chevy brake problems?

i drive a completely stock '54 chevy 210. ive had some brake problems starting to creep up in that last couple weeks.

when coming to a stop, from any speed, the brake pedal will slowly 'bleed' down to the floor. i can pump the pedal to get some pressure and safely come to a stop but the pedal will immediately start to 'bleed' back down until it hits the floor and i start rolling forward again.

my first thought was that the master cylender is going bad and needs to be rebuilt/replaced but someone also suggested that there are some valves attached to the master cylender that could be bad and causing pressure to bleed back.

another problem that has seemed to start around the same time is that the brake lights no longer work. i had the switch replaced a few months back by a trustworthy mechanic when i didnt have the time to do it myself and they started working just fine. i dont know if the brake light switch is a pressure or mechanical switch, but thought i would mention that if the two happened to be related.

thanks!

-j

 

there are no external valves on a stock 54 chev. and i think the stoplite sw is mounted on the firewall and mech not hyd. i would guess if you are not low on fluid the m/c is simlply by passing internaly.

 

Rebuild the master ... always a good idea to pull all 4 wheels while it's up in the air - pull the boots back on the wheel cylinders & check them, too. Don't forget to check the 3 rubber hoses ...

 

thanks, ill be getting to it this weekend.

-j

 

Just a thought, check your hardlines for leaks, too. I've had a couple of cars on my alignment rack that will stop fine in the parking lot, but you get them on a lift and set the brake pedal and they start to leak out little pinholes in the rusted hardlines.

 

I had the rear line "unscrew" itself from the t and then I had total brake failure. If you're gonna replace parts and bleed the brakes, new hoses would definitely be on my list. I replaced it with a chevy truck hose for a lifted 73-87 4x4, t is built in and it has the right length. IIRC it was 20" long. I also upgraded to a dual reservoir master, it was real easy. I copied thefillingstation.com 's kit design, I think buffalo ent. makes one as well.

 

If you haven't gone completely through the brakes yet, do it. It's a good idea, especially on a single master system, and your vintage Chevy is dirt cheap to do.

 

thanks for all the replies! i never thought about checking the hard lines, out here in california we dont get much rust so it never occured to me. i will be going over everything with a fine tooth comb.

if it turns out that i need to replace some hard line, is a special flare tool needed for these lines or can i just pick up a standard one at napa? im used to european cars where everything needs some kind of special tool...

-j

 

It's just the standard inverted flare that U.S. cars used up into the '90s.

 

Like its been said through here, rebuild the master cylinder and check all four wheel cylinders as well. Any leakage will cause this to happen. Even a bad cap on the master cylinder or gasked on the cap will cause this. I have a 51 Chevy 2 dr and I had to rbuild the whole system. Its a few hour job and fairly cheap but well worht the time and money.

 

I had the same problem with my car. I thought it was the master so I rebuilt it, same thing still happened replaced all the lines and it still happened. Then I noticed that the pedal has adjustment as to how far it pushes and returns the master plunger. I played with it and now it works fine. Adjust the eccentric nut holding the pedal to the master. I don't know if this will work for you but worth a try.

 

just to double check, theres 3 rubber lines. 2 in front and one in the rear, right?

-j

 

One to each front wheel and one to rear axle.

 

can anyone give me instructions on how to replace the master cylinder on my 52 chevy ,does the peddel assmbly brake and clutch come out and get mounted on the new master,or do you try to attach every thing while under the car? any help would be thankfull.