How Light is Your Flywheel+Clutch?

[Homeboy981]

Originally Posted by JFP in PA

Just be careful you don't end up with another "boat anchor, your engine:



This is out of a factory X51 engine that was switched to a lightweight flywheel, but without fully harmonically balancing the engine (the dual mass flywheel is the only harmonic dampener in the M96/97 engine).

OUCH! You sure KNOW how to hurt a guy!

Exactly why I went looking for a clutch with 4 springs, and to reduce the gear lash. Hopefully this will do it…at $357 - IF it works - it is a steal! And I will be driving it like it was stolen but that is a given.

Stephen, here is a link:

Brand New Genuine ZF Sachs Clutch Kit for Porsche Boxster S | eBay

JD, I will interested in JUST DRIVING it once it is off my garage floor!

[Skootnasty]

Its not the engagement of the clutch (I assume this is the gear lash you are referring to) you should be concerned with.

The dual-mass flywheel is the only balancing device these engines utilize. With out removing the crankshaft and having it sent to a specialty machine shop to be balanced, you risk the crank assembly vibrating apart at the weakest point (a journal and webbing joint).

That being said, these engines rev SOOO FAST with aluminum flywheels. I think you will enjoy the engine response a lot.

Skoot

[JFP in PA]

Originally Posted by Homeboy981

Exactly why I went looking for a clutch with 4 springs, and to reduce the gear lash.

I think you are mistaking drivability and clutch noise with torsional harmonics. These engines are not particularly well balanced internally, which is why Porsche uses such a heavy two piece flywheel, the elastomer section absorbs those harmonics. Without the dual mass, they are left to their own devices.

We have seen a couple of these failures, Jake has an entire section of his site devoted to them. Porsche even released a TSB about not using single mass flywheels on these engine's, regardless of their weight.

Just food for thought.................

[j.fro]

I've had the Aasco lwfw and a Spec stage 3 plus sprung clutch in my car for 18,000 miles including 40+ autocross events. Street driving requires paying attention to things, but isn't that just part of the experience?

[Homeboy981]

Originally Posted by j.fro

I've had the Aasco lwfw and a Spec stage 3 plus sprung clutch in my car for 18,000 miles including 40+ autocross events. Street driving requires paying attention to things, but isn't that just part of the experience?

Interesting response j.fro….what do mean by paying attention EXACTLY?

I know it will rev fast. Do you mean like doing a "rental car ram" thing?

[j.fro]

The car now definitely needs to rev a bit more so that it doesn't stall, but I also don't want to launch like a top fuel dragster. When the car was stock, it didn't take nearly as much attention to just drive away "normally".

[healthservices]

Originally Posted by Homeboy981

Interesting response j.fro….what do mean by paying attention EXACTLY?

I know it will rev fast. Do you mean like doing a "rental car ram" thing?

Originally Posted by j.fro

The car now definitely needs to rev a bit more so that it doesn't stall, but I also don't want to launch like a top fuel dragster. When the car was stock, it didn't take nearly as much attention to just drive away "normally".

The reason for the weight itself in the flywheel is the momentum. it keeps things constant. With a heavy weight flywheel it will tend to stay at its rpm when you let out the clutch. With a light weight flywheel, as soon as you let out the clutch there is no mass to keep the rpms where it was. Thus easier to stall a car with a light weight flywheel. This also allows the engine to change rpm quickly (like accelerating)

[BYprodriver]

I wish someone would come out with a lightweight clutch replacement for the stock Sachs.

The new Cayman GT4 has a "lightweight dual mass flywheel".

[Meir]

Just out of curiusety.
Is there anyone in the forum that runs with a LWFW for segnificant time?
Or suffered a catastrophic failier due to one?

[thstone]

Originally Posted by Meir

Just out of curiusety.
Is there anyone in the forum that runs with a LWFW for segnificant time?
Or suffered a catastrophic failier due to one?

