Going to attemp LWFW/Clutch install this winter - questions

[skl2]

I am going to pull the trigger and install a LWFW and new clutch in my 06 Cayman S this winter. The clutch in it is fine, but I have never done this before and I think it would be a fun DIY project. I have a few questions:

I will probably go with the Aasco LWFW that Pelican sells, but I need to figure out what clutch to pair it with. I know it has to be a spring-dampened clutch. If I go with the Sachs sport clutch that Pelican sells (that is spring dampened), do I also have to purchase the new pressure plate or can I use the OEM pressure plate? Pros/Cons? I would like to keep the clutch pedal at least as firm as it is now.

I noticed that Suncoast sells a clutch kit w/ pressure plate that is half the cost of the clutch and pressure plate from Pelican, so that is why I ask. Here is a link to the Suncoast clutch kit that appears to be spring-dampened for use with a LWFW but I have emailed them to confirm: Cayman Clutch Kit - 6 Speed:Porsche Parts & Porsche Accessories - Wholesale Porsche Parts & Tequipment - Cayman Panamera Cayenn

If anyone has done this before and has any advice, I would appreciate it. I will also plan to do all the "while I am in there" maintenance.

[JFP in PA]

Before doing away with your dual mass flywheel, let me suggest the following:

(1) Do a search in the purpose of the dual mass, and what some have experienced switching to a lightweight single mass unit.
(2) Also do a search on the “as delivered” balance of lightweight single mass flywheels.
(3) Try contacting a premier M96/87 engine builder, say Jake Raby, and ask him of his opinions of this type of conversion.

[skl2]

I have been searching, reading and then following up. It seems that most people I talk to have had no issue with their LWFW and Clutch upgrade. As always, Im sure you can find people that fall on both sides of the issue. If you have 1st hand experience please share.

[JFP in PA]

OK, this is the crank from a 3.6L X51 engine after running an "off the shelf" light weight one piece flywheel:



On the M96/97 engine, the only harmonic dampening system is the dual mass flywheel, remove it and the end result could be other than you expect. More than one Porsche engine builder has recommended not using one of these lightweight units unless the entire engine is fully internally balanced first, or over time the crank can fatigue, crack, and fail.

We have also seen owners that have installed a lightweight unit and noted slight vibrations; when the new flywheel and clutch were pulled and checked for balance, the flywheel was found to be out of balance all by itself; not a good thing. After properly rebalancing, the vibrations stopped.

If you are going to install one of these units, you should be aware of the potential downsides. Here's a direct quote from Jake Raby about installing a lighweight flywheel, Jake is probably one of the best known M96/97 engine builders out there:

"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."

[JMatta]

The stock cranks are produced of sintered metal (i.e., powder), not forged...in other words, not very strong and any imbalance could cause a fracture.

Of course, I defer to JFP and the experts, and I certainly appreciate their opinions. If Jake and JFP thinks it's not a good idea...

[Jared at Pelican Parts]

I really dont reccomend a lightened flywheel on any road car. You need to read up on mechanical resonance and then you'll understand why it isnt a good idea. Listen to Jake here.

[skl2]

Ok, so Porsche puts a LWFW in the GT3 RS...and that is a "road car". I guess I am just trying to figure out why there are a lot of people out there who have the LWFW in many different Porsche models and yet I dont see a host of threads about their cranks exploding.

The issue seems to be less about the LWFW and more about having one that is unbalanced. So my concern turns to making sure I get the right LWFW for my car, not that I should NEVER have one.

[JMatta]

I recall Jake mentioning something about the crank and flywheel need to balanced as a unit...that would require complete disassembly of the engine.

[skl2]

Another question: Does the sprung clutch help with dampening?

[Jared at Pelican Parts]

Originally Posted by skl2

Another question: Does the sprung clutch help with dampening?

Nowhere near as much as the flywheel does. Trust me, it's not a good idea to have one on a road car.

[skl2]

Originally Posted by Jared at Pelican Parts

Nowhere near as much as the flywheel does. Trust me, it's not a good idea to have one on a road car.

Well that is the thing, you say to trust you but I don't know your reasoning for making such a statement. Like I said above, the RS has a LWFW from the factory. I have driven other cars with one on the street and didn't have any issues. I have a tricked out 71 914 (of which my Dad is the original owner) and it has had a LWFW since the 70s. So, are you saying not to put one in a street car because it hampers driveability or because its going to explode the crank? I really am just trying to gain as much knowledge of your position as possible before I move forward. This is the only place I have seen pushback about a LWFW so I am going to see what others think on other boards as well. I appreciate your willingness to share and help me though.

