I have a 85 trans am ..4 wheel disc . It has excessive pedal travel on braking . Installed new master cylinder ...I believe it maybe rear calipers ...Has anyone encountered this ...how is camper piston reset to allow new pads ..any info would be appreciated...like. from down under ..thank you

 

Needs the typical disc brake piston screw-in tool to reset the piston all the way in. Looks like a cube with abuncha protrusions on each side in odd places.

That brake system is well and widely known to be ... problematic. Don't expect too much out of it no matter what you do. Modifying the prop valve helps; search this forum for something like "grainger spring", that's the very first go-to. Well, the second; behind using the parking brake EVERY TIME you get out of the car, and AT LEAST twice on Sundays, just for good measure. That's what "adjusts" those calipers. If you don't do that it'll rapidly descend into no-rear-brake hell.

Of course I'm guessing you successfully accomplished the obligatory "bench bleeding" on the master cyl before you put it on, right??

 

Yes ..I've been bad for not using the handbrake ..and you maybe right ..in that it's caught up on me ...it's never been great on brakes ...

 

A Wilwood adjustable proportioning valve, adjusted correctly and Goodridge braided stainless brake hoses really helped with pedal feel on my '88 GTA OEM rear disc brakes. Just a word of caution on the Grainger spring mod as not long after I did that the prop valve developed a leak...unknown if it was directly related but something to consider. Also, a flaring kit is needed for the Wilwood prop valve to make everything work so it's not exactly plug and play.

 

FYI, you CAN screw the piston back in w/a pair of needle nose pliers....it sucks, but you CAN do it, if you don't have the tool and are in a pinch.

The rest...man I SO agree!! Even fully functioning/all new parts...that brake system is boarder line unsafe, IMO. It's like the BlackBerry of disk brake systems; they should have skipped it, kept drums in the rear, until they had a proper 4 wheel disk brake system (the PBR) to offer.

 

I worked at the dealer when these cars were new, they came with a brake problem. If your rear calipers are more than a few years old throw them away and get new calipers. The brake fluid attracts moisture and the mechanism in the caliper rusts and gets gunked up. Unless you have the ability to rebuild them properly just replace them. And while you're at it all of the rest of the system if it's original will need replacing too.

 

Amended.