Braking Problems

[B-Cack]

I have a 93 XLT and about a month ago I replaced the rotors, pads and master cylinder. Now every once in a while when I apply the brakes, everything is going just fine until about the last 1/2 inch of pedal travel, this is when it goes limp, feels like it moves about 2 inches down and a kind of low groan comes from under the hood on the driver side. (Right where the boost pump assembly is located), Also the right side feels like the brakes slip and she will lurch foreward a little bit. It is very irritating, I think it might be the Hydraulic assemby, but I am just a shadetree mechanic. Anyone experience this or have a suggestion? Thanks, Jeff

 

[Guest_B-Cack]

Think it migh tbe the power boost unit.... gonna check that thing out today

 

[Guest_DragonDave]

Did you bleed it out good at all four wheels? If the system has a bit of air left in it you will have an intermittant pedal height problem. I cant comment on the noise from the pump, but i can tell you my 93 seems to be sensitive to just a bit of air left in the system after working on it. Good Luck! /emoticons/[email protected] 2x" width="20" height="20" />

 

[Guest_DragonDave]

Did you bleed it out good at all four wheels? If the system has a bit of air left in it you will have an intermittant pedal height problem. I cant comment on the noise from the pump, but i can tell you my 93 seems to be sensitive to just a bit of air left in the system after working on it. Good Luck! /emoticons/[email protected] 2x" width="20" height="20" />

 

[Guest_B-Cack]

OK, so I installed a new power brake booster, and at first I thought it was going to do the job, but after driving for a while I slowly had the same problem again, only this time it was about 1/10th strength........ maybe I have a small leak in one of my lines or something, think I will take Thursday off and then bleed those suckers out on Friday..... thank God I have the long weekend..........

 

[viper]

ok did you bench bleed the master cyl? a little air in there can cause a big problem. and could the weak pedal and funny noise be your abs activating ? somthing else to think about anyway , good luck, drive it like you stole it !!! B)

 

[Guest_B-Cack]

OK, I had the master cylinder put in at a shop.... what is this "bench bleed" you speak of, and should I go down there and whack his head in with a socket?

 

[Ziggy]

Master brake cylinders will come with a kit that allows you to pre-fill the resivoirs with fluid, then pump the cylinder by hand to remove the air. Basically you prime the master cylinder with brake fluid to remove the air. Then you install the Master brake cylinder, hook up the lines and re-bleed the entire brake system. When bleeding the entire system, you start at the bleeder valve the farthest away from the master cylinder and work towards the closests. Normally this is RH rear, LH rear, RH front, LH front. Constantly check to make sure the master is full of fluid or you will re-introduce air into the system and you be back to square one. If your RH side is "lurching", sounds like a warped rotor to me. I never use an impact on disc brakes as this will warp them, and make sure they are torqued to the proper setting. Also make sure all your brake lines are tight, use a "line wrench" to tighten them, not a regular open end or combo wrench as you can distort the "B-Nut" and the line will not seat properly. If you don't have a set of line wrenches, head to "Sears" and pick up a set. They are worth the $$$$ and save you on headaches.

 

[Guest_B-Cack]

Thanks, I should have known better to let the guys at a shop use the impact on it....... I was in a crunch for time though. My own damn fault I guess........

 

[Ziggy]

If you don't learn something new every day, then it wasn't a productive day. Just take the rotor off and have it trued up at any place that turns drums and rotors. Should run you about $5.00 a each.

 

[Guest_B-Cack]

If the rotor was warped a little, wouldn't I be experiencing problems all the time though? It seems like it only gets squirrely when the pedal gets to the bottom, when I am coming to a complete stop. I think I might just have to bleed them out again.... or do like you suggested and bleed the master...

 

[Ziggy]

You'll only feel warped rotor's when you apply the brake since the pads are riding on the brake. There are not riding on the disc when your foot is not on the brake pedel.