Hello all, It would help me greatly if someone were to measure the distance the smaller pin (that contacts the master cylinder) sticks out from the black brake booster rod (that goes into the front of the booster) on their factory disc brake system. I was confused about this "pin" as I discussed in a previous post and I now need to know how far the disc brake pin sticks out compared to the drum brake pin. Or, if someone would remove the pin from the black rod of their disc brake booster and measure it by itself so I know which pin I have. Mine measures 2 and 9/16" Thanks, Chris
Chris, At 2 9/16, you have the short booster pushrod or "pin". The long one is 4". If your converting from a drum to a disc system, simply look at the master cylinder piston, and determine if you need a short or long pushrod. The long pushrod hole looks like the picture below. The need for the long pushrod shows up in some 71 up disc brake masters, and in the repro 69/70 cylinder. All drum systems I have ever seen used the short pushrod, so if you get your hands on a master with the short pushrod piston, your good to go. Here is a pic of the master piston with the deep recess, for the long pin.
Here is the short pushrod piston. This is the application that may have the long piston at times, but since we are using an NOS booster on this resto, and it had the short pin, I simply selected the rebuild kit for this master that takes the short pushrod. This is a 71 master with the bleeders, that we did a stainless steel sleeve and complete rebuild on. JW
Thanks Jim, that was very helpful :TU: Now everything is cleared up. It's amazing what a couple of pictures can do. Now, do you happen to know where I can find a 4" pin? I have a 70 repro Year One master that I would like to use. I also want to thank Ken Warner for helping out in my other post :beer -Chris
Chris, As of yet, I have not run into the need for a source for that long pin. I suggest that you put a parts wanted ad, use those pics, and someone probably should have a booster with that pin in it sitting around. It just pulls right out. JW
