Mechanics

NEED HELP WITH FRONT BRAKE LOCKING ON AC

1992 Acura Integra

Brakes problem
1992 Acura Integra 4 cyl Front Wheel Drive Automatic 260000 miles

This vehicle is my wife's car, but I have provided most of the care for it since it was purchased new in 1992. I have replaced brake pads the last two times that was required and replaced rotors with Centric Premium rotors and both front calipers with fully loaded Centric quiet stop replacement parts. They work smoothly enough and seem to have appropriate grip, but there has been a new problem we are experiencing since my wife returned from a period in Austin, TX. I noticed the brake pedal seems especially soft after the car starts when cold or after days of disuse, but that seems to go away once the car has been running for long enough to become fully warmed up. Thereafter the brake pedal seems to have the right amount of travel and firmness. My thinking about a master cylinder failure (I replaced once previously around 110,000 mi) would be that the pedal shouldn't firm up the way this seems to after little more than five minutes, but the soft pedal effect should continue. Coming back from a visit into the nearby foothills today there was an odd grab of the right front brake and a distinct burning smell when we stopped after a few miles along the route home. Acceleration became more sluggish and difficult, the transmission seemed to work extra and shift at a different point, and the brakes were not only entirely firm and responsive to only a slight touch but they clearly were gripping differently. The right front (passengers side) appeared to have locked to where it simply would not disengage after pressure on the pedal was released, and the braking of the one front wheel was enough to bring the Integra to a halt at idle speed and keep it from normal movement forward after full braking when I left the car idle only. That had never happened before while I used the car, nor according to my wife when she used it, either. If there is any suggestion of how to approach repair of this problem, it would be greatly appreciated.

Dave
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Rockymtndave
May 27, 2009.



Would seem caliper has siezed up. Or flex brake line is at fault. Pull wheel and open bleeder if caliper frees up then flexline faulty if not free caliper siezed.

Docfixit
May 30, 2009.
Thanks for the comment. It seems like the issue is probably more complex, though. After the vehicle cools down a bit, even as little as 10 to 15 minutes, the brakes appear to work normally. When entirely cool, as in the first start of the day or multiple days without use, the brake pedal travels all the way to the floor board without any of the normal firmness. It then firms up as the Integra warms to where after maybe all of 7 to 10 minutes the brakes seem normal. Then, it becomes less predictable for the length of time it might take to start grabbing or having the front brakes apply without pedal force. It has happened four times now with a similar timing pattern. Once left alone to cool, the entire process of almost no braking to what feels like seized front brakes begins again. The car simply won't be driven more than four or five miles from our home until the issue is understood and an appropriate repair made.

If you have any more ideas about what would allow the feeling of a failed master cylinder, where there is little firmness at the pedal, transitioning to brakes which apply without pedal application, please let me know. Have you heard of any related sort of unusual braking application from a failed brake booster module?

Dave

Tiny
Rockymtndave
May 30, 2009.
Was brake fluid flushed? What DOT did you use? Was fluid new or has it set in garage a while? Brake fluid is hygoscopic it holds moisture if your fluid is saturated then when hot it boils expanding in system thus brakes on pedal soft.

Docfixit
Jun 1, 2009.
Flushing the brake system is my next task. I picked up Valvoline Synthetic Dot3/Dot4 fluid over the weekend, which is what I've typically used. The system was last flushed around a year and a half ago, so I wouldn't think that should be the problem, except your observations and comment about the fluid are things I was considering for possible contribution to the Integra problem. Hearing the reminder from an expert leads me to think that is a fully appropriate next step.

I was aware of the nature and ability of brake fluid to attract moisture, much like refrigerant oils where a receiver-drier dessicant is a must. Got certified EPA 609 credentials several years ago for that portion of my automotive service work. I don't have extensive experience with brake work but have replaced calipers a handful of times and a couple of master cylinders along with the more common pads and disks. I appreciate getting your thoughts and diagnostic effort from the descriptions. That seems like adding an extra measure of challenge to having the vehicle in front of you, but accurate descriptions can help a lot, can't they.

The reason I've been looking for help is that this odd combination of brake issues is something I've never run across before. Others I've asked locally seem similarly to be mostly guessing and haven't seen this combination according to their answers.

Thanks. Maybe there will be some follow-up comment I can make after flushing the fluid. At this moment, I'm waiting for drier weather, in part, because of what you mentioned for the fluid's tendency to take on moisture.

Tiny
Rockymtndave
Jun 1, 2009.