I've had the LWFW and Sachs sport clutch installed in my car for 33,000 miles and 50+ track days. No problems whatsoever. I'm not an expert, just relaying my personal experience.

And as always, your mileage may vary.

[thstone]

Originally Posted by thstone

I've had the LWFW and Sachs sport clutch installed in my car for 33,000 miles and 50+ track days. No problems whatsoever. I'm not an expert, just relaying my personal experience.

And as always, your mileage may vary.

I am up to about 62,000 miles and 94 track days and I am on the 2nd clutch (same LWFW) without a problem.

And as always, your mileage may vary.

Maybe I am lucky with clutches and unlucky with valve lifters.

[seningen]

Originally Posted by thstone

I am up to about 62,000 miles and 94 track days and I am on the 2nd clutch (same LWFW) without a problem.

And as always, your mileage may vary.

Maybe I am lucky with clutches and unlucky with valve lifters.

Is your Sachs sport clutch spring loaded?

Which model?

I'm having the Ims done on my track S so I'm considering clutch options

Mike

[thstone]

Originally Posted by thstone

I am up to about 62,000 miles and 94 track days and I am on the 2nd clutch (same LWFW) without a problem.

And as always, your mileage may vary.

Maybe I am lucky with clutches and unlucky with valve lifters.

** Update **

Total of 5 years, 140 track days incl 60 races, and four engines.

Still zero problems due to LWFW.

YMMV.

[maytag]

Originally Posted by thstone

** Update **

Total of 5 years, 140 track days incl 60 races, and four engines.

Still zero problems due to LWFW.

YMMV.

this is goood.... :-)

So, the benefit of the LWFW is clear to you, then?

My car is still primarily a street car; is the added noise from the trans noticeable?
And driveability? I've driven lots of lightened flywheels before, (none in a Porsche) so I understand the need to rev more from a start, etc. But any other driveability issues?

[Krieger]

Originally Posted by JFP in PA

I think you are mistaking drivability and clutch noise with torsional harmonics. These engines are not particularly well balanced internally, which is why Porsche uses such a heavy two piece flywheel, the elastomer section absorbs those harmonics. Without the dual mass, they are left to their own devices.

We have seen a couple of these failures, Jake has an entire section of his site devoted to them. Porsche even released a TSB about not using single mass flywheels on these engine's, regardless of their weight.

Just food for thought.................

So how about lightening the stock dual mass flywheel a couple pounds?

[PorscheFan5]

JFP and others,

In my case where I am doing an Electric conversion of my 2004 Boxster, I wont have the engine but the DC motor. In this case should I keep the stock Flywheel or go for a LW one? What do you guys think? Somewhere I read that people changed it to LW one in an electric conversion but cannot find it now. Note that I will be mostly driving in 2nd or 3rd gear and the RPM will be anyway high.

BTW, if I am driving at highway speeds in 3rd gear, how high will the RPM be? I am thinking of using the stock RPM sensor and stock RPM meter in the dash. Just wondering if I will go out of the meter range...

[maytag]

revival of an old thread.
Now, three years removed from these posts, do any of you who are still here have any further recommendations regarding the Lightweight Flywheel & Sprung Clutch?
Stone?
Any others here with First-Hand knowledge who can share your experiences?

I understand the issue of balancing. I've built some very high-revving engines & I know the sort of harmonics that can occur.
What I DON't have, is experience with these cases, and what sort of abuse they'll tolerate.

I see some reports of crankshaft failure, but none are attributable to someone's first-hand experience. All are "I've heard of ....". Whereas I see several posters saying they have run the LWFW for upwards of 45k miles, with no issues.

Just looking for some experience to chime-in, before I make any sorts of decisions here.

[BYprodriver]

Originally Posted by Krieger

So how about lightening the stock dual mass flywheel a couple pounds?

I have my dual mass flywheels balanced before install, but there's not a lot of room for lightening holes & still maintain dynamic balance.