This is for my truck in sig...the 03 CCLB which is on 35s. Last summer i did ford rotors all around, the blue ford super/severe duty pads and 2 new calipers in the front of the truck. I flushed/bled the brake fluid probably 10 times and its all clear colored now but my brakes are still awful. I understand i have a big truck, on heavy tires and the older smaller brakes but i still think its lacking stopping power... I can hit the brakes as hard as i want and it wont even think about locking up the tires, and it barely moves me forward in my seat. Ive driven my friends 05 super cab long bed 6.0 on 37s and i know it has the little bigger brakes, but his truck will put you through the windshield if you step on the pedal hard. My pedal just feels very soft...

It has 141k on it now, everything brake related besides what i replaced is original as far as i know. Do you think this could be a problem with the hydroboost system? I was thinking about replacing the front flexible brake lines with some of the nice stainless braided ones or something. Should i bleed the brakes again? I have like $500 of brakes into this truck, I definitely think it should stop better. Im a little scared if i have to make any emergency stops, especially if i have any extra weight in the truck. Its nice driving with trailers because my truck stops better...lol

Suggestions? Thanks!

 

First, you mentioned calipers changed but were the brackets and slide pins changed or completely rust free too? While you've bled, are you sure all the air is out of the ABS unit?

Even though 35" vs 37" tires, on an '03 I would have gone with Hawk LTS pads front and rear. The leverage between the brake swept radius to tire rolling radius is much for those pads. You really need the higher friction that the LTS or Porter pads would give.

On this vehicle changing the 5 brake hoses to the firmer Teflon stainless steel version would not hurt. The slight decrease in fluid volume gives you a little more boosted pressure throughout the pedal effort range, especially after you've pushed through the boosted pressure knee and get into the manual effect, usually after 100lbs pedal effort / 1200 psi for example. Air in the lines will screw this up to, giving a longer pedal travel and lower pressure output once the pedal travel knee is past.

 

Yes the entire front caliper/slide pin assembly were changed in the front. The rear i just cleaned and lubed the slide pins with proper grease.

Maybe i'll just try bleeding them again. The pedal really feels useless until probably halfway to the floor...

 

That amount of travel says something is amiss.

Normal bleeding will not get the air out of the ABS if there is any there. The backyard way to get fluid moved around in the ABS module is just before bleeding get it on a slippery surface and get the ABS to activate at 25-39mph.

Any issue with one caliper's piston or one caliper's slide pin can cause the caliper to twist and cause a longer travel. I would be going through everything if bleeding with exercising the ABS did not bring the pedal up to normal.

 

I have auto enginuity...does that let you bleed the abs system or is it something you need to do mechanically?

 

We had the Ford tools so I can't say if the newest AE can. I know the older units could not.

 

I'm attaching two graphs to show how lost travel reduces brake hydraulic pressure and makes it harder to stop and /or develop a skid point.

The top graph shows the pressure development on a Superduty and the booster runout happens at about 5 inches of travel, after-which there is no boost assistance and any increase in hydraulic pressure is directly correlated to pedal force.

The second graph I had to Photoshop, but if there is air or any mechanical fault that causes a higher amount of fluid displacement to fully achieve full contact of the pads and rotors, pressure development takes more travel at the pedal. Yeah, we all know that and have experienced it. But it also effects the higher pressure output. The booster runout is still at 5" of travel, the knee of both travel and boost still occurs, but now you've lost a few hundred psi as you are pushing 80lbs on the pedal and higher when trying to develop high deceleration. Pumping the pedal brings it up as the hysteresis of the caliper seals keep the pistons slightly more applied with each stroke. But if you are in a one-stroke panic stop you don't have time for pumping, you need to stop right ASAP!

 

EarnestEugene? Is that you??

Just joking around. Wonderful information in an easy to understand format. Pushing through the available boost/assistance was not something I was aware of.

 

That's a name I haven't heard in a long time!

 

Has the pedal felt soft ever since you did all the brake work?

If it isn't frozen slide pins, then perhaps one of the pistons could be froze in a caliper.

If you still get air while bleeding the brakes, then you have a problem with air in the system.

 

Thanks guys. I think i will just try bleeding them again maybe...i had to do a somewhat emergency stop in traffic from 70 to 20 today and i had all my weight (250lbs) on my pedal and it was scary...almost thought i was going to need to swerve into the brakedown lane when i had MORE than enough space

Where i stop for a second is how long it takes for the brakes to actually do anything, and then i only have that much travel that isn't too effective

 

In a panic stop, my pedal goes down fast, then the hydroboost actually raises the pedal back up.

 

Ive noticed that a little, but that video is just sitting in the driveway. I haven't really heard of people needing to replace the hydroboost unit at this mileage (141k),..my uncle had to around 90k in his 6.0 but it completely failed, we had no brakes. I wonder if they just need to be bled again? I had the fluid completely clear and went through a ton of it bleeding and flushing the brakes and i opened the resevoir again today and its back to green