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Spongy Brake Pedal

MA87K5

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skyforum New Member

skyforum

Posted
Posted

I have a 1996 K3500 dually with drum rears. I also have a ridiculously spongy pedal and no matter what I do, they still suck. The pedal hits near the top but as you apply pressure, it's like it reaches a point where it has no more power. Keep pushing and the pedal will hit the floor. Pumping up doesn't help. I bench bled the master cyl as required, I completely rebuilt the drum brakes on the rear with all new components, including springs, completely flushed all the old brake fluid out of entire system as well as installing new pads on freshly turned rotors on the fronts.

 

My question would be are there other components that can cause these issues? Can the ABS system have air in it? Is there a Rabs valve to deal with? Is pressure bleeding required or can you use the old stomp on the pedal till you have pressure system to bleed the brakes successfully?

 

I am using my 1996 K3500 as a wrecker. Typically, the ass is loaded heavy and the front axle gets light. this thing wouldn't stop properly even loaded with a p***ants motorcycle. The fronts will do all the work and the rears just lay there like a girl that's so good looking she doesn't think she needs to participate.

dwhults Enthusiast

dwhults

Posted
Posted

How are your brake lines? Could possibly be swelling up slightly reducing the pressure to the brakes. I've read that SS brake lines help with the spongy feel and that's my next mod this spring.

Harvey Halabookie Enthusiast

Harvey Halabookie

Posted
Posted
How are your brake lines? Could possibly be swelling up slightly reducing the pressure to the brakes. I've read that SS brake lines help with the spongy feel and that's my next mod this spring.

 

I agree. My pedal felt spongy in the '04 Yukon when I changed the pads and rotors. I then swapped out to Russell Stainless steel brake hoses and the difference was like night and day. Much firmer pedal and better stopping distances. If your lines are ten years old I would highly recommend changing them. Even if the hoses look good from the outside, they can still be bad.

skyforum New Member

skyforum

Posted
Posted
How are your brake lines? Could possibly be swelling up slightly reducing the pressure to the brakes. I've read that SS brake lines help with the spongy feel and that's my next mod this spring.

 

I agree. My pedal felt spongy in the '04 Yukon when I changed the pads and rotors. I then swapped out to Russell Stainless steel brake hoses and the difference was like night and day. Much firmer pedal and better stopping distances. If your lines are ten years old I would highly recommend changing them. Even if the hoses look good from the outside, they can still be bad.

 

 

Hmm, all good on my truck. Recently replaced.

I think I may have come across what my issue is. My K3500 uses the JB8 (build code) Hydro Boost brake system. Lately I have noticed that my power steering fails when the engine RPM's get down to an idle and since the power steering and the brakes run off the same pump, I might be looking at a failing pump assy. The truck can't lock the wheels up and getting into a scenario where I need to stop quickly is dicey at best.

 

The truck has very high miles (256k plus) and the steering box is also a little loose. I am going to replace the steering box and the pump assy because of the high miles and I think doing this just might solve my problem. On a hydro boost brake system, it is possible to push the pedal to the floor and this is normal. The lack of pressure being delivered would cause the braking power to be weak and would make one think the system is spongy even though it's really not.

 

I'll report on what happens after the repairs are complete.

ironhead3fan Enthusiast

ironhead3fan

Posted
Posted

Same story on my 1990 Chevy K1500. After I replaced the master cylinder, never was able to get a full brake pedal back. Paid to have them power bleed, no difference. Good luck!

  • 3 years later...
MA87K5 Enthusiast

MA87K5

Posted
  • Author
Posted

Well It happened again. Spongy pedal after pad change. The whole system is running clear fluid after I bled it. No air was in system. I bought AutoZone's duralast cmax ceramic pads and I have the spongy pedal. Was fine before. I'm getting tired of this. I have a feeling that the cmax pads are junk. There is 2 inches of pad contact compared to the ceramic pad from advance auto pads with 3-4 inches of contact.

amc31b Enthusiast

amc31b

Posted
Posted

Well It happened again. Spongy pedal after pad change. The whole system is running clear fluid after I bled it. No air was in system. I bought AutoZone's duralast cmax ceramic pads and I have the spongy pedal. Was fine before. I'm getting tired of this. I have a feeling that the cmax pads are junk. There is 2 inches of pad contact compared to the ceramic pad from advance auto pads with 3-4 inches of contact.

 

It sounds like you are on the right track. Try a different brand of brake pads and if that doesn't fix it, I would re-place the brake hoses and calipers up front also. With the age of your truck, replacing all of it isn't a bad idea anyways.

amc31b Enthusiast

amc31b

Posted
Posted

Well if you haven't done the hoses, I would change them out while you change the pads. Bleed the system of air when you are done and you should be all set. If that doesn't fix the problem, you might have a more involved problem.

  • 3 weeks later...
MA87K5 Enthusiast

MA87K5

Posted
  • Author
Posted

I changed the brake pads and I have my stopping power back. Now I know to never go to autozone for the ceramic pads again.

LongrangeLauber Senior Enthusiast

LongrangeLauber

Posted
Posted

Before I went to EBC pads and rotors I used the Wagner thermo quiet pads from advance auto. Great stopping power and quiet. Glad to hear you got it fixed though!!!

amc31b Enthusiast

amc31b

Posted
Posted

Glad it is fixed! Thank you for the follow up. To me, Autozone is like the wal-mart of the auto parts stores. Sure they have tons of stores all over the place and their hours are great but 95% of the parts are re-branded junk! Not to mention the packed stores, long lines, screaming kids all over the place and an underhanded staff that usually knows nothing about cars or barely speaks english. I only go to Autozone when I have absolutely no other choice.

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