1970 12 bolt rear swap in 84 burban

[PrairieDrifter]

The leaf spring perches measure almost perfect, I will have to change one shock mount. I haven't searched yet but I'm sure I can find a conversion ujoint easily, and I feel like my driveshaft will be okay length wise still. I'm not worried about the gear ratios as of right now.

Now the problem I have is brake lines, I believe the 1970 axle has a smaller diameter brake line and for sure smaller/different size fittings.

My question is, are there some adapters available to go from one size fitting to another or would I be able to do some switching on wheel cylinders, or do some aftermarket solution?

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[Blue Ox]

If it was mine, I'd be converting the axle to match the truck and not the other way round. Remember the brake system is engineered as a system. So line sizes, wheel cylinders, combination valves, drum and shoe sizes, rotor diameters, caliper pistons etc. are all designed to work together in a balanced and predictable manner. If you start playing mix-n-match you can end up with some pretty undesirable behaviors.

That's not saying that brake systems can't be modified or improved, but for regular street vehicles I prefer to let the engineers do the engineering. At least for a critical system like brakes. YMMV.

 

[bucket]

Your stock axle has 3/16" brake lines on the axle. They don't come any smaller than that. However the factory tube nuts had a larger hex on them, but the threads are the same size as standard replacement lines.

 

[PrairieDrifter]

If it was mine, I'd be converting the axle to match the truck and not the other way round. Remember the brake system is engineered as a system. So line sizes, wheel cylinders, combination valves, drum and shoe sizes, rotor diameters, caliper pistons etc. are all designed to work together in a balanced and predictable manner. If you start playing mix-n-match you can end up with some pretty undesirable behaviors.

That's not saying that brake systems can't be modified or improved, but for regular street vehicles I prefer to let the engineers do the engineering. At least for a critical system like brakes. YMMV.

Well the problem is I don't want to dump a bunch of money into a 10 bolt, for one it's a 10 bolt for two I have a set of axles so I'm going to be 3/4 ton swapping someday.

The 12 bolt is to get me by for awhile until I can regear or rebuild it, then once I'm ready for a swap the 12 bolt can go back in another project. Or get my other axles going, or until I can find an 80's matching donor axle for a decent price.

 

[PrairieDrifter]

Your stock axle has 3/16" brake lines on the axle. They don't come any smaller than that. However the factory tube nuts had a larger hex on them, but the threads are the same size as standard replacement lines.

Thanks bucket, I swear both the line and fittings looked smaller diameter but I'll take your word for it, I figured gm wouldn't change over to metric or anything crazy like that.

I did notice the drums are smaller on the 12 bolt. It should be possible to swap backing plates from axle to axle, depending on which axles of course, correct? Then I could just take the whole brake assemblies from one axle to the other if I had to.

 

[bucket]

There's a chance your stock axle 'could' have had 1/4" lines installed, but it's not likely.

 

[PrairieDrifter]

There's a chance your stock axle 'could' have had 1/4" lines installed, but it's not likely.

I'll just have to try swapping lines quick. Both trucks aren't drivable so..lol

 

[Blue Ox]

Well the problem is I don't want to dump a bunch of money into a 10 bolt, for one it's a 10 bolt for two I have a set of axles so I'm going to be 3/4 ton swapping someday.

The 12 bolt is to get me by for awhile until I can regear or rebuild it, then once I'm ready for a swap the 12 bolt can go back in another project. Or get my other axles going, or until I can find an 80's matching donor axle for a decent price.

That's certainly understandable. I'd just suggest either swapping the critical parts, or at least verify that they're comparable. And if needed change the pipes. They're not that expensive. Good luck and post pics please.

 

[PrairieDrifter]

That's certainly understandable. I'd just suggest either swapping the critical parts, or at least verify that they're comparable. And if needed change the pipes. They're not that expensive. Good luck and post pics please.

Of course! I've spent plenty of pretty penny's lol. I'm all about saving some money but if my vehicles aren't safe to drive I'm not happy, plus if I didn't care I probably wouldn't be asking questions lol.

Just wasn't sure of the compatibility between the years of axles, and different axles.

I will get some stuff tested out and get some pics taken and I'll be back!