Here's the problem:

The brakes on my sister's Integra ('93 RS) operate perfectly about half the time and the other half of the time the pedal sinks completely to the floor. It seems like it's every-other-time I apply the brakes that the pedal goes to the floor, but it's not quite that predictable.

When the pedal sinks, it feels like what happens when your fluid boils (i.e., the car still stops, but the pedal travels much further). But I know that's not it because a) I put ATE Super Blue in there a few days ago and this is just street driving, and b) the pedal works perfectly half the time.

I've changed out the pads and rotors recently, flushed the lines twice and bled the lines four times, but the problem remains. She needs to drive across the country in about a week, so I'm pulling my hair out trying to figure this one out.

Any suggestions?

Thanks!

Adarsh

 

I would suggest having the master cylinder/brake booster checked out. They will wear out over time and cause inconsistent braking and pedal feel.

 

Mater Cylinder.

 

yup def, a master cylander.

On my Triumph TR6, I was cruising down the road when the the brake pedal went right to the floor.

Sure enough, the master crapped out.

Sam

 

i would bleed the brake lines first before because what it is is that when all of the bubbles are together in the brake fluid it is easier for the air to get squeezed together and whent he bubbles are spread apart more the bubbles are harder to squeeze causing your pedal to sink sometimes and be fine some times too but i may be wrong but bleed the lines first youll be happy you did

 

Thank you all very much for your comments.

I suspected the master cylinder as well, but I was hoping that wasn't it. The air bubble theory also sounds plausible, but I've bled the brakes multiple times. The odd thing is, the problem appears to have resolved itself. The car now brakes like a champ. Beats the heck out of me. The only thing I can figure is that maybe the rears hadn't adjusted (we cranked the parking brake a few times the other day) and now they've clamped down and bedded in properly so the variation is gone.

There is one other problem though: There's a squeaking problem coming from one of the rear hubs. It's periodic with the wheel turning and it's only up to about 20 mph. It also stops when I apply the brakes. I think it might be that one of the pads is off slightly, but I'm not sure. Any ideas?

Thanks again!

Adarsh