73 CJ5 drum-to-disc swap issues

I am in the middle of doing a drum-to-disc swap on the front dana 30. For reference I bought the kit from the-jeep-guy. I ran into a few issues yesterday. I have been searching for an answer here at the forum but can’t seem to find it. These are my issues:

1. On the master cylinder when I removed the brass fitting there was no residual pressure valve (the plastic valve with spring like the one pictured here). Can I just add a 2psi valve?

2. My original wheels do not fit, would 1/4” spacer solve this problem? What have others done to make your original wheels fit?\

Thanks for the help!

 

An inline 2# residual valve will do the trick. You'll probably need to replace the wheels. There is no step to the inner radius to fit calipers on the original so you would have to space it way out.

 

When I did this swap the residual valve literally sprung out and I found it on the drive way sometime later. As for your wheels not fitting, I used 1 inch spacers so my stock wheels would clear the calipers, but your wheels may be different. I have the stock Renegade slots.

 

What does the "Jeep Guy" suggest?


Sent from my iPhone using Tapatalk

 

1. I disconnected rear drum brake line from the master cylinder and removed the brass fitting to check if it had the valve in there. It did not! So my question is do I even need these residual pressure valve? Or are they just meant for master cylinders mount below at the frame and not up high on the firewall?

2. After checking the wheel-caliper clearance last night. I decided to buy some 1.25” spacer. 1” would probably work but will most likely be too close. I might buy new wheels later but the spacers are an economical solution for now. I read that some people grind the caliper but I do not want to do that, it seems that I would need to grind too much from it.


Thanks!

 

i am running a power unit on the wifes 7 with drums all around,took it off of a yj and bolted it on, no valve works fine. your results may vary.

 

1) you can give it a try, you may have excessive peddle travel if the rear shoes are out of adjustment.

2) I ran into the same issues, I bought new wheels.

 

ok everything is in but... It takes me a bout 4-6 pumps to fully lock the front brakes, probably more when driving (just turning the wheel with my hand). Guess I need a a 2psi brake pressure valve or a new master cylinder. Has anyone tried the corvette master cylinder? part MC1321H

Thanks!

 

If your MC is on the frame like an early then the residual pressure valve is needed. But, if it's on the firewall, gravity should be enough. If its a spongy pump up its more likely air. Track that down before you worry about a new MC.

 

It is up on the firewall. Will try to bleed it again tomorrow. Thanks!

 

No luck. Had my girl pump the brakes 6 times (times it take to fully lock the disc) and them hold, I opened the bleed valve and a solid stream came out. I did this twice on each side. I am doing it wrong?

Should I go with a Residual Brake Pressure Valve or a new Master Cylinder?? What do you guys recommend to fix this problem?

Thanks!

 

Ok was reading this thread again and read nickmil post #25 "...Make sure the bleeders are at the highest point on the calipers or you won't be able get the air out."

Of course! Why didn't I think of this!? there is no way air can get out with my current setup! I have the calipers mixed up so the bleed valve is upside down!!


Will swap them tomorrow and hopefully this will fix the issue. Will let you guys know as soon as I can.

 

I do not have discs but i did install a Corvette MC.. On my 75 the fitting size is different than the brake line fitting. I had to use two different sizes of reducing fittings to get mine to connect..

 

How did you like the Corvette MC? better than the stock?

 

Finished installing the calipers on the correct side (bleeder at the top), took the air out of the system, thought it was good because disc were locking at just one pump (when trying to rotate them by hand). When I took it for a test drive brakes were really weak! It brakes but would not trust it in an emergency. If I swap to a Corvette MC would I notice a difference or would it be time for power brake conversion? What do you guys think? Keep in mind that I am running 33" tires.

Thank you!

 

Are you running semi metallic or organic brake pads?
Again, what does the vendor you purchased this stuff suggest?


Sent from my iPhone using Tapatalk

 

Just sent him an email. So far Ryan (the-jeep-guy) has been really helpful. Can you explain what would be the difference? Thank you!

 

Semi-metallic pads are meant to be used with a power booster. Hard compound. Organic pads are much softer and can be used with manual brakes. Organics also do not chew up rotors the way semi-metallics do. Trade off is organic pads fade quicker. Normally a non issue with a CJ.


Sent from my iPhone using Tapatalk

 

Seller says I have organic pads. He suggests power break conversion. Strange how for some people the stock MC works and for some don’t? I wonder why is not working right on mine??

 

I bet he does. He sells parts remember.....

Look at the pads. If you can see shiny metallic particles or striations in the pads then most likely they are semi-metallic and need changed out. Organics are much cheaper by the way.
Typically these conversions work very well with manual brakes once the correct parts are used. I'm running 4 wheel discs with Chev 1/2 ton calipers on the '59-5 with the stock under floor m/c and it stops on a dime....