Semi OT: Chevy 1/2 Ton Rear Differential Rebuild Questions.......

[Dave M]

Finally hammered my work trucks rear diff hard enough to puncture the diff cover and lose all the fluid. Of course, I didn't discover the lack of fluid until an ass clenching screech, followed by a clanking and subsequent thunk informed me.

So, I've removed the diff, removed the innards and inspected. The inner pinion gear bearing exploded and was chewed to bits by the pinion gear. Most of it remained on the bottom of the casing as no fluid was present to help distribute the shrapnel. The ring gear looks OK, but I will replace it along with the pinion gear (found a pair on e-bay). What I'm wondering is what folks here think about the minor damage to the casing (pics below). The flopping pinion gear scoured it to a maximum of 1 mm depth. Everyone around here I've spoken to has indicated that any casing damage is very bad, but I can't see this affecting seating the inner pinion gear bearing at all.





Other pics of the damage

Damaged pinion gear with pieces of the blown bearing fused to it



Con't

[Dave M]

Con't

Damaged pinion



ring gear acctually looks OK



what was left laying on the bottom.......

[Dave M]

these were bearings



heres my lovely bush truck. Actually quite a money maker if i can keep it on the road ($0.50/km)





Thanks again guys

[Brandon J]

OMG. I have worked on the Chevy 1/2 ton axle, have worked on my Jeep ZJ axles, and have done a few of the big rig ones. It sucks when that happens. I am assuming the axle shafts are okay. I would sand the casing smooth and make sure the teeth contact profile is good. As long as the pinion angle in the housing is the same, then lets hope the bearings will be okay too. Perhaps call axle places to see if you could use a shim too. I hope your rebuild works out well. Oh, get that diff guard .

Your pics are great for others to see what can happen to the BMWs internals if a differential seal is left leaking. Good pics to inspire preventative maintenance.

[Dave M]

OMG. I have worked on the Chevy 1/2 ton axle, have worked on my Jeep ZJ axles, and have done a few of the big rig ones. It sucks when that happens. I am assuming the axle shafts are okay. I would sand the casing smooth and make sure the teeth contact profile is good. As long as the pinion angle in the housing is the same, then lets hope the bearings will be okay too. Perhaps call axle places to see if you could use a shim too. I hope your rebuild works out well. Oh, get that diff guard .

Your pics are great for others to see what can happen to the BMWs internals if a differential seal is left leaking. Good pics to inspire preventative maintenance.

Brandon,

I don't drive the thing very often when the e34 is on the road (warmer, non-snowy months), so I'm glad it happened now rather than February. Plus, its a job I've never done and I'm learning quite a bit about gears/ratios etc. The few shops/scrapyards I've spoken to wanted $500-$1000 for either a used rear end or a rebuild. I'm hoping to get all the parts for ~$100 and be done with it

Anyhow, common sense tells me that the removal of 1 mm of material will not affect the allignement/longevity of a bearing pressed 1 inch into the casing. Especially as the pinion gear is cranked down to some awful torque value (required a 6' cheeter bar to remove). But, thats just my common sense

Yes, the axle shafts are fine, but what do mean by the use of a shim?
Oh, and yes, I'll admit to abusing the truck a bit, as it doesn't seem to mind (I think??), but I've thought more and more about checking the diff on the e34.

Take heed fellow owners !!

Dave M

[pingu]

I'm no expert on differentials but it seems to me that the 1mm that has been scoured won't matter - I'd have thought that if the distance from the pinion gear to the casing was critical then the casing would have already been machined flat during manufacture (of course, it has now been machined flat - in a fashion - by the flopping pinion gear!). Good luck fixing it.

[bubba966]

Talk to these guys about it. www.ring-pinion.com From my dealings with them I'm sure they'd be happy to answer your questions. They also have a few how-to pages on their site.

They know their stuff. And you should see their warehouse (I went there to get the rear axle bearings for my '79 C20). I wouldn't have thought there'd be so many parts they could have in stock for the makes that they deal with. It's too bad they don't have any BMW stuff yet. You all should ask them to carry BMW diff parts...

[Dave M]

Thanks guys. Bubba, I guess there is a '.com' for just about everything. I'll give them a call and see if they can hook me up. I know exactly what I need, just looking for the best price as locals want both arms for this stuff.

Dave M

[bubba966]

Thanks guys. Bubba, I guess there is a '.com' for just about everything. I'll give them a call and see if they can hook me up. I know exactly what I need, just looking for the best price as locals want both arms for this stuff.

Dave M

I'd be surprised if you could find a better price than Randy's.

Not sure if he deals with mail order, but when I bought the parts for my truck my salesman was Micah. And he gave me quite the deal. You might want to see if you can buy your parts from him.

[Bill R.]

buy the parts for 100?.... in fact i'd say its not possible based on my experience rebuilding rear ends and the amount of damage you show in the photos. I'd buy a low mileage junkyard rear end in the neighborhood of 300 to 400 and put it in instead of messing with it. I've been doing quite of few of those lately and haven't had many that i've had to return. Use this for your junkyard search

Thanks guys. Bubba, I guess there is a '.com' for just about everything. I'll give them a call and see if they can hook me up. I know exactly what I need, just looking for the best price as locals want both arms for this stuff.

Dave M