I replace all 3 rubber brake lines about a year ago. The pedal used to engage the brakes high and firm until this winter. Now they're engaging way low and but not quite as firm, it is tricky for me to get use to the change. I can pump the pedal and get it to sit higher but not as high, and after I get to the next stop the pedal engages low again. No fluid has been lost. I replaced the master cylinder about a year before replacing the rubber lines. I don't believe it has any issues, it is an Aisin brand.

My brakes are good and even with no sign of leak down when pressing firmly. I purchased the lines from either a AZone or AAuto and I'm not sure of the brand. I really liked the high engagement they had and the low engagement they've developed is really annoying to me. My guess, the new rubber lines have developed a dilating flex when pressure is applied, and I'm a bit worried that may brakes may fail. I thought I'd ask here about this issue hoping for ideas and advice, Thanks for reading.

 

Using the E-Brake to keep the rear shoes adjusted ??

 

Yeah I use it every time I park. I will try a manual adjustment to see if it makes a difference. Thanks.

 

If you set the parking brake, then hit the brake pedal, how does it feel? Still low and soft, low and firm, high and soft or high and hard?

 

I can't tell a difference with PB applied. They're still low and firm.

 

Take your front wheels off and pry the brake pads away from the rotors so the pistons compress back into the calipers. If one doesn't move, there's an issue. If they do move, slide the pads back against the rotors and have someone step on the brake, watching the Pistons come out of the calipers. If one doesn't move like the rest, there's an issue.

 

I'll do that soon, thanks. I'd think it would cause an uneven brake pull if a caliper was acting up. I have a set of steel braided lines, maybe I could swap to see a difference. I used them for about a year not knowing they weren't street legal. They engaged even higher than the rubber lines did when new. It'll be hassle but at least it would isolate the issue and piece of mind.

 

Poor Quality rubber hoses ?? Ballooning already??

Drums worn beyond specs???

When you did the rubber hoses did you do brake pads and shoes as well??

Could just be worn pads worn rotors just plain old brakes worn out??

The further the Hydraulics need to move the pads and shoes the longer the pedal travel

 

Over a period of 4 years the whole brake system has been rebuilt. The last was the master cylinder and rubber lines. I suspect your first line to be accurate. New drums, shoes, rotors, pads, rebuilt wheel cylinders and calipers. I don't drive truck much about 1500-2000 miles a year.

Just this month I noticed the pedal difference, the new lines only have about 2000 on them, but 2 winter cycles. It just crossed my mind, everyhting was fine before I slid into a ditch due to ice. I don't see how that could cause it without disabling the whole system. Who know it might have screwed something up.

 

I have reason to believe it maybe a bad wheel bearing. Only when I roll and stop it requires pedal pumping to get a high pedal position. Anyway I'm parking the truck till I get it figured out.

 

I finally had time to solve the issue, they just needed bled. I'm not sure how air got into the system, other than slipping into the ditch caused air trapped in the MC to be introduced into the system. I didn't bench bleed it before fitting the new one. Now the pedal is firm, high and predictable again.