When I got my 04 last fall, I replaced all the steel brake lines. I bled them with new fluid, ran the ABS auto-bleed sequence, and bled them again. Then the snow hit...
As the winter wore on, I noticed the ABS was very active. Eventually I realized that it was activating just as the truck was about to stop, even on bare dry pavement. To make a long story short, the front wheel speed sensors were pushed out a bit by a layer of corrosion, making for a weak electrical signal at low speed. Basically, the ABS computer thought one wheel was locking up around 8kph. Removing the sensors and cleaning off the layer of corrosion on the caliper fixed that problem.
But now I'm noticing a mushy feel to the brake pedal. The pads make initial contact with little enough travel, but then there's a long non-linear stretch of little more before substantial braking force occurs. Truck stops fine from there. It seems as though it is possible to "pump them up" -- releasing and reapplying the brakes seems to make the pedal feel firmer on the second application. In other vehicles, I have found that is usually a sign of air in a line.
There has been no fluid loss from the master cylinder in the 6 months since I replaced the lines. No sign of leakage anywhere. Brakes do not release when lightly holding the pedal at idle. Yesterday I bled the brakes (all 4 calipers), ran the auto bleed sequence, and did a final bleed. No difference. (FWIW: I'm using a MityVac vacuum bleeder and new DOT 3 fluid).
I came across this old post that asserts "So the AV brakes are designed to use the back brakes first a little ahead of the front brakes. The brakes should wear evenly and you don't get that familiar drop in the front end on a hard stop. The soft feeling in the pedal is due in part to this redesign." So some of this may be normal to this truck, but that perception of pumping up the brakes still makes me think something more is going on here.
I'm wondering if the 5 rubber flex lines are playing a role here? And if I'm going to change them, should I go the extra step and buy stainless steel lines? Has anyone tried SS lines on their Avy, and if so, how much difference did they make to the pedal feel? Or is there another obvious solution that I am missing?
As the winter wore on, I noticed the ABS was very active. Eventually I realized that it was activating just as the truck was about to stop, even on bare dry pavement. To make a long story short, the front wheel speed sensors were pushed out a bit by a layer of corrosion, making for a weak electrical signal at low speed. Basically, the ABS computer thought one wheel was locking up around 8kph. Removing the sensors and cleaning off the layer of corrosion on the caliper fixed that problem.
But now I'm noticing a mushy feel to the brake pedal. The pads make initial contact with little enough travel, but then there's a long non-linear stretch of little more before substantial braking force occurs. Truck stops fine from there. It seems as though it is possible to "pump them up" -- releasing and reapplying the brakes seems to make the pedal feel firmer on the second application. In other vehicles, I have found that is usually a sign of air in a line.
There has been no fluid loss from the master cylinder in the 6 months since I replaced the lines. No sign of leakage anywhere. Brakes do not release when lightly holding the pedal at idle. Yesterday I bled the brakes (all 4 calipers), ran the auto bleed sequence, and did a final bleed. No difference. (FWIW: I'm using a MityVac vacuum bleeder and new DOT 3 fluid).
I came across this old post that asserts "So the AV brakes are designed to use the back brakes first a little ahead of the front brakes. The brakes should wear evenly and you don't get that familiar drop in the front end on a hard stop. The soft feeling in the pedal is due in part to this redesign." So some of this may be normal to this truck, but that perception of pumping up the brakes still makes me think something more is going on here.
I'm wondering if the 5 rubber flex lines are playing a role here? And if I'm going to change them, should I go the extra step and buy stainless steel lines? Has anyone tried SS lines on their Avy, and if so, how much difference did they make to the pedal feel? Or is there another obvious solution that I am missing?
