front disc brake conversion

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arab

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first of all i had a mechanic install a power front brake disc conversion kit on 72 plymouth duster. it had manual brake all around. i purchased the kit from pirate jacks. everything seemed to go on ok he bled the brakes followed instruction from the kit. i still dont have the stopping power i thought i would get...did he overlook something..if you can keep it simple when explaining the problem or solution would be appreciated..i am not a mechanic,sorry.. any help will be appreciated. thanks arab
 
What brakes did you start with- disc or drum? What was in the kit? Was a M/C part of the kit? What size is the M/C?
 
i'm guessing you need a master cylinder with 15/16" or 7/8" pistons
if everything else is installed correctly.
 
Not familiar with that kit. Can you post a list of parts included in the kit? And just so you know, i did the "stop on a dime" conversion on my 68 Roadrunner about 10 years ago. I was never happy with the way the brakes felt. I spoke to Cass at Dr Diff and he recommended a smaller bore master cylinder. I had a manual Abody disc cylinder. The new late model (ok 90s Dakota maybe) master made a great improvement. Pedal feels much better. Maybe not your issue but I just wanted to share my experience.
 
You need the correct master cylinder, also a porportioning valve to decrease rear pressure.
 
The “pirate jack” kit is based on the 73+ factory disk brakes. In working order they actually stop these cars pretty well, as well or better than some of the aftermarket kits out there.

But without the details of the installation it’s gonna be really hard for us to diagnose what’s going on. Do you have a parts list for the kit that was installed? It would be a big help in determining what you actually have, which will make it easier to figure out what you might need.

As far as the brakes, can you describe what it is they’re doing that you’re not happy with?
 
The “pirate jack” kit is based on the 73+ factory disk brakes. In working order they actually stop these cars pretty well, as well or better than some of the aftermarket kits out there.

But without the details of the installation it’s gonna be really hard for us to diagnose what’s going on. Do you have a parts list for the kit that was installed? It would be a big help in determining what you actually have, which will make it easier to figure out what you might need.

As far as the brakes, can you describe what it is they’re doing that you’re not happy with?

20220506_181714.jpg
 
The “pirate jack” kit is based on the 73+ factory disk brakes. In working order they actually stop these cars pretty well, as well or better than some of the aftermarket kits out there.

But without the details of the installation it’s gonna be really hard for us to diagnose what’s going on. Do you have a parts list for the kit that was installed? It would be a big help in determining what you actually have, which will make it easier to figure out what you might need.

As far as the brakes, can you describe what it is they’re doing that you’re not happy with?

20220506_181714.jpg
 
This is the kit I bought from piratejacks. Old brakes were manual drum brakes. I didn't see much improvement over manual. Brake pedal still goes down too to the floor.any suggestion would be appreciated. Arab. (1972 duster)
 
So that entire kit was installed and the pedal goes to the floor?

I’d look for leaks, barring that it’s most likely air in the lines. Brakes need to be bled. Was the master cylinder bench bled?

Are the calipers installed so the bleed valves are on the top? Because they can be installed on the wrong sides, which puts the bleed valves on the bottom instead of the top.
 
Check clearance between booster pushrod and M/C piston. It should be as close as possible w/o applying M/C. How is the proportioning valve adjusted? To what number? Pedal should never go near the floor. Hopefully it was bled properly.
 
When I gor my rear disc kit for 70 Dart, 8 3/4, it had s troubleshooting guide that came with the kit. some of what you are saying was in the guide. Call them.
 
You need the correct master cylinder, also a porportioning valve to decrease rear pressure.
Check clearance between booster pushrod and M/C piston. It should be as close as possible w/o applying M/C. How is the proportioning valve adjusted? To what number? Pedal should never go near the floor. Hopefully it was bled properly.

20220506_181714.jpg
 
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