Rear disc caliper bleeding question

[Glenn_tx]

I got some caliper brackets for my Dodge rear Dana 60, turns out I ordered Chevy Dana 60 brackets, my mistake. Anyway, I was able to use them but had to shave about 1/4" off the inner brake pad on each side to get things lined up to work. I've bled the system, got the nipples pointed up :D , all the brakes work, but I'm unable to lock up the rears, even on grass, and the pedal is kinda soft thru the first 1/2 or so of travel. I know the rears are working cause I also put a line lock on them and it holds well.

Is it possible that having shaved that much of the pad isn't allowing full pressure on the rear rotor? I figured the caliper would self adjust. Do I need to add some kinda spacer behind the pad on the other side to compensate? Oh, yeah, all the hardware is new, not used. Any ideas?

[Crazy_Jeepman]

Proportioning valve used? If so that will cut the pressure to the rear. Other than that I am out of ideas

[Glenn_tx]

I used the same proportioning valve, was that bad? I meant new hardware for the rear axle, new lines, calipers, rotors.

[Crazy_Jeepman]

I am not sure, if that was bad or not. However it is the only thing that cuts pressure in the system. I plan on doing the disc brake conversion as well, I think the answer would be an adjustable Proprtioning valve. This would alow you to set the brakes to work best for you.

[Glenn_tx]

So, would the calipers adjust to the thinner pad kinda like old worn pads?

[paddyp]

They should adjust, but the proportioning valve for disc and drum brakes are set way different. Get an adjustable proportioning valve for the rear to dial the rear brakes in.

[Glenn_tx]

I'll probably get an adjustable one but I figured I'd have probs with the rears locking up quicker with the standard valve, not the other way around.

[blt2krl]

Did you push or pull(depends on proportioning vavle) the little deal in the stock befroe bleeding the brakes? I had to do this to get my brakes real firm.

[Glenn_tx]

Yeah, I pulled the little nub out, but it didn't come out very far at all. I'll try the whole bleeding process again tomorrow when my wifes here to push the pedal.

Were you still getting air out of the nipples after you pulled/pushed the nub when bleeding them?

Thanks for your help, I'm getting to my wits end. If I can't fix it properly before Thursday, I'm not gonna take it to Ouray, I'll just drive the Ford on the trails.

[blt2krl]

I got a few more and then none. If that doesn't do the trick then I would look into an adustable vavle. It could be that your is old and has crud in side.

[Ralph]

Ditto on the adjustable proportioning valve. The factory p-valve is set up for rear drum brakes, which do not require as much pressure to activate; hence the tiny little wheel cylinders as opposed to the larger cylinders inside disc brake calipers.

Jegs or Summit would have what you're looking for so far as the p-valve is concerned. But you'll probably also have to bend your own brake lines to fit the new valve.

[Glenn_tx]

Ralph, that makes perfect sense. ******, there's no way I can get that all done before Ouray.

[imported_Big Red]

GlennTX, I just sent you an email about the axle.

[scotty]

kids,the prollem people usually have in doing a rear disc swap is that the rear calipers get too much of the pressure and lock up the tires before the fronts. if you are having the reverse prollem,an adjustable prop valve will not help you,since all it is is a valve with a knob to let you tone down the amt of pressure geting to the rear.

i left my stock prop vaslve in place and i cannot lock up 38" tires on the road,but i can in the dirt.what size tire are you running? this has a great deal to do with wether you can lock them up or not-the bigger and heavier they are,the more effort will be reuired to keep that much spinning mass from spinning.

i would also reccomend altering your bracket so that you do not have to shave a brand new set of pads to get them to work. sort of defeats the purpose if you ask me. i originally had the same prollem with my rear 44 discs when trying to make them work with a front bracket.i solved the prollem by tossing the front bracket and welding a home made flat bracket to the axletube in the correct spot for the caliper with a brabnd new set of pads to fit the rotor.not trying to discourage you or criticize your setup,but i think youll be glad in the long run if you dont have to shave your pads every time youve got to change them. 1/4 sounds like alot to me(bout half the pad?) so youre going to have to repalce them alot more frequently.

after you get the brackets modified and completely bled if youre still having a prollem,id remove the stock prop valve completely from the system. add an adjustable valve to whichever set of wheels locks up 1st. start with it wide open and turn it down alittle at a time till all 4 lock up at the same time.

my thots on that anyway ;) smile.gif

[orangecherokee]

i was gonna say get an adjustable valve too. the problem is that the ratio is like 70F/30R on FSJs but i'm not sure on Dodges. i think scotty's got it licked, go with that.

[blt2krl]

The adjustable will do the trick when you take out your old valve and I believe that is what everyone was saying.... :D

[FSJeeper]

Glenntx, I have a friend with a sweet Wagoneer with a GM diesel conversion. He did rear discs and had the exact same problem. He solved it by taking the guts out of the proportioning valave. Has been driving it like that for a couple of years so I guess it is safe. I am just throwing it out and do not recommend it.

I am just plumbing in an adjustable prop valve in my system and not using a stock prop valve at all.

[grantc]

Grinding the pads is not a good idea. Especially if they're not perfectly flat. At worst you'll get warped rotors, pedal pulsation, and wear out pads. in the long run it might be cheaper to fix the brackets.

One of the main reasons the rears will lock up first in a system with wacked or no proportioning is that when the vevicle slows down all the weight shifts to the front axle and off the rear. The better the traction and the heavier the weight the harder it is to lock em so the rears naturally lock first. Just like driving on dirt the wheels lock up easier cause there's less traction. Bolt on a flux capacitor levitation device and you can lock em everytime (but you'll never stop).

Get rid of the rear drum prop valve. If you wanted a temp fix. Take out the prop valve gut and see what happens. If it doesn't work out you can always put it back in.