how to check rotors and other questions.

[1low4x4]

Hey I Am pretty fed up with my brakes. Last month I finally figured out that red light in the dash was an indication of a big problem. Pulled the master cylinder cover off and the rear brakes were bone dry. No wonder I had problems stopping. So I ended up replacing booster, master cylinder, front brake pads, the proportioning valve, and finally the light went off and I got pressure back to the rear. What I am experiencing now is hoping and vibrating and shaking when I hit the brakes at any speed above 45 miles per hour. I am looking to fix this this Saturday. What I want to do is replace the front calipers, the front rubber lines, the rear rubber line, the rear wheel cylinders, and the rear brake pads in the drums.

what I want to know is how do I test the thickness of the front rotors, what tool do I need to buy and what is the thickness they should be. And if I need new ones I will buy them. Also can you check the rear drums? I want to do this one time. I have a few questions, like I know there is a brake pad in the back with Arij on it that goes on a certain way in the drums, I need to know how that goes together because I pulled my drums the other day and there is no Ridge left on the pads, though they do not look too worn. I heard an improperly installed pad on the back could cause the hopping and vibration. So basically I am looking for tips and replacing the rear wheel cylinders and the drum brakes and checking all for rotors for wear. I've done the lines and calipers before and that's simple.

another problem I'm going to have is getting the right parts. I guess I should measure the thickness of the rotor, up front, so I know what caliper to get. But what about the rear brakes? I know they are going to ask me all kinds of codes and or if they are heavy-duty brakes, all I know is it is a semi float 14 bolt rear end.

 

[1low4x4]

Bump

 

[GTME94]

I think a caliper would be the proper tool to measure the rotor thickness. I don't know the spec, I have seen some rotors with the min thickness cast into the rotor.

For the rear shoes, the longer friction material one goes on the rear. I'm not sure how to measure a drum thickness.

My tip for drum brakes is to do one side at a time so if you get confused on how the parts to together you can go look at the other side to figure it out.

I know there is another thread where chegny has posted some great pictures of the drum brakes assembled.

Does your SPID label have a brake code reference? I have frequently referenced the information packet downloaded from the GM Heritage website. I gives you all sorts of details including the brake system code that is std and then optional heavy duty codes. Since mine is a camper special the brake code is "hidden" in the content list that comes with the C6P heavy duty suspension list. I think there is a sticky here about the GM Heritage site and how to download it for your year.

I definitely had to know my brake code because the first MC they gave me was for std 3/4ton brakes and not the heavy duty.

 

[GTME94]

Here are the service manual specs on rotor thickness:

ROTOR THICKNESS

MINIMUM AFTER REFINISHING -(DISCARD)

1.480 1.465
1.230 1.215
0.980 0.965

I'm guessing these are for 3 different rotor designs with different thicknesses.

Here are the drum specs:
DRUM DIAMETERS
ORIGINAL -MAXIMUM REFINISH -(DISCARD)
11.000 11.060 11.090
11.150 11.210 11.240
12.000 12.060 12.090
13.000 13.060 13.090

 

[GreaseDog]

Replacing pads, calipers, and hoses are not going to fix your vibration problem. The fact that it only happens when you're on the brakes indicates a warped rotor. Take them off, and take them to have them machined.

 

[1low4x4]

Replacing pads, calipers, and hoses are not going to fix your vibration problem. The fact that it only happens when you're on the brakes indicates a warped rotor. Take them off, and take them to have them machined.

Yes, but, lines are brittle, and if I'm replacing lines I may as well replace calipers. And if I'm replacing or turning a rear drum, I may as well replace pads.