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Clutch Slave Bleeder Valve Remote
Last Updated: 11/15/2010
Author: Skip

A couple of years ago, while running at NHIS, I had some difficulty getting good, clean downshifts into second gear without double clutching. While some would attribute this to poor driving technique, I was sure that there had to be a mechanical cause for this problem. Grudgingly, I got under the car, removed the starter (the fundamental impediment) and bled the clutch. Things improved for a while, but  the problem eventually reoccurred. In the process of getting the car ready for the next season, I removed the inspection plug on the driver’s side of the bell housing to check the shaft of the slave cylinder. Lo and behold, there was evidence of seepage around the slave cylinder shaft seal. The necessary rebuild kit runs about $35.00 while a new slave cylinder goes for about $49.00. Not wanting to do this twice, I opted for the new unit. My increasing familiarity with the space constraints under the car convinced me that fabricating a remote bleeder would be a relatively simple process. Many Formula and circle track cars use a concentric clutch actuator that can only be bled via a remote outlet. While there is clearly no performance advantage to be gained with this modification, it certainly does help to simplify one of the more onerous maintenance tasks by eliminating the requirement of raising the car and removing the starter. With this modification, you will clearly be the envy of anyone who has had to bleed a 944 clutch at the track. If you are still interested, you will need to acquire the following parts:

  1. Brass 90° male/male 1/8 NPT fitting.
  2. 30” AN-3 braided SS flex hose with both 1/8 NPT female ends (a common circle track part).
  3. Wilwood bleed valve insert for 1/8 NPT male (this is a standard repair insert sold by Wilwood).


     When you install the new slave cylinder, note that the bleed valve is located on the top and rear of the slave cylinder. After ensuring that the bleed valve is fully closed,  make a mark on the flat of the nut portion of the bleed valve that faces the gap between the top of the drive tube and the bottom of the floor pan. This is the direction that the new bleeder line will be directed.

     Remove the bleed valve fitting from the installed slave cylinder. With a bench grinder or file, carefully remove the raised, beveled lip at the outlet end that would normally secure the drainage hose. If this is done correctly, the modified bleeder will fit almost perfectly into the end of the of the 1/8 NPT brass fitting (approximately 3/16” dia.). The brass fitting can easily be drilled out to accommodate any difference. Now insert a drill bit (7/64” worked for me) through the outlet end of the bleeder and drill through the center of the conical seat, taking car to remove as little as possible of the conical face. I had a friend, who is a MUCH better welder than I, braze the two parts together in the correct orientation, as noted in the paragraph above. 

     Reinstall the newly fabricated bleed valve in the end of the slave cylinder and attach the SS hose to it. Recheck the orientation of the fitting and the clearance of the flexible hose over the drive tube (if you need to re-fabricate this fitting, the metric bleed valves are available from VW in a variety of lengths). Feed the flexible hose up to the top of the firewall and install the new bleed valve insert. Carefully check for leaks at each union. I used red Loctite on all of the threaded unions (the Wilwood insert has a factory applied sealant on the threads). I used a pressure bleeder (E-Z Bleed) to push fluid through the system. From this point on, you simply bleed the slave cylinder along with the brakes, prior to each event. It’s an elegant solution to a messy problem.

Credits:    Kevin Kehoe

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