Rear Disc Brake Help !!!

[9inch]

I have a 9" BB , HD out of a 77 bronco. I would like to do a disc brake conversion but require a 5 on 5.5 bolt pattern. I can't part with the $500 or so bucks for the kit. There's got to be a cheaper way. What rotor and caliper combo will work?
Thanks

 

[broncnaz]

Check out the links section to the left of the page there are several write ups on the different conversions.

 

[SteveL]

Check out the rear disc brackets from BC. You can get the caddy calipers from the boneyard. It uses off the shelf cj rotors.

 

[OX1]

I just swapped in MK VII rear disk stuff. Have to either cut off and re-use the stock caliper mount or make your own (not that hard, just a flat plate) . I could not find any MK V's around by me for caliper mounts. I figure the MK VII's, made until 92 will have parts avail for a long time. Used 94+ fullsize bronco rotors. Did also swap out the wheel studs for one's that had a full dia shank that was longer than the axle flange thickness (using yukon 31 spline alloys) to make sure rotor was centered. Axle flange needed 1/16 taken off to fit rotor over flange.

Pics here.
http://ox.users.superford.org/70 EB SPORT/REAR AXLE/REAR DISK BRAKES/

 

[OX1]

Check out the rear disc brackets from BC. You can get the caddy calipers from the boneyard. It uses off the shelf cj rotors.

Does the CJ rotor have a big enough hat (internal dia.) to fit over the axle flange without turning down flange?

 

[9inch]

Check out the rear disc brackets from BC. You can get the caddy calipers from the boneyard. It uses off the shelf cj rotors.

Thanks for the heads up ! Any idea what year caddy calipers and Cj rotor or does it matter?
Thanks

 

[toddz69]

Thanks for the heads up ! Any idea what year caddy calipers and Cj rotor or does it matter?
Thanks

79-85 Cadillac Eldorado/Olds Toronado/Buick Riviera calipers.

Can't recall exact years for the CJ rotors, but I believe it's '79-newer? There's a cutoff year there when they went from "thick" to "thin" rotors and I don't remember when it was.

Todd Z.

 

[OX1]

79-85 Cadillac Eldorado/Olds Toronado/Buick Riviera calipers.

Can't recall exact years for the CJ rotors, but I believe it's '79-newer? There's a cutoff year there when they went from "thick" to "thin" rotors and I don't remember when it was.

Todd Z.

Also went to 5-4.5 at some point


NAPAonline has great technical specs on their rotors/calipers. Like this one from a 79 CJ7.

http://www.napaonline.com/masterpag...er=85645&Description=Brake+Rotor+Only+-+Front

 

[9inch]

79-85 Cadillac Eldorado/Olds Toronado/Buick Riviera calipers.

Can't recall exact years for the CJ rotors, but I believe it's '79-newer? There's a cutoff year there when they went from "thick" to "thin" rotors and I don't remember when it was.

Todd Z.

So any one of those calipers from 79-85 will work as long as I have the THICK CJ7 rotor? What do you use for a caliper mounting bracket... should I purchase the one that goes with the caliper I choose or will i have to fabricate one?
Thanks

 

[9inch]

Also went to 5-4.5 at some point


NAPAonline has great technical specs on their rotors/calipers. Like this one from a 79 CJ7.

http://www.napaonline.com/masterpag...er=85645&Description=Brake+Rotor+Only+-+Front

Is the rotor shown on the nappa online you provided, the correct rotor for my application?
Thanks

 

[OX1]

Is the rotor shown on the nappa online you provided, the correct rotor for my application?
Thanks

Not sure, I've only used the larger pre-78 caddy calipers, which used a 1.205 thick rotor

http://www.napaonline.com/masterpag...ber=85518&Description=Brake+Rotor+Only+-+Rear

and are very close to a stock D44 front rotor thickness (1.185), which is what I was going to use (before I decided to go MK VII stuff).

http://www.napaonline.com/masterpag...=4885611&Description=Brake+Rotor+Only+-+Front

I just posted up the 79 CJ7 as someone else mentioned it (and to show you the specs you can get at napaonline). Here is the stock 80 rear eldorado rotor, looks to be substantially thicker than the CJ rotor?? (1.035 vs .875). Means the caliper piston starts out farther (using the CJ rotor), not sure how or if that will affect the pakring brake mechanism life, since it racthets out (kinda).

http://www.napaonline.com/masterpag...ber=85668&Description=Brake+Rotor+Only+-+Rear

I checked 82, it is the same as 79, 88 is the YJ (same thickness, but 5 on 4.5), and 76 was drum brakes. ?:?

 

[OX1]

So any one of those calipers from 79-85 will work as long as I have the THICK CJ7 rotor? What do you use for a caliper mounting bracket... should I purchase the one that goes with the caliper I choose or will i have to fabricate one?
Thanks

This guy claims that even the CJ rotors will not fit over the axle flange without grinding it down a bit.

http://www.pirate4x4.com/forum/showthread.php?t=229934

This may be why most kits use redrilled chevy 6 lug rotors. ?:?

