From the little I've read, sounds like a balance issue. On assembly, the crankshaft is ballanced to the mating flywheel. On aftermarket installations, no way to ballance, so vibrations cause problems, obviously varying from car to car, depending on state of imballance. I was going to do this mod, but now I'm holding off until more is known.

 

Did you do the pulley also?

 

yep i did the pulley also.

 

So although the gt3rs and gt3 997's both have the same crankshaft, the shafts "may" be balanced with different specs ? hmm. . .

 

I read it even more severly than that...every engine is uniquely and individually balanced, so that you cannot swap flywheels at all (even replacing the same kind) without the risk of taking the engine "out of balance" as a unit.

Do we think that is the case?

 

Is it possible to machine the new LWFW so it's balanced to the same spec as the actual dual-mass FW it's replacing? Then the motor shouldn't know the difference, right? I would think a machine shop could do that.

 

can you balance the LWFW before installation? is that what the RS has?

 

you guys are worrying too much for nothing. LWFW is a fairly common mod. look at what sharky is doing with the LLWFW.

 

true...you don't need to worry about the lwfw...just the fact that Porsche will no longer warranty a 997GT3 that has one

likely to be less common since Porsche's service bulletin....10/15/08

 

Aren't you covered since you did it before the bulletin came out?

 

perhaps if the mod was done by the dealer and they suggested that because they were doing the work it would be covered the dealer will cover it but as I read the bulletin, Porsche will not cover...here...read it for yourself...

Technical Information
Service
36/08 ENU 1360 1
GT3 Engine: Flywheel and Pulley
Vehicle Type: 911 GT3 (997)
Model Year: As of 2007
Concerns: Flywheel and pulley
Information: Replacing dual-mass flywheel with single-mass flywheel.
We have discovered that the dual-mass flywheel, which is installed as standard in the GT3 engine (vehicle type 997810/-811), is being replaced in the dealer organization with the single-mass flywheel from the GT3 RS engine (vehicle type 997850/-851).

Information

Due to an increasing number of reported faults, we expressly wish to point out that the installation of the single-mass flywheel (from the GT3 RS) in the GT3 engine is not approved by Porsche.

Since the 911 GT3 (997) engine application is designed for the dual-mass flywheel, conversion to the single-mass flywheel results in the following problems and consequences:

• The single-mass flywheel causes fluctuations and vibration in the lower rpm range, thereby reducing the smooth-running performance of the engine.

• The crankshaft is subjected to one-sided loading, causing stress peaks that can result in damage to the crankshaft.

• The one-sided loading of the crankshaft can cause the pulley to come loose, resulting in damage to the belt drive and engine.

• Any damage relating to conversion or damage that can be attributed to conversion is not covered under warranty.

Please advise your customers of this information accordingly.

©Porsche Cars North America, Inc.

October 15, 2008

 

I had the LWFW installed by my dealer about 3K miles ago, they were very suportive of this mod. I'll be taking the car for service soon, should I ask to install a new pulley?, can they fix the balance of the LWFW related to the crankshaft?

What are the diferences between the GT3 and the RS pulleys? As stated by Porsche NA, this is not the solution.

How many people has done this mod?
How many engine failures directly related to this mod?
We should ask for a real solution from porsche!!.

 

you should know that many 996 GT3's have had this mod without any engine and only a few pulley problems...replacing the pulley is less of an issue than making sure the pulley bolt is properly torqued and installed with loctite.

How many people have done this mod? Many 996's and 997's (mostly done when rms replaced) Dealers were originally willing to do this mod and many enthusiasts desired the mod because of the increase in throttle response....no one considered that the different flywheel could cause a rotating mass imbalance....Porsche's reaction has been due to requests to fix the pulley failures under warranty.

How many engine failures directly related to this mod? No GT3 engine failures but plenty of pulley failures.

We should ask for a real solution from porsche!!. Ask away...you have the real solution from porsche...don't do the mod...buy an RS

 

I had the single mass LWFW from the RS installed a year ago. Within 2 weeks of install I had the incident of the pulley coming loose and getting mangled.
My deal who did the install handled the entire process without question.

I now have driven the 997GT3 a year without incident. The car runs stout and feels completely right.
At the time of the repairs I do remember the frustration regarding how long it took. I had to wait approx. 5 weeks for the pulley. I was told it came from Porsche Motorsport and it was a race part hence the wait until one was available.
Now I do not know if this was the proper pulley that needs to be installed with the LWFW mod?
As I said my dealer behaved perfectly and except for the wait everything was taken care of to my full satisfaction.

Ranger

 

Ranger, it will really suck if someone with the lwfw mod goes to sell their GT3 and a Porsche dealer won't CPO the car because it has the mod...