single mass flywheel - should I?

[fatboynash]

So my 997 goes into Hartech next Wenesday for a full engine rebuild and so whilst the engine is out I want to replace the clutch.

Was looking at changing to a single mass flywheel just wondered what other members experiences and opinions were.

[PGNSagaris]

A resounding yes from me. The increased reviness (sp) is a joy and makes the car feel much more alive. It can be slightly more tricky pulling away from a standstill but over, the smf really adds to the sensation of driving the car. Perfect for a Porsche

[Dr S]

SMF is one of the great differences between vanilla 7.2 GT3 and RS. I think SMFs should be standard on any sporting car. A pity the 1.2 GT3 does according to AP not work with SMF...

[EGTE]

I believe there can are question-marks over longevity after putting a SMF on M96/M97 engines in particular. Not my area of expertise (but probably is Hartech's), but I think it's recommended to get the transmission balanced, to compensate for the lack of mass in the flywheel?

[BertBert]

What does "transmission balanced" mean? Never heard of that before.
Bert

[Roberty]

fatboynash said:

So my 997 goes into Hartech next Wenesday for a full engine rebuild and so whilst the engine is out I want to replace the clutch.

Was looking at changing to a single mass flywheel just wondered what other members experiences and opinions were.

If you are going for a Full rebuild have you considered upping the capacity?

More power and torque rather than swapping the flywheel to make it more revvy but potentially less drivable?

Also out of interest how long have they quoted for the rebuild?

[EGTE]

BertBert said:

What does "transmission balanced" mean? Never heard of that before.
Bert

The whole thing is put on a jig and tested for vibration. Then small weights are put on (the flywheel, I guess) to smooth these out, very much like a wheel balance.

I think this site might be helpful:

https://vibrationfree.co.uk/our-services/motorspor...

If you look at the last sentence on this page, you see that even flywheel-lightening companies recommend balancing:

http://www.hthoward.co.uk/engine-machining-service...

"H T Howard recommend that all flywheels are balanced after lightening. Even though we ensure that all dimensions are symmetrical, cast materials can vary in density and may also contain voids in the material which will affect balance. While it is possible to balance flywheels as individual components, it is much better to balance all the rotating components (crankshaft, pulley, flywheel, and clutch) as an assembly."

[Cheib]

Have a read of Sharkwerks tuning guide...there's a bit oabout lightweight flywheel's in there

http://sharkwerks.com/porsche/porsche-modification...

[ChrisW.]

I do know that for the 997 GT3 MkI Porsche actively dissuaded customers from fitting the single mass flywheel ....

There is most certainly a solution since the RS version has the SM Flywheel ... but worth checking that the work is done properly !

[matfinch]

I have a single mass flywheel on my 997 CSR and it really transforms the car.

The engine revs a lot more freely, feels more sharp, spins up a lot more quickly and acceleration off the line is quicker. You have to be a bit more careful with over-revs on gear changes.

It does make the clutch biting point and pull away from standstill still a little harder, although I have a lightweight clutch too so it might be that. On idle there is a more a more mechanical noise too.

I would recommend it if you want a more sporty drive.

[cuda]

Having one fitted to my 7.1 GT3 as we speak - with a new 4.0l clutch as mine is 'toast' apparently...

Can't wait to see / feel results.

[n12maser]

personally didn't like it on my 964 as was primarily a road car and it makes it it so much easier to stall.became annoying. track car yes, road car no.

[fatboynash]

Thanks a lot for all your feedback guys. I'm not sure how long the rebuild is going to take, I spoke with them (Hartech) today as I'm dropping the car to them Wednesday, all they said re timings was that they were very very busy.

Think I'll wait and see what they come back with re diagnosis (had a bore scope test already so something needs doing) and discuss the options with them regarding the rebuild and clutch replacement.

[cuda]

fatboynash said:

Thanks a lot for all your feedback guys. I'm not sure how long the rebuild is going to take, I spoke with them (Hartech) today as I'm dropping the car to them Wednesday, all they said re timings was that they were very very busy.

Think I'll wait and see what they come back with re diagnosis (had a bore scope test already so something needs doing) and discuss the options with them regarding the rebuild and clutch replacement.

Just got mine back - love it! Some funky chatter at idle with clutch disengaged but its like a new lease of life for the car!

[fatboynash]

Thanks for the feedback Cuda, can I ask where you bought your clutch and flywheel from?

[IMI A]

I really wouldn't do this. NVH is ruined and your newly built engine may have a shorter life if the flywheel is not properly balanced as someone else has eluded too.

Did this on my 997 and it sounded like car was broken it was so loud. Made the clutch very grabby too.

[fatboynash]

So after doing quite a bit of research and taking the advice of Hartech I have now decided to go-ahead and install a single mass flywheel and new clutch to my car.

my question now is which one do I fit and where do I purchase it from?

[vsonix]

n12maser said:

personally didn't like it on my 964 as was primarily a road car and it makes it it so much easier to stall.became annoying. track car yes, road car no.

I think that propensity to stall can be mapped out - i.e. when the rpm drops below a certain threshold the engine can be made to 'blip' to catch the stall.

[Slippydiff]

http://www.aascomotorsports.com/search

[Dblue]

IMI A said:

I really wouldn't do this. NVH is ruined and your newly built engine may have a shorter life if the flywheel is not properly balanced as someone else has eluded too.

Did this on my 997 and it sounded like car was broken it was so loud. Made the clutch very grabby too.

its the one area i find a little disappointing in my 997.2 GT3 , compared to my 997 RS. Makes heel and toe less easy and intuitive,
For the type of car it ism SMF every day. How much do Hartech charge?