Vacuum Brake question

[turboman38]

My pedal seems really soft. Not good when trying to slow down from 117 at the track. I can only hold 4-5 pounds of boost at the line. I have the S-10 wheel cylinders and the big brake shoes. When heating the tires at the track I do have to over come the rear brakes so I know they are heating up. But 4-5 pounds? Is my master cylinder going bad? If so what kind and from what car can I replace it with?

Thanks

 

[Red Regal T]

Your rear shoes need to be adjusted up close to good drums and they should be organic. To overcome heating while heating slicks, your going to need a line lock. If you want to try a new master cylinder, they're pretty inexpensive, about $30. Get one for an 87 NA Regal, but all G bodies from 83 thru 88 (MC) take the same master cylinder.