Whits end with brakes

[SCOTI]

Originally Posted by theastronaut

Adding this here since it got bumped up-

Check the caliper seal grooves. I recently ran across a disc brake kit that had low-drag calipers in it, and couldn't get the front brakes to build pressure no matter what. I eventually figured out that the calipers were the low drag version where the piston seal grooves are cut at an angle that cause the piston to be over-retracted for less pad drag and better mpg. The problem with that is those need a special step bore master cylinder which pushes a ton of fluid initially to get the piston back out to the pads, then internal passages switch to a normal size bore that makes adequate hydraulic pressure (thats what causes the whooshing noise when you hit the brakes on 80s/90s GM trucks).

Yep.... Seems like it was on the LtDuty C10's (81-87) as well as S10's & g-bodys (for sure) in those years.