I have a question for any of you out there that have done a rear disc conversion, first off heres a semi brief description of whats been done to mine:

82 Scrambler

* Rear disc conversion using 87 Lincoln Mark VII calipers and discs,

* Installation of rubber rear brake hoses, which meant re-plumbing hard lines from the existing hard line by the fuel tank to each caliper, fabbing brackets and installing the rubber hoses to the caliper (Don't know what hoses are off of, I went to auto parts store and spent an hour or so searching through brake hoses until I found some that met my needs)

* Removed existing proportioning valve and installed an adjustable one, which meant re-plumbing some lines. Proportioning valve is on wheel well next to (but below) the master cylinder. and I have tried adjusting it to see if that was the problem...

* I had a '79 caddy (from a caddy witth rear discs) master cylinder on it, that was suppose to provide the extra ummph req'd for rear discs, but went back to my original due to this issue, thought maybe it was the problem, but the problem still exists with the stock cylinder,,,,stock cylinder still on at this point...

Thats the jist of my rear disc projsect....now the problem is that I don't have any pedal until about an inch or two before it gets to the floor. I have bled the brakes with a hand pump (at least 6 times), Pumped the brakes while someone else bled them (both with the jeep running and not running numerous times), I have gravity bled them at least twice, and maybe more I can't remember anymore...

The Jeep will stop, but won't lock up or really stop great when I really slam on the brakes.No matter what I do I can't get the back pressure in the pedal that should be there, I have tested the power bosster and all the linkages, all ok,,,,,,,,,

The rear calipers use the brake pads for the emergency brake and are actuated by cables and a hand brake I installed, they are semi working but need a little more adjustment on the cable.....

The only thing I can think of at this point is that the rear hoses I have installed are too large in diameter (they are larger, or appear to be than the steel line), and maybe my pedal is going away because of all the fluid suddenly going into a larger area causing the pressure to go away.....

When the engine isn't running, the brakes seem to pump up and hold pressure fine, as soon as I start it and the power booster does its job, the pedal is gone....

anyone have any ideas,,,,,I'm pretty close to having this thing on the road and this is driving me crazy.....thanks

kerryp

I think I heard something about the length of the rod between the pedal and the master cyl. This may need to be longer.

1st, adjust the e-brakes. If they are out of adjutment then the caliper needs to move more than it should.
2nd, have you adljusted the proportioning valve?
3d, play with the actuator rod.
Before all this tho' I would reinstall the disc brake m/c.

On the rear brakes, are the bleeders facing up?

Adjust the rear ebrake and see if that helps.

Yeah, my calipers are on right with the bleeders up....there is adjustment on the ebrake cabling (which I've adjusted some), is there another way to adjust them?

I noticed the piston has two holes for turning the piston, is that the adjustment you are referring to? I have them adjusted out enough to where I can get the caliper installed, I didn't use my c-clamp to push the piston back down in the caliper, can you do that with the Ford calipers?

kerryp

I have an 82 Scrambler and just installed rear Disk brakes.
My Disks are from a 1981 Ford Bronco, put onto my Ford 9" rear.
My Calipers and hoses are from an 80 something Chevy Van.
I to ran hard lines from the stock Gas tank mount to each wheel well then to the Calipers with the stock Chev long hoses.
Proportioning Valve is stock AMC whatever as is the Master cylinder.

Brake pressure starts at 1/3 -1/2 way down and stops firmly if I step hard before hitting the floor everytime. Brakes have a tendency to grab in the rear a bit more than the front at first, but is within acceptable parameters.

Thats on the street.

Off road at times (off camber, bumps, and on uphill grades) I will have to double or even sometimes need to triple pump before getting my brakes back.

I have learned to anticipate the problem while wheelin but would like to hear any suggestion as to a fix.
It Sounds like this posts method ain't it!

Originally posted by mrmacrro
I have an 82 Scrambler and just installed rear Disk brakes.
My Disks are from a 1981 Ford Bronco, put onto my Ford 9" rear.
My Calipers and hoses are from an 80 something Chevy Van.
I to ran hard lines from the stock Gas tank mount to each wheel well then to the Calipers with the stock Chev long hoses.
Proportioning Valve is stock AMC whatever as is the Master cylinder.

Brake pressure starts at 1/3 -1/2 way down and stops firmly if I step hard before hitting the floor everytime. Brakes have a tendency to grab in the rear a bit more than the front at first, but is within acceptable parameters.

Thats on the street.

Off road at times (off camber, bumps, and on uphill grades) I will have to double or even sometimes need to triple pump before getting my brakes back.

I have learned to anticipate the problem while wheelin but would like to hear any suggestion as to a fix.
It Sounds like this posts method ain't it!

Well you are the third Scrambler owner including myself that I know of since I made this post that can't get their brakes working the way they should......there has to be a common sense reason why we can't get good pressure built up in our pedals.....

I would like to hear from Cj-7 owners who have done the conversion to see how theirs are working, if theirs work ok, then it may be something to do with the Scramblers longer wheelbase.......any 7 owners that have rear discs? How are they working......

Does anyone know if a late model chevy , ford or dodge p/u master cylinder/booster setup will fit on the jeeps? They have four wheel disc brakes, may be a thought.....there just may not ber enough fluid or pressure for the set up....

kerryp

I had the exact same prob you both explained with my cj, until I went to a mc off a 79 trans am, that fixed the pedal prob, now they work great and I still haven't changed the stock prop valve either...

With my discs on my CJ-5, I run chevy calipers front and rear and when I got it twisted up this weekend I had no problems with the brakes,

I run a 68 vette manual disc brake mastercylinder, Do you think the lack of brake pressure is because your not building enough vaccum?

I would think that it wouldnt matter if it was on or off-road..

See if you can beg, borrow, or somehow acquire a line pressure gauge. Using one will tell you more about what your brake system is doing that just about anything else you can do.