7.2 GT3RS lightweight flywheel on 7.2 GT3

[SFO]

has anyone fitted the lightweight flywheel (and associated bits like the drive belt, bolts and pulley) from the 7.2 GT3RS on to a 7.2 GT3?

would be good to hear about:
how it changed the driving experience
costs
things to watch out for
upsides, downsides, any regrets
anything you would do different

[Planetstank]

Haven’t done it as my previous .1 RS had a lwfw but iirc you only need to do the 4.0 clutch & 4.0 flywheel.

I used rennworks to do a clutch replacement. Bill was near 4k but that did include a major service and few other little bits and bobs. May be best to give them a shout

[arcamalpha]

And the damper at the front of the engine too, I think.

[rrroro]

I did this to my 997.1 GT3 a few years ago, went with the 4.0 clutch & flywheel

how it changed the driving experience
+ Easier to rev match on downshift
+ More revvy/livelier/stronger ‘feeling’ engine
+ Upshift blips are fun!
+ You’re NOT more likely to stall, the cars idle valve will still maintain rpm as it does now - in traffic or slow manoeuvres I still creep clutch without throttle unless on an incline or turning hard

- Bit of extra noise in the cabin but hello it’s a GT3
- Revs drop quicker when changing gear, upshot is you need to be quicker and smoother when shifting - say goodbye to cruising around making slow lazy gear changes

costs
- Did same time as coolant pipe welding so everything was out for that, parts were maybe around 3k

things to watch out for
upsides, downsides, any regrets
- See above, none in my case

anything you would do different
- With hindsight I should have done lower final drive mod at the same time

[SFO]

arcamalpha said:

And the damper at the front of the engine too, I think.

I thought there isn’t a damper ..

[SFO]

rrroro said:

I did this to my 997.1 GT3 a few years ago, went with the 4.0 clutch & flywheel

how it changed the driving experience
+ Easier to rev match on downshift
+ More revvy/livelier/stronger ‘feeling’ engine
+ Upshift blips are fun!
+ You’re NOT more likely to stall, the cars idle valve will still maintain rpm as it does now - in traffic or slow manoeuvres I still creep clutch without throttle unless on an incline or turning hard

- Bit of extra noise in the cabin but hello it’s a GT3
- Revs drop quicker when changing gear, upshot is you need to be quicker and smoother when shifting - say goodbye to cruising around making slow lazy gear changes

costs
- Did same time as coolant pipe welding so everything was out for that, parts were maybe around 3k

things to watch out for
upsides, downsides, any regrets
- See above, none in my case

anything you would do different
- With hindsight I should have done lower final drive mod at the same time

Thanks!

Is the 4.0RS clutch and flywheel even lighter than the 3.8 RS?

[isaldiri]

SFO said:

Thanks!

Is the 4.0RS clutch and flywheel even lighter than the 3.8 RS?

Iirc, it's the same flywheel but a beefed up clutch in the 4.0 so not lighter.

[rrroro]

SFO said:

Thanks!

Is the 4.0RS clutch and flywheel even lighter than the 3.8 RS?

Sorry no idea. I have a feeling it might be that the 4.0 part just supersedes the 3.8

Good point though, yes that’s another positive over the standard flywheel (clue is in the name!), LWFW is much lighter. Can’t remember how much, maybe 4/5kg

[rrroro]

Sorry overlapping posts, what Isaldiri said ^

[arcamalpha]

SFO said:

arcamalpha said:

And the damper at the front of the engine too, I think.

I thought there isn’t a damper ..

I could be wrong about application in gen2, but there's mention on this page ref gen1. Do a search on the page for "pulley". https://www.sharkwerks.com/tuning-guides/997-gt3-2...

[SFO]

arcamalpha said:

I could be wrong about application in gen2, but there's mention on this page ref gen1. Do a search on the page for "pulley". https://www.sharkwerks.com/tuning-guides/997-gt3-2...

sharkwerks article very informative

[Planetstank]

The 4.0 clutch has damper springs so no need to do pulley mod if paired with 4.0 flywheel

[ffc]

The internet has stories of cam actuator screws backing out with the LWFW fitted to the standard GT3. Something to do with the vibrations/harmonics of the LWFW against the normal version. Rennlist has some discussions. https://rennlist.com/forums/997-gt2-gt3-forum/9200...

Edited by ffc on Saturday 13th April 21:32

[Planetstank]

ffc said:

The intermnet has stories of cam actuator screws backing out with the LWFW fitted to the standard GT3. Something to do with the vibrations/harmonics of the LWFW against the normal version. Rennlist has some discussions. https://rennlist.com/forums/997-gt2-gt3-forum/9200...

Damper springs in the 4.0 clutch resolve this issue if I am correct

[SFO]

Planetstank said:

Damper springs in the 4.0 clutch resolve this issue if I am correct

Makes sense

[SFO]

ffc said:

The internet has stories of cam actuator screws backing out with the LWFW fitted to the standard GT3. Something to do with the vibrations/harmonics of the LWFW against the normal version. Rennlist has some discussions. https://rennlist.com/forums/997-gt2-gt3-forum/9200...

Edited by ffc on Saturday 13th April 21:32

Seems problem affects RS too

[VPD255M]

ffc said:

The internet has stories of cam actuator screws backing out with the LWFW fitted to the standard GT3. Something to do with the vibrations/harmonics of the LWFW against the normal version. Rennlist has some discussions. https://rennlist.com/forums/997-gt2-gt3-forum/9200...

Edited by ffc on Saturday 13th April 21:32

I was advised, by Matt at Fearnsport who did mine, that there is no issue with the correct/matched pulley fitted.

(typo corrected)

Edited by VPD255M on Sunday 14th April 23:46

[SFO]

VPD255M said:

I was advised, by Matt at Fearnsport who did mine, that there is no issue as with the correct/matched pulley fitted.

that’s what my OPC senior tech says too