Aasco flywheel is here.
 

If you watched my 3.4 start up video, there was a rattle from the rear. My Dual mass flywheel was shot, once again. So I bought a light weight flywheel from aasco. The thing is sweet looking. I may have it in tomorrow. I already pulled my tranny and yanked out the clutch and flywheel. Well enjoy the pics.

http://i149.photobucket.com/albums/s...DSC_0495-1.jpg
http://i149.photobucket.com/albums/s...S/DSC_0496.jpg
http://i149.photobucket.com/albums/s...S/DSC_0499.jpg

Notice the sweet pilot bearing. Nothing like the factory one.
http://i149.photobucket.com/albums/s...S/DSC_0500.jpg

I like this one!
http://i149.photobucket.com/albums/s...S/DSC_0502.jpg

Look for a multi-faceted article on this topic on my site in just a few days, with data, with pictures.

What is this going to be about? I tossed my first flywheel with about 35k on it. My second one, also porsche oem part. Lasted about 4k miles. It shifts a good 3/4 of a inch in both directions. It rattled like a mofo at idle. I'm just done with a dumb problem like that. I have driven many puck clutch lwfw cars and the chatter and how to drive it is not an issue for me. Give me some insight on your article please :) :cheers:

I'm going to guess that its in regards to the light flywheels breaking Porsche crankshafts, because they no longer keep the crankshaft in balance, and it eventually shakes the crankshaft in half.

BC.

I would love that. JK They seem to work great on peoples track cars. I had light weight flywheels on 3 other cars and never had such a issue. One of the cars had over 90k on that setup.

It depends on the engine manufacturer.
Some companies fully balance the crankshaft, and the only thing that the flywheel does is provide needed inertia.

Other companies rely on the flywheel to provide the balancing forces for the crankshaft, along with the needed inertia to keep things spinning.

I could almost guarantee that your other engines were all internally balanced crankshafts, and that's why you didn't have any issues using a lighter flywheel.

Maybe your company took the balancing needs of the Porsche engine into consideration.
I don't know, so we will have to wait and see what Jake has to offer.

But yes, its kind of need having an actual sealed bearing as the pilot bearing.
Still doesn't make it much easier to replace if it goes bad, though.

BC.

ok. I see where this may go. I just read an article that Jake posted back in 08. The article was about a track car with 12k track miles. That is a lot of miles for any car on a track. In my opinion. I know nothing about how often track cars are rebuilt or whatnot. I hope your article is going to be good news for me not keep buying junk porsche flywheels.

Installing this flywheel removes ALL harmonic dampening of your engine and transaxle..

One person has recently broken a crank... He didn't listen to me when I told him what caused his issue more than likely, so he reinstalled the same flywheel on his new crate engine. Two events later I got another phone call from him stating that he had broken another crankshaft and he should have listened to me. He is now on engine #3 and is broke, so broke that he is having to make one engine from 3 broken cores..

Another engine (2.7 DE car) had a knock, it was pulled apart and had a cracked and breaking crank.. When I threw the assembly for this engine onto the balancer it was immediately 10 grams out of balance, when the pressure plate was added that went to 19 grams and the flywheel was nearly new and had never been touched..

Both of these are in addition to the X51 engine that snapped a crank in half last year, also using a LWFW... There have been two other instances of similar consequence that people have contacted me about since the new year, but I did not see their parts first hand.

Harmonics have to go somewhere... The dual mass was utilized for a reason-Components that are forced to absorb them won't like it.. And it appears that these harmonics also end up being sensed by the knock sensors as possible detonation, so then the ECU retards timing and that reduces HP. I have gathered data that proves that these harmonics that can't be absorbed are directly related to reductions in net power, as much as 5HP in one instance from my test car.

I don't mean to burst your bubble, because you'll probably never have an issue, but it is my obligation to share my experience with the direct development of these engines.. If nothing else I like to stimulate the readers thoughts, because then the common sense might start to kick in....

We are working on a harmonic dampener for the M96 that should help with these issues, but it is not completed as of yet.. Porsche utilized this damper on the 997 engines, so they must have had some reasoning for this....

EVERY broken crank I have seen was broken when coupled to a LWFW, 4 of 5 of them were track cars and 1/5 had never hit the track and it was the worst failure of all..

You may also want to consider that the stock flywheel isn't junk but is just doing it's job... Something is causing the flywheels to fail as it is the job of the dual mass to ABSORB the harmonics and that damages the flywheel's second mass...

Just think about that.. This is the kind of stuff I think about 24/7-

I have whittled flywheels on all sorts of other engines to virtually nothing with no adverse effects, these were not the M96 and these previous experiences of mine, and yours mean nothing.. I have an aircooled Porsche engine that revs 9K that has a 2 pound flywheel installed, the stock flywheel for that engine weighed 16 pounds.. But it isn't an M96 and was not an externally dampened engine..


