rear disc
- Thread starter camo66
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BroncoJoe19
Active member
I've never done a conversion. Could it be that the old master cylinder does not deliver enough fluid to drive the disc brake calipers?
BroncoJoe19
Active member
Did you replace the rear brake lines? Could they be partially/almost completely clogged?
Do the James Duff rears expect ABS? I've never done it, so again, I do not know, but I seem to recall reading that the ABS system bleeds off pressure from the slipping wheel. I know... it is computer controlled and you do not have one, but I am thinking that you have been at this a bit, and perhaps I am just looking at this from a different perspective. I hope that I can throw something at you that you haven't thought of. Sorry if I am not being too helpful.
One last thought... is the wilwood proportion valve the type used prior to ABS? Are the pre and post ABS valves different?
Did you install ABS?
Hopefully I helped somewhat.
joe
Pete, First off, ABS will have nothing to do with what you have going on now. What kind of front disc set up do you have? What is the bore size of that MC? A smaller bore MC tends to have more problems with disc/disc than the larger ones. Is your prop valve adjustable or not? If it isn't, I might think about getting an adjustable one to offset the pressure and dial it in. This also is a good time to start to think about power brakes. Hydroboost or vacuum assisted, if you do go power, I highly recommend hydroboost over VA. There are a number of reasons, but I won't go into it right now. I know that when I went from disc/drum to disc/disc, I had to adjust the calipers before it worked right, then I went to h-boost brakes. BTW, what brakes does the Duff kit use? Are those adjustable? Reason I ask is that I used the BC rear disc kit and it was extremely simple and user friendly, I am not 100% up to verse on the Duff kit.
Duff has real good quality & use their kits on their own rigs.....I'm assuming you have discussed this with them...?
"...it has the duff disc/disc master on it actually this is the fourth one this week"
I think you mean it has the "disc/disc" porp. valve... not "disc/disc" master cyl....
"...Could it be that the old master cylinder does not deliver enough fluid...?
Assume fr. the above.., this M/C has been removed..?
Four diff. M/C's (or porp. valves)....that's a clue...
And there could still be air in the M/C (rear res.) that very thing happened to my neighbor. I made him take it off & bench bleed....& wa-la..! it worked. (puked lots of air)
The rod travel can also be a problem...if not adj. correctly
HTH
B
"...it has the duff disc/disc master on it actually this is the fourth one this week"
I think you mean it has the "disc/disc" porp. valve... not "disc/disc" master cyl....
"...Could it be that the old master cylinder does not deliver enough fluid...?
Assume fr. the above.., this M/C has been removed..?
Four diff. M/C's (or porp. valves)....that's a clue...
And there could still be air in the M/C (rear res.) that very thing happened to my neighbor. I made him take it off & bench bleed....& wa-la..! it worked. (puked lots of air)
The rod travel can also be a problem...if not adj. correctly
HTH
B
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I have a 76 bronco front the bore size is 1-1/8 the prop valve is adj and I have power brakes with the brake booster pushing 21 pounds of pressure
First off, like Bully Bob said, make sure that MC is bled good. What calipers does the Duff kit use? Are they Lincoln or are they Cadillac? By the pictures on the site, they look Caddy. If they are, then you can adjust them by that big zinc plated nut on the side of them. Try that, and then call Duff it that doesn't do the trick.
