Soft Brakes

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Peter Arseneault

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Hi All,
After changing out rear calipers, rubber brake hoses, pads and rotors on a 2003 KJ I have very soft brakes. I have no leaks anywhere. I double checked everything was seated and tight. I did bleed them out (roughly put a quart of DOT 3) through and am getting clean fluid with no air at all bleeding through. I bled all 4 wheels. If the vehicle is off and I pump up the brakes I get a hard pedal, as soon as I start the vehicle the pedal drops to the floor with the slightest pressure. Anyone else had an issue with this or have any suggestions? TIA
 

JasonJ

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May want to re-bleed but begin at the master cylinder.. then proceed to do the fronts, then rears in the specified order.

A Soft pedal can only be caused by air or a leak. It may be trapped and difficult to get out.

What method to bleed the air out did you use?
 

Peter Arseneault

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Thanks so much for the reply. That's kind of what I was wondering if air was trapped in one of the rear rubber lines since they have an upward loop to them. When you talk about bleeding the master cylinder, I am familiar with bench bleeding the master cylinder. Do you crack open the flare fitting where it taps into the m/c and then pump the brake pedal?

For the bleeding process I did all the work. I then bled all 4 starting with rear passenger, rear driver, front passenger, front driver. Fronts never pushed any air out but I got a good bleed on them. Rears I got quite a bit of air out of which cleared up, but still getting soft brakes. I had an assistant pump of the pedal firm, then hold. I went under opened the bleeder and shut it down before the fluid stream stopped. I also made sure the fluid reservoir was always full and never ran dry. I've done a ton of brake work before and have never had this so I was wondering if there was something simple I was missing.
 

tommudd

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Thanks so much for the reply. That's kind of what I was wondering if air was trapped in one of the rear rubber lines since they have an upward loop to them. When you talk about bleeding the master cylinder, I am familiar with bench bleeding the master cylinder. Do you crack open the flare fitting where it taps into the m/c and then pump the brake pedal?

For the bleeding process I did all the work. I then bled all 4 starting with rear passenger, rear driver, front passenger, front driver. Fronts never pushed any air out but I got a good bleed on them. Rears I got quite a bit of air out of which cleared up, but still getting soft brakes. I had an assistant pump of the pedal firm, then hold. I went under opened the bleeder and shut it down before the fluid stream stopped. I also made sure the fluid reservoir was always full and never ran dry. I've done a ton of brake work before and have never had this so I was wondering if there was something simple I was missing.
Bleed Right rear first, then left rear , right front, left front
soft pedal can be booster, master cylinder or air, rule out air first
 

J33Pfan

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May want to re-bleed but begin at the master cylinder.. then proceed to do the fronts, then rears in the specified order.

A Soft pedal can only be caused by air or a leak. It may be trapped and difficult to get out.

What method to bleed the air out did you use?
Hi All,
After changing out rear calipers, rubber brake hoses, pads and rotors on a 2003 KJ I have very soft brakes. I have no leaks anywhere. I double checked everything was seated and tight. I did bleed them out (roughly put a quart of DOT 3) through and am getting clean fluid with no air at all bleeding through. I bled all 4 wheels. If the vehicle is off and I pump up the brakes I get a hard pedal, as soon as I start the vehicle the pedal drops to the floor with the slightest pressure. Anyone else had an issue with this or have any suggestions? TIA

could it be your new pads have to brake in?
 

JasonJ

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could it be your new pads have to brake in?

In my experience, which as a DIY mechanic, taught by a professional mechanic-dad, new pad break in, while important, doesn't cause a soft pedal. Really, what changes there is that the brakes "bite" in harder as they've been bedded into the rotors (which also should have been replaced). So while the pedal will start and stay firm, the actual grabbing power and stopping "feel" of the brakes as a whole will increase afterwards.

It should not change the feel of the pedal at all, only perhaps how much pressure you need to apply to it in order to stop at the desired rate.
 

dillon

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do you have abs? if so you may have to cycle the abs solenoid with an adequate scan tool while bleeding
 

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