Thats all I am willing to say prior to my article which is guaranteed to start a flame war, mostly with those that have never touched the internals of an M96, a balance machine and probably don't have a tool box- but they are experts.

maybe I am reading this thread incorrectly... BUT it sounds like Jake is saying our engines are balanced from the factory.

if you do a clutch job, I am under the impression that in many cases the stock flywheel needs to be replaced due to wear.

so it comes off and a new one goes on.

Assuming you put on a LWFW, I can understand how you throw things out of balance, as it is a lighter part.

if, however, I put on a new OEM flywheel - even though it's a stock part - because everyhting has been taken apart and put back together - will it STILL be "out of balance" and potentially fail - just like it would with a LWFW???

if that is the case - then anyone who does a clutch job and changes out the flywheel now is on the verge of a crank failure??

i'm confused...

Not sure I get why the Porsche flywheels are junk. There are several folks with more than 150k miles on their cars on PPBB, one even with 218k+ miles on his 2.7L boxster, still on his original clutch and flywheel. It may not look as nice or is crafted as well as the LWFW, but it seems to last. I'm at 59k on my original clutch and flywheel, and so far no issues at all. Could your issue be due to something else affecting your flywheel life?

Balance and harmonics are two different things... Sure an engine thats out of balance will have more harmonics, but even an engine thats perfectly balanced will still have harmonics that need to be absorbed..

The dual mass flywheel and it's dampening characteristics help to absorb these harmonics, the LWFW does not have any dampening capability because it has no second mass separated from the primary mass by absorption material.

Consider the fact that the dual mass flywheels that do fail may be failing because they are actually doing their job!! A flywheel is a wear item, it is a component that is designed to be disposed of after it's job is complete... A crankshaft is not a disposable item and if not absorbed somehow, somewhere these harmonics will find the weakest link and thats when things break.

With the M96 everything is rigid once the dual mass is removed, that means the harmonics from the engine, transaxle, CV joints and even the axle bearings are all going upstream directly to the crankshaft.

When the mass of a dynamic assembly changes as radically as it does when a LWFW replaces a DMFW the plane of balance must be compensated for, that means even if the flywheel that is placed onto the engine is perfectly balanced, when coupled to the rest of the dynamic assembly it will be imbalanced if the plane is not corrected.

The only way to do this is with the engine disassembled in a balance machine like mine. Thats why I refuse to install a LWFW onto any engine unless I am creating it's engine from scratch and can ensure the unit is balanced as a complete dynamic assembly then indexed for reassembly.

FWIW I have yet to see a single LWFW that has ANY balance marks on it brand new out of the box. Every unit I have spun up has had imbalance that exceeds my tolerance threshold...

When the second mass is removed where do those harmonics go?????

Interesting stuff, I sure like learning more about our engines. In my case I have almost 3 years and 40K on my Aasco lightweight flywheel, and I love the driving experience with it, engine and car are much more responsive.

I did not think much of it at the time, but right after it was installed, it did seem to me that there was a bit more vibration comming from the engine compared to the factory flywheel, another subjective data point for the discussion.

As I said, I really like the performance of the car with the lightweight flywheel, but I must say, if I had known back then what I know now about the harmonic balancing function of the flywheel, I pretty sure I would have kept the unit stock, live and learn.....


:dance:

Calling my Porsche buddy to see how much a stocker is. But. Why did my other go within 4k miles?

If your car is a 5 speed, I have a brand new one in the box that I'll let go..

Ed,
If you felt a difference in vibration in the driver's seat what do you think the engine felt??

I want to make it VERY clear that I am not discounting any company's product! My concerns are with the CONCEPT much more than any company as failueres have happened with all brands thus far..

I'll call you. When do u get I ?

I'll add my $0.02.

1) These types of crank failures were seen with the M64 (aircooled 964/993) when people pulled off the front (harmonic balancer) pulley and added a single mass pulley when ditching the AC, like the RS versions of these cars came with from the factory. Guess what, with track use, the cranks snapped.

2) The M97 3.8 engines come with a different front pulley that incorporates a harmonic balancer, might be worth looking into if you have a LWF.

3) I'm not sure of the cars Jake is referring to, but most people doing LWF swaps on the M96 platform are not doing them correctly. They simply swap the DMF for the SMF and use a stock unsprung clutch disk. Well Porsche and other manufactures have used SMF for sometime, and guess what, they use a sprung disk. Why? Because driveline vibration and shock has to be taken up somewhere. If there is no sprung component (either DMF or sprung disk) guess where all that shock is transmitted? Right to the crank. So using a single mass flywheel with an unsprung disk is going to make the harmonic vibration issues even more of a problem.

