Technical Hard brake pedal

Hello,

I'm installing a new master cylinder and brake booster in my 55 Ford Fairlane. The front is disc (55 chevy front end) and rear is standard drum. I purchase a booster/master cylinder with proportion valve kit that fits the 55 from ebay (Auto City Classics) and the install was pretty straightforward. I can bleed the brakes and the pedal will go to the floor, but when I close the system the brake pedal is super stiff and only moves about 1/2 if I slam on it. Here's what I've done to try to narrow down the issue.

Thought the proportion valve was the issue. So removed it completely and just connected from the master cylinder to the front disc brakes, capped off the rear brakes to eliminated the rear brakes being the issue as well. Rebleed and still having the same issue. All new brake lines have been installed. I had done a bench brake bleed on the master cylinder. Thinking there may be in issue with the master cylinder? Any insight would be appreciated.

 

is your pedal not coming back far enough to allow the master to be fully released from pressure??

 

Not exactly sure. The pedal is high and has very little movement when I put my foot down on it. Only time I can really move it is when I go to bleed it and then I can push it to the floor.

 

first place I would look then is the rod length that pushes against the master. check to see if you can wiggle it or if there is a gap between it and the pedal arm.
also, are you checking it when the engine is running?? good vacuum??

 

Is the engine running?

 

Revkev6
I gotta recheck that rod length on the booster. That rod hits the pin that pushes the master cylinder. Should there be a gap or should it be right against it?

I've try it with and without it running, its the same. Suspecting not getting the needed vacuum. Just ordered a vacuum reserve canister to help with the vacuum.

 

unless you have a cam that is really crazy you should have plenty of vacuum.first thing you should have done was call the people that supplied kit.after saying that I suspect you need to modify the rod as someone said.if it is too long you will have the problem.if too long to put it simply it will not release the fluid when you lift off pedal leaving the calipers in a applied state.

 

Have you verified your pedal ratio is correct?

 

54Vicky

I did call the company that I purchase the kit from. They weren't much help. I suspect you are right about the booster rod being too long. I'm going to try to adjust it. Someone mention about shorting the pin that goes into the master cylinder that the rod comes in contact with. Not sure this is good idea. I'll start with adjusting the booster rod.

 

should be a slight gap. just enough to make sure the master cylinder is fully released.

not usually a problem with needing a vacuum canister.... I would put a gauge on it first to check vacuum. chances are either you have a bad connection to your booster or the rod length is incorrect... I'm leaning towards rod length.