Brakes failed after rear brake replacement


#1

My car is a 1999 Honda Civic (I can’t afford a new car, so please don’t suggest it.)

This morning I went in for a state inspection, oil change and rear brake replacement. Driving home while going downhill on the highway, I hit the brakes - and they failed completely. At first it felt like the car actually bucked forward. I tried flooring the brake, but felt no resistance and the car didn’t stop. I kept my foot off the gas and coasted to a stop.

The tow truck driver told me he could feel a problem just getting the car onto the tow truck, and again when he took it off.

The Honda place checked it and did a test drive, found nothing.They said it couldn’t be air in the brakes be took me for a short test drive and assured me I’d be fine. The

I headed home again and the brakes failed again at almost the same spot. This time it wasn’t a complete failure. After no resistance at first, the brakes “caught” though somewhat mushily. I put on my flashers and kept going, at about 45 mph. Got off the highway and had to crawl because braking wasn’t taking effect immediately. But as I drove on at 10 mph, they began working again. Not as well as they should, but enough to get me home.

It seems the brakes fail after 15 - 20 minutes of driving at 65 mph. They work better after a rest and at slower speeds.

If it makes a difference, my compressor is gone, so the car doesn’t have a/c, and it is hot out so I’m wondering if the heat is affecting something. However, I haven’t had these brake problems until today.

Tomorrow morning, Honda will tow me back and look at the again. Since they had no ideas today about what caused the problem, I’m hoping someone here might think of something I can suggest to them.


#2

Sorry, part of this got wiped. They said it couldn’t be air in the brakes because they hadn’t opened anything; they only replaced the rear brake pads.


#3

My first guess would be a master cylinder on the way out. They can be intermittent when first starting to fail.


#4

Master cylinder is bad.


#5

To find out if there’s a problem with the brake master cylinder, start the engine and let it idle until the cooling fan comes on and then shuts off.

Now get in the vehicle and step the brake pedal.

If the brake pedal sinks to the floor, the problem is with the brake master cylinder.

Tester


#6

Yes. Most likely it’s the master cylinder.


#7

Another vote for a bad master cylinder. Installing the new pads required the pistons in the calipers to be retracted, which causes fluid to be pushed back through the system. Maybe this damaged the master cylinder?


#8

I agree with everybody else . . . the symptoms seem to point to a bad brake master

I’m not going to waste time thinking about what may have caused it, because it can serve no purpose at this time

the car’s old enough . . . a bad brake master at this stage in a car’s life is not unusual


#9

I vote for replacing the master cylinder and making sure the brake fluid is all fresh. Although the brake work probably pushed it over the edge, as NYBo said, I don’t think you can really blame the shop and expect them to pay for it.

Until you’re sure this is fixed, be mentally prepared to downshift quickly to slow the car if needed.


#10

I too feel its a bad master cylinder and as @lion9car mentioned this car is old enough to expect a bad master cylinder at this point. I think it’s just a coincidence that it showed up after the brake job.

Yosemite


#11

If the air is out of the system it has to be the master cylinder.


#12

Another vote for master cylinder failure here. What probably happened is that the caliper was squeezed all the way open to install the new pad. Then the brake pedal hit the floor the first time they were used as the caliper travel was much farther than normal until it self-adjusted properly.

When the pedal hit the floor it made the master cylinder piston travel farther than normal, which picked up all the gunk that’s been building up beyond its normal travel over the years, and caused the rubber seal to stop sealing.

This could technically have probably been avoided if whoever used the brake the first time after it was taken down from the lift had been very careful not to let it travel too far until the pedal had firmed up, but realistically your MC was probably going to die before too long anyway.


#13

Thanks to everyone who responded. The car is now back at Honda. I suggested the master cylinder idea to them.

To clear one thing up, the brakes did NOT fail the first time I used them. They worked just fine during the test drive and around town on my way to the highway. It wasn’t until I’d been driving on the highway for 15 - 20 minutes that they failed. This was the case both times.


#14

For the moment I disagree with the master cylinder being at fault. On this car, if that was the case the brake light on the instrument panel should come on and set a code. I find it too much of a coincident having this brake problem right after a break job. Am I wrong?


#15

For the record, I’ve replaced lots of faulty brake masters, where the red brake warning light was never on

As have many of the other regulars, I’m sure

If there were an external brake fluid leak, such as a rusted out line or a cut brake hose, the brake pressure differential switch would be off center, which would cause the red brake warning light to be on

But a brake master which is bypassing internally will not cause that to happen


#16

[quote=“db4690, post:15, topic:94123, full:true”]
For the record, I’ve replaced lots of faulty brake masters, where the red brake warning light was never on

As have many of the other regulars, I’m sure

If there were an external brake fluid leak, such as a rusted out line or a cut brake hose, the brake pressure differential switch would be off center, which would cause the red brake warning light to be on

But a brake master which is bypassing internally will not cause that to happen
[/quote]I’ve only replaced a few, but none caused the brake light to come on.


#17

So are you in agreement with me . . . that a bypassing brake master typically does NOT cause the red brake warning to illuminate?

I feel perhaps I didn’t word my post clearly enough


#18

I have a related question.

When the master cylinder gives out like that. Would it be possible to get some braking back by pumping it? Like when there is vapor lock in the brake line?


#19

While master cylinder failure isn’t expected when repairing other parts of the brake system it is a common enough coincidence that I made it a habit to make a determined effort to force them to fail whenever I road tested any brake work. And often quick, strong pressure on the pedal would indicate that there was no problem while a few slow, soft applications would result in the pedal slowly sinking.

Mechanics hate comebacks on any work but most particularly brake work where overkill is more common than work on other systems. Can you blame them?


#20

[quote=“db4690, post:17, topic:94123, full:true”]
So are you in agreement with me . . . that a bypassing brake master typically does NOT cause the red brake warning to illuminate?

I feel perhaps I didn’t word my post clearly enough
[/quote]Yep, I agree completely. I guess I’m the one who didn’t word my post clearly. Replace “but” with “and”.