Even if you read the LUK site (the manufacturer of the DMF) they state this was simply done for noise and making cars easier to drive. And yes my car has an Aasco LWF with a sprung disk.

-Todd

Jaay,
I was on the dyno when you tried to call.. The engine is cooling now, so I have a few minutes.


Todd, you are sooooo righttttt!

The rigid disk is hell on the harmonic issues, the sprung disk is the key to the LWFW install thats done thoroughly.. Everytime I use a LWFW it is done with a sprung center disk, but I only do it if I build and balance the entire engine's assembly..

But guess what... Most people just don't use their brains.

Totally with Todd and Jake here.

We want the balance issues, harmonics and shock loading to be absorbed by the flywheel and not the crankshaft. The dual mass flywheel serves this purpose well. If we eliminate the DMFW we need something else to take up these issues to preserve reliability. Top Porsche race teams use LWFW but always build and balance the motor from the ground up taking these issues into consideration. You would never see Penske or Farnbacher bolt on an aftermarket LWFW without a complete motor balance and harmonic dampeners in place.

One of our regular track hounds "Insite" from Atlanta recently tossed his motor. He put a lot of track miles on that 2.5 but it failed shortly after the LWFW install. I wonder now if the two are related. Something to consider.

"The rigid disk is hell on the harmonic issues, the sprung disk is the key to the LWFW install thats done thoroughly.. Everytime I use a LWFW it is done with a sprung center disk"

So would it be worth while for me to replace my 40K old stock clutch with a Spec clutch or similar unit that has a sprung center disk? How much would that compensate for harmonic issues without going in and rebalancing the whole engine assembly?

Ed

:)

The sprung center disc at least gives some of the harmonics somewhat of an absorption point...

I have the Aasco LWFW with a sprung clutch. Acceleration and responsiveness is great, shifting is butter smooth. I absolutely love it other than the rattling noise in neutral. Because of location / access this is the first vehicle I haven't worked on the motor myself, but do these motors not have balancers in the crank pulleys as well?

Jake, I am fully aware of the damping I am losing and the potential failure it could cause, but it is a risk I've decided to take for the type of driving I do. You clearly know far more about motors than I ever will, but do you really need to repeat multiple times that anyone putting in a solid FW is brainless or an idiot?

I never said or implied that!

What I did say was people wouldn't make these decisions if they sat down and actually used their brains before making decisions..(to use a brain you must have one, right??!!)

You assume the risks and you understand them, but you are one of the few that has done this. If it fails you pick up the pieces and go on, thats what I do. If what I learn and share saves one engine in the hands of the normal Porsche driver it is worth it to me.

I see lots of people choose components for these engines for the wrong reasons.. Things like exhaust systems that sound better, but cost efficiency and MPG along with net performance is just one of the dozens of things people do thoughtlessly on a daily basis.

I have strong feelings concerning components and feel that nothing should be added to an engine or vehicle that doesn't increase it's performance in some way, without c reating a compromise.. Performance isn't sound or looks to me, but thats just me.

Sorry if anyone felt I called them brainless.. I never meant to, I just want to stimulate thought so people can put those brains to work that they do have.

I'll be first to admit that even if i sat down and thought about light weight flywheels all week i would be no closer to making a better decision much less a "good" one.

I have a brain but it doesn't have the relevant and necessary motor-knowledge to reason through auto performance decisions like this or most (any) others.

I very much respect and appreciate the amount of time/knowledge that you put into these engines Jake. I hope to be able afford buying myself the benefits of that knowledge in the not too distant future. That said, in the mean time please be patient with us commoners.

No worries..
This is the reason why I am working hard on the tech articles on my site and putting them in laymans terms as mush as possible..

I have the Aasco LWFW with a sprung clutch. Acceleration and responsiveness is great, shifting is butter smooth. I absolutely love it other than the rattling noise in neutral."

I thought others have reported that a Spec or other sprung clutch with LWF got rid of the rattling noise when the car is in neutral and the clutch is out. Mine does the rattling thing in neutral when the clutch is out, but I thought that was because I was using a stock clutch.

Ed

:rolleyes:

so can you do a LWFW as long as you do a sprung clutch - and be okay - or do you still throw it all out of balance and risk crank failure??

The sprung clutch just absorbs some of the initial shock but does nothing for the harmonics from my understanding. I am putting a stock flywheel back in. I just put the 3.4 in and do not want to chance something as stupid as a flywheel messing the whole thing up.

How about a little balance here? 911s until atleast the early 90's had solid flywheels. Some of the early 911s even had cranks without counterweights. No harmonic balancers. None of these had breakage issues.

