Need some help and advice about my brakes!

Hey guys, I have a few questions on brakes, not sure if what I'm feeling is normal or not.

I often get this sound, almost like air is being pushed out, or the pedal is rubbing something, from under the dash when I compress the pedal. It happens in the first ~ 1 inch or so from the pedal stroke. Then the brakes actually engage and slow the truck. Here are a couple videos of it, though the sound is really quiet, so you'll have to listen closely and turn it up to hear it.




Also, while either sitting at a stop light, or slowing down using consistent pressure on the brakes, like while going downhill, the pedal will sink slightly.

I don't have any issues with actually stopping or anything, they seem to work fine.

I have steel brake lines installed front and rear, with extended lines in the rear, they're the Wheeler's Off Road brake lines. The front brakes have new rotors, calipers and pads, and the rears have new pads and shoes, all parts are OEM spec replacements, no bigger brakes or anything like that, with the exception of the extended rear lines. The lines have been bled by the shop that replaced the rear brakes pads and shoes.

Any ideas if all of this normal? I was expecting the brakes to feel firmer after replacing all of these parts, but it seems softer than before. Is there some adjustment I need to make somewhere in the system to firm it up? Or replace some part?

Thanks for any help!

 

bump for some help

 

Sounds like a master cylinder issue considering you are hearing an air purge
If you replaced the pads on the front and shoes on the rear , your pedal should be nice and high with no sinking pedal as you sit at a stop light .
Are you using your emergency brake on a constant basis ?

 

yea, plus when the truck is off, if I pump the brake pedal, it stiffens up considerably, then when I start the truck it becomes soft again. Are those things related?

yes, use it every time I park.

 

A lot of work was done. I'd inspect the brakes and make sure there's no fluid leak at calipers, or where stuff got extended, along the new lines. If everything looks good and dry (no wet boots around the rams in the calipers either) then I'd re-bleed them. The symptom started after the swap, yeah? so they either goofed or you have a very coincidental part failure.

 

yea it did. but the reason i swapped parts was because of a tear in the front driver brake line while off-roading. so I supposed its possible air got all the way up into the master cylinder, which I never thought to bleed or replace. I haven't noticed any fluid or leaks around any of the parts, and I imagine that if there was leak somewhere the problem would get progressively worse, but it's stayed consistent for a few months now.

 

I'm not familiar with braided steel brake lines, but using my imagination here, i dont know that the leak *would* get worse. Even the rubber stuff used on 'em is pretty darned sturdy and well suspended, so i wouldnt expect to see a leak get worse necessarily. *EDIT* even if it didn't get worse, it would continue. I get that.
But it may not be a leak, and just air, yuh know?

My maintenance background doesnt include resto, full rebuild, classics, recreational, just preventative maint. checks, services, OEM type stuff. I've never seen a BMC fail personally. I'm sure they have, but sh*t, they don't gotta do much, or get exposed to any hardship.
Do you think the inflexibility of the new braided lines could have exasperated a pre-existing fault via reduction of pressure loss?

I'll keep scratchin my head with yuh, and do some reading on brake system failures

 

I just found this: Leaks with new lines

If you happen to deal with stainless steel brake lines, it’s not uncommon to experience a small initial fluid leak when a new stainless line is installed. If this occurs, loosen the connection and re-tighten. This often corrects the issue. Stainless lines/flares are relatively hard and sometimes require repeated cycles of loosening and tightening in order to obtain a leak-proof seating at the flare.

Courtesy of

https://www.moderntiredealer.com/articles/15877-avoiding-brake-service-comebacks

It's a theory.

 

That's normal. You're feeling the brakes manually when you pump and they firm up, but when you start the truck the booster comes into play and amplifies your effort causing travel and sinking of the pedal.

 

Ok thanks for this, I'll get back under the truck and check the line connections for fluid or leaks again.