I really didn't need this!

[ncgirl05]

Hi All,

I'm not sure how to 'search' this problem so I'm just going to ask the knowledgeable folks here...

Yesterday I was driving my '89 Blue home from work and when I pulled up in the driveway I noticed that the brake pedal seemed to vibrate under my foot, which felt VERY weird. We then had to run an errand so we jumped in Blue and hit the road - and then the vibration in the pedal happened almost every time I had to brake - and it kinda freaked me out to be honest! What in the world is this?? The pedal even seems to make a noise when the vibration occurs, like a grinding sound.

What's the problem? I'm afraid to drive it right now... As always, your help and kind assistance is always appreciated!

[DAVES89]

I would guess a brake job [pads/rotors are in order. Vibration thru the pedal is typical of rotors warping. The grinding you hear is most likely the "squeelers" wear indicators rubbing into the rotors. I am assuming that you are not getting either or both the amber or red brake warning light?

[ncgirl05]

Actually, I know the vibration you are talking about, and that is not the vibration I am talking about - I would describe the rotor/brake thing as a "pulsing" in the brake pedal. I have good rotors and pads so I know that's not the problem... this is something I've not experienced in any of my cars... it's like a stutter in the pedal.

I know it's not calipers, rotors or pads - maybe something related to the ABS system?

Oh, and no, there are no lights on. The yellow ABS was on for a few months, and then, after I didn't drive the car for a few weeks (month or more?), the yellow light did not stay on anymore (it still comes on when I start the car though).

Like I said, I've not felt anything like this through a brake pedal before so I'm mystified... and I've had my share of brake problems!

[Ronnie]

From what you describe it sound like a cracked rotor or maybe broken or loose caliper parts. Does the vibration start as soon as you drive after the car has cooled down overnight? If there is no vibration until you drive it some, you may have a caliper sticking and overheating, causing the rotor to warp by excessive heat which can lead to a cracked rotor. If this is the case you may see the rotor actually glow at night when you drive a long distance.

The caliper can stick in two ways. The piston can stick or the caliper can stick/freeze on the pins that allow it to move from side to side to center it's self on the rotor. Either one can lead to overheating due to friction from the pad dragging on the rotor.

I hope this helps you find your problem.

[harry yarnell]

Are you saying this vibration happens when the car is STOPPED in your driveway, and you apply the brakes?

[Guest joereatta]

Sounds like something is causing ABS to actuate, a sensor gone bad?

[Guest Kitskaboodle]

I know EXACTLY what you are talking about. My 90 coupe does the same thing but ALWAYS

just after I put the car in gear and it hasnt been driven yet that day.

I have found that during this brake pedal pulsing episode, the brake pedal does go down

toward the floor a little bit. What seems to help is to pump the brake pedal a few times

and them the pulsing stops and the brakes get more solid.

I also do not know why it occurs but other than this "hiccup" my brakes stop ok.

Kit

[Guest Reatta1]

I would suspect something in the ABS system. I sometimes get that if I have my foot on the brake when I start the car. It is the system pressurizing. If it's happening while you are driving, I would suggest checking to see if the pump is running continualy. Would think that the amber light would stay on though. Just my two cents.

[Ronnie]

Is there an easy way to temporarily disable the ABS system and keep the regular brakes functioning as if the car didn't have ABS?

[ncgirl05]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: harry yarnell</div><div class="ubbcode-body">Are you saying this vibration happens when the car is STOPPED in your driveway, and you apply the brakes? </div></div>

The vibration was happening when I was driving - the first time it happened I was going up the driveway and was breaking to park the car. Then, when we were driving the car again 20 minutes later, it happened quite frequently while I was driving through town, but not every time I hit the break - more like every third time....

[ncgirl05]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: joereatta</div><div class="ubbcode-body">Sounds like something is causing ABS to actuate, a sensor gone bad? </div></div>

Any way to check this out?

[ncgirl05]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 'Reatta1'</div><div class="ubbcode-body">I would suspect something in the ABS system. I sometimes get that if I have my foot on the brake when I start the car. It is the system pressurizing. If it's happening while you are driving, I would suggest checking to see if the pump is running continualy. Would think that the amber light would stay on though. Just my two cents.

</div></div>

Another good suggestion Reatta1

I just remembered last night that I had felt this vibration once before when we were bleeding the brakes last year and I was pressing the brake pedal to flush. It only did the vibration thing one time but I thought I had 'broken' something....never felt anything else until Tuesday.