I was staring at my truck having a beer and a smoke when I had an epiphany.. could the brake linkage system cause the problem?
so the new MBC and BB came without the support frame. I luckily was able to purchase one from a member of this forum.
but instead of the pushrod going from the pedal directly in to the booster, there is a linkage system. ( see pics) how likely is it, that this diminishes the power I apply to the pedal to what eventually goes into the MBC?
further more I looked at the size of the booster and thought it was pretty big..(compared to European cars yes) but I have these two old MDC and BB's which I didn't use, because I bought the new one and looking at those, there is a significant size difference..not so much in diameter, but more in the depth.. the new one from bracket to mbc is 4" thick and the old one is almost 6" thick...that's, substantial!
