Besides the rattling at idle is there anything else to be aware of with a light weight flywheel? is there any added gear whine or anything else?

 

You may find that the car stalls more often unless it's been tuned for it. You have less spinning mass and therefore the flywheel slows more quickly, the idle circuit isn't tuned to catch it quickly enough out of the box.

 

Can you provide more detail. Do you mean you are more likely to stall upon launch. Will the clutch have a higher release point?

 

It's a little trickier to launch, but easy to get used to - that is not the problem. The stalling is when coming to a stop and you let off the gas. I believe what people are descibing is that when the RPM's drop after lifting off the gas, a certain percentage of the time the car will stall, as you are coasting down to the stop.

 

I dont' have a LWFW, but in checking into it, you have to consider that a dual mass flywheel is heavier....therefore it has more weight or "mass" to keep the engine's centrifical force going....the LWFW is (by obvious definition) much lighter, therefore it tends to decelerate quicker upon release of the clutch....this really requires a readjustment of your driving style and ability to react to the engine boggin down quicker unless you give it more gas to overcome the deceleration ....but by the same token, it reacts much quicker to the application of the throttle and will allow the engine to rev up quicker....nothing more than a balancing act you have to learn. It's quicker to respond to a throttle blip...sort of depends upon what you're used to and wherther instantaneous response is something you feel you really need. I've never had one, but my oppositon to them was the rattle of the flywheel at a stoplight...a common complaint by many who didn't like it to sound like something was loose in there, and didn't like folks looking over at a $100K car thinking it sounded like a Plymouth Horizon. I found that Im quite content with the stock feel of the clutch and the way a dual mass flywheel reacts....but that's just me.

 

off idle engine stalling is something I could not live with. lwfw is great for the track.

 

Agree 100% with Oak...

 

Damn browser crashed, lemme' try this again!

Okay, noise. Dual mass flywheels are used to dampen engine pulses that can make noise as the transmission lashes back and forth during firing pulses. It's a damper but you should only hear it during idle with the clutch out in my experience with my Supra.

Stalling. Let me relate my tuning experience WRT on my Supra as well. When I switched to a LWFW on the Supra from the HEAVY dual mass I began to experience stalling. The dual mass is heavy and as such spins down more slowly. the Idle Air Control (IAC) has a motor or solenoid to control idle. When tuned for a heavy flywheel this motor reacts somewhat slowly since the motor doesn't slow quickly when the clutch is applied. When tuning for a LWFW you must accelerate the IAC circuit's response and raise the RPM target at which it begins responding - generally IAC close up past a certain RPM so they must open to catch the falling RPM. If this acceleration strategy is applied to a heavy flywheel idle hunts badly getitng worse and worse until it stalls or runs out of upper range because it looks for a correction before the correction has time to occur - hysteresis. When that slower strategy is applied to a LWFW corrections do not happen early enough and when they do occur they are too slow. Raising overall idle speed helps with this as well as assiting the driver with not stalling from a stop.

Now, there's some argument as to the benefits of a LWFW. For drag racing it's GENERALLY not desired especially for heavier cars. You see the flywheel stores ENERGY and when you want to launch a car you want to expend a bunch of energy pretty quickly. Heavier flywheels store more energy and can "launch" a car more quickly as well as maintain revs down the track during shifts. On a road course this is probably not desired as RPMs go up and down a good bit over the course. On the street you probably will be most comfortable with a heavy flywheel for leaving lights and I would THINK that you would most certainly want the ECU tuned for this. That said, I do not know exactly how much access tuners of these computers have. Since some apparently offer tunes for LWFW I would imagine that they have some access to idle settings and hopefully not just simply to raise idle as a band-aid fix for this. <shrug> So long as the IAC on these cars is fast enough, adjusting to catch falling RPMs would be the way to go...

Hope that provides some general insight into idle management and flywheels Sorry if it's not 996 specific but this effects all platforms really...

 

So no gear "whine" after you start moving?

 

No gear "whine" after you start moving.The only downside is the rattling at idle and if the car is not tuned for it ,it will somethimes stall.
I have a lwfw and a tune from Tony (EPL) which prevents the car from stalling but to be honest I would stick with the dual mass because the rattling is annoying..

 

So all this time I thought my Plymouth Horizon was a peice of sh*t and dumped it, and all it was was the LWFW!!!

 

Does the rattling only occur with the clutch out and not in gear or does the transaxle rattle with the clutch in also? If so I'm surprised!

 

Mine only rattles in neutral with clutch engaged, (pedal up), As soon as you push the pedal, noise is gone...While I like my LWFW and am used to it, I MIGHT try going back to a DMFW next time I'm in there, as I have never tried the DMFW with any amount of power...The LWFW does s*uck to launch at the track.

 

I have noticed rattling (with varying intensity from very very minor to noticable) under these conditions:

1. idle
2. A/C on
3. coasting (ie acelerating in 2nd or 3rd to 4 or 5K RPM, then taking foot off accelerater and just coasting down to 2-3K RPM)
4. full load acceleration in higher gear (ie uphill full acceleration from 2-3K in 4 or 5th gear)

Granted I've only had my setup for 3 weeks, and have not broken in the new clutch or flywheel...I have noticed that the loudest it gets is no louder than my friends 997 GT3 RS, but it is definately there.

My clutch engagement, however, feels stock...easy launch, easy modulation. (I did not remove my hydraulic assist.)

 

ari have kevins setup no neg. stuff except the rattle at idel, it's louder with the air on so i just turn up the sterio