How to remove the Clutch Delay Valve, and why you might want to.

[webkris]

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Located inside your plastic clutch slave cylinder (thanks FCP Euro for the pic. )

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There is a shiny metal clip, a rubber gasket, and a plastic valve with a small hole in it.
Sheetrock screw removal tool for scale. Take a screw driver and drive the screw into the clip and pull out.
Remove these three parts and re-install.

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The slave cylinder is spring loaded and full of fluid so it's easy to remove and a bit of a pain to re-install, but can be done with some persistence from under the car. You can position the cylinder so that it locks onto the transmission under tension, and get the bolt started. The fluid line has a metal clip that just needs to be pulled up and then the line will pop right out. All of this is plastic, so be careful. You will need a 12mm E-Torx plus a clamp on the rubber hose to stop the fluid leak.

Mandatory to bleed the cylinder and the clutch after this. A pressure bleeder is also needed. I spent 15 minutes pumping the clutch back up and I can't imagine doing this without one.

Why do it?
If you've ever experienced clutch slip at high RPM.
If you've ever experienced buck and chatter at low RPM when cold.
If you know how to drive a manual quickly and you autocross / track day.
If you can heel-and-toe down shift.
If you want a much better clutch feel.

The valve is literally adding a time delay and damper on clutch engagement. (filtering out some of the amplitude) When you clutch out quickly (let's say in 500ms) it adds 300ms of delay to that engagement. So then the clutch starts to grab and the wheels start to hop or slip and you quickly clutch back in (another 300ms before the clutch is disengaged) and you fee like an idiot that can't drive. It is damping out enough of the feel that if you can clutch quickly, you run up against that valve and get very inconsistent shifts. I literally thought my clutch was gone when it slipped during a hard run up through 3rd at 6K RPM, and then I did it a second time and had no issues.

It's designed to help smooth out the shift engagement, but I believe that it can do just as much harm by not engaging the clutch completely when getting back on the throttle at high RPM. You let the clutch out, you then got back on the throttle within a few milliseconds: This is too fast with that delay valve installed and the clutch is still engaging when you hit the throttle.

After a day of driving it's so much better. The engagement point is lower and longer. The pedal feels like it's directly connected to the clutch - imagine that!

[Arne2]

My Cayman is a PDK, but I did this to a former BMW years ago, a '96 328i. Huge improvement in clutch feel and action. Definitely recommended.

[J-Dub]

Did this to mine as well. It is fiddly to get the slave cylinder back in place but with some persistence it goes in.

[J-Dub]

@webkris

Here is the post from @Ix_ where he showed me the valve, afterward I was able to easily duplicate it.

I measured the orifice size to be 1.45mm, I mention this as on other boards people will increase this orifice size with a drill bit instead of remove it to fine tune the clutch feeling they want.

Jeremy,

The clutch slave cylinder has a small red plastic restrictor inside. Supposedly it is there to prevent overly aggressive launches. If one wants to remove it, a properly-sized screw makes quick work of it. Just a thought.