Anyone replace Clutch master or slave cylinders?

[WS6speedpaul]

Can you tell me the bleeding procedures for both?

Thanks, Paul

[keliente]

If you buy them from GM new, they come pre-bled. Otherwise bench bleed the master and once you have both installed, bleed the clutch as you would normally.

Bleeding the clutch with new fluid can be a bit of a pain due to the less-than-convienient location of the bleeder screw. If you get beneath your car and see the line from the master into the slave (it is a steel braided line going into the trans), grope around a couple inches above it and you will feel the bleeder screw. It is 7/16" or 11mm...you'll need a thin-walled socket and a 1/4" driver.

Something I did to make the bleeding process a bit easier was to cut a 1" circular hole in my floorboard directly across from the bleeder screw. This way I can pull back the carpet and bleed the clutch from inside the car without help from anyone - using a few extensions the bleeder screw is much easier to get to. I tape the sockets/extensions together for safety lol. At all times you need to keep the master cylinder topped off otherwise you'll be drawing air into the system and defeating the purpose of bleeding.

Whether you do it from inside the car or have a helper underneath - you will depress the clutch pedal (and hold) crack the bleeder screw, allow fluid to run out. Close the screw and THEN release the clutch pedal. Pump it back up, and repeat this process...sometimes 20-30 times, until you have a nice, firm pedal. The fluid coming out of the slave will drain into the bellhousing...if you look underneath where the bellhousing meets the transmission, there is a little slot designed just for this.

When you're finished, top off the master cyl halfway (the little black condom thing will take up a bit of space) and be on your merry way.

[WS6speedpaul]

Thanks for the very well laid out response and through-the-floorboard trick!

The bleeding procedure is identical to the brakes... I just did not know where the bleed screw was located....thanks!

I am buying brand new parts from GM, so per your statement they should be pre-bled(NICE). I would imagine that the lines for both master & slave have check valves in them to retain the fluid when not connected. Once fully seated, the check valves are disabled...correct?

Do you know that if there is some small amount of air in the system, is it a closed loop designed to self-purge air back to the reservoir via pumping the pedal?

Also, I'm thinking about performing the "drill mod". I assume that after removing the master cylinder braided line, opening orifice up with an 1/8 drill bit, and flushing....I can just simply hand fill the line prior to re-installing & replacing roll pin. Is this correct? Is a 1/8 drill bit correct or other size recommended?

I restore old muscle, and have not yet had much need to work on/fix the WS6. I currently have a '74 SD-455 auto, '69 Firebird 400, 4-speed, convert; and a '69 GTO RAIII 400, 4-speed, convert which is currently being reassembled.

Thanks again for your assistance!

Best regards, Paul