74 CJ5 Disk Brake Swap

I have a 74 CJ5 that has drums all around (which sucks) and was looking to add disk brakes to the front Dana 30. I have already robbed a 77 that I had originally bought for the steering column, dash, pedal assembly and windshield frame. I want to take the disk brakes off of that axle and add them to this one. I have read a couple of threads that had some informative information, but still cant quite grasp everything. Can I use the existing reservoir and the existing proportioning valve or does all that need to change as well? (some say yes some say no). I have a SOA lift on it now so I would need the longer brake lines up front, which model chevy where the lines 6" longer?

Thanks

 

When I did my 1975, I bought a rebuilt Master Cylinder for disc/drum (1979 in your case) and left the rest stock. I think I paid about $25 for it. Works great. What are you doing with the drum brakes? I need the backing plates for my 1964 CJ5. PM a price please.

 

I also changed out the master, but I left in the existing proportioning valve. Not sure about your Chevy brake line question, but i know you can often buy brake line in various length.

 

good flaps guy should be able to look up the lines for you

 

Looks like I am going to be doing this this weekend! Thanks for the help, and I will get the pm to you as soon as I get back to the house.

Any good tutorials or write ups on how to do the swap? Would rather not go at it blind! Lol

 

Hum does you're jeep 1977 have a powebrake booster. I suggest you to swap it if you have it. Use everything from the booster to the prop valve and everything will be just fine. Another thing the windsheild of the 1977 will match youre 1974 body but you will need a top from the older generation.

 

and pull pretty much everything from the outer axle stubs out (knuckles, etc.), including the axle stubs I believe.

 

Axle stubs are different as Norm pointed out. I was recently schooled on this.

 

The 77 does not have the brake booster, so I might try to get one from a Cherokee or something.

So basically I'm pulling off everything from the axle tube?

 

Here are the highlights. I hope they are in order.

Remove the screws holding the lockout.
Slide it out then remove the snap ring on the end of the stub.
Remove the bolts that hold the lockout body to the hub.
Slide the guts and body off and bag these to keep them together for reassembly.
You will see a big nut on the and of the spindle. Should be 2 1/8".
There is a washer behind it that is bent outward against a flat on the nut.
Take a punch and flatten the bend away from the nut so you can turn the nut.
Remove the nut, the lockwasher (flatten it or replace it), and the next nut.
Remove the caliper from the bracket and remove the line from the frame bracket.
Slide the hub and rotor off the spindle. The bearings are loose so be careful.
Remove the 6 locknuts and if you have the 6 bolt bracket, tap it loose.
Use a spindle socket and a slide hammer to pull the spindle.
Remove the axle shaft.
Remove the cotter pin and castle nut on the upper ball joint.
Loosen the nut on the lower ball joint so it is just on a few turns.
Get a small sledge hammer an carefully whack the knuckle just outside the top ball joint until it pops off.
Remove the lower nut.

The drums are the same except you pull the drum with the hub and tap the backing plate loose.

I suggest you consider new ball joints, u-joints, and a spindle bearing kit while its apart. Its a lot of work to get to those parts later. You should replace the spindle stud nuts.

Reassembly is reverse. Lower ball joint nut gets 80 ft/lb, split ring gets 50 ft/lb, top ball joint nut gets 100 ft/lb.
Spindle nuts get 50 ft/lb then backed off until smooth wih no play. Make sure to repack the bearings. Only use a white lith spray on the lockouts.

I am sure others here can cover what I missed.

Bob

 

Wow thanks a ton! You should consider a write up with pictures with that info !

So here's some pics of the proportioning valve I currently have! (yes I know one brake line is not connected)

 

Personally I'd ditch the stock proportioning valve and install an adjustable unit in the rear circuit so you can adjust it where you want it. Relying on an unknown an used part that may or may not be compatible with your set up is asking for potential problems. Adjustable units are available from Jeg's, Summit, speedway motors, R&P, and many others.


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If the adjustable valve is what came with the 77 then I think I will just have to rob that off of the jeep too!

Also looking at installing the hydraulic clutch while I'm at it. Yes or no to that?

 

Adjustable valves are an aftermarket part, not stock. They are about $40-50. The thing is, if you upgrade to rear discs or larger drums down the road you can still dial in the brakes. The later CJ's had 10" or 11" rear drum brakes and the proportioning valves must be different for the different brake sizes. Do you know what size rear brakes the donor had? Are the the same size as what you have? If you don't know, then I'd go adjustable. If you KNOW it was functional and you KNOW the brake size is comparable then the stock proportioning valve may work ok. I'm lazy and like to do things once.
It may take some trial and error to initially get it dialed in but once you do you can rally have it fine tuned. Again, it also makes potential future upgrades very easy.


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I thought what you show in the bottom picture is a tee, since it is sending the same brake fluid pressure to the front brakes with no adjustment. I replaced mine after I couldn't get the old line to the mc out. I found an nos one on eBay. For what you are planning, I'd go with what Nick recommends.

 

Okay so now that it settled, I'm going to get a front disk/rear drum master cylinder and keep the existing line straight to the rear drum, then insert an adjustable valve in the line somewhere to keep them from locking up. Then just run the line to the disc brakes, and use a T (like the one below) and go to each side? Sound correct?

Sorry if this is such and easy concept for some, but since this is a HUGE safety feature I want to make sure it's done right!

 

Well unfortunately the Allen bolts are stripped and I can't drill them out. Luckily I found a Dana 44 with new calipers rotors and brakes I'm gonna pick up for $100...hopefully that is!