[Jared at Pelican Parts]

The GT3 RS is also a different engine case, based off the 964. The M96/97 cases are a totally different design, where the flywheel acts as the harmonic balancer for the engine. We built a Super Boxster here at Pelican with a 3.4 that can blow the doors off just about anything and we didnt use a lightweight flywheel.

As for why I don't like them on street cars... Most people buy one and don't realize how an engine revs with one installed. It certainly makes driving in traffic a pain. They really don't have any place on a road car.

With the M96/97 engines, there is NO other means of absorbing harmonic resonance except for the flywheel. It's a HEAVY flywheel as well. it is NOT the same as the old air cooled motors. The manufacturing of the rods and crank are different, they are literally pressed into shape from powdered metal.

If you install a LF, you will have to have the entire motor re-balanced. Of course you could also do things like installed forged rods, blueprinting, etc.. but that would send your costs into race engine territory.

[JFP in PA]

Originally Posted by skl2

Another question: Does the sprung clutch help with dampening?

Not really, the sprung clutch disc helps with driveline shock and shuddering (drivability) as the clutch engages, but it does not dampen harmonic loadings.

[JFP in PA]

You seem to be comparing apples to oranges; the "other" vehicles may be fully internally and harmonically balanced, but I can assure you the M96/97 is not, which is why the dual mass flywheel was used. The M96/97 uses a crank production method that is different from other Porsche engines to help keep costs down; but it has durability drawbacks if forced to absorb harmonic loads.

In the end, it is your money and your car, so proceed as you please. You asked a question about anyone having experience against using a lightweight single mass flywheel on an M96; and you have gotten a consistent answer, which is obviously not the one you wanted. At this juncture, you are the only one that can decide how to proceed...............

[skl2]

I have gotten a completely different set of answers here than I have when talking to other people, so forgive me if I keep asking questions and trying gain further insight as to where you are coming from. I could care less if drivability is not as easy with a single mass FW because I know how to drive...not to mention the Cayman is my toy and not daily driven so I rarely worry about traffic.

However, some of the other points you raise have merit so I am keeping and open mind. I also appreciate Pelican being upfront because he stood to make about 2K when I purchased all this stuff and is still being honest about his opinions.

Originally Posted by JFP in PA

You seem to be comparing apples to oranges; the "other" vehicles may be fully internally and harmonically balanced, but I can assure you the M96/97 is not, which is why the dual mass flywheel was used. The M96/97 uses a crank production method that is different from other Porsche engines to help keep costs down; but it has durability drawbacks if forced to absorb harmonic loads.

In the end, it is your money and your car, so proceed as you please. You asked a question about anyone having experience against using a lightweight single mass flywheel on an M96; and you have gotten a consistent answer, which is obviously not the one you wanted. At this juncture, you are the only one that can decide how to proceed...............

[tdady]

FOR THE LOVE OF PORSCHE......... DONT DO IT!!!

Trust me I know

[JFP in PA]

Originally Posted by skl2

I have gotten a completely different set of answers here than I have when talking to other people, so forgive me if I keep asking questions and trying gain further insight as to where you are coming from. I could care less if drivability is not as easy with a single mass FW because I know how to drive...not to mention the Cayman is my toy and not daily driven so I rarely worry about traffic.

However, some of the other points you raise have merit so I am keeping and open mind. I also appreciate Pelican being upfront because he stood to make about 2K when I purchased all this stuff and is still being honest about his opinions.

I don't think anyone here is overly concerned about "drivability", but is more focused on the longer term results of using this equipment. I'm sure nearly everyone has come across more than one website where a poster has lauded the joys of running the lightweight flywheel; only problem is that you don't always know what happened the day or week after that posting. Those of us that sell and install this type of hardware get to see the aftermath, and it has not always been rosy.............

[skl2]

Thanks everyone for your time and explanation. This has definitely given me pause as I look at other things to keep me busy this winter

[JMatta]

I had a light flywheel installed on my '93 911 RS America, which I did many HPDEs in. The 964 aircooled engine is a completely different animal than the M96/97, but to my point; track driving was great, however, the car would stall at every other stoplight when you depressed the clutch. Fortunately, I'm skilled at heel and toe, so I had to feather the throttle to keep it running. Idle was fine, but just the initial drop would be problematic. Car felt like it had 25% more power over stock.

[thstone]

Almost every Spec Boxster has a LWFW. No reports of massive failures of any kind from that community.

My car has a LWFW. Runs fine on the street and track. That's it, there's no more to the story.