'70 Chrysler Stops As Though It Has Anti-Lock Brakes

Okay, fellow Moparites, I am still experiencing the following symptoms with my 1970 Chrysler 300 with power drum brakes.

Under normal conditions, the car stops with no noticable problem. But under sudden-stop conditions, it stops as though it has anti-lock brakes or the brakes on only one axle are working -- the brakes slow the car but will not lock up under any circumstances <img src="http://forums.aaca.org/images/graemlins/shocked.gif" alt="" />. The brake pedal seems to have a 1" "false bottom" which it will not move past, though when a bleeder is craked or a master cylinder line is removed the pedal goes all the way to the floor. I cannot otherwise force the pedal farther than 1" down.

Five years abo, I replaced just about everything in the system during a comprehensive brake overhaul. This year I installed a new master cylinder, rebuilt booster (by Booster Dewey) and I bled the brakes, all to no avail. Could it be the little "dual master cylinder valve" in the junction block causing the problem? I am not going to do any more gratuitous repairs until I get some feedback from the Mopar braintrust about this problem; I'm counting on you guys.

This is an HPOF car so, no, I don't want to "solve all of my problems" by switching over to disc brakes. I just want the factory brakes to again work as intentded.

So . . . any suggestions <img src="http://forums.aaca.org/images/graemlins/confused.gif" alt="" />?

Jeff

You have introduced a lot of new parts like master cylinder and booster that require careful adjustment of booster pushrod to master cylinder piston for a positive return to resting position of the MC piston.

Assuming you have gone over those adjustments per the shop manual, what about the brake shoe linings? If they were relined was the correct coefficient of friction lining used or did the shop just put anything they had on hand on them?

Another item could be were the drums turned to over size inside diameter and were the brake shoe linings "Cam Ground" to cause the linings to make full length contact with the new drum diameter? I had such conditions with an older car that required re-relining the shoes with proper material. (Front shoes & rear shoes usually have different lining material and if the fronts[Harder} and rears[softer] are reversed you can get strange stopping effects) *Usually rear linings on front shoes cause grabbing but if the lining hardness is not correct you could expect fade just the same.

Stude8