While swapping the wheels on my new-to-me 1/2 ton, 4x4 '91 Suburban I noticed a slight drip of gear oil from the passenger side rear wheel bearing, and the bearings themselves seem to have a bit of play. The truck has 176k, so I'm thinking it's time to install new bearings and seals. I'm pretty sure it has the 8.5 GM 10 bolt rear, though my brain isn't the massive warehouse of GM knowledge like it is with Volvo 122's. So, here's some pictures of said rear end:
I have a new differential cover (they were $15 from Rock Auto, why mess with the old rusty one?) and gasket. My plan is to clean out the diff and run Redline gear lube, but before that happens obviously I need to address this bearing issue. I've replaced a few rear end bearings, on Chryslers and Volvos, but never a GM. Although, from what I do know about older GM stuff, it'll probably take like 30 minutes and require nothing but a slide hammer and a seal driver. 
Still, any advice?
Sounds like you're on the right track to me. Nothing magical in there. There is a small bolt in the carrier you have to remove to drop the spider gears, then slip off the c-clips and pull the axles. Someone will chime in that 10 bolts suck and you need to upgrade. If it made it this far, it's fine.
I was sort-of surfing around, looking at 12 bolt and 9" Ford replacements, but even for GM stuff, it's kinda pricey. The gears don't have a lot of slop in them (very little, actually, for as many miles as it's got), though, and like I said, I plan to run synthetic lube, which should help.
I've heard horror stories about c-clip axles coming out, although this seems like it would be something that a track car would be more susceptible to than a highway-cruising SUV. Any easy/ cheap upgrades for these?
going to work, will report back later, the job is simple with a couple tricks i learned.
14 Bolt is a bolt in. Full Floater for the win.
I've seen plenty of 10 Bolts take abuse off road. You won't even be doing any of that so just keep it and upgrade/rebuild whatcha got.
so here you go.
jack up, stands under axle, wheels off.
remove drums and rear cover. spin diff around until you get to the bolt that holds the pin for the spider gears. should be 5/16". pull pin and then push each axle in until the c clips fall out, then pull axles.
out on ends, use whatever(screwdriver) to remove seals and bearings. if the races are worn/chewed, get new ones. at that point, the easiest way to go is get a 1/2" pipe about 6 feet long, and go through the entire axle to tap the race out. i keep one on hand for this reason, and it makes race removal simple.
there really are no simple upgrades unless you feel the need for a powertrax or something that replaces the spider gears with a locker.
In reply to patgizz:
Thanks for the tips. Would it be roughly the same procedure for my 2500 suburban with a 14-bolt?
tuna55
UltimaDork
3/27/15 11:10 a.m.
Check the axles carefully. I may be wrong, but I think they are case hardened and I've seen more than one have deep scoring or pitting.
Make sure the cover gasket has the two notches/squares cut into it on the left and right side. Some gasket makers forgot this and it can starve the axle bearings of oil.
I have the same leaky seal problem with my 12-bolt.
My luck, however, is always full of win (it comes from my effluent background). Here is what I am preparing myself for:
I will likely break the wee 5/16" bolt that holds the cross shaft in place. Either the drill I use to extract it will also break, or the cross shaft and/or carrier itself will need some destruction to remove.
Both axles will likely be badly worn, and "offset" bearings will likely have already been installed (it is a '77). Because that's how I roll.
So, to prepare, I will be ordering up the gear set that I want, the limited slip that I want, axles as well as bearings, and do a full-on rebuild. Maybe this summer when I can afford to have the truck down for a while.
2002maniac wrote:
In reply to patgizz:
Thanks for the tips. Would it be roughly the same procedure for my 2500 suburban with a 14-bolt?
no, you should have the full float 14 bolt. you don't have to remove the cover. there are 8 bolts that hold the axle shaft in, and behind that is a nut that you need a special 6 nub socket to get off, then entire hub with drum comes off and you replace bearing and seal as if it were your run of the mill rear wheel drive front rotor.
if i know one thing, it's gm truck rear axles.
one more thing - paper gasket on cover sucks. use rtv with it. and while in there drill the cover for a drain plug and a fill plug. by this time your stock fill plug is probably rusted solid in place.
Luckily, new axles aren't $$$.
Just to clarify, this is just to replace the bearings and seals at the wheel end, right? I'm a bit confused about the 6 foot pipe.
EDIT: I reread, I think I figured it out. You go in through the right side, all the way through the diff, to pop the bearings out on the left side, and vice versa, correct?
Appleseed wrote:
Make sure the cover gasket has the two notches/squares cut into it on the left and right side. Some gasket makers forgot this and it can starve the axle bearings of oil.
You mean these little rectangles:
One other Q: What axle oil does everyone prefer? I like redline stuff, but they have 3 or 4 different rear end lubricants. What's best for a towing/ hauling vehicle?
http://www.redlineoil.com/Products.aspx?pcid=4
Any time I see a leaky seal, it's because the bearings have worn a canyon in the axle.
You use a slide hammer to yank the bearings out from the side you're working from. You're not going to drive the bearing out from the opposite side.
volvoclearinghouse wrote:
Appleseed wrote:
Make sure the cover gasket has the two notches/squares cut into it on the left and right side. Some gasket makers forgot this and it can starve the axle bearings of oil.
You mean these little rectangles:
Yes. Some gaskets (maybe real old ones) didn't have those. Also, don't get RTV spooge in there for the same reason.
For tow/haul service I think you'd want a 75w140 in there.
Synthetic.
Don't be surprised if the gears look to be so worn that they don't have a visible pattern anymore. It seems that the original gears/bearings would only last about 80-100k before being just plain worn out, in this timeframe. If it were mine, and the carrier/pinion bearings weren't screaming, I'd throw new 75W140 synthetic in there and call it a day. After replacing the axle seals/bearings of course.
Thanks for the good advice, everyone. I plan on dropping the diff cover this weekend, I'll take some pics and post them up here for thoughts/ analysis/ humiliation.
Knurled wrote:
Any time I see a leaky seal, it's because the bearings have worn a canyon in the axle.
You use a slide hammer to yank the bearings out from the side you're working from. You're not going to drive the bearing out from the opposite side.
I do just that, and it makes life easy. My slide hammer sucks or something, so i started driving them out from the opposite side.
If you find wear on the axles they make an offset bearing that moves out to a non chewed area of the shaft. Never tried one, i always just ordered a new axle.
Oh yeah, the axles are hosed.
The case hardening is completely worn through on both sides. That might explain the howl I heard driving the truck home. 
At this point, I feel better just replacing the axles, rather than fugutsing about with offset bearings. New parts will be ordered today.
On the plus side, the inside of the diff looked really clean, the gear oil was plentiful and not-horrid-looking, and the pinion bearing is smooth and has basically zero play.
Pinion bearing should have preload, not just zero play.
But, heck, if the gear oil didn't come out looking like brown nail polish, I'd just as soon not mess with the bearings even if they weren't totally perfect play-wise.
Yeah, if I have to mess with the pinion, it's going to the shop for that.
