Rear brakes

[a5150nut]

94 k2500, has factory 13x2 1/2in rear brakes. What is the difference in parts to change to 13x3 1/2in brakes? Drums, shoes, backing plates? And arn't the 13s duel servo too?

But all in all, are the axel houseings the same?

[tom.mcinerney]

I'm pretty sure the 13s are duo-servo. Pretty sure my '72 C10 had duo-servo; an aftermarket(Haynes) brake book suggested the reason duo-servo aren't used on cars is because they brake too strongly.
I would guess the axletubes are possibly the same.
I think you hit it on the head that the key items are drums+backing plate, and of course shoes. The backing plates seem to be designed so that the "dish" form offsets the inboard edge of the drum(&shoe) enough inside the center of the wheelbearing that the braking force is centered over the bearing/axlehub. This means when braking there is minimal force bending the outer part of the axle, most force(like the weight) directed through the heaviest(best-supported) components. I'd expect the back plate for the wider shoes to be dished more.
Post back if/when you do upgrade....

[Petrella]

i wanted to do also do this conversion, the backing plate on a 2500 and 3500 look identical, the only difference i can see is the drum and shoes, but on a 2500 you gotta remove the axle shaft and hub, on the 3500 the drum slides off the studs, so i wanted to know if i punch the studs out of the hub to seperate the drum from the hub, can i still use the same hub for the 3 1/2" drum and shoes? do i just slide the drum over the existing hub? if backing plate needs to be changed lemme know cause i am very interested in all that needs to be done for this conversion.

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[a5150nut]

I called the Chevy dealer today and was told the axel housings on the 10 1/2 ring gear are all the same. Couldn't get him to look up other # though. He did say they 15k duel rear did come with disc brakes, but just the caliper brackets were $300 each. I'll see what I can find out about hub/drum fit.

[Petrella]

yeah if you found out that would be awesome, cause im tired of pulling the hub and bearings, everytime you do that you gotta change the seal and its gettin to be a pain in the neck. If its not a hassle i will definately change to 3 1/2 brakes

[MikeC]

Petrella and all.

Check your individual axles, my K2500 Burban had the axle that the drum came off the hub without the need to remove the axle.

Mike

[Petrella]

MikeC, the 2500 suburbans are rated 2500 series but realistically have a 3500 braking system, any 3500 srw truck will have the same braking system as a 2500 suburban diesel with a 10.5 full float axle and thats with the 13 x 3 1/2 shoes. any pick up truck diesel 2500 series with the 8600 GVWR has the 13 x 2 1/2 rear drums and shoes, and it is required to pull the hub in order to remove the drum. so realistically any 2500 suburban is equivalent to a 3500 series pick up, they rate it as a 2500 because they take into account the more passengers you can carry. Im tired of pulling the hub on my truck to change or check the brakes, therefore wondering what i have to change for this conversion.

Petrella

[Petrella]

i guess no one knows if this could be done

[Dvldog 8793]

Anything can be done! :D
How much do you want to spend in time and money?
I would start by finding a GOOD salvage yard that will work with you. They normally have cross over books and can tell you what parts are what. AND they will have some old vehicles for you to LOOK at. Nothing explains things better than visual! ;)
L8r
Conley

[number two]

Hey guys-I think the mid to later 90's saw a change in both the C/K 2500&3500 trucks to slip off drums rather than having to pull the axle out.My '93 still has the old style while a friends '98 has outboard mounted(slip-off). I believe the only difference is shoes and drums,and wheel of course. Mill Supply in Cleveland,OH sells complete assemblies-backing plate,shoes,hardware,wheel cylinder all assembled correctly brand new for like $225-$250 a set for both sides-seemed like a deal to me. It's listed for P-series stepvans,but are the same parts for pickups. They probably have a decent deal on drums too.Thanks