TJ with Ram MC hard pedal

[Commando81]

So last night I did the Ram MC swap into my TJ. I made the push rod about an inch longer than the factory one and rounded it all purdy like the factory one is on the end.

When I step on the brakes the pedal is nonexistent then gets hard right when it works, but doesn't seem to travel as far down as it did. I also don't seem to build any pressure by pumping.

I bench bled the master and went around on the lines so I don't believe air is my issue. I didn't gut my prop valve since I still have rear drum and WJ front calipers.

Any ideas are appreciated I don't like to chance it when it comes to stopping

[Rinkrat456]

By going up .25" in master cylinder bore size, you traded brake pressure for extra fluid displacement. You also traded your pedal feel for one that will go down further and be harder to press. This swap should have only have been done if you enlarged your calipers. Doing it on a small disc Dana 30 and drum D35 (I assume since you didn't mention axles) wont change anything for the better.

If it were my vehicle, I'd keep the Dodge MC and upgrade to hydroboost. You'll have your predictable brake pedal, high line pressure and good fluid displacement thanks to the bigger Dodge MC.

[Rinkrat456]

Forgot to add, I'd also bleed all the brakes again, starting with the drums furthest away from the MC, then moving to the discs.

[Commando81]

I have the D30 with the WJ dual piston caliper mod with a TJ D44 with drums. The rear disk conversion is in the works just haven't got all my parts yet.

I'll go back through the system tonight its difficult to accurately explain how the pedal feels if I can't get it to improve I will go back to stock untill I put in the rear discs

[mrblaine]

Originally Posted by Commando81

I have the D30 with the WJ dual piston caliper mod with a TJ D44 with drums. The rear disk conversion is in the works just haven't got all my parts yet.

I'll go back through the system tonight its difficult to accurately explain how the pedal feels if I can't get it to improve I will go back to stock untill I put in the rear discs

First off, what possessed you to do something so stupid as the Ram master? Please tell me you didn't learn that pile of horseshit from the internet?

It it positively the single most ignorant and stupid modification ever recommended for THE brake system in a TJ that was ever foisted on the unsuspecting and anyone that recommends it, need a hearty and swift kick to the nuts.

It doesn't work now, it has never worked, and it will never work. Anyone that tells you it will work needs to hire a bulldozer to pull their head out of their ass.

You pedal feels the way it does because you fucked up the length of the pushrod. You have too much free travel before you hit the hard pedal that will never go away with that master. It's simply too large for your calipers.

As far as your WJ swap. The WJ has a 1" bore master stock and a very similar booster to what's in the TJ. Guess what? The TJ has a 1" bore master, so that means to do the WJ swap, you MAKE NO CHANGES TO THE SYSTEM TO RUN THE WJ STUFF AND THAT INCLUDES YOUR PROPOSED SWAP TO REAR DISCS.

Did you get that part? ZERO, ZILCH, ZIP, NADA, NOTHING, AS IN NO CHANGES except to modify the lines to get everything hooked up.

[mrblaine]

Originally Posted by Rinkrat456

By going up .25" in master cylinder bore size, you traded brake pressure for extra fluid displacement. You also traded your pedal feel for one that will go down further and be harder to press. This swap should have only have been done if you enlarged your calipers. Doing it on a small disc Dana 30 and drum D35 (I assume since you didn't mention axles) wont change anything for the better.

Even if he enlarged the calipers, the largest master the TJ booster will support is at the most 1 1/8" and even then you better have some big ass calipers.

If it were my vehicle, I'd keep the Dodge MC and upgrade to hydroboost. You'll have your predictable brake pedal, high line pressure and good fluid displacement thanks to the bigger Dodge MC.

If it were my vehicle and it has been more times than I can count, I would throw that master as far as possible and start over. All you'll get using it on a hydroboost is a high hard pedal that goes from rest to full lock up with a hard leg in about 1.5" of pedal travel.

For the record, going from 1.0" to 1.25" in bore size with that master is almost a 50% increase in piston surface area. That means you upped your pedal pressure considerably to wind up with a 50% decrease in line pressure at the caliper. That's both feet on the pedal all the way to the floor.

[flatlander757]

Originally Posted by mrblaine

First off, what possessed you to do something so stupid as the Ram master? Please tell me you didn't learn that pile of horseshit from the internet?

It it positively the single most ignorant and stupid modification ever recommended for THE brake system in a TJ that was ever foisted on the unsuspecting and anyone that recommends it, need a hearty and swift kick to the nuts.

It doesn't work now, it has never worked, and it will never work. Anyone that tells you it will work needs to hire a bulldozer to pull their head out of their ass.

You pedal feels the way it does because you fucked up the length of the pushrod. You have too much free travel before you hit the hard pedal that will never go away with that master. It's simply too large for your calipers.

As far as your WJ swap. The WJ has a 1" bore master stock and a very similar booster to what's in the TJ. Guess what? The TJ has a 1" bore master, so that means to do the WJ swap, you MAKE NO CHANGES TO THE SYSTEM TO RUN THE WJ STUFF AND THAT INCLUDES YOUR PROPOSED SWAP TO REAR DISCS.

Did you get that part? ZERO, ZILCH, ZIP, NADA, NOTHING, AS IN NO CHANGES except to modify the lines to get everything hooked up.

X2... I was duped into the Ram MC shenanigans... I can just barely stop my Jeep in 4LO... plans to experiment with a Dakota 1-1/16" or 1-1/8" (both were available depending on year and options) for my OWN brake setup for a short term fix... but long term really need to get hydroboost to be optimal... especially since I want to get an auto transmission which will drive right through the brakes.

For the WJ calipers you need to just use a stock master cylinder and bleed it properly.