Brake pedal stroke

[manyo]

My 71' brake pedal has a great deal of movement and seems to kick in at close to end of the stroke . I have had a few mechanics look into them with not much luck. Any suggestions?

I thank you in advance.

 

[Doug's 73 Mach1]

I believe there is an adjustment on the end of the master cylinder rod that goes into the brake booster. From what you describe it needs to be adjusted to make the tip of the rod longer.

 

[Hemikiller]

I'll agree with Doug, if you have power disc, the pushrod length is worth a check since you've already had a bunch of eyes on this problem.

Under normal circumstances, a low pedal is usually caused by rear brakes that are not adjusted properly. If you pump the brakes once or twice, does the pedal engage higher?

 

[manyo]

I'll agree with Doug, if you have power disc, the pushrod length is worth a check since you've already had a bunch of eyes on this problem.

Under normal circumstances, a low pedal is usually caused by rear brakes that are not adjusted properly. If you pump the brakes once or twice, does the pedal engage higher?

I will give it a try tonight. Thank you guys for the great information!!!!
View attachment 66496

 

[manyo]

I will give it a try tonight. Thank you guys for the great information!!!!

 

[Stanglover]

I doubt any of us have, or can make the tool Ford shown, but there's a little trick I learned years ago when I was prototyping air cleaners. We used pieces of Plasticine to gauge hood clearance.
When I did my m/c to push rod adjustment, I took a small pill of Plasticine, (or similar) placed it in the bore of the m/c piston, then assembled the m/c to the booster. Disassemble and look at the plasticine. If the rod hasn't pushed all the way through, it's still too short. What you need is a contact area the size of the ball that has just pushed through so you can see bare metal. Then if you add about a 1/4 turn more to the ball adjuster, that ought to be close to the 5 lbs tension mentioned in the Ford manual. If, when you reassemble the m/c to the booster, you feel too much tension, then back off the ball adjuster and start again.
This has worked for me, but yes, it's time consuming. Clean out the plasticine after of course.

 

[timachone]

I doubt any of us have, or can make the tool Ford show, but there's a little trick I learned years ago when I was prototyping air cleaners. We used pieces of Plasticine to gauge hood clearance.
When I did my m/c to push rod adjustment, I took a small pill of Plasticine, (or similar) placed it in the bore of the m/c piston, then assembled the m/c to the booster. Disassemble and look at the plasticine. If the rod hasn't pushed all the way through, it's still too short. What you need is a contact area the size of the ball that has just pushed through so you can see bare metal. Then if you add about a 1/4 turn more to the ball adjuster, that ought to be close to the 5 lbs tension mentioned in the Ford manual. If, when you reassemble the m/c to the booster, you feel too much tension, then back off the ball adjuster and start again.
This has worked for me, but yes, it's time consuming. Clean out the plasticine after of course.

That's a very good tip and description! Thanks!

 

[boilermaster]

When I replaced my booster, I used the Stanglover method and it worked out quite well
other than cleaning out the remains of the plasticine and what about the 5 pounds of pressure ?.
How about a piece of flat stock with a hole drilled in each end and add a bolt with a nut on each side
threaded to the specifications ? . one could still put a gob of plasticine on there and no mess to clean up on the master cylinder and could also (judge) the 5 pounds of pressure.
I am not going to remove my mc to try this, but it should work.
Boilermaster

 

[vintageman]

I used one of these to measure my pushrod during the install, worked great. Got it from Amazon for about $15

 

[manyo]

I am fortunate to work at a tool shop. I will give it a try this weekend.

I thank you all for sharing your information. Have a great weekend!!

 

[Bill73Ragtop]

When adjusting length of rod, I cut a thin (1/8" wide or less) strip of clear plastic wrap long enough to push down into the bore and leave 1/2" or so on each end hanging out. The insert very small ball of plumber's putty (BB size) into the bore. Slide MC into threaded studs tight to the booster. Pull off MC.
You can then pull out the compressed putty easily and measure depth of space between the rod and MC piston. You can use razor to slice putty if you want to measure cross section.

 

[Stanglover]

When adjusting length of rod, I cut a thin (1/8" wide or less) strip of clear plastic wrap long enough to push down into the bore and leave 1/2" or so on each end hanging out. The insert very small ball of plumber's putty (BB size) into the bore. Slide MC into threaded studs tight to the booster. Pull off MC.
You can then pull out the compressed putty easily and measure depth of space between the rod and MC piston. You can use razor to slice putty if you want to measure cross section.

That's what I do with plasticine, but I like the idea of thin plastic strip idea. It is pretty messy getting all the plasticine out.