Brake pedal goes to the floor after new shoes

[97c1500ext]

97 C1500

After recently changing the drum shoes in the rear several issues are occuring.

First thing, yes i believe they are adjusted correctly. I can barely pull the drums off due to how tight the pads are pressing against them.

The pedal when the truck is off is squishy for the first press then has decent pressure on following presses temporarily before getting lighter after not pressing for a bit.

With the engine on the pedal goes right to the floor with little effort and the brake lights turn on about half way down before turning off once it goes all the way down. Pumping repeatedly builds some pressure but not much and it goes away quickly

I tried a new MC and it did not change anything. Bleeding the lines then bleeding the ABS then the lines again yields no air, only fluid.

I pressed the pedal a few times with the drum removed to see if the adjuster was working, could this have damaged something?

I have the truck on jacks in the rear and put it in drive. when pressing the brakes i get no loss of wheel speed until about half way when it sounds like they slam on to full braking. Is this normal for being off the ground?

I have been trying to research for ours and cant seem to find any solution beyond "air in lines or abs bleed them"

 

[97c1500ext]

97 C1500

After recently changing the drum shoes in the rear several issues are occuring.

First thing, yes i believe they are adjusted correctly. I can barely pull the drums off due to how tight the pads are pressing against them.

The pedal when the truck is off is squishy for the first press then has decent pressure on following presses temporarily before getting lighter after not pressing for a bit.

With the engine on the pedal goes right to the floor with little effort and the brake lights turn on about half way down before turning off once it goes all the way down. Pumping repeatedly builds some pressure but not much and it goes away quickly

I tried a new MC and it did not change anything. Bleeding the lines then bleeding the ABS then the lines again yields no air, only fluid.

I pressed the pedal a few times with the drum removed to see if the adjuster was working, could this have damaged something?

I have the truck on jacks in the rear and put it in drive. when pressing the brakes i get no loss of wheel speed until about half way when it sounds like they slam on to full braking. Is this normal for being off the ground?

I have been trying to research for ours and cant seem to find any solution beyond "air in lines or abs bleed them"

To clarify, pedal was going to the floor before new MC, I bench bled the new MC before install and when bleeding my truck is on downward angle with the front lower than the rear plus it was on jacks in the rear only do i do not believe there is air trapped in the MC. Could this be an issue with the ABS module? Or a combination valve issue? I am seriously stumped.

 

[SUBURBAN5]

Do you have access to a scanner?

 

[97c1500ext]

Do you have access to a scanner?

I have a Fixd code reader but i haven't been able to get it to work lately so really no.

 

[SUBURBAN5]

Ok normally you need to bleed the abs module(kelsey hayes) per a scanner... second you replaced the mc. Did you bench bleed it first?

 

[GoToGuy]

What was the original problem? As there is no load on the raised wheels, your spinning them up and then braking tells some braking pressure is there, but nothing else. Very little brake pressure will stop the raised wheels. Activating the brakes with drums removed risk blowing out brake cylinders.
Bench bleed mas/ cylinder, very thoroughly? Replacement M/C is verified correct unit? What method to bleed brakes?

 

[Jeff Janssen]

do your drums have a "lip" (where the pad has not worn down the drum) on the outside, or were they machined? If there is a lip on the outer side of the drum they will feel tight but are actually not ajusted as your new pads are only contacting about 5% of the drum surface (contacting the lip only).

 

[97c1500ext]

Ok normally you need to bleed the abs module(kelsey hayes) per a scanner... second you replaced the mc. Did you bench bleed it first?

As stated in my original post, I bench bled the new MC before install and yes it is the correct part its identical to the old one and the only ACdelco option that comes up on Rockauto for my make model and year.

 

[97c1500ext]

do your drums have a "lip" (where the pad has not worn down the drum) on the outside, or were they machined? If there is a lip on the outer side of the drum they will feel tight but are actually not ajusted as your new pads are only contacting about 5% of the drum surface (contacting the lip only).

I polished the lip off myself. They are tight all the way on and off

 

[SUBURBAN5]

As stated in my original post, I bench bled the new MC before install and yes it is the correct part its identical to the old one and the only ACdelco option that comes up on Rockauto for my make model and year.

Awesome just want to clarify because bleeding can be a pain with these systems. Bleeding the mc was important. Did you bleed from the mc to the module, then bleed out the module, then bleed from furthest wheel to close wheel to mc? If all checks and bled right meaning via 2 person or a vacuum brake bleeder , then you would still have to bleed the abs module after all that.... the combination valve you asked about if determining a difference in pressure . If you bleed the brakes and the middle valve moved, your only bleeding front or rear depending of the pressure difference.