A GMC 2500HD brake question....

[Alan Schlosser]

...for the Brain Trust.
Going to help my neighbor put new disc's and pads on his truck. I've done tons of front disc and rear drum, but never rear disc.
I think there's a tool we need to run the pistons back in on the rears, but that's about all I know. I'm sure I can pick one up at the auto parts joint, but is there a procedure, or correct versus incorrect way to do it? I know someone can answer this. You've never let me down.
Thanks in advance!

[Suzukizilla]

Never done a 2500 myself. Is it the combo disk & drum? Thats what my '01 4wd Blazer has. If it is you dont need any special tools. Just compress the rear caliper with an old break pad and C-clamp like the fronts. The piston on the caliper should have some kind if indentions so you can use the 'special' tool to turn them in. If you dont see any then its probably just like regular calipers. Of coarse when bleeding the breaks always start with the farest break from the mastercylinder and work to the closest.

[bwringer]

Never done a 2500 myself. Is it the combo disk & drum? Thats what my '01 4wd Blazer has. If it is you dont need any special tools. Just compress the rear caliper with an old break pad and C-clamp like the fronts. The piston on the caliper should have some kind if indentions so you can use the 'special' tool to turn them in. If you dont see any then its probably just like regular calipers. Of coarse when bleeding the breaks always start with the farest break from the mastercylinder and work to the closest.

Why would he need to bleed the brakes when they're just installing new pads and rotors?

Anyway, if possible, you might want to pull one of the rear calipers and see what the indentations, if any, look like before you buy a tool. I've had to customize one of those special tools before to get it to work, but it was fairly straightforward. If they are the pistons that screw in, just apply pressure and turn, turn, turn.

You might also just drop the $15 for a Haynes shop manual, which will explain the procedure clearly.

GM likes to play mix-n-match with brake components, so it's hard to tell what the truck actually has back there.

[Suzukizilla]

Why would he need to bleed the brakes when they're just installing new pads and rotors?

Depends on the color of the fluid. If its black/dark brown bleed them. Also breaks can still be soft after a break change. Air can get in the lines if theres enough miles on the truck and break fluid does goes bad after a while. Had to do it with my blazer at 80k.

[Alan Schlosser]

I think I've got it. They're disc rears. I can get the tool to turn the piston back in. The cheapie tool is around nine dollars that goes on the end of a socket wrench. Press and turn, press and turn. Shouldn't be too much of a problem.

[Buddy]

The piston on that truck should just push back, no turning needed. It has a seperate park brake activated by a cable. It is a good idea to open the bleeder screw and let the fluid push out rather than back to the master cyl. Some ABS systems dont like having fluid pushed back through them. Also there may be sediment in the caliper that could harm other components.