1999 Chevrolet Silverado Extended cab 4X4 brake question?

[Big Bubba]

Happy Sunday afternoon to everyone,
I own a 1999 Chevrolet Silverado 4X4 extended cab, 5.3 liter V-8 motor pick-up truck. My question is I replaced all 4-wheel disc brake shoes since they where worn especially the rear axle real bad. Anyway, after I changed the brake shoes out I took my truck for a ride and noticed it was dragging and when I stopped had a real noticeable brake burning smell. So I went and touched all of the rotor hubs, not the shiny part, to feel how warm they were. I touched the front and it did not burn me immediately but when I went to touch the rears it immediately almost burned my fingers on contact and I immediatel removed my fingers. Also, I jacked my truck up from the rear and in nuetral I could not spin the rear wheel/tire assembly and then I went to the front and jacked it up and could spin the front wheel/tire assembly just fine. So what I think is going on is my rear calipers are hanging up internally and are not relaxing when the brake pedal is not being pressed down to apply the brakes. So I am going to replace both rear calipers tomorrow. I was told that if I replace just the rear calipers that I wouldn't have to worry about bleeding the front axle since it is on its own reservoir. Is that true and the reason I am asking is because my left front caliper's bleeder fitting is corroded and I can't brake the bleeder fitting lose and afraid that I will strip it out or brake it off plus I am on a tight budget and trying to make this job as cheap as I can. Let me know, Bob

 

[TilliamWe]

Re: 1999 Chevrolet Silverado Extended cab 4X4 brake question?

Bubba, I am sorry I can't answer your exact question about bleeding, but I wouldn't believe that "the front brakes have their own reservoir." Yes, every reservoir I have seen in a GM truck has two "bowls", but I wouldn't say they are truly separate.

But I am going ask another question. What is the parking brake mechanism on those rear discs? Is it the "drum brake shoe" type that works against the inside of the rotor? If so, is there any chance it is staying partially engaged? And if it is the type that manually activates the caliper, is it possible the cable is out of adjustment? I only ask, cause I'd hate to see you replace calipers and still have a problem, due to the parking brake.
Good luck.

Haynes manual sold at Autozone might give you a definative answer on the bleed both axles question.

 

[MrBigStuff]

Re: 1999 Chevrolet Silverado Extended cab 4X4 brake question?

The rears are disc/drum right? The main brake is disc with a drum parking brake...

Make sure the parking brake isn't hanging up. When you installed the new pads, you made sure to clean and grease the caliper slider bolts, right? This is important so that the calipers will slide on the pins as the pads wear and apply even force to the rotors.

When you pushed the caliper pistons back into their bores, did you crack the bleeder or did you force the brake fluid back with it closed? Opening the bleeder insure that all of the sludge goes out the bleeder rather than being back flushed up into the system. Especially true for ABS systems.

If both rear brakes are acting up, it might be due to the distribution block being gunked up.

Yes, the circuits are separate. The master has a slot between the two reservoirs but once the fluid goes down below the depth of the slot, they act separately. A big safety concern in their design to insure that if one circuit fails it will not drain both of them.

When you bleed the brakes, it is very important on an older system to avoid pushing the brake pedal to the floor. Do not go past the normal travel point of the pedal. There will be a debris layer built up in the master and if you push the piston past this point, it can easily score the seal and now you have an internal master leak. It will take slightly longer with more pedal strokes but it's worth not risking damage to the master seal.

Sometimes, when one brake fails, it is the flex hose that degraded internally. This acts like a one way valve since the hydraulic pressure can force fluid past the obstruction but relaxing the pressure, it does not return. If both are bad, either the distribution block is plugged or the calipers are sticking.

 

[Big Bubba]

Re: 1999 Chevrolet Silverado Extended cab 4X4 brake question?

Mr. Big Stuff,
I went back and pulled the calipers off the rear axle and used a c-clamp to compress the pistons back in then I installed both calipers and put the wheel/tire assembly securely back on and spun both tires and they spun easily and then I went ahead and cranked the truck up and depressed the brake pedal a few times and then went back to the wheel and tire assembly and tried to spin them by hand and I couldn't so I am hoping that the calipers are the issue. Now the brake blocking valve your talking about where is it at so I can check it out and what will I need to do if I do take this off or what will I be getting myself into basically if I remove this brake blocking valve? Also, I did remove and clean, 2 each per caliper, the caliper pins and even cleaned lubed each of those 2 each silver slides

 

[MrBigStuff]

Re: 1999 Chevrolet Silverado Extended cab 4X4 brake question?

The distribution block is the T fitting on the rear axle that splits the main rear brake line to the two rear wheels. It's the last thing I would try because it is likely to be corroded up something fierce. Sometimes, they get gunked up when you force old fluid back up into the system.

Based on what you wrote, it could be both rear calipers are sticking. If it were mine, I'd pull them off and retract the pistons again, seeing how much force it takes to push them back into their bores. They should slide in with relatively little force. If not, they're gunked up, the seals are hard or their is something blocking the reverse flow of the fluid, like a collapsed flex line or plugged dist block for example.

When you press the brake pedal, the pistons move forward in the bore. The seal rocks in its groove as it drags behind the piston movement. When you release the pressure, the tension created by the rocked seal causes it to retract the piston slightly as it relaxes back into shape. If the piston seals are hard, it won't retract the piston properly. Gunk will also inhibit retraction.

Oh yeah, forgot to mention, now that the master is full again, you'll need to be careful pushing those pistons back so you don't overflow the master...

 

[slasmith1]

Re: 1999 Chevrolet Silverado Extended cab 4X4 brake question?

The first question is did you replace the rotors also or just the pads. If you only replaced the pads the first thing to check is if the rotors are warped. as well as whats beeen said about parking brake adjustment. If that is all within specs then try the compensator (check) valve. and get the abs system checked last possible solution is the calipers on that system.

Also if you are having trouble opening the bleeder valve use a line wrench or 1/4 drive socket not a standard open end wrench.

 

[Big Bubba]

Re: 1999 Chevrolet Silverado Extended cab 4X4 brake question?

Good afternoon everyone,
I went ahead today and changed out both rear disc calipers and that fixed my problem. I bled them about 6 times each and took it for a drive and she worked great plenty of brakes and no burned brake smell like before. After the drive I jacked the back end up and the tires spun good both sides and then I jacked the front end up and the front tires spun easily to so I am thinking that the calipers where shot and they were corroded up pretty well and I did have to really force the pistons back in the old calipers. Thanks for your help. Again replacing both rear axle calipers fixed my brake dragging problem today.