Rear axle swap vs rebuild stock axle.

[klaassybrand]

If you can, get the combination valve that went with the FF 14 bolt.
And,, welcome to the forum.

You mean the proportional valve? I'm affraid there are no more parts left..will have a look for it..

 

[klaassybrand]

Can you find out if the 3500 had hydroboost brakes? I know on the C/K 3500 they did for sure, I would also think on the Express 3500 was the same way. Should be pretty easy to add.

Lots of threads on here on how to do it.

Yes they did! My 1500 also has it, but that part is indeed different from the 3500 version.

Edit: I am wrong! My 1500 express only has vaccuum powered i see now..

 

[stutaeng]

I think hydroboost was JH6 RPO code on glovebox. I think the only 1500 that may had hydroboost was the diesels, not certain though. On

the CK2500 only big block and diesels had them, and all CK3500 had them, regardless of engine. This is on late GMT 400s. I have read someone here had an early GMT 400 3500 with vacuum?

 

[Gibson]

You mean the proportional valve? I'm affraid there are no more parts left..will have a look for it..

People commonly refer to it as a "proportioning valve", but the correct name is "Combination valve", and that's what Chey and GMC call them.
The FF 14bolts generally came with either the JB7, or the JB8 brakes.
They both use a 13in drum, the difference is the width of the shoes.
The 8,600 GVW trucks usually used JB7, while the 9,200 GVW and above used JB8.
Both were used with Hydro-Boost units, along with a matching master cylinder,, although there were some 8,600 GVW vehicles that used vacuum boosters.
The masters have a bigger bore to supply a larger volume of fluid to the larger rear wheel cylinders,, and the Hydro-Boost gives the needed extra pressure boost,, the Hydro unit is capable of much higher line pressure than any vacuum unit.
And yes, it was not just diesels, small blocks got Hydro-Boost too, the application is GVW rating, not engine type.
However,, YMMV, Chevy and GMC are known to have mixed parts up in vehicle production.

 

[klaassybrand]

Thanks alot for all the info. Should be doable to convert to hydroboost. But let's say i would do that later on? Would the heavier 3500 braking caliper/rotor/drums work OK with the standard master cylinder+vaccuum booster setup?

And one more question about the drive shaft: Will this need to be shortened if i change from 10 bolt 8.5 to 14 bolt FF. That's the only thing i'm not so happy about if i have to shorten it.. I tried to lookup driveshaft lengths but i'm not sure:

Express 1500 with 4L60E: DORMAN 936096 {#15151395} Length: 80.57"

Express 3500 with 4L80E: DORMAN 936061 {#15151398} Length 79.25"

That's over an inch difference, but ofcours with a different setup. Looks like it will just be try and see i guess?