[GreenMM]

Hi:

I have a car that has ABS Power brakes and the pedal goes down quite a bit and the brakes do nothing. When you really strongman "leg press" against the brake pedal it bites and brakes the car, but it also mostly locks up the front wheels suddenly as well.

I had convinced myself 99% it is a brake booster failure. Now, I am not sure. I read a post that could be a Master Cylinder failure. Since replacing the booster while easy is fiddly and I have to remove things to get at it, I was a little reluctant to install a used booster I got at the junkyard if it's the master cylinder.

My experience with failed master cylinder is a locked on front brake on my motorcycle that would not release at all (tons of brake residue gunk plugged up the 'plunger' in the MC... cleaning that out thoroughly fixed that problem).

Thanks for any opinions you might shed.

The brake problem as been consistent for 6 months, and the car is either not driven at all or just into town carefully by a family member a couple times in an emergency.
(fwiw, it's a 2007 Hyundai Sonata V6, I know it's no Honda, but this forum I'm on the most and I would be pretty sure booster and MC failure symptoms should be fairly universal).

 

[stiller fan]

i have never heard of the brake booster on a honda going bad. but, i have had personal experience of the brake master cylinder being faulty.

my recommendation would be to replace the master cylinder, and then report back on your findings.

good luck!

 

[TX Accord]

For my most recent brake replacement:

1. Brake pedal felt fine, but all of my pads were wore down from use. Braking action was fine.

2. During pad replacement, I couldn't get the right rear caliper to push back in so I could install the new pads and rotor. Found that the caliper was seized. Bought and installed new right rear caliper.

3. After installing all new pads, rotors, and right rear caliper, I bled the brakes. Even after much bleeding, the pedal was still soft.

4. During test drive, the pedal was very soft. By firmly pressing on the brake pedal, the right front wheel would lock up. That wheel seemed to be the only wheel with any working brakes.

5. Took car in for alignment and had the shop bleed the brakes. No improvement in brakes. I was told the right front caliper was bad because it locked up easily. I was told I should replace both front calipers. Because the right rear was new and now I had front caliper problems, I replaced the other three calipers so they would all be new.

6. After all new calipers and bleeding, braking action and brake pedal feel returned to normal.

Keep in mind that I never knew I had any bad calipers til replacing my pads and rotors. Replacing them exposed the right rear caliper. Replacing that caliper exposed the right front caliper.

Maybe something similar for you.

One owner '03 Honda Accord EX V-6 6-spd trying for...

Got the car back together. What a week. I got everything apart to the point where the transmission was ready to come down. I took off the front suspension and took the subframe out myself. Big thanks to my friend Nick for coming over and helping get the transmission down and getting the car...

www.driveaccord.net

 

[GreenMM]

I've had several calipers seize on me. Many I've rebuilt, some I've just pulled a OEM Nissin from the local pull yard for cheap.
This issue is not a seized caliper or two even. It's zero braking at all unless you super stomp the pedal all the way down as hard as about one can, and then the front end starts to actually brake and locks up extremely quickly.
FWIW, I personally don't replace calipers in pairs or sets, just the ones with issues.
Sometimes it's locked up caliper slides which is an easy fix, sometimes it's the main piston seizing in the bore. Both can be rebuilt with seals and good brake lube (I use Sil-Gyde). The main piston is a fiddly pain to reseat the boot but it is doable.

 

[TX Accord]

I'd never had a caliper fail on me, but what you're describing sounds almost exactly how my car acted. I'm interested to hear the solution on this.

 

[WiiMaster]

It's not hard to diagnose a dragging brake with something like an IR temp gun. Go for a drive and then use it to check the temperature of each wheel. The fronts will be warmer than the rears naturally but there shouldn't be one that is noticeably hotter than the rest. Easy thing worth checking.