Soft Brake Issues

mudpie said:

I'm having similar issues. I had to tow a car on a dolly a few days ago and noticed my front brakes were getting real hot and my rear didn't seem to be doing much. Like you, my parking brake seems to be functioning well.
I was doing a search and this thread came up. I'm wondering if you found the problem with your truck.

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Check your RPO codes to determine which brakes your truck was given.

RPO JB5 or JD5 is common on many C/K1500s, which are 10" leading/trailing brakes that generally do not stay in adjustment. The shoes are 9.96" x 2.24".

RPO JB6 or JD6 provides the 11" duo-servo brakes which are much better, with bigger diameter drums and wider shoes (11.15" x 2.75")

@Schurkey may weigh-in on the matter, he knows the brakes well and has posted much about the 10" and 11" drums, and other info.

My brakes are JB7. I pulled it apart and my rear drums were way out of adjustment, and my front calipers are not quite frozen up but pretty close to it. I'll be doing everything, and I'll start another thread to ask questions. Not trying to hijack this thread, though any thoughts you have would be appreciated.

A few things that are often overlooked;

Make sure the calipers float properly.
Bolt the caliper down without the pads. You should be able to slide them in and out with one finger. You may need to push FIRMLY with one finger. If they don't fix it. Use official brake lube only. It really is better.

Check the rear backing plates for wear on the raised pads where the shoes contact the backing plate.
Weld/braze/smooth them out or replace them if needed. The shoes get stuck and it leads to inconsistent braking.
I smooth the contact areas of the shoes with a wire wheel to remove any burrs. Do not remove any metal! Just smooth them out.
Put a small smear of brake lube on the backing plates so they will move smoothly next week as well.

Bleed the system well. If the brake fluid is dark it is dead. I use the Earl's Solo Bleed bleed screws. They have a check valve built in making bleeding ultra easy. They are sold by size. You need diameter, thread pitch, and overall length to get the right ones.

Braided PTFE hoses are a very good upgrade and really help with the brake feel. Be warned if you do braided brake hoses on one vehicle you will put them on everything else you own. The same goes for the solo Bleeds.

Upgraded frictions are next. Pads/Shoes have a letter code that tells how hard they pull. The first letter is for cold braking and the second is for hot breaking like when the trailer is on the back. The farther down the alphabet you go the harder they grab. The higher level of braking frictions may accelerate drum/rotor wear as well as increasing brake dust production.

Follow the friction manufacturer's bedding procedure. I does make a difference.

mudpie said:

My brakes are JB7. I pulled it apart and my rear drums were way out of adjustment, and my front calipers are not quite frozen up but pretty close to it. I'll be doing everything

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You should monitor this very recent thread which covers the same topic, i.e., wholesale replacement of many brake parts.

I was having soft brake issues as well, seems common on these trucks. Turned out to be a leaking rear axel seal. Replaced the seal cleaned everything up adjusted the brakes and all is well.