Modern cars should be able to withstand this. This is also why engine mounts provide both compression and decompression resistance. If drive train cannot survive high RPM transition from WOT to closed throttle, then it is not adequately hardened.

 

I agree with you, but Jag appears to be using the computer to compensate for an under engineered driveline.

 

I didn't take this feature as making up for an inadequate driveline, it's more of a comfort feature. If someone isn't used to driving a manual, keeping it at the correct RPM for the next gear for half a second makes the shift up go more smoothly.

 

Just to make sure we don't create confusion with this discussion. F-type DOES NOT offer rev-matching functionality.

 

Ok now I AM confused! What do you call what it has then? When I put in the clutch, it'll automatically hold for a half second at the RPM of the next gear. Is that not rev-matching?

 

Jaguar claims that the automatic does. At least, in this document, under 'Dynamic Launch', they imply that all that dynamic launch does is not do rev matching, for more violent shifts. If you believe it.
https://www.dropbox.com/s/wskjex70o2...ntrol.pdf?dl=0

 

What year is your car?

 

I call it a 60 pound flywheel.

 

2016
No, it very specifically and intentionally hangs at a very specific RPM for a portion of a second. I'll take a video next time I'm in the car since neither of you seem to believe me!

 

If this were done for the purpose of rev matching on the up shift, they would have allowed the rpm to drop a few hundred rpm before causing it to hang.

 

I agree, and since that's not what it does, I don't think that's why it's doing it. It's repeatable and consistent enough that I've adapted to not have it happen. I'll have to deliberately try to induce it now to see if the VAP tune has eliminated it.

 

 

Could well be. I never hesitated long enough between upshifts to notice this phenomenon, and on downshifting I take matters into my own feet with an extra clutch pedal pump.

 

That's exactly what it does! If I wait, it drops the rpm to where it needs to be for the next gear, holds it there for a bit, and if I don't shift in time, then it drops it all the way to idle.

 

Took a while, but here's the video proof...!

 

I never noticed that. Does that hang always occur at around 2700rpm or does it depend on the rpm at which the shift is initiated?

 

No need to eliminate the effect. I played with it today. It does indeed hang for a second at an engine speed based on the road speed and next higher gear. The reason I never noticed it is that I typically complete an upshift in half the time it takes for the engine to slow down to that hang point. However, there may be some real value to having that hang point when the lightened flywheel is installed. One of the challenges of driving a lightened flywheel would already be addressed.
BTW, the clutch/flywheel builder will have the parts to measure by next Wednesday. The OEM clutch is 18 lbs and the flywheel is 38 lbs.

 

Beyond quick shifting, it's also hidden by shifting at a higher RPM. It seems the "timer" for it starts when the clutch is depressed, not when the engine reaches the specific RPMs for the next shift. Shifting at higher RPM's (where there is more RPM spread between gears) means the engine may not have time to reach the hang point before the timer runs out and it won't hang at all. In my video, you can see that it holds for a very short time on the first shift for that reason.

Back on topic - this is an exciting project! I will definitely be interested in a lightened clutch/flywheel when the time comes for replacement.

 

 

yeah...that’s me.