How Light is Your Flywheel+Clutch?
 

Samc asked how much the new Aasco lightweight flywheel tipped the scales at and how it compared to the stock weights, this should offer a comparison:

Lightweight Flywheel only - 13.0 lbs.
Lightweight Flywheel + New Sachs Clutch Assembly - 25.4 lbs. *
Stock Dual Mass Flywheel only - 26.5 lbs.
Stock Dual Mass Flywheel only + New Sachs Clutch Assembly - 38.8 lbs.
Lightweight Flywheel + New Sachs 4 Spring Clutch Assembly - 18.0 lbs. **

All I know is the stock FW and clutch were HEAVY! And my engine has to spin that up. Whereas, the LWFW and clutch…I had to check to make sure the clutch was in there! 13.4* to 20** pounds LESS may not seem like a lot, unless you're the engine! One went CLUNK on the scale and the other made a slight noise. I was even able to control it better!

The total weight for the 4 spring clutch AND housing, Throwout bearing, and spacers is only 6 pounds! And that is shipping weight! The 4 spring ZF Sachs clutch is for sale right now for only $357 - shipped! PM me for details.

So maybe you can have the BEST of BOTH worlds…AND the price is right!

Lighter is better AND the Aasco LWFW offers the ability to resurface (for around $100) instead of replacement, which is good. Anyone want an old flywheel?

Funny how all the HEAVY stuff ends up in my garage - now I have a couple boat anchors - flywheel & stock muffler. Now all I have to do is get my car back together and I'll let you know how it goes!

It will interesting to see how you like it once you drive it ?

Do you have a link to the clutch you're using? It doesn't sound very "street friendly".

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

http://www.flat6innovations.com/imag...s/dscf4881.jpg http://www.flat6innovations.com/imag...s/dscf4880.jpg

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!

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

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.................

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?

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?

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? :eek:

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".

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.

Some seem to get away with it for long periods, others not so much. That said, there have been enougn failures to warrant PCNA making mention of it.

Purely a matter of how risk tolerant you may be.

Any updates on this combination -- thinking about the pros/cons for a
drive to the track car.

Wonder how many of those crank failures were with the original non-sprung clutch?

Mike

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. :)

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)

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".

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

Yes, the clutch disk is spring loaded.

Flywheel: AASCO Lightweight Flywheel PN 106412-11
Clutch disk: Sachs Performance Clutch PN 881861 000 017
Pressure Plate: Sachs Performance Sport Pressure Plate PN 88 3082 999 754

From our forum owner's website;
Pelican Parts.com - Lightweight Flywheels
Pelican Parts.com - Performance Clutches

Not sure if these parts will work on an S-model. Be sure to check before buying any parts!

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

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...:)

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.

If you look hard enough, Jake Raby has posted first hand results of busted cranks from LWFWs.

** 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?

still looking... can't find it.
I see where it looks like he MAY have posted a photo of it once, but no photo there any longer.
I'll keep looking. BUT I'll be honest; after reading a ton of his posts on this topic and a couple others, the guy clearly has his own agenda in what he writes, so it's a little hard to take what he's writing as unbiased, first-hand-experience. He certainly has more knowledge and experience than I do, though.

You won't get any argument from me on that! :D

It seems he's removed the post from his site, but here are the pictures that google has saved:

http://986forum.com/forums/uploads02...1533851547.jpg

http://986forum.com/forums/uploads02...1533851563.jpg

I installed the LWFW at 142000. At 189000 no problem with that ( do have a cracked head). 9 years of competitive autocrossing and all of the beating that goes with it.

Yes, its all good! Five years of racing Boxster's has been hugely rewarding! Engines (for me) are wear items just like tires and brakes. Some engines have lasted longer than others, but none of my engines failed due to anything related to the LWFW.

Some noise from the trans might be noticeable with the top down and the clutch out. Push in the clutch, no more noise. Top up, not noticeable. Otherwise, no drivability issues, just a little quicker to rev.

Do you know if those photos are from a Boxster? My memory wants to say that is a 996 engine but ... I'm lucky to remember my home address these days. :)

I don't recall, just that it was an M96 with a lightweight flywheel.

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

Pray tell what benefit would Jake have re the dual mass versus lightweight flywheel choice. He makes neither so no financial incentive. And since he has been inside more failed engines than most posters here, he just might have some insight. That PCNA advises against it in a TSB also adds to the weight of the dual recommendation. Maybe if you have rebuilt your engine and balanced it to a micro ounce or if you just happened to get one balanced that way from the factory, you may be in the group that has a positive experience with the light weight flywheel. Or not...

Your car, your money, your choice.

Isn’t there a harmonic balancer pulley available for the M96?

Yes, but it is not equivalent to the action of the dual mass flywheel.

Porsche wanted the lightest crank they could have and those cranks cannot stand the huge torques both in Revs and downshifting loads. Many light weight flywheels installed have caused the cranks to fail.

Can you cite more than one?
In the WHOLE of the internet, I can find only one.
Please, show me "many".

Sent from my SM-G930T using Tapatalk

We have seen a couple, but also do not post everything we see on the web.....

Which one are you talking about Maytag? I remember reading a couple of articles about the reason cranks broke, and others that spoke of hearing about broken cranks that were light flywheel related were in a public conversation. I somewhat remember the article I read, and if I can find it, I will post it up for you to read. If it's a different article that you mention, that's two of the many.