As for the "using your brain" comments - there isn't alot of info out there, and alot of it is purposefully mis-info. Does an Aasco lwfw come with a warning like "hey, this things gonna break your crank"? If they really had that tendancy, would they still be selling them? Jakes examples are a small statistical sample set, and under extreme conditions. If you're into sidestepping the clutch throttle down, stuff is going to break. There is driver error involvement. That said, I do appreciate Jakes efforts here.

First off, prevuious 911 engines had forged steel cranks, not cranks made of sintered material... I have only seen one 911 crank, two 914 cranks and two 356 cranks break in all my days with aircooled Porsches. NOTHING with this engine and the prior 911 or other Porsche engines is the same. The vintage Porsche engine was not designed to have a dual mass arrangement and the design is what is creating some of these issues coupled to the cheap ass materials used in modern engines.

The cranks in early engines were extremely strong and wll over built for the application, never confuse anything that the Porsche engine of yesterday and the Porsche engine of today may have in common. The only thing they have in common is being 6 cylinders and horizontally opposed-

Aasoco and other providers do not build engines and until our program came along not many people had ever torn into or rebuilt these engines. When a crank would break people would just discount it as an extreme case and would never even consider the flywheel as a source, until it happened twice to the same person.

Lots of components are manufactured without the manufacturer having direct interaction with the entire engine as a primary objective, so they may never see the things that their component actually does..

So I sent my aasco flywheel to Jake Raby in exchange for a stocker. It will be interesting to see what he does to the aasco. Maybe well see a harmonic balancer in a crank pulley or something cool like that?
:cheers:

I'll be using that flywheel to attempt to collect data on engine harmonics with both a stock and LWFW in iterrations per second via a couple of new sensors that I have located that give analog inputs into my data acquisition system.

I may soon be able to see exactly what the engine feels and graph the differences for overlay comparatives. This could make my article very interesting.

Yeah, I don't know. Sometimes even pushing the clutch in doesn't eliminate the noise. It can be embarrassing at times when people are drooling over your car and then they hear it rattling like an old Ford. I can live with it for the performance though I'm sure I'd have a hard time selling the car with this flywheel installed. LOL

Ummn, what do you think the components feel if they are screaming that way just at idle?

Just wanted to chime in and say thanks for a very informative (and civil!) discussion.

LWFW to prevent RMS/engine damage
 

Just curious as to whether anybody knows whether a light fly wheel could mitigate crankshaft and RMS damage by reducing the overhung weight at the back of the crankshaft. I would think the DMFW at 40 lbs, slightly unbalanced, on a slightly untrue crank could cause undue crank shaft deflection resulting in RMS damage and leaks. I would think by the time you have an RMS leak you already have engine damage.

I was thinking of a LWFW just to prevent this scenario but I am just learning about all the negatives associated with it. I have a very low mileage engine (m96) that I would like to make reliable.

What flywheel would I use to be safe? Do I need a clutch to go along with it? It is not a race car so I would like to keep it as streetable as possible. What are the risks? Will a dynamic balance problem be caused?

Thanks,

jaykay

It's questionable to put a lightweight flywheel on the engine without some sort of harmonic balancing to offset the loss of the dual mass flywheel. I have had many phone calls from individuals and shops alike with broken crankshafts, attributed to lightweight flywheels and it's bad enough that Porsche issued a TSB that use of a lightweight flywheel will void the warranty, likely due to harmonics I would imagine. It's been touched upon in this thread and I highly doubt that a reduction in mass would fix the RMS issue. Engines with multiple RMS failures are indicative of a larger problem - drooping of the crankshaft carrier in the crankcase.

Thanks Charles. I was not aware of the crank carrier issue and have never seen the internals of these engines. That big heavy DMFW hanging off the end of the crank right beside the RMS got me wondering.....

I would like to keep my 2000 3.2 from ever developing problems if I can..

Take care

I concur with Charles' statements. These days the RMS leaks are few and far between. Much more significant failures are taking the engines out of service.

The LWFW continually creates problems for these engines related to harmonic dampening.

Thanks Jake.....hopefully I will be able to install the L and N IMS retrofit to give me some insurance. I would think this actually the most common issue.....if things go bad I will be calling you, although I kind of want a 3.6 now!

Do you have any test cars or customers yet? I sure would like to hear what a Box is like with this power..

Yes I have many clients who would be willing to share their experiences of the 3.6 big bore engine with you.. Some of these have my Stage I and Stage II versions of the engine.

We do ALL our own evaluation work, we do not depend on our purchasers to give us feedback on new products.. Our fleet of 4 M96 powered test cars helps us to understand our components on the street and track from DEs and AXs to Land Speed Racing.

These same track cars see 83 mile per day round trip commutes.