Picked up a GM 14 bolt rear end for the 63 C20

[Asshat]

Got this for $40, so I don’t think it’s a bad deal at all. I believe it is a 4:10, which is a bit lower than I had hoped for, but for $40 I can’t complain.

Pretty sure I can buy a gear to make it taller. Also need to buy drums.
A new project for me, and a pretty big one.

To check the gear ratio, it’s two turns of the wheel?

[Asshat]

After doing some research, it looks like a GM 9.5”, 14 bolt.
more pics

[Asshat]

I'm not sure - but I think this would work to convert to a taller gear:
https://eastcoastgearsupply.com/i-12...-42-ratio.html

[Steeveedee]

Originally Posted by Asshat

I'm not sure - but I think this would work to convert to a taller gear:
https://eastcoastgearsupply.com/i-12...-42-ratio.html

Try these guys, if you can get the diff to them. Everybody I know has had good luck with them.

https://hoopersrearends.com/

[Asshat]

I have been reading some of the posts on converting to the 14 bolt and it is beginning to make sense. And, it does not seem as difficult as I first thought.

I was thinking about getting a drum / brake kit for this 14 bolt, however, I'm wondering if it would be better to just update the rear to disc brakes. Probably a little more money, but it should pay off in the long run.

Are there any reasons to not do the disc brakes and just keep it drums?

Can anyone recommend a good kit for the 8-lug 14-bolt?

I found this one:
https://lugnut4x4.com/product/14-bol...BoCX_QQAvD_BwE

[Asshat]

And, if I go to disc brakes, I heard that I would need to swap to a dual master cylinder and a proportioning valve. I understand the dual master, but what does the proportioning valve do? It just lowers the pressure so the back brakes don't lock up, right?

I will probably stay with drums on the front; is it better to just stay with drums at the rear?

[Steeveedee]

The valve is for two things.

A slight delay for the rear brakes so that the disc brakes come on at the "same time" as the rear drums.

The valve shuttles and closes off a leaking circuit.

The pressure in the system is the same. Braking force is derived from the swept area of the friction surfaces. If you are going rear disc, why not find a late-model diff with the ABS on it? If I hadn't already switched to front disc, and I was 10 years younger, I'd look into ABS. You don't really need rear discs, TBH. I pull a 6k pound travel trailer with the "stock" setup like you would see on a '71 or '72 C20. Of course, the trailer is equipped with electric brakes.

[Asshat]

Originally Posted by Steeveedee

The valve is for two things.

A slight delay for the rear brakes so that the disc brakes come on at the "same time" as the rear drums.

The valve shuttles and closes off a leaking circuit.

The pressure in the system is the same. Braking force is derived from the swept area of the friction surfaces. If you are going rear disc, why not find a late-model diff with the ABS on it? If I hadn't already switched to front disc, and I was 10 years younger, I'd look into ABS. You don't really need rear discs, TBH. I pull a 6k pound travel trailer with the "stock" setup like you would see on a '71 or '72 C20. Of course, the trailer is equipped with electric brakes.

If my plan was just to go disc brakes, I would maybe look for a different rear end. Since I am on a budget, and I got such a great deal on this rear end, I may as well just stick to the drums. It’s only $215 for the drums and brakes for this axle. Still planning on upgrading to a dual master cylinder.

[cwcarpenter98]

If your plan is to stick with the drums in the front, I see no reason to add discs to the rear

[SCOTI]

Originally Posted by cwcarpenter98

If your plan is to stick with the drums in the front, I see no reason to add discs to the rear

x2.

Most of these trucks can lock-up the rears as-is w/drums. Rear disc brakes won't improve that. For 85% of us out there who just do normal driving back/forth, rear discs are a cool upgrade but not a needed upgrade. Rear disc brakes are better in heavy duty environments where extended usage & temps come into play. When that happens (severe service) the discs are better as they don't heat soak as fast & recover faster when pushed.

[Asshat]

Is there a trick to loosening these nuts? The clamp that hold the unbolted to the axle.

[SCOTI]

After so many years, they're usually corroded in place. Pre-soak w/some penetrating oil. A nice long (extended-handle) type ratchet tool & have a can of heat handy (Mapp gas).

[jayoldschool]

A big air impact attached to a big CFM compressor. And a torch if needed. I needed both on mine!

[Asshat]

Originally Posted by SCOTI

After so many years, they're usually corroded in place. Pre-soak w/some penetrating oil. A nice long (extended-handle) type ratchet tool & have a can of heat handy (Mapp gas).

Originally Posted by jayoldschool

A big air impact attached to a big CFM compressor. And a torch if needed. I needed both on mine!

Applied some heat and a 3 foot cheater bar.

Now, all the bolts are loose, but it’s not coming apart. I may have to take it all out with the trailing arms.

Are bushings available for all these areas that need them?
I checked Rock Auto and I did not see anything.

[Steeveedee]

The threads protruding from the nuts are going to be peened over after being pelted by rocks and gravel for so many years. I'd crack the nut if a cracker that big is made and chase the threads and use new nuts when putting it back together. Even if you're changing the bushings, those nuts have to come off if you're changing the diff, right?

[SCOTI]

Or..... Cut the U-bolts off & get new parts/hardware. Multiple aftermarket sources & board supporting vendors should have them.

[Steeveedee]

Originally Posted by SCOTI

Or..... Cut the U-bolts off & get new parts/hardware. Multiple aftermarket sources & board supporting vendors should have them.

Right, this does look like a job for a gas hack saw! It would be way less work than what I first proposed.

[cwcarpenter98]

Even if you can get the nuts off without doing any cutting, I would recommend replacing the U bolts anyways. I know for my c10, I had to torque them to 230 ft lbs. I was able to take my original u bolts to a driveshaft shop where they made up some new U bolts for me to the same diameter and length as the old ones

[Asshat]

Found this in the Truck Shop catalog:

Will these saddles work? I can't really tell from the picture.
They also have the u-bolts. Can't seem to find any bushings for the rear leaf assist mounting.

[SCOTI]

14bolt axle tubes will be larger OD & will prob require modifying 1/2 ton 12-bolt brackets to fit the housing properly.

[Asshat]

Originally Posted by SCOTI

14bolt axle tubes will be larger OD & will prob require modifying 1/2 ton 12-bolt brackets to fit the housing properly.

I measured the new one I have, same diameter.

[jayoldschool]

Your local driveline shop will have the U bolts you need, in stock, and cheap.

[Asshat]

This a heck of a lot harder than I thought. Just getting to this point was a pain, still not done getting it apart. I used a pickle for and sledge to get it where it is now in the pics.

Any suggestions?

[SCOTI]

Originally Posted by Asshat

I measured the new one I have, same diameter.

Cool. I know some measure 3.25" (my 99/OBS is).

[cwcarpenter98]

The way the bolt flattens out as it goes over the axle tube makes it too big to fit through the holes. Cut it again on a more round part of the bolt