Power brake 'adjustment'

[Timothy B.]

I recall seeing a post that I now can't find in the archives that discussed the length of the rod from the power brake booster to the master cylinder. I believe a oldtimer that actually started "Dr. Rebuild" was one of the posters, saying that he had experience in the effect of different rod gaps. I would like to find out more about what the end-effect is of having more or less gap in that rod. My car, with new calipers, booster, mc, lines, etc., now seems to have a bit too much "throw" before the brakes engage. Brakes feel OK once they do engage, just maybe a bit spongy, and I will be rebleeding soon to see if that helps. It does seem to me however that the amount of gap in MC rod would effect the feel of the brakes. Any insight from anyone?

[Harry Sadlock]

Re: Power brake 'adjustment'

I have a 63 with PB, therefore this post is from a 63 point of view.

The rod between the power booster and the MC is adjustable. As I recall each 1/8 inch of adjustment to the rod will result in 1 inch of change in the pedal. Based on your post, it sounds as if you need to adjust the rod and make it 1/4 inch longer. You can remove the bolds from the MC and remove the MC from the booster. Have help to hold the MC as you adjust the rod from the booster. After the adjustment, just re-bolt the MC and give it a test. Do not remove any of the brake lines or you will need to re-bleed the brake lines.

I suggest you check the clevis adjustment under the dash first and ensure the brake lights work prior to adjusting the booster and MC.

Good Luck

Harry

[Harry Sadlock]

Re: Power brake 'adjustment'

I type too fast, that was bolts not bolds, but it's actually the nuts.

Harry

[Timothy B.]

Re: Power brake 'adjustment'

Thanks Harry,

I think from what I have read that the rod on the later midyears is different, as mine had no apparent adjustment when I installed it. I have seen photos of some with a small screw adjustment on the end. What does yours look like? I did try rotating the rod before I assembled the MC, and it did not appear to go anywhere when I rotated it. There is a reference in the overhaul manual to a "special adjustable rod" that can be installed when adjustment is necessary. Sounds like I might need such an adjustment?

[Harry Sadlock]

Re: Power brake 'adjustment'

The adjustment rod has a hex head not a screw head. I adjust mine with an open-end wrench.

Harry