Rear axle disc brake conversion calipers.

XJsavage

Wizard of the woodsman's colony
Joined
Aug 15, 2009
Location
G-ferry
Axle application in question is a 14 bolt. Every kit I've seen uses the 75-88 3/4 ton front calipers or caddy e-brake calipers with the same vehicle specific rotors. I start to wonder, what other GM calipers out there would also work for this? I know the thickness of the rotors would come into play and so would the slider bolt pattern. Has anyone experimented with other vehicle specific calipers or are we stuck with the 3/4 ton fronts?
 

BUCKEYE PERFORMANCE INC.

BUCKEYE PERFORMANCE INC.
Joined
Dec 3, 2006
Location
swannanoa
Gm used the same mount on a lot of applications and just changed the piston size so if you can get your hand on an old school brake parts manual you could research that. Some of the casting had a rib under the piston that prevents it from clearing the 14 bolt caliber brackets so look for that before you purchase. Dunno if this was the answer you were going for but its what I got.
 

XJsavage

Wizard of the woodsman's colony
Joined
Aug 15, 2009
Location
G-ferry
Thats a great start. I may have a PDF file on calipers somewhere and aside from grab 30 different calipers from junkyards, I don't know of a better way to know. The only reason I'm wondering is because sometimes the k20 calipers aren't the easiest to find (argueable, but whatever) and it would be nice to know what's out there as spares in a pinch.
 

Croatan_Kid

How's your hammer hangin'?
Joined
Nov 4, 2007
Location
New Bern
Best thing to do would be buy or make the adapter/spacer to bolt on the backing plate, caliper bracket, and internal e-brake from a newer style AAM 10.5/11.5 axle. It'll use dual piston calipers, a much better selection of pads or rotors, and might possibly change it to a slide on rotor setup.
 

XJsavage

Wizard of the woodsman's colony
Joined
Aug 15, 2009
Location
G-ferry
I just found out recently that fs cars and 1/2 ton truck calipers will not work for a DBC. They are about 1/4 narrower in the clamping area than the 3/4 ton. Other than that they're identical. If using half life pads they would work but with new rotor and pads there's not enough clamp room to house everything.
 

GubNi

8 lug disc brakes?
Joined
Mar 20, 2005
Location
Jonesborough, TN
Good info guys. The older calipers are getting harder to find. I have not problem with the newer calipers like 1986 Chevy 3/4 ton 4x4 front with JB6 brakes. It does have that extra rib that someone mentioned and will not fit all caliper brackets. This caliper has the standard 7 1/8" pin spacing and it has a 2 15/16" piston diameter. To me the key factor is the opening of the caliper for the pads and rotor. I tried to make half ton caliper work, but I wasn't able to find a good pad. I think it is possible, but why cut the life of the brakes by using a smaller pad? You can use a JB7 caliper which was the optional bigger caliper for the same truck and has 3 5/32" piston diameter. It will work, but on some master cylinders will create a soft pedal.

I subscribed to this thread and will try to help any way I can since disc brake conversions is my job, lol.
 

XJsavage

Wizard of the woodsman's colony
Joined
Aug 15, 2009
Location
G-ferry
ai1266.photobucket.com_albums_jj521_XJsavage_IMG_20141107_113933369_HDR_zpsh5flg3zt.jpg
I found a set of calipers in pull a part today that caught my attention. They're off of an early 90s Chevy G20 van. I decided to take a gamble and take them home to see if theyll work on my 14 bolt. Sure enough they do. They're perfectly identical to the k20 front calipers except for the brake line location. Just another option for the junkyard builder as these are very easy to find.

List of parts used here: Ruff stuff brackets, new k20 rotors, new k20 pads, '93 camaro front brake lines, 92 G20 front calipers.
 
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