Break vacum problem

[Custom/Ten]

I will leave you will one more wild theory. First there are some things that can cause your master cylinder pistons to move forward. The thing is though that your brake pedal is not(should not be anyway) attached to your master cylinder in any way. It's not an attaching rod, it's a pushrod. What I'm saying is if you had your master cylinder pistons moving forward on they own, that should not drag the pedal down. I say remove the master and see if the pushrod is stuck in it, jammed together. While your at it take snipers advice and see if you have a power brake mc, then see if you have an adjustable booster rod. Like I said before he though, I really don't know what's going on here, good luck bud!

[swamp rat]

When i bought my replacement booster it had a push rod with it, i also had my old one that i removed before turning in the core, they were about .050 different in length, what i did was put a little ball of clay on the end of the rod and pushed the master into place then looked at the clay to try and determine how much space was between, i wound up using the one that came with the booster as it gave me approx .020 freeplay.

[Mator]

Well I finally got back on my break problem. After reading through the post again, I looked at it further and I do have the adjustable rod. After a few times of making adjustments it has seemed to do the job. Thanks for all the input. I never changed the length and really didn't even notice it was adjustable until now. Thanks again.

[Custom/Ten]

Thanks for the follow up! Threads with a solution are the best part of this forum. Did you have to shorten the pushrod or lengthen it, just curious. Let us know if you can find the time. Glad you got it figured out!

[Mator]

I had to shorten it about 1/4". It was pushing the master in causing the breaks to be applied. Never thought about an adjustable rod. I thought they were all the same. Thanks everyone.