12 bolt questions
 

I have a 1963 c10 step-side and it appears that I need to rebuild the rear diff.
It needs a new pinion seal for sure, but there is some play, so I think i need new bearings too. I have done a ton of reading about the rebuild so I don't need advice there. However, I do have a few questions.

It is a 12 bolt, but it only has 11. In the picture you can see some old leakage at ~1 o'clock. I am hoping that the other bolt just fell out. Is the housing ruined if the bolt has been broken off in it? Any ides what to expect?

Is it totally unadvised to try to replace the bearings while the axle is still on the truck?

Most of the kits include wheel bearings too, can i just replace the bearings in the diff without pulling the axles?

Thanks

Re: 12 bolt questions
 

The 12 bolt has a pinion bearing, two carrier bearings and two axle bearings. You have to pull axles. Here is a page showing a member rebuilding theirs. http://67-72chevytrucks.com/vboard/s...d.php?t=509262

Re: 12 bolt questions
 

It is no big deal to get a broken bolt out. Center punch it to keep the bit centered and drill into it. Use an easy out to back out the broken bolt. 1/8"? The easy out will determine the correct size but must be small enough to go inside the bolt.

Re: 12 bolt questions
 

Why not change the bearings? Your 90% there when your changing pinion seals etc. also many need new axle seals anyway.

Re: 12 bolt questions
 

You should look up a tutorial on 12 bolt GM axles. The "Play" you describe could be lots of things, when the cover is off rock the carrier assy back & forth & see if the cross shaft is loose in it's bore or if the lock bolt is broke off or even if the spiders are loose on the shaft. Be advised that the pinion uses a crush sleeve, these can be intimidating for a 1st time axle mechanic!
The tutorial you find will let you know what kinda tools you need.
Oh yeah "12 Bolt" refers to the number of bolts holding the ring gear to the carrier flange. The number of cover bolts just happens to match the 12 & 10 bolt GM axles by coincidence. Go figure!:waah:
Good luck!

Re: 12 bolt questions
 

Thanks for the replies. I ordered the rebuild kit yesterday. I have the shop manual. I am going to try to do it all without taking the axle off the truck.

It is only a slight bit of up and down play. Seems like a worn bearing, but I will make sure to check for those other things. Thanks for the tips.

Re: 12 bolt questions
 

You don't need to remove the axle from the truck, just support it with jack stands. There is however a better than average chance the lock bolt is broke or will break when you try to remove it. There is tons of information on the internet about how to remedy that, most require a small pick. Don't let that scare you though, you just might want to do some research on that before you get started.

Re: 12 bolt questions
 

You can do it under the truck laying on your back its just going to take longer and a lot harder. Its not that much more work to pull it if you are going to do it all. There are a good bit of tools needed and a case spreader does make it easier. A shop press to get the inner bearing off the pinion gear and a good gear puller to get the carrier bearings off. A slide hammer is needed to get the axle bearings out. I like to use a shop press to put the carrier bearings back on. You will need a foot pound and inch pound torque wrenches. For the preload on the pinion you will want a dial type. A long drift pin and a 2 pound hammer works for getting the races out for the pinion if you dont have the right slide hammer fingers. Work on lining this stuff up so when you start you will have what you need.
Jimmy