Brake weirdness.

[Don87LX]

When I am comming to a stop my brakes feel normal, but when my autobox lets up and the revs drop back to idle just before I get the car stopped the pedal suddenly becomes soft, the brakeing force goes down, and extra pedal travel is required to stop the car, almost to the floor. I have full fluid and bled the system of air when I changed my pads a year ago. this is recent problem. I have a bad feeling my master cylinder is showing its age., however whith the car off after driving, if you pump the brake pedal it builds up resistanbce like it is supposed to.

[DBMaster]

Does it tend to do it more once the engine compartment gets heated up? Mine did that when the master cylinder went bad. You end up braking with only one braking circuit (opposite wheels front and back). When the thing ages the rubber piston seals start leaking pressure a little.

Not a big or expensive job to change the thing, at least.

[accordlx]

To me, it sounds like you have a leak in the vaccuum assist for the brakes. This is not really related to the master cylinder itself other than the master cylinder is attached to it.

The vaccuum assist is the big round black thing that the master cylinder is bolted to. I would check the bottom of the vaccuum assist for rust and check it visually underneath with a mechanics mirror. If there isn't any rust on the vaccuum assist, I would check all of the vaccuum hoses in the car.

When your car is not revved up, the vaccuum in the engine drops hence your soft pedal.

I hope this helps.

PS. If you had a soft pedal all the time, you would have a brake bleeding problem or maybe a problem with the brake proportioner. I don't sense you are having this problem.

[Don87LX]

Ah. ok I'll check the Vaccuum assist. I'll also break out the carb cleaner and spray what few vac lines I still have (weber). If the vac assist (also called brake booster right?) is faulty is it and awful bear to change? It dosent look like it would be too hard.

[vtec11]

i have the exact same problem. when i'm driving the the brakes are fine.

when i come to a stop, that's where the pedal goes soft, and goes to the floor.

And yes, it does it on hot days. It did it on really hot days last summer, but its been fine in the winter.

now its warming up again and the pedal is acting up again...

what is it ??? master cyl. or vacuum thing accordlx was talkin about.

BTW, turned 198k yest.

[Lester Lugnut]

The vacuum assist device that ACCORDLX mentioned is referred to as a BRAKE BOOSTER in the '87 Accord factory shop manual.

How to test this device follows. Taken straight out of the book.

- With the engine stopped, depress the brake pedal several times, then depress the pedal hard and hold that pressure for 15 seconds. If the pedal sinks, the master cylinder, brake line or wheel cylinder is faulty.

- Start the engine with the pedal depressed. If the pedal sinks slightly, the vaccum booster is working. If the pedal height does not vary, the booster or booster check valve is faulty.

[YK86]

It's not hard to change. You need to unbolt the master cylinder from the booster and carefully get it out of the way without bending the metal lines. Then take out the pin that holds the pedal to the booster "rod". Then remove four nuts that hold the booster to the wall. Then carefully manuver the booster out of the engine bay.

[damackz]

check for leaks in ur brake lines

[SYKO5150]

were can i get cheap brake lines that are braided