brake problem

[matt]

OK I need some input. I have a 1974 D100 my brake pedal gets firm when I pump it up and if I wait for about a minute and hit the pedal again it goes to the floor. Any input would be appreciated, thanks.

 

[7mopar]

Has anything been replaced lately? Fluid level been checked? What happens with the pedal when the brakes are pumped and keep them applied?
Power or manual brakes?

 

[HALIFAXHOPS]

Could be the seals in the master are starting to go if there are no leaks.

 

[matt]

Wheel cylinders are new, master cylinder new, brakes good, booster looks newer. Could it be the rod between the master and booster not adjusted properly ??

 

[Polara_500]

Not if you can get a good pedal feel and then it goes away. Sounds like a leak of some sort.

 

[bear]

Check the adjustment on your rear shoes . Also ,Did you bleed the system real good ?

 

[matt]

Yes adjustment is good and bled system

 

[7mopar]

Gravity or pressure bleed? If you are not getting a hard pedel on the first pump there has to be air somewhere or a leak.

 

[matt]

OK ordered new calipers and going to bleed system again after installed. Will post info after. Thanks for replies.

 

[bear]

When you pump up the peddle and hold it . Does it bleed down or does it stay up ?

 

[matt]

If you pump it up and hold it they stay firm but when you let off for about a minute and press pedal again they go almost to floor until you pump up again.

 

[7mopar]

Hard to believe brake lines would expand that much but have you checked them?

 

[bear]

Hard to believe brake lines would expand that much but have you checked them?

Possible but I doubt it .

 

[bear]

Hard to believe brake lines would expand that much but have you checked them?

Then that sounds like one of three things to me . #1 Air in the system . And I know you said you bled them . But sometimes they can be a pain in the butt to get all the air out . You are bleeding them with the engine off and starting from the farthest wheel , right ? #2 Front pads low or rear shoes either worn down or not adjusted properly . With the rear jacked up and out of gear , When spinning the tire you should hear and feel the shoe making contact with the drum and when you spin it by hand the tire should only spin maybe one revolution before it stops on it's own . #3 Bad master cylinder . Is it wet under it toward the back or is the paint coming off the booster right under the master ? Even if it's dry under there , you could be losing pressure and or fluid into your booster . If your losing fluid in the back bowl and it's dry under it . Sometimes you can pull the vacuum line off of the booster and see that the inside of the hose is wet . Hope this helps .