Brake line Cross reference

I picked up a nice d30 with disk brakes, supposedly from a 74, this weekend. I want to swap from the knuckles out on my Current drum brake 30. I'm going to need extended brake lines.

I have 2 questions.

1) are the outer axle shafts the same for drum and disk?

2) I cant seem to find a listing for a 74 extended brake lines. Will the banjos and lines for a 78-81 work? ( i think it has the 6 bolt caliber brackets, but I will check that along with rotor thickness tonight.)

Thanks,
-Dante

 

looks like 2-bolt caliper brackets and the thinner (7/8th-ish) rotors

 

No listing because the '74 never came with disks. Either it's a later axle ('78-on) or it's been swapped over to disks.

 

I did the disc brake swap on my 72 with parts from a 78 CJ7 which had the 6 hole caliper mounts and the thick rotors and I had to replace everything from the knuckles out including the outer stub shafts because the area where the inner spindle seal rides was a different diameter. There are 2 different front brake hoses for CJs one has a round end and the other has a square end it depends which calipers you have you will also have to add a proportioning valve and replace the master cylinder with one designed for disc brakes.

 

So would it be possible to run with the stock drum master cylinder for a while. This jeep really dosent see any road miles.

And from your response i am to understand that the front outer stub shafts are NOT interchangable between disk and drum front ends?

 

I am told that you can use the drum brake master cylinder but you will have to remove the check valve from it so that it doesn't cause the front brakes to drag (or so I am told) I had to replace the stub shafts because the drum brake spindles have an inner seal that presses into spindle and seals on the stub shaft and the disk brake spindles use a rubber seal that rides on the stub shaft and seals against the spindle and the area where the seal rides on the stub shaft is a different diameter, I don't know if you can mix spindles and hubs but I do know that they use different inner wheel bearings.

 

thanks, That's good info.

I found a swap write up detailing exactly what I am doing. But now I'm thinking it might be easier to just weld new spring perches on the donor, since its in good condition, and I could probably do that faster than I could swap the brakes and locker over to my current axle.

hmmm...

 

Why does it need diffrent, or new perches? Does it have the same gear ratio?

 

Same 3.73's as my current set up. I'm spring over, and this axle has sping over perches, but they are welded on at the wrong angle, so I need to remove and replace them to get the steering geometry right.

 

In that case, I would change the perches too, it would be a lot less work.