brakes

[joel]

Could someone please go over or give an overview of front disc brake troubleshooting and the best general brake bleeding technique.  My truck is an 86 c-10 with a vacuum booster.

[Irish_Alley]

lets start off with whats your truck doing

[mattgood]

Yeah... first off what is your brake problem?

[bake74]

     As with the other two, more info.  Is there a problem with your front disk brakes, or are you wanting general information ?  Front disk brakes are pretty straight forward, compared to drum brakes.
     Generally when you bleed a brake system, you start with the one that is farthest away from master cylinder and work up to the closest, making sure you get all the air out while not letting any in.
     There is a host of things that can cause brake problems, that is why we asked for more info.

[joel]

ok it pulls to the left some while driving.  when you brake, it pulls to the right.  I replaced the left caliper (old one frozen).  Of course i looked at ball joints etc.  Other than gentle pull to the left it rides great up to highway speed for distances. Havent got any leaks or fluid usage, just need some ideas to act on and wanted a good recipe for bleeding. seems i always have problems getting all the air out.  Also, the pedal acts good not too hard or soft.

[winky]

sounds like the pulling while driving may be bad alignment or tires? try swapping tires on the front and see if that helps any, as far as bleeding if you just have a regular tool set you get someone to pump the breaks then hold them down as hard as they can then you loosen the bleeding valve, tighten it back right before it quits letting fluid out. you may need to do this a few times. also keep a check on your break fluid levels. this is how ive always done it. besides when i worked at Mercedes and i used there break bleeding machine, any one else have a better suggestion?

[Irish_Alley]

if the pedal is good i would say the air is out. like said the pull to the left is probably something out of whack or tire wear. i have a little tube and cup that you can put on the bleeder so when you do crack it open it catches it and then you can put it back in the master cylinder. the pull to the right could be the cylinder or hose acting up

[joel]

Yeah i have been wondering about the flex hoses. They could be bad and not leaking right? And I had bad ball joints in a Jaguar and the handling is different but it pulled and darted around.  What i have is a hard pull to the left, like if i let the wheel go Id run off the road to the left.  When i apply the brakes, it pulls off to the right slightly. Think that could ball joints and/or anything else in steering or suspension.  The brakes stop really well and the pedal feels like it should nice and easy with good pressure and pedal return. No hopping but a light shimmy sometimes.

[bake74]

Yeah i have been wondering about the flex hoses. They could be bad and not leaking right?

     Usually when the hose is bad, it either collapses on the inside, or is weak and expands when you put pressure on it.  In either situation you get brake fade, not brakes grabbing. (as you described on the right side)
     As far as pulling to the left upon driving, Winky is right, alignment and tire rotation and balance is what I would do first.
     The grabbing of the brake and pulling to the right, I would have the brake rotor and brakes checked on the right side (both while you are at it), if the rotor is warped you will get grabbing on one side and shaking also due to the rotor being warped.

[winky]

you can check your wheel bearings and ball joints by lifting the front tire up and seeing if there is any slack. lift it up, try to turn it left and right by the wheel, see if you can find any slack, if so that's wheel bearing slack, trying putting a prybar under the tire and lift up (helps to have someone else there) and watch the ball joints and see if it comes up or not. i know this might be kinda hard to understand if you've never done it so ill try to find a video and post a link. but like blake said rotors would be my first place to check, also check the brake pad materials, see if one side has more than the other pad (on the same wheel)

[Gusgus74]

My 74 would pull hard to the right when the brakes were applied. I changed the front calipers and still had the same problem. The front hoses looked fine, no leaks, no cracks no obvious  problems. The only weird thing was I could not bleed the rt front caliper properly. It would not let out a good, solid stream of fluid like the other three. So I replaced that hose and the problem disappeared. The brakes now apply evenly with no pulling at all.

[bigchevyc30]

my truck has this same problem where it pulls to the left but if i hit the brakes fast for say a idiot cutting me off it will pull hard to the right with the brakes on. im thinking it would be the hose as after a while the truck will run straight but only after a while

[joel]

well checked that right side caliper last night and found the cylinder frozen and brakes full on.  Worked with the cylinder and it worked right when i test drove it and this morning when i went to work. I had new tires put on two weeks ago so I'm thinking i probably have the front end out and the rotor on the right side is probably the culprit on the shimmy. I'll get new rotors and try again this weekend.

[mattgood]

Yes a sticking caliper is usually the cause of a brake pull. You said you "worked the cylinder back and forth" which would lead me to believe you have rust in there so make sure the caliper boot is not torn. If so, the caliper needs replacement. Also make sure to take both sides apart and fully clean the caliper pins and slides and lube them with silicone brake lube. As for shimmy... a brake pulsation is due to warped rotors.

[87454westernhauler]

i have had the same issue on almost all of my trucks. replace the flex hoses! they rot out inside and cause the calipers to stick.