I'm reading conflicting stuff in my forae-searching and googling.

So the 6MT has a dual mass flywheel and solid spider clutch disc. Everyone says going to single mass (IE, lightweight) flywheels causes clutch chatter... but.

Why can't you just use a clutch disc with a sprung spider? IE, like 90% of manual transmission cars? What am I missing here? Chatter is usually absorbed by the spring system in the DMF... OR, in the springs in the clutch disc.

Looks like the JWT lightweight kit is built like that, but again people complain of chatter. Someone please educate me on the tech here.

 

Bump? Still not finding the why of it online.

 

Bump - Still would like to know.

 

Z Speed Performance offers a quiet disk options that helps with the chatter. Mine isn't too bad.

 

That's pretty subjective, because what I'm reading from your comment is, "Mine chatters too."

 

Yeah. My oem clutch chatters occasionally.

Zspeed's website isn't that descriptive. But their 20# flywheels look like they come with sprung hub discs.

OK edited - my point is not that there is chatter - enough people have experienced it that I believe that it is real. I'm sure it can be minimized. But - WHY does it chatter? What is different than all the OEM clutches that aren't dual mass?

 

During normal combustion, the crankshaft is being shoved 3 times per revolution (for a v6) and it speeds up and slows down slightly. This can rattle the gears in the transmission.
With a dual mass flywheel, the crankshaft's change in angular velocity is greatly reduced, since there is spring around the circumference to absorb it. Also, since that spring is part of the dual mass flywheel, a solid friction disk can be used.

With a single mass flywheel, the change in angular velocity goes strait into the transmission and rattles the gears. The lighter the flywheel, the worse the rattle.

 

Yep, I'm with you there. But they make sprung hub clutch friction disks, and have fo-ever.

Is it something with a V6 specifically? Because I've changed clutches on V8, I4, I6, R2 and R3, but never owned a V6 before. They were all solid flywheel, sprung hub disk.

 

Upgrading to a "stage one" clutch & flywheel package has been on my tentative list forever. But it never actually moved up to an actual, scheduled mod because of the chatter. Every time I find myself researching this topic, I step back deciding it's not for me. So if you come up with a reasonable path forward, I'd like to know.

 

The spring hub clutch will transmit more of the speed variation to the transmission. Since the friction disk springs are very close to the centre, they need to be very stiff.
The dual mass flywheel spring(s) are on the outer edge of the flywheel and are not as stiff. This as well as the extra mass, allows more speed variation to be absorbed.

A solid flywheel with a spring hub friction disk, will always send more speed variation to the transmission (resulting in more noise) than a dual mass flywheel with a solid friction disk.

It isn't a V6 thing. Dual mass flywheels are generally used on engines that have a high torque output as they have the highest speed variation.
Until about 5-10 years ago, they have been mostly installed on European vehicles. The newer turbo engines has changed this (lots of torque) and they are now common place (if they offer a manual transmission)

 

I this kit from Z Speed and the only time there I hear chatter is in a drive-thru with the sound rebounding of brick walls. Even then it's not bad. as a bonus, Joe is awesome to deal with and really knows the Z/G platform.

 

"plus CMAK"

That's a good point. If anyone is going through the cost and effort for a clutch & flywheel upgrade, they absolutely should be ditching the OEM CSC.

 

THANK YOU! Ok this I can wrap my head around.

Is the sprung-hub occasional chatter damaging to the transmission? Or is it just noise?

 

Rochester, I'm iffy on the CMAK. I think the HD CSC would be adequate as long as you aren't seriously increasing clamping force to copper-puck racing levels.

Rethinking my question re: noise above. We used solid unsprung 4-puck copper friction disks, with uprated pressure plates, for the RX7 race cars. They chattered when cold - it was the friction disk stick/unsticking to to the flywheel and pressure plate - but once the car was warmed up they didn't. Clutch engagement was brutal though.

For milder race cars (IT, where the car is mostly stock) we used stock friction disks and an uprated pressure plate (from a B2500 pickup IIRC). They tolerated more shiftor error.

So unless anyone chimes in with it causes damage by doing X, I think this is like the weird blow-off sound you get with HFCs when decelerating - it's a thing, but not that important.

 

Mike, have you ever had your CSC fail on you while driving? It's pretty unnerving. The kind of thing you never forget.

Granted, it's been 6 years later, and the RJM pedal claims to mitigate the underlying design flaw... but still, I think about it in some way every time I drive the car.