Later, bigger rear drum brakes???

[spudder]

Can the bigger drum brakesfrom later trucks be retro-fitted onto a '63-'66 rearend? What are the options? Can 6 lug 4WD drums be used
I intend to redrill the axles for 5 on 5" and turn down the center register to accept the right drums.
Can anyone share some info this?

[luvbowties]

Originally Posted by spudder

Can the bigger drum brakesfrom later trucks be retro-fitted onto a '63-'66 rearend? What are the options? Can 6 lug 4WD drums be used
I intend to redrill the axles for 5 on 5" and turn down the center register to accept the right drums.
Can anyone share some info this?

We put a set of later axles w/5 lugs and wider drums in a stock '66 differential. Axles were 3/4" longer. Brakes were wider than 2", but I don't recall just how much. We spaced the orig. '66 backing plates out the needed distance for the wider drums to cover the wider brakes. Been working great for several years. IIRC, the drums and wider shoes came from a G20 van.
HTH,
Sam

[Captainfab]

The '71-'87 trucks were available with optional 2.5" wide brakes on the rear for both the C10 and K10's. These can be swapped onto any year truck 12 bolt from '64-'82 and the 8.5 10 bolt from '80-'86 on the C and K series and '87-'91 for the R and V series. You will need both the backing plates and drums. The shoes and hardware can be sourced from your local auto parts store.

I do not recommend installing the longer 31.25" axles into housings that are designed for the 30.5" axles

[luvbowties]

Originally Posted by Captainfab

The '71-'87 trucks were available with optional 2.5" wide brakes on the rear for both the C10 and K10's. These can be swapped onto any year truck 12 bolt from '64-'82 and the 8.5 10 bolt from '80-'86 on the C and K series and '87-'91 for the R and V series. You will need both the backing plates and drums. The shoes and hardware can be sourced from your local auto parts store.

I do not recommend installing the longer 31.25" axles into housings that are designed for the 30.5" axles

Good info, Captain, as usual. One thing arouses my curiosity, and hoping I never get too old to learn: I'm curious why installing the longer 31.25" axles into housings that are designed for the 30.5" axles is a bad idea. Or, does it depend on how it is accomplished? We did one that way, but used the orig. '66 backing plates, and machined a spacer block that fit between housing flange and backing plate. Also, the axles had plenty of length of machined bearing surface('meat')to run inside the bearings.
Hope I don't have to do a 1-vehicle recall!
Thanks a bunch,
Sam

[Captainfab]

Yes it does depend somewhat on how it is done, as well as how the truck is going to be used.

Most of the ones I have seen done, were nothing more than sliding in the longer axles with all the original brake parts. I don't know if all the axles have a long enough machined area to accomodate the bearing being moved inward 3/4". Most guys doing this aren't going to check that. As for the backing plate spacers, most guys do not have the means to accomplish that them selves. If someone had to pay a machine shop to make those, how much is a guy really saving versus purchasing the correct axles in the first place?

Originally Posted by luvbowties

Good info, Captain, as usual. One thing arouses my curiosity, and hoping I never get too old to learn: I'm curious why installing the longer 31.25" axles into housings that are designed for the 30.5" axles is a bad idea. Or, does it depend on how it is accomplished? We did one that way, but used the orig. '66 backing plates, and machined a spacer block that fit between housing flange and backing plate. Also, the axles had plenty of length of machined bearing surface('meat')to run inside the bearings.
Hope I don't have to do a 1-vehicle recall!
Thanks a bunch,
Sam

[luvbowties]

Thanks for the informative reply. Since I see the truck about every week, I dreaded having to face him requesting we lick that calf over.

I tend to forget we don't all have the same means, machinery, and skills. With this particular job, the owner had a gratis set of nice longer axles; and we tried and erred our way thru to using wider drums and shoes. We used some industrial-plant scrap that needed mostly sawing off and drilling to make the spacers, very little precision. A roundabout method I agree, but it seems we determined it was a reproducible job, with used parts, for just over half the cost of new axles.

I agree the simplest way, with NO downsides is to buy new axles. And admittedly not being so cost-conscious today, were I to do my own it would be my 1st choice, with re-drilling my other. Whichever method, I prefer keeping stock width due to otherwise limiting the space & thus choice of wheels.

Thx again for sharing so much with our group.
Sam

[robber grin]

Capt. Fab,

Great fan of your work.

Question - With the parts we have on hand we are considering a quick upgrade on a 63 C10 long fleet.

Can we used the 2.5 rear brakes on an 86 5-lug rear in conjunction with the 81 1/2 ton LD front brakes without creating brake-ratio or system balance issues?

If not would an adjustable proportioning valve take up any system balance issue?

Thanks,
Bob

[66Submarine]

Just a note; the later six lug K10 brakes are actually 2-3/4" wide as standard.

FWIW, the GM "info kit" for an '81 lists the same front rotor diameter for the C10 with 2" brakes and the K10 with 2-3/4". http://gmheritagecenter.com/docs/gm-...olet-Truck.pdf

[robber grin]

Originally Posted by 66Submarine

the GM "info kit" for an '81 lists the same front rotor diameter for the C10 with 2" brakes and the K10 with 2-3/4".

So my intention of possibly using an 81 2WD 1/2 ton front cross member with it's LD 1" brakes / rotors combined with an 86 2WD 1/2 5-lug rear end may not be a factor for overall brake system balance.

I'd be using a Capt Fab bracket and 88-98 booster/master combination to power things on a 63 C10 long fleet we may be getting.

Thanks!
bob