Clutch Bleeding and Adjustment

Summary

Time after time on the forums the same old question comes up, "I just replaced my slave cylinder, and now I can't bleed my clutch. The pedal just goes straight to the floor".

Annoying isn't it? What is even more annoying is those countless hours of pumping of the pedal was in vain. Read on to find out why, and how to bleed your clutch to a perfect pedal inside 10 minutes.

The 600ti has the mixed blessing of being equipped with a hydraulic clutch, this means it is easier to fit an uprated cover plate without the complications of dealing with fragile clutch cables. However there is one caveat. Unlike most other hydraulic clutches, the clutch system on the 600ti is almost impossible to bleed in the normal way.

This stems from the location of the bleed nipple, on the top of the slave cylinder. This means that it traps air inside the cylinder which no amount of pedal pumping will shift.

The procedure outlined below explains how to remove this trapped air and restore a solid pedal to the clutch. There is also a section on adjusting the pedal properly to avoid clutch slip.

Requirements

To do this job you will need:

For Bleeding:

  • 11mm or 10mm spanner to suit bleed nipple
  • Socket extension bar or appropiate lever
  • A suitable tube and container to catch fluid in

For Adjustment:

  • 17mm Spanner to adjust height stop
  • 12mm Spanner to adjust travel length

Procedure for Bleeding

Please Note: The clutch bleeding guide was based on an original guide and technique developed by Rovertech's MGJohn - all credit and thanks to John!

Put spanner on Bleed nipple and ensure it is a good fit. Attach tubing to the bleed nipple in the normal way and allow it to drain into a suitable container.

Position the Extension bar in such a way as you can lever the clutch arm where it connects to the slaver cylinder plunger.

Open the bleed nipple a little, using the extension bar push the clutch arm and slave cylinder plunger back into the slave cylinder as far as possible.

Note the stream of bubbles from the trapped air swirl down the pipe.

Close the bleed nipple and allow the plunger to return to its normal position.

Repeat this several time until there are no longer any bubbles in the fluid.

Once the process has been completed, if two people are available, an additional step of normal bleeding may remove any small amounts of air in the system, usually this step is not required.

Update from MGJohn

"I've since changed the procedure a little which has made the bleeding process even quicker and easier. The difference is simply this. Instead of using a bar to overcome the heavy leverage required to depress the bell housing crank connected to the clutch slave's push rod, simply disconnect the crank from the push rod by removing its pin. Then, with the push rod free of the crank, use your fingers or thumb to push the push-rod fully in with the bleed nipple open to expel any air from the slave cylinder."

This is considerably easier than trying to lever against the pressure of the clutch - Thanks John

The pedal should now be tested to check satisfactory operation and adjusted as required.

Procedure for Adjustment

It is imperative there is some free play in the pedel travel, without this play the the bite point will move and it will result in clutch slip.

To ensure correct operation the clutch should be adjusted to include around 1mm of free pedal travel.

Roll the seat back to gain access to the clutch pedal and master cylinder adjustment.

The clutch master cylinder has a bar with a threaded rod and a nut, this is pedal adjustment.

There is a blue plastic stop on the pedal which rests up against a bolt with a nut which is the pedal height adjustment.

Slacken off the height adjustment and run the bolt out so the pedal comes up.

Once the pedal is fully up, it is possible to feel three different points of travel.

Firstly there is the point where is pressing against the return spring, then there is a point where it starts taking up the slack in the mechanism, and then finally it will start pushing the hydraulics.

The pedal should be adjusted so there is about 1mm of free play before it starts taking up the slack in the mechanism. i.e. the 2nd stage.

This can be checked as it will be possible to move the threaded rod about slightly by hand and as the pedal is brought down the play bring the pedal down the play will disappear, the pedal should be adjusted so there is still some free play in the rod when the pedal is at rest.

Adjust the height stop till this is the case. If the pedal is too high then the bite point can be altered by adjusting the threaded rod and the height stop in conjunction with each other WHILE always keeping that free play

Be aware if the rod is adjusted too far it will not be possible to disengage the clutch and it will "catch" reverse gear.