67 Brake issue help!

[Mark C.]

OK
I replaced the PB booster and now the brake pedal goes to the floor. If i pump the brakes the pedal seems to work normally. Before I changed the booster the brakes worked like manual brakes but the pedal didn't go to the floor. Now with the new booster it does. I didn't open any brake lines (so i dont think any air could be in the lines) and the fluid level is good. Whats next?

[Ken A.]

Re: 67 Brake issue help!

Silly question, but are you checking with engine running?

[Mark C.]

Re: 67 Brake issue help!

Yes car running, I took it for a short drive too, the car stops but not too fast.

[Edward J.]

Re: 67 Brake issue help!

Mark, by pumping the brake pedal, and the pedal goes higher indicates air in the system. I think I would try beelding the system first just to be sure.Won' t hurt anything to try.

[Mark C.]

Re: 67 Brake issue help!

I will try the bleed but how would air have entered the system. There was none prior to the booster change and I didnt open any lines?

[Edward J.]

Re: 67 Brake issue help!

Mark, I really have no answer, but have been a mech. for 40 yrs, There maybe be more of a underlined problem, but like I said pumping the pedal and getting higher generally indicates air in the system. The booster may have a push rod adjustment that maybe incorrectly adjusted.

[Mark C.]

Re: 67 Brake issue help!

Ahh now that sounds like a possibility. I installed the booster so it is likely I made a mistake in adjusting the booster. I'm guessing that I need to increase the length? (back off the connector?)

[Edward J.]

Re: 67 Brake issue help!

Mark, if you have a serv. manuel make sure you make the correct adjstment, I am not sure of the correct length of the rod. Extending the rod will bring the pedal higher.

[Mark C.]

Re: 67 Brake issue help!

I dont have the service manual I just figured I would back it out some and see if my problem is solved. Worth a shot?

[Mark C.]

Re: 67 Brake issue help!

I adjusted the extending rod and the pedal is as high as it can go. Should I continue to extend the rod a little more. The pedal still goes to the floor. Is there anything else I should try before bleeding?
Thanks
Mark

[Edward J.]

Re: 67 Brake issue help!

Mark, I would proceed with bleeding the system.

[Paul J.]

Re: 67 Brake issue help!

Mark, by "the pedal goes to the floor" do you mean that there are still brakes? If so it is either air in the lines or misadjustment of the rod, as Ed has suggested. There is also the possiblity that your new booster isn't working, although this isn't very likely. You don't hear any hissing from around the booster do you?

If there are no brakes and the pedal goes to the floor, then you have uncovered another problem. Probably your master cylinder. If the the pedal sometimes goes to the floor, then the seals in the MC are not working. If it sometimes works as it should, then that confirms it. With the engine off, press the pedal hard. If it slowly goes to the floor, it's your MC.

It is not unusual to make a simple repair on a vintage car and uncover other issues.

Paul

[John H.]

Re: 67 Brake issue help!

Mark -

Is the booster-to- master cylinder pushrod on the new booster the same length as the one on the old booster? '67 was the only year where the power brake master cylinder was the same as the manual master cylinder, and had the "deep" hole in the rear piston and the booster had the "long" pushrod; '65-'66 power brake master cylinders had the "shallow" hole in the rear piston, and their boosters had shorter pushrods. If you have the "short" pushrod, you're not going to have any brakes.

[Mark C.]

Re: 67 Brake issue help!

Hello and thanks for all the help, Prior to the new booster the brakes functioned as if they were manual brakes. The car would stop fine but you really needed to stomp on the pedal. The new booster seems to be working although the pedal goes to the floor and the "brake" light lights.
The car has brakes just not what you would like. If i pump the brakes they work properly. I can easily check the booster to master cylinder so I will do that now. Thanks in advance
Mark

[Mark C.]

Re: 67 Brake issue help!

update
the booster to master cylinder is the same as the old one.
Mark