How is the Spoon flywheel different from the AP1 flywheel? Also, not sure about the wider tires...

 

Link to the thread?

I've seen this idea propagated a lot, so I'm going to have to respectfully disagree here, unless someone can provide concrete data (and by all means, someone do so, because my knowledge isn't godlike here).

The clutch pretty much directly dictates how fast the pressure plate pushes down the friction plate against the flywheel. While it's true slippage can be due to the pressure plate not having enough grip, the grip is directly realized by the amount of force it can apply to the friction plate (hence its whole purpose and name). "Grabbing" force = coefficient of friction (mainly from your friction/clutch plate) * Normal Force (force exerted by pressure plate).

For example, PP1 can apply 5000N of force under full engagement. Let's say, half engaged, it can only exert 2500N. You throw in a CDV, and now it takes longer for PP1 to go into full engagement = delay before you get to its full "pressure" = less normal force.

"if you've ever experienced this slippage in an AP2 on a hard shift, the slippage lasts much longer than the cdv delays the clutch. "

There's one possible explanation I can think of for this. The coefficient of friction of a static object is higher than the coefficient of friction of a slipping object. Hence why your ABS is always trying to make sure your tires never lock up. Locked tires = less grip because now you're sliding one point of the tire across the ground, whereas if the tire kept spinning, the contact point between the tire and the ground is not really moving = static friction. Back to the clutch. Throw in a CDV, you experience delayed engagement of your pressure plate = less force = initial slipping under a hard shift. You're already slipping, but you ignore it because you're hard shifting. It's going to take a lot longer to grab now because you're already slipping, and to make matters worse, if you're fast shifting, you're probably also laying down on the gas.

Weight of the flywheel. As far as I can tell, from a physics stand point, for the purposes being mentioned, it has very little bearing to whether the pressure plate can grab on or not. We're trying to match the speed of the friction/clutch plate (tranny speed) with the flywheel (engine speed), we're not trying to stop the flywheel from spinning.

Imagine a 60 ton flywheel spinning. You grab a sticker. You slap that thing onto the flywheel. It sticks. Now imagine a 5 million ton flywheel. You grab a sticker. You slap that thing on. It sticks. Now, imagine trying to stop that flywheel with your sticker. Then you're going to get slip. But we're not trying to stop the flywheel here, or with our cars. We're trying to match the different speeds of our transmission and engine.

Best case, we succeed, clutch grabs on, and the tires break traction, or if you have godly tires that could rip chunks of tarmac off the road, the engine yields to the tires, and slows down to match the speed of the transmission.
Worst case, friction plate doesn't grab on, but it's not gonna be because of the weight of the flywheel. The main culprit would be torque, and if you're pressure plate can handle it. I'm guessing that is the biggest reason why aftermarket pressure plate manufacturers list how much torque a PP can handle.

Having said that, I removed my CDV in January and have no regrets. A couple of caveats though. If you have always shifted like crap prior to its removal, getting rid of it isn't going to save you from symptoms down the road. If anything, the CDV probably protected you from crappy shifting. If you're constantly missing your shift points, not rev matching, etc, you're just putting even more work on the pressure plate and causing it to wear even faster. Get some sand paper. Put it face down on the cement. Lightly, without putting much pressure on it, rub it against the ground. Now, try again, applying maximum downward force. Get the idea? Or you could just get a stronger PP and be done with it, because like I said, "grabbing force" = friction coefficient * normal force (pressure plate force). That's just going to allow one to mask crappy shifting for longer periods of time though..

 

Spoon and CT flywheels are similar weights, about 9 lbs.
AP1 is, umm, 14 lbs or so?
And I thought I heard the AP2 flywheel is somewhere around 24 lbs?

(The tire comment is from my experience with my old AP2 - stock tires = bad understeer, exact same car with 225/255 tires on Volks = nicely balanced car. I just like the drive from 225/255 tires.)

 

I had the same problem as the OP. Removed CDV and all is bliss.

 

Would a removed CDV net a lower quarter mile time?

 

maybe 0.05 second assuming all else equal ?

 

I would think that crisper shifts would net a .1 or .2 better quarter mile time. Just a thought.

 

Not likely, since the clutch will still slip.

 

This is defiently something i am looking to do because i have the same exact problems with my car. Is it easier to say just get a slave cyliner from a 00-03 S2k? i know you can get them from hard top guy.

 

I've had some magnificent spinning-tire launches with my CDV valve still in. I was surprised, given all the griping about CDV. I know our clutches are fundamentally weak, my AP1's slipped more, so maybe it'll slip later in life.