rear disc conversion
#1
Registered User
Thread Starter
rear disc conversion
First , I bought this truck from a barn sitting for five years.the trans an rear end needed rebuilding , which I did. while I had the rear end out I also did the disc mod on rear. after 4 months an everything back together, I don't get much fluid out of rear calipers. bleed repeatedly, got some better but not much (spongy pedal). so after reading a lot on here, I bypassed the RWAL an removed it. bleed again , still very spongy. since it was a very old MC and sat for 5 yrs I replaced it, with orellys reman(all that's available). minor improvement not much (very spongy). if you pump it 4 or 5 times rapidly you get a good half pedal, but leaks down. so is MC bad or combination valve? can I bypass combination valve altogether with 4 wheel disc? I have no idea how brakes worked prior to sitting up 5 yrs
#4
Registered User
First , I bought this truck from a barn sitting for five years.the trans an rear end needed rebuilding , which I did. while I had the rear end out I also did the disc mod on rear. after 4 months an everything back together, I don't get much fluid out of rear calipers. bleed repeatedly, got some better but not much (spongy pedal). so after reading a lot on here, I bypassed the RWAL an removed it. bleed again , still very spongy. since it was a very old MC and sat for 5 yrs I replaced it, with orellys reman(all that's available). minor improvement not much (very spongy). if you pump it 4 or 5 times rapidly you get a good half pedal, but leaks down. so is MC bad or combination valve? can I bypass combination valve altogether with 4 wheel disc? I have no idea how brakes worked prior to sitting up 5 yrs
If that is the case Try bleeding the front. You should only need to do one.
This should center the piston in the valve. I ha a old chevy that was famous for doing the same thing.
#7
Administrator
I think that you have a bad master cylinder. Unfortunately the state of re-manufactured MC's is weak at best. You may have to Keep trying until you get a good one...Mark
One other thing, did you use the calper with the E-brake? If so, make sure that you have the actuator arm indexed correctly, that is very important. It is also important to use the E-brake, that is how it stays adjusted...
One other thing, did you use the calper with the E-brake? If so, make sure that you have the actuator arm indexed correctly, that is very important. It is also important to use the E-brake, that is how it stays adjusted...
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#9
Registered User
MC on these trucks= Nasty can of worms.
#10
1st Generation Admin
FWIW: I did the rear disc conversion on my mess using the Eldorado calipers with E-brake. With the stock/OEM MC, I felt the pedal stroke was too long so, . . . .
- I changed the master-cylinder to one from a 1983 Dodge B350 gasser. It has a cylinder diameter of 1.3125" where as our stock/OEM cylinder is 1.125". That will move more fluid with the same stroke length compared. (Had to narrow the new cylinder's mounting holes to fit our power booster).
- Added a 10lb residual-pressure valve to the rear brake line. This reduces the amount of "Pump-Up required" if you will, with the rear calipers.
Works like a champ!
- I changed the master-cylinder to one from a 1983 Dodge B350 gasser. It has a cylinder diameter of 1.3125" where as our stock/OEM cylinder is 1.125". That will move more fluid with the same stroke length compared. (Had to narrow the new cylinder's mounting holes to fit our power booster).
- Added a 10lb residual-pressure valve to the rear brake line. This reduces the amount of "Pump-Up required" if you will, with the rear calipers.
Works like a champ!
#12
Registered User
FWIW: I did the rear disc conversion on my mess using the Eldorado calipers with E-brake. With the stock/OEM MC, I felt the pedal stroke was too long so, . . . .
- I changed the master-cylinder to one from a 1983 Dodge B350 gasser. It has a cylinder diameter of 1.3125" where as our stock/OEM cylinder is 1.125". That will move more fluid with the same stroke length compared. (Had to narrow the new cylinder's mounting holes to fit our power booster).
- Added a 10lb residual-pressure valve to the rear brake line. This reduces the amount of "Pump-Up required" if you will, with the rear calipers.
Works like a champ!
- I changed the master-cylinder to one from a 1983 Dodge B350 gasser. It has a cylinder diameter of 1.3125" where as our stock/OEM cylinder is 1.125". That will move more fluid with the same stroke length compared. (Had to narrow the new cylinder's mounting holes to fit our power booster).
- Added a 10lb residual-pressure valve to the rear brake line. This reduces the amount of "Pump-Up required" if you will, with the rear calipers.
Works like a champ!
#14
Registered User
#15
Banned
this seems to be the trend today. hahaha
i would never ever do a rear disc conversion on these trucks, especially with those junk eldorado calipers.
you're sacrificing pad surface and a good e-brake when switching to discs. 3" pads and 1 ton cylinders are great on the backs of these trucks when properly adjusted.
i would never ever do a rear disc conversion on these trucks, especially with those junk eldorado calipers.
you're sacrificing pad surface and a good e-brake when switching to discs. 3" pads and 1 ton cylinders are great on the backs of these trucks when properly adjusted.