GeoJoe

Disclaimer - this is not a 6mt vs PDK thread and if you turn it into one you are fair game to be lambasted and ridiculed for using your flappy paddles. This is also not a heel-toe discussion.

I had a GT4, tracked it for a couple of years and got some great lap times at Road Atlanta, Barber, AMP, etc. I got used to the predictable down shift rev matching that the GT4 offered. It was spot-on every time and reliable. As soon as I shifted into a lower gear, revs went up and all was great. Simply putting the shifter in the lower gear seemed to make this happen, almost independent of the clutch point.

Now with my GT3, rev matching seems to have a different formula of factors. It doesn't seem as predictable to me and I think there is a combination of gear shifter placement and clutch point release. The GT3 hasn't missed a down shift, but I've been surprised a time or two on what it wants to do.

How can these be so different? I thought these were similar components. Maybe not? I'm trying to keep things as smooth as possible. Any tips are welcomed.

cox1974

Same here.... The gt4 rev matching feature is much better than the gt3 one....

Jimmy-D

I would not say one is better than the other- just that they are different

GeoJoe

Well... different yes, but GT4 seemed "better" in that it is more predictable and shifts the same way each time... where as the GT3 seems to do what it wants and acts like you're what's wrong with it.

CAlexio

Concur also, exact same impression. the gt4 (or spyder one in my case) seemed much more precise than the one in gt3... could it have to do with the quicker revving engine on the gt3?.. maybe the algorithm is programmed differently?

GrantG

First of all, the two are totally different gearboxes (I've had both also). I think the different Rev Match behavior is probably related to the GT3's having some extra software parameters related to its ability to do the No-Lift upshifts (think this complicates the algorithm)...

Bossing

Yup they're different.... I liked my GT4's rev matching performance (algorithm/programming related?) better than the .2 GT3's. It's weird at first but in the end my first thought was wow the GT4's rev match is so spot on all the time... natural like it consistently behaves according to your brain's thinking of heel & toe action. Well this is my personal feedback but now I know I'm not the only one.

Alan C.

On the drive home with my 991.2 GT3 I thought it was broken. Nothing like the GT4 which seemed a lot like the Nissan 370Z rev match, not a dig. As noted we are dealing with two different transmissions with two different software solutions. The GT4 felt/sounded more like what I was used to when making a manual rev matching downshift. A bit of overshoot. The GT3 appears to give only what is really needed. Playing with the GT3 it seemed it responded somewhat to how quickly I moved between gears and where the engine was in the rev range when changing gears. After driving home from Perimeter the weather has been crap so no additional data.

GeoJoe

Thanks for the input guys. Glad to see I'm not crazy. All I'm looking for is consistency and predictability. I guess this just means more track time. Something is going on with the clutch release point with the GT3 that makes a big difference here. Trying to narrow in on that. The GT4 didn't seem to care where the pedal was.

GrantG

Once on track, you'll find that you get into a rhythm with your shift and braking points and the Auto Rev Match becomes very predictable and reliable. I don't really bother with the Auto Rev Match on the road (do it myself there and I wouldn't need it on the track either if the pedal positions were better for my heel-toe needs - thinking about a Rennline adjustable gas pedal).

GeoJoe

Funny, as I think part of my issue is that I have to unlearn how I drove the same exact track in the GT4 now that I'm in a GT3. Those damn long and tall 2nd gear runs have ruined me!

Listen to these GT4 rev matches...

Now this...(just having fun with my buddy)

-eztrader-

I had some occurrences where downshifting the gt3, and rev match just didn't work at all .

GrantG

I've had this happen too, but I think I understand the reason. If you even touch the throttle slightly during the downshift, the system thinks you are trying to blip yourself and will defer to the driver. If you didn't touch the gas, then it's an error with the system...

Jamie140

GT3 .2 seems to base rev match on clutch engagement. I find it much harder to mimic and replicate than on the GT4 or Boxster Spyder.

e6tme

I never had a GT4, so I can't comment on the comparison between the two, however I have a couple of observations after putting ~300mi on my GT3 Touring.

In the process of driving around town and some short highway cruises, (with Sport mode disengaged) I noticed that if I attempt a ham-fisted downshift by selecting a low gear (1 or 2) from a high gear (4-6) without a driver induced throttle blip, before I release the clutch pedal, the software will attempt a pseudo "rev match" to offset the differential in RPM vs gear speed.

So, there is still some sort of a safety net programmed in, regardless of Sport setting, most likely to minimize the chance of a "money shift" locking the rear axle on deceleration.

I've also noticed (occasionally and inconsistently) when driving the car and blipping the throttle on my own during a downshift, something happens in the engine management, almost like timing is retarded to induce a "burble" in the exhaust. In this case, I don't quite get the rev spike that I asked for, (although the exhaust sounds extra flatulent, fun!) and the resulting downshift isn't as smooth. This seems to occur if my "blip" on the throttle pedal is a short stab. If it's a slightly longer, smoother depression of the throttle pedal, the burble doesn't seem to happen as readily.

Does the "no-lift shift" function work regardless of sport mode? Maybe that programming is somehow induced during my downshifts? I dunno.