub bearings don't seem to hold the wheels vertical i.e. there is about +/-5 degrees of slop as the shafts flail around. Is that normal? I assume it's probably ok as the spline usually supports the other end of the shaft, but haven't taken the hubs apart to see what sort of bearing is in there.

I guess I'm on the look out for either a 4.88 LSD or an open one and some form of locker.