Setting brake booster pin depth

[Mopars & Missiles]

I'll also add that the factory method often used a "combination valve". This valve was the distribution block AND the proportioning valve all in one unit. Proportioning was pre-set by the factory and not adjustable AFAIK. Different makes/models had different setups, so you need to refer to your FSM for your cars requirements. I do not know exactly what your car should have, as there are many different combinations possible.

 

[Lineman]

Previous posts have shown you how to set the push rod (match it) to your Master Cyl., so be sure to check that. FSM shows the spec and how to do it. IIRC, the push rod length should be about 0.900" +/- 0.020. Check the manual and measure your M/C depth and push rod extension before mating the two together.

Front disk/rear drum car needs to have a proportioning valve to set the front/rear brake ratio. Since you say your car is a "factory front disk" car, it should have a factory proportioning valve on it unless it was removed at some point. If not, you need to get an aftermarket proportioning valve and install it in the rear brake line.

What you are describing as the rears doing 75% of the work is very DANGEROUS. In a panic stop situation, the rears will LOCK and you will most likely NOT be able to control the car, as the back end will try to come around in front of you. In other words, you WILL spin.

One other thing, there is a big difference between a "proportioning valve" and a "distribution block". Many people confuse the two.

Thanks for the help, to save the math I think I will just get the little tool they are talking about in the thread to measure the rod depth. I added a pic of the distribution block, but I thought it took care of some proportioning duties? I thought the limiting valve going to the rear brakes on disk brake cars, (which mine has) was there because they didn't have different proportioning/distribution blocks on disk to drum cars?

BTW - I think I mentioned something about It thought this was a uncomfortable situation so I appreciate the help..

 

[CoronetDarter]

This thread is good information, but is it my problem? I have a 69 GTX with factory disks. Somebody had a Summit booster on it so I assume it was a power brake car. I just put the almost correct booster on it from inline tube with a new master cyl. The brakes are pretty touchy and it seems to be stopping on the rear brakes mostly. I am going to say 75%.. on the rear brakes maybe more. The rears are getting pretty hot when I check them and you can put your hand on the fronts.. I think when you really mash the brakes it would turn the car around quick.. I have pulled the master cyl and it doesn't seem like the rod is pushing on the piston in the master cyl..

Can anybody put me on this one..

Thanks

Jay

I was experiencing the same thing on the Coronet - the rears got so hot I couldn't touch the lug nuts. The push rod was adjusted too long. I used the caliper/straight edge method to check the gap. I also put a dab of red brake grease on the end of the pushrod and then torqued the m/c to the booster (off the car). Any grease transfer at the cup meant the pushrod was still too long.
BTW, that proportioning block looks correct for disc/drum.

 

[69 hemibee]

Going through this right now, this thread has tons of great info. Thanks!

 

[mrmolding]

Just wanted to thank you for this thread! I put in all new master cylinder, booster, lines, hoses, brakes, etc. But the pedal was going to the floor and the shoes were not going out very far and I was stumped. I'd bled the brakes twice and rechecked shoe adjusters and since I converted to power brakes, I'd forgotten about this adjustment. Bought the tool, adjusted the rod and the pedal feels great. We'll see how well it stops soon. Thanks again!