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Unread 11-12-2008, 04:49 PM   #1
Brant000
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Join Date: Sep 2007
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1978 CJ5 Brakes - Identification

I am replacing the front brake calipers, rotors, and pads. I can't seem to get a solid answer on which parts I should be using, even after reading many posts here from very knowledgeable folks.

Here's what I discovered when I pulled it apart:

Rear: 11" x 2" drums
Front: 7/8" thick, one-piece rotor/hub assembly
caliper: Bracket is six bolt. Caliper looks like every picture I see in catalogs that appears to be for the 77-78 (not 78-81 2-bolt)
Pads: both pads installed are curved along the inner edge (nearest the hub)

The confusion I think I have is that I thought the early 78's had the 7/8" rotor, 6-bolt caliper bracket AND 10" rears, AND a straight edged bottom of the pads. But I apparently have a combination.

Is it possible the previous owner bastardized the setup? This seems very possible as I am having so much trouble myself figuring out what parts I should be getting at the parts store. I want to get it right as the front brakes appear very new but are horrible (dragging, pulsing, pulling) so something isn't right.

Any thoughts or suggestions? Thanks !

Also...where can I get the tool for the proportioning valve for proper bleeding? It is a type W.

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Unread 11-13-2008, 02:12 AM   #2
78treehugger
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I have a 78 CJ 5 and I have the exact same setup. I am pretty sure mine was unmolested. At least that's what the previous owner said and when I tore into it it look all original.


Do a search for bleeding brakes. jeephammer has a really good write up on bleeding brakes. There is not tool needed besides a wrench. Bleeding them front to back to get the pin inside the valve is the key from what I got out of reading his write up. Now I am able to lock up all 4 wheels at whatever speed I am going.
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1980 CJ 7--3" Black Diamond, 1" body, locked both ends, 4.56, 35x12.50x15 SS LTB, "family" cage

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Last edited by 78treehugger; 11-13-2008 at 02:15 AM.. Reason: more info
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Unread 11-13-2008, 08:00 AM   #3
Nickmil
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78 with the 6 bolt removeable caliper brackets should have 1 1/8" thick rotors. The later, '80 and newer that used the 2 bolt caliper bracket used the 7/8" thick rotor. The rotor and hub are not really one piece, the wheel studs hold the rotor to the back of the bearing hub and by removing the studs the rotor can be removed. If you do this I recommend replacing the studs and not re-using the old ones. If you have 7/8" thick rotors on the 6 bolt caliper brackets then either the rotors are severely worn throwing off the measurement, or someone has swapped them out during a past brake job. Not saying the thinner rotors won't "work" as they can, but they aren't correct. If the pads and rotors get too thin then you run the risk of the piston popping out of the caliper bore and losing your front brakes.....

I find people putting on the thinner rotors all the time because they are cheaper and don't seem to care about safety...
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Unread 11-13-2008, 08:31 AM   #4
Brant000
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After speaking with a local jeep parts supplier (thejeep.com), I am straight. I did indeed have a messed up situation having the 7/8" rotor on this setup. And also I was set straight about the "one piece rotor/hub". The shop manual describes it as one piece, but you just knock out the wheel studs and they separate.

For others having similar issues, this apparently is the arrangement for 1978 with front disk brakes:

Early 1978 ("Big Brakes"):
Rear: 11" x 2" drum
Front rotor: 11.75" x 1.185" thick
Caliper Bracket/steering knuckle: 6-bolt
Pads: Both pads curved along the bottom edge closest to the hub.

Late 1978:
Rear: 10" x 1-3/4" drum
Front Rotor: 7/8" thick
Caliper bracket/steering knuckle: 2-bolt
Pads: One pad has a straight bottom edge

Thanks 78TreeHugger for the lead to jeephammer's bleeding info. Good stuff.
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Unread 11-13-2008, 08:39 AM   #5
78treehugger
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I will have to measure mine rotors when I get home. Sorry about the mis-information.
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1980 CJ 7--3" Black Diamond, 1" body, locked both ends, 4.56, 35x12.50x15 SS LTB, "family" cage

It's easier to get forgiveness than permision.
Salad is what food eats!!!
http://emptypocketsoffroad.org/
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Unread 11-13-2008, 08:41 AM   #6
Brant000
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Nickmil,

Thanks...I was typing up my last post as you responded. That accounts for the very poor front braking I was experiencing.

The confusion all started (thankfully) when I ordered new rotors online and they came in thicker. FYI, if anyone is interested, I ordered and received a set of slotted, drilled rotors, made in the USA, including pads for $146.41 total from BrakePlanet. Will post later on how they work out.
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