Clutch Bleeding, what not to do
01-02-2006, 12:30 PM
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Clutch Bleeding, what not to do I have been reading alot about people having trouble with soft pedal half way down after opening up there hydraulics for clutch change etc, so I changed mine out recently with new Ram hd clutch, ground fly wheel, new slave 01-02 style, drill mod and make factory master an adjustable.
Mine is soft about half way down too but have no issues with engagement/disengagement. To get to this point I bench bled the master to the quick disconnect and then after installing, bled the unit as a whole with no air coming out for about 5 openings of the bleeder.
I thought maybe this is not right with soft pedal half way so I hooked up a heavy duty HVAC vacuum to the top of the master fill and started a 27" pull and seen a ton of bubbles coming up in the fill. I went inside and pushed on the pedal and it went almost all the way to the floor due to the vacuum pull.
I then thought to trap the back side of the piston at the master and found that the vacuum pump was pulling air in past the piston seals due to they are only designed to have preasure applied one way,not good!! This is only puting air back into the master.
I turned off the vacuum and pulled the pedal back up and let it draw fluid back into it and slowly pumped the pedal to the floor and I am back where I started with half pedal softness.
I then removed the starter and used a fiber optic viewer to watch the slave/clutch movement when the pedal was pushed. What I found was surprising. From the start of the pedal movement the slave is linear all the way until the pedal stops so that means no air to buffer the start when the PP diaphram spring gets stronger.
I then watched the PP diaphram spring and it moves in alot before disengagement of the disk. So everything is working normal and when you upgrade to a heavy duty clamping force clutch this is to be expected, which answers why the pedal gets harder to push half way down because of that extra force.
I post this for all the ones that are having this same feel in the pedal and think is is not good enough. As for the disengagement probs. adjust the master-pedal out more and it will put more fluid into the master/slave on pressing in and move the slave a little more in.
If you have any questions on what I did let me know.
Dave
Mine is soft about half way down too but have no issues with engagement/disengagement. To get to this point I bench bled the master to the quick disconnect and then after installing, bled the unit as a whole with no air coming out for about 5 openings of the bleeder.
I thought maybe this is not right with soft pedal half way so I hooked up a heavy duty HVAC vacuum to the top of the master fill and started a 27" pull and seen a ton of bubbles coming up in the fill. I went inside and pushed on the pedal and it went almost all the way to the floor due to the vacuum pull.
I then thought to trap the back side of the piston at the master and found that the vacuum pump was pulling air in past the piston seals due to they are only designed to have preasure applied one way,not good!! This is only puting air back into the master.
I turned off the vacuum and pulled the pedal back up and let it draw fluid back into it and slowly pumped the pedal to the floor and I am back where I started with half pedal softness.
I then removed the starter and used a fiber optic viewer to watch the slave/clutch movement when the pedal was pushed. What I found was surprising. From the start of the pedal movement the slave is linear all the way until the pedal stops so that means no air to buffer the start when the PP diaphram spring gets stronger.
I then watched the PP diaphram spring and it moves in alot before disengagement of the disk. So everything is working normal and when you upgrade to a heavy duty clamping force clutch this is to be expected, which answers why the pedal gets harder to push half way down because of that extra force.
I post this for all the ones that are having this same feel in the pedal and think is is not good enough. As for the disengagement probs. adjust the master-pedal out more and it will put more fluid into the master/slave on pressing in and move the slave a little more in.
If you have any questions on what I did let me know.
Dave
