93 EX Accord
Bought this car about 3 months ago- drove it for a month and it was fine. One day both the BRAKE light and the ABS light came on in the dash. I drove it for about 2 miles until the pedal locked and I could barely stop; took it to a mechanic and he said it was the ABS pump. At that point I could drive the car for 3 days until it locked up (the brakes came on and I could floor it and eventually the car would stop and would not move in drive- BRAKES ARE ON). Once it locked up, it would take about 6 hours for the pressure to release then I could drive it again for 3 days. This went on and I took it into the shop a couple weeks ago- since then, I have replaced the module control (part that the abs reservoir sits on with all the valves) and the master cylinder. The master that goes on the EX (with abs) did not fit because the 2 ports coming off were not the same size; the one that was taken off the car was stock, no one had messed with it and the 2 ports were the same size. The only master that has the same size ports is the one for the DX (without abs). They are the same except for this one thing. So the DX master is on my EX car. The rod was adjusted and the cyl shimmed out. He has the brake booster but doesn’t see how changing it is going to fix the problem. I also bought the abs pump, but the abs is working fine now. Once the master was changed, it seemed to be fine, it was taken out and driven about 10 miles and didn’t lock up, I let it run for about 10 minutes in the driveway and came back to it and the pedal was hard as a rock. The only way it will release is if you crack the line from the master cylinder. It’s the front brakes, not the back. Once you release the pressure, it will move and drive, but if you put it in drive then into neutral, the car won’t continue to roll, it just stops.
More than a few people (Honda guys too) have looked at this and no one can figure out what the hell is wrong. Any ideas?!!

Thanks.

 

Honda has a SPECIAL jig [mounts on booster] to set the depth of the brake push rod.
From your description your push rod is too tight, not fully releasing the master cylinder piston.

Go under the dash and back off [shorten]that push rod, try about one turn at a time on the nut, between test drives.

I have also seen where P/S fluid was accidently put in the brake master and when the P/S fluid warmed up it caused the brakes to lock up.

 

I agree with Yamada-san. As a side note, when you release pressure at the master cylinder and the brakes loosen up, you are proving that the problem is not beyond that point, the calipers are good, the rubber brake hoses are not collapsed internally and the metal brake pipes are not clogged.

If you are sure that both the left and right wheels are locked then you have an adjustment issue as mentioned, if only one wheel was locked up then you may still have an adjustment issue and an air in the line issue.

Just recently I has a similar problem, I disassembled the master cylinder to get an idea of what a rebuild kit might include and when I put it back together and bleed all 4 wheels of course, the problem went away. Of course on your vehicle an adjustment was made and needs some readjustments.

I also do not like an improper master cylinder being on the car. If there was an investigation after an accident, you will be help liable for the accident. Go on ebay or where ever to get the correct part for your application, brakes are nothing to play with.

If for some odd reason incorrect type fluid was installed then the entire brake system will as a minimum need completely resealed, thats all of the rubber components in the entire system will be effected and damaged due to contamination.

 

Do you know what the special tool is?

 

You can just make the one turn adjustments like Yamada-san stated, under the dash at the brake pedal push rod adjustment.