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.

http://img.photobucket.com/albums/v11/dave_macisaac/Chevy/DSC01813.jpg

http://img.photobucket.com/albums/v11/dave_macisaac/Chevy/DSC01815.jpg

Other pics of the damage

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

http://img.photobucket.com/albums/v11/dave_macisaac/Chevy/DSC01820.jpg

Con't

[Dave M]

Con't

Damaged pinion

http://img.photobucket.com/albums/v11/dave_macisaac/Chevy/DSC01819.jpg

ring gear acctually looks OK

http://img.photobucket.com/albums/v11/dave_macisaac/Chevy/DSC01817.jpg

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

http://img.photobucket.com/albums/v11/dave_macisaac/Chevy/DSC01824.jpg

[Dave M]

these were bearings

http://img.photobucket.com/albums/v11/dave_macisaac/Chevy/DSC01823.jpg

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

http://img.photobucket.com/albums/v11/dave_macisaac/Chevy/DSC01821.jpg

http://img.photobucket.com/albums/v11/dave_macisaac/Chevy/Chevy2.jpg

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 :p.

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 :p.

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 :D

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
(http://car-part.com/)





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

[Dave M]

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
(http://car-part.com/)
All I 'figure' I need is the ring and pinion gear and the larger pinion bearing. This truck is no honey so isn't expected to last much longer. I may be wrong about the $100, but there happens to an auction for exactly those three items and I'm guessing at the final $$

Thanks Bill

Dave M

[icesoft]

I would say, a ring/pinion set, inner pinion bearing, outer pinion bearing, a new crush sleeve, and a new pinion seal. You will need to press the race off of the old pinion to get the shim off of it and reuse the shim with the new pinion, the shim effects the pinion depth/gear contact pattern and backlash. Other than that, it shouldn't be too bad to set up.

A word of advice though, don't just crank on the pinion nut with an impact/cheater bar, as its a guaranteed way to **** up a new set of pinion bearings (and it will howl like a S.O.B.). Take some time to tighten it up slowly and check the preload on the pinion bearings, it should be around 20-25 IN/LBS to turn the pinion, or light drag when turning it by hand. If you run it down too tight, you'll need to pull the crush sleeve back out and start over with a new one. It only takes about a 1/2 turn to go from too loose to too tight, so be careful when setting the pinion preload.

How much did you grind down the inner pinion bearing seat? If you didn't spin the outer race for the inner pinion bearing, then just swap the r/p use the old shim and new bearings and you should be close enough, if you chewed up the pocket for the outer race, you'll need to add more shim thickness to compensate for the lost metal.

Course, I just pulled a Ford 10.25" 1-ton dually axle out of the junk yard for $150 today, maybe you can find a better price at a 'you-pull-it' yard.

[632 Regal]

dude, you have a huge ass crack in the case, never saw a casting line like this. Like Bill says grab a whole unit, change the fluid and call it a day... much easier, cheaper and faster to do than rebuild into a cracked case.

http://img.photobucket.com/albums/v11/dave_macisaac/Chevy/DSC01813.jpg

[ryan roopnarine]

i didn't want to say anything, buuuttt....

the local LKQ self-service in orlando will let you pull a axle assembly, for a truck (w/ drums) for $84, or $99 if it has discs. chevy 1500 (WT i guess?) isn't that rare. $20 if you just want the insides. ontario is going to be different, i'm sure. i assumed that you wanted to do a thorough job if you were going to all of that trouble, but if you aren't trying to be fancy, i can't imagine spending all of that time and effort.

[icesoft]

dude, you have a huge ass crack in the case, never saw a casting line like this. Like Bill says grab a whole unit, change the fluid and call it a day... much easier, cheaper and faster to do than rebuild into a cracked case.

http://img.photobucket.com/albums/v11/dave_macisaac/Chevy/DSC01813.jpg

That's just a casting line, look where the pinion wore into it at the back, see where there's wear on the left side and not the right, if it was a crack there would be even wear on both sides of the crack.

Regardless, for what it's going to cost for a r/p and bearings, he should be able to pick up a good used axle.

[Dave M]

Guys,

If I could find a used unit in the 'hood' I'd swap it in, but this area isn't rich with wreckers. The closest rear end I've found is ten hours away, $800 and shipping something like that is out of the question. It seems to be a comletely different story on your side of the border, which is why I'm bidding on a ring and pinion in NC. A place here wants $300+ for a ring and pinion (no bearing), so I may as well take my chances.

Thanks icesoft, I'll be taking your advice when it comes time to re-assemble

it should be around 20-25 IN/LBS to turn the pinion, or light drag when turning it by hand

I'll be sure to let everyone know how it works out.

Dave M

[RockJock]

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


man the forestry sector is cheap!!! ;) :p

.......just kidding, are you a contractor/consultant, work for a pimp, gov, or an employee of a forest products company?

[Dave M]

man the forestry sector is cheap!!! ;) :p

.......just kidding, are you a contractor/consultant, work for a pimp, gov, or an employee of a forest products company?

I work for a Forest Management company. I plan activities on ~ million ha (2.5 mill acres) of crown land. The Federal (Canadian) gov sets a cap on the $/km one can be payed without being penalised with additional taxes. I believe $.50 is the limit. The way I work it, it basically pays for fuel /maintenance in all my vehicles (work and non-work related) with money remaining. Lately, I've been traveling as much in helicopters as my truck. Now those are hard on fuel ;) We went through 100 L of jet fuel in 10 min gaining 200'.

Great job, but forestry is suffering in a huge way due to global markets, the strngth of our dollar etc.....

Dave M

[Dave M]

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
(http://car-part.com/)

Just won an auction for the ring and pinion gear and inner bearing. $30 for the bits, $18 shipping :D

We'll see how it goes,

Dave M

[RockJock]

I work for a Forest Management company. I plan activities on ~ million ha (2.5 mill acres) of crown land. The Federal (Canadian) gov sets a cap on the $/km one can be payed without being penalised with additional taxes. I believe $.50 is the limit. The way I work it, it basically pays for fuel /maintenance in all my vehicles (work and non-work related) with money remaining. Lately, I've been traveling as much in helicopters as my truck. Now those are hard on fuel ;) We went through 100 L of jet fuel in 10 min gaining 200'.

Great job, but forestry is suffering in a huge way due to global markets, the strngth of our dollar etc.....

Dave M

sounds like a great job with lots of diversity, not stuck in a cubicle either......if forestry goes **** up i assume you could always head west to ply your trade on the 'dark side' and get into doing land access management stuff.

you've got me curious now, i know it's way OT, but.....do you do your GIS/spatial analytical stuff in-house or send it out?

[Dave M]

sounds like a great job with lots of diversity, not stuck in a cubicle either......if forestry goes **** up i assume you could always head west to ply your trade on the 'dark side' and get into doing land access management stuff.

you've got me curious now, i know it's way OT, but.....do you do your GIS/spatial analytical stuff in-house or send it out?

Yeah, we're lucky. I choose the days to get to the field (nice ones :D ) and can take my office type work home with me if I feel so inclined. Nobody looking over your shoulder.

We do all our GIS and modelling (long term timber management/wildlife habitat etc) in house. I've recently been training myself on a new program developed locally and hope that if something does happen, it will be another tool I can add to the resume. Are you inthe GIS field or something related?

Oh, and I moved from 'out west' (interior BC) a few years ago. Great job there as well, but my wife-to-be couldn't find work and wanted to go back to school. She could do both where we are now and we're loving it here.

feel free to pm with questions, off to work..........

Dave M

[Ross]

Like you say the pinion bears on the....bearing so this shouldn't be a problem.