As for brackets either of these should work, depnding upon if you go with pre 78 or 78+ caddy calipers. The older one's are bigger and have larger pistons. Depends upon how big a tire you are going to run.

http://www.speedwaymotors.com/p/3346,,_GM-Caliper-Bracket.html?itemNo=caliper

 

[9inch]

Not sure, I've only used the larger pre-78 caddy calipers, which used a 1.205 thick rotor

http://www.napaonline.com/masterpag...ber=85518&Description=Brake+Rotor+Only+-+Rear

and are very close to a stock D44 front rotor thickness (1.185), which is what I was going to use (before I decided to go MK VII stuff).

http://www.napaonline.com/masterpag...=4885611&Description=Brake+Rotor+Only+-+Front

I just posted up the 79 CJ7 as someone else mentioned it (and to show you the specs you can get at napaonline). Here is the stock 80 rear eldorado rotor, looks to be substantially thicker than the CJ rotor?? (1.035 vs .875). Means the caliper piston starts out farther (using the CJ rotor), not sure how or if that will affect the pakring brake mechanism life, since it racthets out (kinda).

http://www.napaonline.com/masterpag...ber=85668&Description=Brake+Rotor+Only+-+Rear

I checked 82, it is the same as 79, 88 is the YJ (same thickness, but 5 on 4.5), and 76 was drum brakes. ?:?

Holy mind bender!! Thanks for all the leg work. I'm not really sure what to do?
Is the Mark V stuff is tried and true... that's for sure, but this 9" is going into a 1983 CJ7 and I'm wondering if I should stick with jeep components if at all possible?
Thanks again!!

 

[OX1]

More fuel to the fire

I was told that MK IV or MK V rotors would fit over the axle flange, but both are 5 on 5, so neither of them will work.

http://www.napaonline.com/masterpag...646&Description=Brake+Rotor+Only+-+Right+Rear

http://www.napaonline.com/masterpag...5647&Description=Brake+Rotor+Only+-+Left+Rear

I think if I was going the chevy route, I'd use stock D44 front rotors (76-79 bronco, 1/2 ton), the larger caliper bracket and the larger caddy calipers. Need to grind down axle flange, but that looks like it is a given no matter what rotor you go with. According to that pirate thread, the larger caliper will clear 15" rims.

I'm not crazy about the rotor thickness difference between the CJ7 rotor and the 78+ caddy stock rear rotor (using the smaller caddy calipers), maybe someone who has done it will post up.

 

[chuck]

I sale a rear disc brake kit based on the CJ7 rotors and caddie calipers. It is a bolt on kit and you can buy the bracket kits only and find your own rotors and calipers. With my set up the the cj rotors mount on the inside of the axle flanges so the rotor and axles are unmodified. The CJ rotors will not fit over stock EB axles. I tried the lin. rear disc brakes but aside from having to redrill the rotors I was unable to fix the occasional rear brake drag that would cause the rear brakes to smoke and stop the
EB.

 

[67u13]

I don't know where you are located but AAron's auto parts in austin texas has a mark 5 that just showed up last week. It would have everything you need except rotors

 

[OX1]

I tried the lin. rear disc brakes but aside from having to redrill the rotors I was unable to fix the occasional rear brake drag that would cause the rear brakes to smoke and stop the
EB.

What do you think the reason is that they would do that on an EB, but be fine on the rear of my capri and a buddies Mk VII for 15 odd years??

 

[9inch]

I don't know where you are located but AAron's auto parts in austin texas has a mark 5 that just showed up last week. It would have everything you need except rotors

Thanks for the heads up, but I'm in PA and got no brakes!
I think the simplest way to go is Ford truck rotors," 1979 or so", with the 5 on 5.5 lug pattern + Caddy callipers, "pre 1978", so it'll have the large piston and e-brake, and purchase a mounting bracket from Summit Racing, "part # HRE-340". Dishes are done, man! Whaddya think?

 

[chuck]

What do you think the reason is that they would do that on an EB, but be fine on the rear of my capri and a buddies Mk VII for 15 odd years??

I don't think it happens on all EBs but it does happen on some, not just mine. In fact the Lin. dealer mechanic I talked to about the problem was not sure why it happens but was aware that it does happen occasionally to lincolns also.

 

[toddz69]

I don't think it happens on all EBs but it does happen on some, not just mine. In fact the Lin. dealer mechanic I talked to about the problem was not sure why it happens but was aware that it does happen occasionally to lincolns also.

Funny you mention this - I remember another prominent member of the EB community tell me about 10 years ago that he had the wierd locking problem with those first gen Mark VII rear discs too.....had almost forgotten about that.

Todd Z.