10 Bolt Input Slop

[1987 GMC Jimmy]

I smelled a hint of gear oil when I was changing the t-case extension housing seal, I checked the play on that end, and it’s definitely got some up and down/side to side play when you rock the u joint flange. It also howls at cruising speed. It seems like this would be the front/outer pinion bearing and seal. Just wanted to confirm that, and if so, are there any tips/tricks/important steps?

 

[crazy4offroad]

When you remove the pinion nut, remove the outer bearing and replace the crush sleeve. You'll never get the preload right if you dont. Change the seal. The old one will be wallered out too bad to reuse. Put some silicone around the housing surface before you put the seal in to help prevent leaks. When you reinstall the pinion nut, use a large pipe wrench to hold the yoke, and use an impact with at least 450 ft/lbs torque to run the nut down. Also slather plenty of red thread locker on the pinion threads. If you dont get a new pinion nut, lay the old nut on a solid surface like the anvil on the back of a vise, and use a chisel and hammer to make 3 indentations around the crown of the nut. This makes it like a locknut. Put a little silicone on the splines of the yoke before installing to help prevent leaks. When you get it ran down there will be only a little rotational resistance. If you have an inch/pound torque wrench, you want around 20-25 in/lbs rotational resistance. Lastly don't forget to top off the gear oil. Hope this helps.

 

[Blue Ox]

Pull the cover and look at what's going on in there. There's a good chance that the problem is bigger than just a seal.

 

[crazy4offroad]

Pull the cover and look at what's going on in there. There's a good chance that the problem is bigger than just a seal.

Yeah if you've heard the howling for a while, the gears may be short-lived.

 

[1987 GMC Jimmy]

Thanks. Yeah, my next question was about the gears being killed by the bad pinion bearing.

 

[dvdswan]

pull off the diff. cover and check the wear pattern on the ring gear. Your howl could be from the gears or the bearings.

 

[1987 GMC Jimmy]

pull off the diff. cover and check the wear pattern on the ring gear. Your howl could be from the gears or the bearings.

Is the ring gear gonna be the main one to look at for wear, or are there others that could have taken some heat from the bad pinion bearing? My concern is if I’m needing a full rebuild, which I know is hard to answer without the diff. cover off.

 

[Blue Ox]

Look at the ring gear, look at the carrier bearings, look at the spider gears, look for glitter.

Some grey matter on the magnet is normal, metal flake is not.

 

[dvdswan]

Exactly what @Blue Ox said ^^^, check the wear pattern

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spider gears are the 4 gears in the carrier (differential case in this pic).

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metal shavings or metal flake like this would be a bad sign...

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[1987 GMC Jimmy]

Okay, thanks guys. I’m at a crossroads with some exhaust stuff I already started on, but this is my next project coming soon.

 

[1987 GMC Jimmy]

Follow up opinion question. I know the G80 Gov-Lock isn’t the best thing in the world so would it be worthwhile to upgrade to a posi unit that won’t break if you look at it the wrong way? Also, I spoke to a reputable 4x4 shop in New Orleans today, and the guy said that depending on how long the issue has gone on, how bad, etc., the differential housing could be damaged. He said what he would do is put a Grizzly locker in it, upgrade to 30 splines, and use GMT800 parts if so much of what’s in it was damaged. I asked him how much would I be looking at for his services, and he said worst case scenario $1800. Fair or not, that’s a lot of money. I’m still willing to do it myself, but my concern is having to deal with more problems after a relatively short period of time.

 

[dvdswan]

If the housing is toast, it does happen from time to time, then look for a GMT800 heavy-duty 1/2T or light-duty 3/4T rear axle. These are 14 bolt SF axles that are 6 lug. I think the frames are wider on these truck compared to the squares so you would have to cut off and install new leaf spring perches. Complete axle will vary in price in the area from a junkyard. Here in WA you will pay 125 to 175 depending on the yard.

Rebuilding the 10 bolt or any axle really isn't hard just time consuming. Getting the ring and pinion shimmed correctly to set the wear pattern is key. Most shops have bearings that are a couple thousandths larger so they slide on and off the pinion and carrier to get the correct amount of shims.

I haven't rebuilt an axle in quite some time and would have to read up on how to tell if the housing is bad. Hopefully someone will chime in and give a bit more info.

IMO, I would look for a larger axle with the 3.42 gear, with or without the G80 and buy it. Then find a locker that you like and swap you ring gear on to it and shim that. You shouldn't need to shim the pinion gear as it is already set, just shim the new carrier.

 

[crazy4offroad]

At $1800 that guy is thinking he's got a big fish on the hook, **** that. I've had the carrier grenade in one and the housing was still usable. The 14 bolt semi-floater would be a better option, if you shop around the junk yards you may find one with a limited slip and the right gear ratio already installed. Not sure if time is of the essence but I wouldn't even go back to that guy's shop asking $1800. Fixing up the toasted axle would probably be the cheapest route. If you're not running high horsepower/big tires I would just run the G80 if the locking mechanism gears still look ok. I have one in my parts pile and there's a needle looking gear with a larger wheel looking gear, and the larger gear has a couple teeth missing. It still works but would only be a matter of time till it doesn't work anymore.

 

[78C10BigTen]

Just to show you, heres what a blown up "gov bomb" looks like when all the broken pieces are gone. Yes im still driving this....

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[dvdswan]

yeah... it's supposed to look like this... I think you may be missing a few parts.

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