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Old 05-12-2009, 06:15 PM   #1
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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.





Notice the sweet pilot bearing. Nothing like the factory one.


I like this one!


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Old 05-12-2009, 06:25 PM   #2
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Look for a multi-faceted article on this topic on my site in just a few days, with data, with pictures.
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Old 05-12-2009, 06:31 PM   #3
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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
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Old 05-12-2009, 06:34 PM   #4
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Quote:
Originally Posted by JAAY
What is this going to be about? Give me some insight on your article please
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.
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Old 05-12-2009, 06:37 PM   #5
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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.
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Old 05-12-2009, 06:48 PM   #6
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Quote:
Originally Posted by JAAY
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.
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Old 05-12-2009, 06:49 PM   #7
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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.
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Old 05-12-2009, 07:19 PM   #8
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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.

Last edited by Jake Raby; 05-12-2009 at 07:32 PM.
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Old 05-12-2009, 07:50 PM   #9
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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...
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Old 05-12-2009, 08:24 PM   #10
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Quote:
Originally Posted by JAAY
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.
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?
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Old 05-13-2009, 03:26 AM   #11
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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?????
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Old 05-13-2009, 04:28 AM   #12
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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.....


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Old 05-13-2009, 05:18 AM   #13
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Calling my Porsche buddy to see how much a stocker is. But. Why did my other go within 4k miles?
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Old 05-13-2009, 05:34 AM   #14
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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..
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Old 05-13-2009, 05:55 AM   #15
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I'll call you. When do u get I ?
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Old 05-13-2009, 06:07 AM   #16
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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.

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Old 05-13-2009, 06:19 AM   #17
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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.
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Old 05-13-2009, 07:43 AM   #18
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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.
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Old 05-13-2009, 09:54 AM   #19
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"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

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Old 05-13-2009, 10:57 AM   #20
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The sprung center disc at least gives some of the harmonics somewhat of an absorption point...

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