[52Dodgecoronet]

I've got a '62 Valiant resto-mod with the Kelsey-Hayes discs in front and 10" drums in the rear. The problem is that I've got to pump the pedal 2 or 3 times before it comes up to where it should be. Aside from that, the brakes work fine. I am using a disc brake master cylinder, but I am not sure it is the correct one.

I understand that I should be using the 1-1/32"-bore master cylinder rather than the 15/16"-bore master, so that's the first thing I am going to check.

However, I'm still using the pushrod from when the car had its old single-circuit master cylinder. Could that be my problem? What pushrod should I be using?

Thanks very much.

 

[dana44]

One of two things. I believe there are two small plates with three holes drilled in it that is needed at the brake pedal itself. The top hole attaches to pivot point on the brake pedal support, the second hole attaches a rod to the brake pedal and the bottom hole is the master cylinder pushrod. This gives you the extra leverage for the larger pistons and same pedal movement. I had the same problem with my 68 Charger when I converted to power booster, I had the parts readily avialable, but I might be wrong, this was a B body system and you have an A body system, but this would explain the extra pumping necessary. Hopefully someone else will chime in, I don't have my shop manual handy to verify.

 

[68RT]

To see if the push rod is the correct length, you take your hand and push the pedal down. You should only go a short distance and feel the pushrod touching the master cylinder piston. There are many different ways they have been adjusted. Variable length rod (2 piece threaded w/lock nut), Eccentric bolt where the rod connects to the pedal, Eccentric bolt on the pedal pivot, & multiple holes in the pedal. Also, if you have a power brake booster, they may have an adjustment between the booster and the master cylinder too. If you have an assistant, you can check all of this by watching the master cylinder piston start moving through the hole in the bottom of the reservoir and see how much the pedal has moved before moving the piston. If you do this method, be very slow moving the pedal or your assistant may have a face full of brake fluid. (You need not ask as to the source of this knowledge.)

 

[AC TC]

You will need a "discbrake" master cylinder.
The discs uses much more oil than the drums.

 

[Volunteer]

I will now proceed to hi-jack this thread (as it's been dormant over 4 years). Similar situation, dealing with brakes but slightly modified.
Just to update, my 'lovable' '69 Signet has the stock OEM 9-inch front and rear brakes - drums of course. I need to know the possibilities and procedures involved with converting to power-assist. ie: what booster, what master cyl., what proportioning valve, etc.? Is this do-able (with my present 'infrastructure'?
My current (power-assist) consists of both feet on brake pedal.