Soft brake pedal 04 silverado

[Silveradoz7104]

After changing brake pads and turning rotor a few months back on the rear the brakes have been super soft I am able to push brake petal all the way to the floor and it still take a second or two to come to a stop, I have checked all pads and rotors, scrapped where the pad clips sit and rebled the rear brakes but still not better. Not sure what to do 

[txab]

Start by thoroughly bleeding the brakes system

[richard wysong]

Also check the brake hoses for damage. Did you open the system  or run out of brake fluid when you did the brakes? If so there may be air trapped in the abs unit. If you did not open the system and just compressed the pistons on the calipers you may have forced any sludge/debris back into the abs unit, a costly mistake. When compressing caliper pistons always clamp off the brake hose and open the bleeder to avoid this problem. The fluid passages in the abs unit are almost microscopic, it doesn't take much to cause problems. As txab suggested follow the factory bleeding procedure and hope for the best. Any chance you twisted a brake hose reinstalling a caliper?

Edited June 5, 2024 by richard wysong

[thx1138v2]

You probably need to bleed the anti-lock system. I'm not sure about the '04 Silverado but it's located on the frame rail under the driver's side seat on my '07 Sierra.

 

They are tricky to get right so if you don't know how to bleed it take it to a shop.

[Silveradoz7104]

On 6/5/2024 at 11:49 AM, richard wysong said:

Also check the brake hoses for damage. Did you open the system  or run out of brake fluid when you did the brakes? If so there may be air trapped in the abs unit. If you did not open the system and just compressed the pistons on the calipers you may have forced any sludge/debris back into the abs unit, a costly mistake. When compressing caliper pistons always clamp off the brake hose and open the bleeder to avoid this problem. The fluid passages in the abs unit are almost microscopic, it doesn't take much to cause problems. As txab suggested follow the factory bleeding procedure and hope for the best. Any chance you twisted a brake hose reinstalling a caliper?

I havent opened up the system, or ran out of fluid. I think I compressed the calipers wrong. If what happened is correct what would be the correct bleeding procedure? Do I bleed abs first and then bleed all brake lines? I was super careful about twistingnorbtugging on break hoses 

[richard wysong]

If you didn't open the system then there should not be any air in the system. Try clamping off 1 brake hose at a time and see if the pedal improves. Sometimes air will become trapped in the lines before the abs unit and cracking the lines there usually eliminates it but again if you did not introduce air into the system and there are no leaks then there should not be any air in the system. When you are bleeding do you get a strong steady flow at each wheel?

[Silveradoz7104]

I have not tried bleeding yet do you know the specs for the rear rotor thickness im wondering if they turned it down slightly too much, if thats not the case then ill start eith bleeding the lines then go from there. 

[richard wysong]

rotor thickness should not make a difference in the pedal as the calipers self adjust. Have you driven the truck so you are sure there is a weak pedal? ABS brakes seem to have a lot of pedal travel when just sitting still and stepping on the pedal but feel fine driving. If pumping the brake improves the pedal there is air somewhere in the system, If it does not then do not waste your time bleeding. Most rotors these days are not designed to be cut as the minimum thickness is only 20 thousandths less than new and the cost to machine them may be equal to the price of new. Specs are stamped on the rotors usually

Edited June 21, 2024 by richard wysong

[Silveradoz7104]

1 hour ago, richard wysong said:

rotor thickness should not make a difference in the pedal as the calipers self adjust. Have you driven the truck so you are sure there is a weak pedal? ABS brakes seem to have a lot of pedal travel when just sitting still and stepping on the pedal but feel fine driving. If pumping the brake improves the pedal there is air somewhere in the system, If it does not then do not waste your time bleeding. Most rotors these days are not designed to be cut as the minimum thickness is only 20 thousandths less than new and the cost to machine them may be equal to the price of new. Specs are stamped on the rotors usually

Yes i have driven it, i can stomp the peddal completely to the floor and it still takes a second or two to stop at 5-10 mph, the brakes are really soft. Would you recommend replacing the rear rotors? 

[txab]

Rotors aren't your pedal problem. Replace rotors if they are under the spec.. If had them turned at a reputable place they should have told you whether there was enough left to remove. Like Richard said today's rotors are pretty much disposable.

 

Get your brakes including the ABS, bled thoroughly. Make sure your rubber brakes lines aren't degraded.

 

Bleed your brake system properly!

Edited June 22, 2024 by txab