Sensitive disc brakes

[long1776]

It's never boring with old cars, one problem solved and another pops up!
Slightly touching the brake pedal and full stop! M/C has been restored, new brake hoses, new fluid and system has been aired.

[Rerun]

quote:M/C has been restored

Looking at this and your other post, I suspect that the problem is in your M/C. But first, check the adjustment of the rod on your booster. It should be 1.250" to 1.245" from the face of the booster. If it is too long, it can create both problems that you describe. If this is OK, I would re-check the M/C.

Do you have the original type M/C that supplies all wheels from a single port, or has it been upgraded to a dual circuit system? Did these problems begin after the M/C was restored? Not knowing what was done to "restore" it, is it possible that an incorrect M/C was installed? If a M/C designed for drum brakes was used, the residual pressure valve would need to be removed. If it was rebuilt, could the piston be incorrect? If the primary cup of the M/C is too thick, or the spacer behind it is too thick, the brakes would be as you describe, too.

Jim Bradley
Lewistown PA
'78 Avanti II

[Dwain G.]

Is this the 'creeping Avanti' you are working on? Severe power brake action usually means something wrong inside the booster, like control valve or return spring.