Brake Master Cyl Pushrod Adj

[jgkurz 52]

I am just getting my car on the road after a long restoration. My 69 is a Q code Mach 1 with front power disc. I completely replaced the brake system mostly with stock replacement parts. The new brake lines are stainless and the rubber lines were replaced with new stainless steel braided. When I installed the new booster, I carefully adjusted the pushrod so it had about 1/16 gap. I don't remember where I got that spec. I now have the 69 service manual that actually states the MC piston should contact the pushrod but move it no more than .015". My brakes are bled properly, but the pedal is lower than it should be and has a gap before the brake pedal engages. The pushrod is obviously adjusted incorrectly.

Here's my question. Can the pushrod be adjusted without completely removing the master cylinder out of the car? I would guess no, but I'd like to hear your feedback.

Thank you!

  

[1969_Mach1 333]

I don't think the master cylinder can be moved far enough without disconnecting the brake lines attached to it.  My Ford service manual gives also gives that 0.015" movement spec but it also states, ideally, there should be no movement.  Be careful, that is a delicate adjustment, a little too far with the adjustment in an attempt to get a higher brake pedal and the brakes will burn because the master cylinder doesn't fully release them.

[jgkurz 52]

Ok, thanks. I suspected that. I'll plug the MC ports so fluid doesn't drain the just bleed the brakes again. I think I'll buy a pushrod adj tool so I get the measurement perfect. 

[1969_Mach1 333]

If your fittings are plugged at the master cylinder and you cap the open end of the lines with something like a vacuum plug, usually very little air will get in.  Therefore, before bleeding the brakes again at the wheels try bleeding the system at the master cylinder.  Have somebody hold the brake pedal down (not pumping it several times) and crack open one brake line fitting at the master cylinder.  Retighten the fitting before releasing the brake pedal.  Put a rag around the fitting when you crack it open.  Then do the same with the other fitting.  Maybe two or three times for each fitting.  Doing this is usually enough to remove any air trapped near the master cylinder.  It's easier than bleeding the brakes at the wheels to remove air at master cylinder.  If it doesn't completely work then you will need to bleed the system at the wheels.

[ClubSport 29]

[jgkurz 52]

 Interesting. I already bought the tool but this would be cool for those who don't have one. 

[1969_Mach1 333]

jgkurz,  the sketch to make that tool is in your Ford service manual.  It's on the bottom right of the page previous to where you found that 0.015" specification.

[jgkurz 52]

Clearly my pushrod wasn't adjusted correctly.   Looking forward to much better brakes.

 

[1969_Mach1 333]

Where did you find that tool.  I used dial calipers and a parallel bar.

[jgkurz 52]

It's made by Baer Brakes. Summit has them for 49.95.