Low brake pedal

[Supercharged111]

I have the 9.5 rear, so whatever that is. I adjist them regularly, but the drums are warped. I have 2500 front calipers and Hawk ceramic pads up front. Everything seems to work well, but the pedal doesn't do anything up top like the dually. This causes it to bottom out and just leave you screwed no matter how hard you stand on the pedal. No leaks, I have Russel braided lines, and flush brake fluid every year or 2. Adjusters are all in good condition, but the drums have over 250,000 miles on them. They could be oversized, it'd probably be worth it to take them to Blow Reilly's to measure ID. I had the 3 channel ABS but that was deleted years ago. I do have a stock TBI era rear prop valve though.

 

[Gibson]

Because this is a forum specifically dedicated to GM products, some of this might be moot, but there is no "hard and fast" rule about the size of brake shoes as used in "leading-trailing" and "duo-servo" brakes.
Examples can be found where both types have used both equal and un-equal sized shoes, depending upon the application.
The term "Duo-Servo" comes from a design by Bendix that dates back to the 1930s, and other makers such as Kelsey Hayes built similar types that have some mechanism changes so as not to infringe on the Bendix patents.
There are "duel leading shoe" brakes, they were used on many Chrysler products and also International.
They use two wheel cylinders, they are very good going forward, actually better than the Bendix design, but not as good in reverse, and are a pia to adjust,, using cams to set the clearance.
In the old days, a good brake shop would "arc-grind" the shoes to ensure good contact, because in both types the travel of the shoes is not circular, but rather an ellipse,, but today nobody wants the brake dust in the air, and so shoes are just allowed to "wear to fit" to conform to the drum.

 

[gordonm1]

I'm going through something similar with my 1991 K1500 W/T standard cab. It has the crappy adjusters over the axles in the rear. When I pulled the drum and adjusted one side the parking brake pedal got stiff/less travel but I didn't really feel any change in the regular or service brake pedal. The right side was dragging more so I did not adjust it but I will adjust it eventually.

I have recently done RB master, RB calipers, new rotors, new Wagner TQ semi-metallic pads pads, and fluid flush/bleed. I still can't seem to get the fronts to lock up on dry pavement but they do lock up in gravel. The rears are RWAL and they do not lock up.

Original tires were 225/75/16 and I have new 245/85/16 traction tires now so I think a lot better tire grip now. Maybe that's the issue (too much grip for my brakes) but the pedal is a little low.

I read the sticky about brake up grades and using light duty 3/4 ton calipers. I also found at Auto zone a 10-1/2" booster that is supposed to fit where my original 9" booster is. Does either of these work? been done?

I will post my own thread too. Mostly posting here to say adjusting the rears raises where the parking brake pedal engages.