master cylinder

Any clues as to replacing the master cylinder on a 94 Accord?? Do I want to everntry it? thanks :banghead:

Its not that bad. Bleeding the system is the worst part about it.

Its held on to the brake booster by only 2 nuts. And then there is ofcourse the 2 lines that thread into the master.

Just be carefull. On the new master there is a rubber gromet on the piston/pushrod side of it. Sometimes when you remove the old on that gromet stays inside the booster. Your gonna need to remove it with a pick or small screwdriver.

The brake lines are on really tight. Spend the money and buy the special wrench to loosen the fittings. It is like a box end with a small notch to allow it to slip over the line. Don't try using an end wrench. It will slip and round the fittings.

Sometimes on imports you have to swap the plastic resevoir over to the new M/C....it's easy enough, just follow the directions included. You just get under it with a lever from either side and pry upwards and pop it out, then push it onto the new one. Lube the new one's grommets with brake fluid first....

Never put a M/C in a vice by clamping the bore (longways)...you can distort the bore's shape and ruin it.

I like to install the new M/C on the car, and use the pedal to bleed it, rather than bench bleeding. I install it, put the bench bleeder kit on it, fill it, and pump the pedal slowly until I can feel the pedal firming up, at some point it won't get any better, that means the air is gone...hook up the lines, pump a couple of times to purge and verify pedal height, then you're done.

You just don't wanna bottom out the M/C when doing this. There is an overtravel bumper and spring inside them, but doing so is hard on the seals. About half way to the floor is all you need. Remember there will be little or no resistance the first few strokes.

I know if some have never done it this way, you'll say "How can you feel the pedal firming up with no brakes lines connected?"...trust me, it does, and you feel it. Much harder to move fluid through an orifice than air....

Question for you. I did what you recommended and I could see no more bubbles flowing thru bleed tubes. I hooked up the lines and I have nothing but a mushy pedal. Master cylinder and booster are new. Will a bleed firm up the pedal? (I did not alter booster pushrod length)
Thanks

Anyone have any idea on why my break pedal is hard? The break is working, but not effieciently. I bleed the system yesterday and it soften a little but it's still stiff compare to other cars. I took it to a shop and the mech said I need new master cylinder. Is this something I should look into replacing?

Anyone have any idea on why my break pedal is hard? The break is working, but not effieciently. I bleed the system yesterday and it soften a little but it's still stiff compare to other cars. I took it to a shop and the mech said I need new master cylinder. Is this something I should look into replacing?

I don't recall ever hearing of a bad master causing a hard pedal...usually the opposite, you get a soft, dropping pedal...

Sounds more like you have a bad booster...try this: with the motor off, go pump the pedal about a dozen times and then hold it down, then start the motor...the pedal should drop as the booster becomes active...if there's no difference, the booster is shot.

I can't explain why it would feel different after bleeding, unless you got a little air in the system while attempting it, and made the pedal a bit spongy....

Here's the deal. I had the same problem with the brake pedal going to the floor after I installed a new rebuilt master cylinder from Pep Boys. (1995 Accord, 2.2 liter, VTEC). After bench bleeding the master cylinder and bleeding the entire system with a MAC Tools air bleeder tools four times, I still have the same problem.

I finally took the new master cylinder out and returned it for another one at Pep Boys. After following the below procedure to the letter, I have no more problems. I hope this is helpful to whomever.

Step 1 of Master Cylinder Installation - Bench Bleeding Unit

Note: Bench bleeding to remove air trapped in the master cylinder, must be done prior to installation. Failure to bench bleed the unit may cause low pedal height and/or "spongy brakes".
Important Installer Notice: Installation of a new replacement master cylinder may require the proportioning valve and failure warning switch removal from your original master cylinder if so equipped. (not necessary on the 1995 Accord.) When reinstalling the original proportioning valve and failure warning switch on the replacement master cylinder, the new rubber "O" ring supplied in the kit must be used. Prior to installation, make sure to coat "O" rings with brake fluid.

1. Clamp the master cylinder mounting flange in a vise. Do no clamp the unit by the body, Position the unit to be sure that it is perfectly level.
2a. Install and tighten the threaded barbed plastic fittings (enclosed with most remanufactured master cylinders) into the master cylinder outlet ports (where the brake lines attach).
2b. For cylinders with more than two ports, install and tighten the two barbed fittings into the top ports. Make sure to plug the remaining ports.
3. attach a section of clear tubing over the ends of each barbed fitting. Place the bleeder tube-positioning clip (also supplied) on the top of the reservoir divider and insert the open end of each tube through the positioning clip into each reservoir opening as deep as possible without restricting the flow of fluid.
4. Fill the reservoir with clean, manufacture specified, brake fluid. Check that the tubes are full submerged in the brake fluid. Use a Phillips head screwdriver to slowly depress and release the master cylinder plunger, using 3/4" to 1" strokes. Using slow even strokes, stroke the master cylinder until no bubbles are present in the lines and master cylinder. (you will have to keep filling the reservoir at the same time. Remember to wait 10 seconds between strokes.
5. Tapping the bottom of the master cylinder will help to bleed the air out. Make sure to bleed the system until no bubbles are present. Pressing and releasing the plunger too fast will cause brake fluid to spray from the reservoir and air may enter the system. "Top-up" the brake fluid reservoir, as needed.
6. Leave the tubes submerged in the reservoir while you carefully install it back on the brake booster unit.
Next Step: Installing the Master Cylinder
1. Reinstall any gaskets, shims or packing material (none on the 1995 Accord) that was removed with the old master cylinder. Reinstall the ABS module if one was removed earlier (the 1995 Accord has a separate ABS unit toward the front of the left fender well. You shouldn't have to mess with it.).
2. Match the push rod of the master cylinder with the push rod of the brake pedal/booster assembly. You should not encounter much resistance. If so, ensure you have matched up the push rods.
3. When the push rods are center correctly, the master cylinder should seat flush with the mounting face of the brake booster.
4. Install and tighten the master cylinder and mounting bolts or nuts to manufacturer's specification.
5. Remove the bench bleeding fittings one at a time, being careful to hold the hose up so tha excess fluid will drain into the reservoir. Attach the respective brake lines to the master cylinder ports. Check that the brake lines are full of brake fluid (no air) before attaching the lines. DO NOT TIGHTEN THE LINES YET.
6. With the engine off and the brake lines loose on the master cylinder, have somone press the brake pedal down slowly until the pedal makes contact with the floor and hold the pedal against the floor. Now you can tighten all the lines on the master cylinder.
7. Reinstall the plastic reservoir, tighten the clamp, insert the plastic filter if supplied and fill with brake fluid. Leave the cap off for now.
8. Release the pedal and allow the pedal to return to normal height.
9. Start the engine and check the brakes by pressing hard on the brake pedal. The pedal should feel firm, and should not travel too close to the floor. If the brakes feel "spongy", or there is too much pedal travel, bleed the brake system at the wheel cylinders/calipers, making sure to follow the proper manufacturer's instructions for proper bleeding procedure (this procedure usually says to start with the wheel cylinder/calipers the farthest away from the master cylinder first and work closer with each wheel.)
10. "Top off" the Plastic reservoir and securely attach the reservoir cap.
11. Test the brake function in a driveway or parking lot before driving the vehicle on the street.
12. Make sure the reservoir is not overfilled as this may cause the brakes to "drag".

That's it. I followed these steps and didn't have to bleed each caliper at all. Thank You!

Again, I hope this helps someone not to have to go through what I did.