LOL, I ordered two of those last week for the same reason.I picked up the M39309 master for an eventual swap
Well.....you made me wonder so I went to make sure I didn't have a brain fart.Joel...on the rear brakes hitting first...I'm wondering if you have the front line going to the front port on the MC, and vice versa? IIUC, the front line is supposed to go to the rear MC port, and v-v. No idea how big a thing that may (or may not) be...but maybe?
It's correct. Plain old 1.125" disc/drum MC with an equalizer hole drilled in the divider and a Wilwood prop valve on the rear brakes. Had the usual crap making the lines. Bought three double flaring tool setups, the third one wasn't junk.
While i haven't taken both types of masters apart for inspection.... I defer to piston areas and OE master/caliper pairing.
The M39309 master is a 1.34" bore and used with those front D60 Bendix calipers on all 4 corners. The caliper piston is 3-3/8" in size vs dodge wheel cylinders from 7/8 to 1-1/8" in size.
The disc/drum master probably doesn't move enough fluid volume to the rear circuit.
I would look for a disc/disc master that fits.
Switching to hydroboost should change the booster stud spacing and you have more options for a master. I picked up the M39309 master for an eventual swap - it fits 80's/90's Chevy hydro or vacuum booster, and 94-95 dodge vacuum booster.
Edit: I never evaluated Corvette or Cadillac masters for fit; same with 01+ dodge. Something else to check.
Yessir, combo valve is yanked. I've bled these things pale, including with a home brewed pressure bleeder. I don't think it's a blockage, they function just not very well. They also don't drag like they would if a line was a bit plugged, and it doesn't pull to either side when braking. I bought the best pads they had, but that means little these days in the way of parts house stuff. But even cheap pads wouldn't cause a low pedal. I also turned the rotors while doing the brakes.Did you do away with the factory combination valve? It has a feature that holds off the front for a few pounds of pressure to let the rear brakes move into contact with the drums.
Otherwise, I would suspect air or a blockage in the front lines. Or just plain cheap pads that do not have great friction.
Sorry no.... just trial and error.Wouldn't happen to have a link to a load of highly useful dimensions on stud spacing, mounting register OD's etc?
I'll fax you a cold beer if you do.
What did you do to correct it with the dual pistons?I would separate the lines and see if you are getting full pressure or comparable pressure to the fronts when compared with the rear. You will need a buddy. If you have a problem the adjustable prop valve may not be working correctly or the pressure is off on the master. I ran into this when I went to dual piston fronts on my rig, instead of the stock singles.
Neil
couple thoughts, if the rod Between the booster and master is too long, it could be blocking the fluid from returning to the master. You could loosen the master, and put a washer or spacer between the master and booster, then test drive it. Or just loosen the front line at the master after driving it to see if there is retained pressure.It's a bit odd George. I was riding around the neighborhood with a laptop a couple weeks back, tinkering with the trans and doing repeated stops. When I pulled into the carport the front brakes were hot as a pistol and smoking a bit. I was of course doing the one pump Polly on those stops. But the dang things just don't feel like they're doing much. When it comes to a full stop I can feel that the rears are the ones doing the majority of it, especially if I don't pump them.
Once stopped, at a light for instance, I have to pay attention to keeping a bind on the pedal or it can actually start creeping forward even though the pedal doesn't bleed down. I sometimes rest both feet on the pedal if it's a long light. Despite that the pedal effort isn't higher than it should be, as in the booster is bad. The things just don't bite and if I unconsciously back off a tiny bit at a light it creeps. A new side effect of a 4" crank and low 1st gear ratio. 4LO would be a real hoot.
It's possible I suppose that the master has some sort of an internal issue.
Same here.That would be a good thread, I have a handful I could measure and start a list.
I was reading Sam's conversion threads from '09 and '14 this morning. One for Oxx which was diesel and the other is Homer's rig. Homer's is a Mag block engine so I wasn't sure the pump they used on his would fit. But if my stock pump will do the job with maybe just a reshim of the relief valve.......cool.Cheby used the same PS pump, it just had a two inlet reservoir, and a slightly higher relief spring. Many do the conversion by using a T on the return line, and nothing else. Back in the day, cheby diesel owners used to convert to vacuum boosters because of the HB's leaking so bad. I guess they got the leaking fixed, you do not hear about it any more. I left a couple of hydro boosts behind in Pa, Not sure if Tony, or Dan grabbed them.
Let the parts gathering begin.
