Spongy Brakes

Jed700 · January 1, 2011

I have a 2003 Gmc Sierra 1500 ext cab 4x4 Z71. Ive only owned it a little over a year but as long as Ive had it the brakes have been very soft, I have to push the pedal nearly to the floor for anything to happen. I was going to start replacing all the calipers, rotors and pads but though I might be able to find some upgraded parts form newer years. Are there any known problems with these trucks causing them to have soft brakes? And are there any upgrades from newer models that will bolt on to my truck?

Thanks in advance

Shane

redsled2007 · January 1, 2011

Spongy Brakes is more than likely air in the system.

The pedal travel could be a self adjuster not working or air in the system.

Jed700 · January 1, 2011

I forgot to mention that I did bleed the entire system and it made no difference. thanks for the reply.

wicked ace · January 1, 2011

I have a 2003 Gmc Sierra 1500 ext cab 4x4 Z71. Ive only owned it a little over a year but as long as Ive had it the brakes have been very soft, I have to push the pedal nearly to the floor for anything to happen. I was going to start replacing all the calipers, rotors and pads but though I might be able to find some upgraded parts form newer years. Are there any known problems with these trucks causing them to have soft brakes? And are there any upgrades from newer models that will bolt on to my truck?
Thanks in advance

Shane

You may have the original rotors yet and these can be a source of heart ache as they were composite.

New rotors and pads should do the trick. If you do it yourself you'll be out an afternoon and about $300.

Something else to think about are the front brake lines. Inspect them for advanced rusting and make sure there are no leaks.

desrtrat · January 1, 2011

I have a 2003 Gmc Sierra 1500 ext cab 4x4 Z71. Ive only owned it a little over a year but as long as Ive had it the brakes have been very soft, I have to push the pedal nearly to the floor for anything to happen. I was going to start replacing all the calipers, rotors and pads but though I might be able to find some upgraded parts form newer years. Are there any known problems with these trucks causing them to have soft brakes? And are there any upgrades from newer models that will bolt on to my truck?
Thanks in advance

Shane

my 03 has the soft peddle also. a lot has to do with disk breaks all around.. best investment to start if all your breaks are in good shape, is go with stainless steel lines. they replace all the rubber hoses with braided lines. over time the rubber can get soft and expand a little giving a soft peddle feel. the SS lines correct that.

also check your master cylinder, the seals may be going bad..

good luck

Silverado4x4 · January 2, 2011

Try pumping the brake pedal very fast and see if the pedal gets firmer (build pressure) if it does hold the pedal down and if it slowly goes to the floor then your master cylinder is on its way out. How many miles on the truck?

Jed700 · January 2, 2011

It has about 120 000 miles on it

txab · January 2, 2011

You may need to bleed your ABS unit too

jblakeney · January 2, 2011

You may have the original rotors yet and these can be a source of heart ache as they were composite.
New rotors and pads should do the trick. If you do it yourself you'll be out an afternoon and about $300.

Something else to think about are the front brake lines. Inspect them for advanced rusting and make sure there are no leaks.

WTF.... brake pedal pressure from rotors???? Not possible

my 03 has the soft peddle also. a lot has to do with disk breaks all around.. best investment to start if all your breaks are in good shape, is go with stainless steel lines. they replace all the rubber hoses with braided lines. over time the rubber can get soft and expand a little giving a soft peddle feel. the SS lines correct that.
also check your master cylinder, the seals may be going bad..

good luck

More than likely you have a brake hose that is nearing the failure point (beginning to bulge when you press the pedal) or you have some trapped air in the system.

Stainless Brake hoses will definitely firm the pedal up, unless you have trapped air and you don't get it out after changing the hoses.

This is all providing you are not loosing brake fluid..... Which is another problem all together.

Jbo

jro909 · January 2, 2011

my brake pedal is like that also new pads and rotors all the way around..i always thought it was the norm with gmt-800s

Hilo · January 3, 2011

Try this: Undo one line from an outlet from the master cylinder. Plug the outlet. Press the brake and see if there is a difference. Reconnect the line and try the other outlet. If one is noticeably softer than the other, trace the line along that route and test each component (E.G., flexible lines for swelling under pressure, wheel caliper leaks). Also check to see that rotor thickness is still within specs.

Although you already bled the system, make sure that you got all of the old fluid out. Bleed until clean fluid comes through.

Diesail · January 3, 2011

This is a common problem on the GM trucks. The problem is with the pins that the caliper slides on and the fit of the pads in the caliper. Start by removing the pins and make sure they are clean and free of corrosion. Next check the fit of the pads in the caliper, the should slide easily. It is common to have to file a small amount off the edges of the pads backing plate to get them to slide easily. Then when re-assembling make sure you add a little bit of the proper lubricant to the side pins.

Jed700 · January 3, 2011

Thanks for the input everyone, once I get some cash im gonna replace the front calipers, rotors, flex hoses and I'll check out the master cylinder. Im wondering if anyone has swapped out to drum brakes on the rear? instead of spending the money to fix up the discs I may just try to find a whole rear end with drums. what all would i need to swap? ABS unit, proportioning valve maybe?

thanks

Shane

ChevyTech77 · January 3, 2011

Rotors are probably rust pitted/flaking and the pads are only hitting part of the rotor surface so friction is lost big time. Add in some frozen up rear caliper pins, pad guides and possible caliper pistons and you have your recipe for a spongy brake pedal. Never seen master cylinder issues on these. I have seen ABS units bypass internally though but that usually lets the pedal fall to the floor if it is held applied for a few extra seconds.

Diesail · January 3, 2011

Thanks for the input everyone, once I get some cash im gonna replace the front calipers, rotors, flex hoses and I'll check out the master cylinder. Im wondering if anyone has swapped out to drum brakes on the rear? instead of spending the money to fix up the discs I may just try to find a whole rear end with drums. what all would i need to swap? ABS unit, proportioning valve maybe?

thanks

Shane

Before you start throwing money at it, do yourself a favor and take the few simple steps I suggested. If you woudl like to do some more reading on the topic pay a visit to dieselplace.com and do a search for Heymccall and brakes. He maintains a fleet for a construction company and has much to say on the topic with his primary recommendations being those I made above. Also be careful if you decide to go the route of brake lines or calipers. IMO you don't really want to open these brake systems up and get air in them. If you get air in the ABS system you have to take it to somebody with a Tech II to bleed it.