Really Heavy Clutch Pull

[ChrisK]

Hey all, working out more bugs with my baby since we're back on the road.

The clutch has a super heavy pull, like it's not even an option to use just two fingers to pull it because I can't, and when I start to release the lever it really snaps back into position. Really annoying when in traffic. I'm suspecting the slave cylinder. When I try to bleed the clutch it literally never gets better, the air bubbles never go away. To me it sounds like air might be seeping in at the back side of the slave cylinder. Is this possible?

That said, wouldn't a ton of air in the line make the clutch pull feel super mushy, not heavy?

I recently updated to Nissin master cylinders with the external reservoirs, they're in great condition and I highly doubt they're the problem. Fluid level is correct. I have a Ducati Performance pressure plate, with all 6 springs still installed.

Thanks for your help.

[kokis]

my stock brembo master was light to push. new brembo cyl I installed is really pain for the hand.

[SpikeC]

 If you changed the master and it is harder then that might be the problem? The ratio of the master to the slave can be the issue here. If the piston of the new master is not the same as was designed for the slave, there is your problem.

[kokis]

If you changed the master and it is harder then that might be the problem? The ratio of the master to the slave can be the issue here. If the piston of the new master is not the same as was designed for the slave, there is your problem.

Can not be so. 22' cylinder is much bigger than stock(i guess)

[ChrisK]

I hardly no anything about masters, slaves, and their specs. But it seems to me that this Nissin one should have at least as much, if not more, force capability than the OEM Brembo one? Anyways, aside from that, it was hard to pull before I switched anyway, I'm just now getting around to addressing it.

I feel like I've read somewhere that if the end of the push rod isn't greased up properly it might cause a hard pull? Or did I make that up?

The other thing I should add, is that even with air in the line I don't have the common problems of not disengaging the clutch fully. I can still easily find neutral and shift up through the gears.

[kokis]

But it seems to me that this Nissin one should have at least as much, if not more, force capability than the OEM Brembo one?

same thing, man. don't know why is that.

[Buckethead]

If you changed the master and it is harder then that might be the problem? The ratio of the master to the slave can be the issue here. If the piston of the new master is not the same as was designed for the slave, there is your problem.

This.

A larger diameter master cylinder piston will move more fluid, but will require more force to do so. A smaller diameter piston, on the other hand, will require less effort to generate as much force, but won't move as much fluid.

Air in your clutch lines will make the clutch lever feel soft, and will make it harder to fully disengage the clutch.

It sounds to me like you now have a larger master cylinder piston and are having to fight it. On the off chance that there is something binding up, you could pull the pushrod and make sure it's greased.

Other options include switching to another master cylinder with a smaller piston diameter, swapping in a larger diameter slave cylinder, or removing a pair of springs from your pressure plate.

[ChrisK]

Is removing the pushrod as simple as taking the slave cylinder off and then pulling the rod out?

I think I'll need to replace the slave cylinder regardless because I'm pretty certain it is the reason I'm getting air in my line, so what is a good option to move up in slave cylinder size?

[kokis]

This.

thank you.

[Buckethead]

Is removing the pushrod as simple as taking the slave cylinder off and then pulling the rod out?

Yes.

I think I'll need to replace the slave cylinder regardless because I'm pretty certain it is the reason I'm getting air in my line, so what is a good option to move up in slave cylinder size?

From your description, I don't think you're getting air into your system. Air in the system makes the lever squishy and prevents you from fully disengaging your clutch.

But any of the aftermarket clutch slave cylinders that tout "reduced lever effort" or something similar do so via a larger diameter piston, which requires less lever pressure to operate.

[memper]

I agree with what has been said about the masters. Though a question popped in my brain:
What levers you got? If running shorties it will compound the above stated issues.

[ChrisK]

Normal length levers.

[Speeddog]

I've seen this kind of behavior when the pushrod bearing (on the right end of the trans shaft) has failed.

[ChrisK]

I've seen this kind of behavior when the pushrod bearing (on the right end of the trans shaft) has failed.

That doesn't sound too fun.