Beantown Kman

+1 On most race tracks 2nd gear in the GT4 works great. It is a tall gear that allows you to stay in the power band of the motor over a fairly wide speed range. This is good for most drivers because it requires less shifting and it feels like you're in the right gear. It's only when you are in very tight hairpins that 2nd feels too tall.

I believe the issue with the gearing is less about lowering lap times than it is for the street driving experience which would be more satisfying if we were shifting gears more often. In addition, 2nd gear is so tall that it's often difficult to be in the power band without grossly exceeding the local speed limit.

stout

So the current gearing is a handicap on the street, on the autocross course, and in terms of enjoyment. As to the track, I can see where the current setup might be fine, but I suspect the vast majority of GT4s will spend more miles on the street than the track. They're track day cars, not track cars. The GT4 vs Clubsport data point above is interesting, but too many variables—Pobst being the biggie. Even if there wasn't a huge difference on same day with same driver at that one point on that one track, I'd still opt for a new gear set.

Mooty offers sage advice, of course. Been trying to use first a bit more, and I don't shift all that often—but do like the process of shifting and find myself in second and third too often waiting for the power band. If my GT4 is a keeper, headers/intake/tune/LWF are in the future.

I'm less and less interested in an R&P swap for the reasons that have been stated before, and more and more interested in seeing if someone can come up with a way to adapt the factory 1, 2, 3, 4, 5, and 7 gears from a 991-1 to work in the GT4 gearbox. I've never driven a 991-1S that didn't feel quick, and those ratios were made for the engine in the GT4, with a gearbox that gave the engineers more room to play with due to seven gears. And I never use 6th in a 991. But maybe some who like the current 6th could option that instead of the 991-1 7th to match their preference? That would be pretty cool. Wondering what it would take to get 991 gears into a 981 transmission case. Custom main shafts? Other gears? Could it be done with factory parts? Aftermarket shafts or gear mounts? Or? Would the transmission case be strong enough, or is a billet cover like the old 901 setup needed to strengthen it? I remember someone at PAG telling me that the gearbox was THE limiting factor for the GT4. I thought he was talking about reliability if you added power, but maybe the comment was as much or more about performance. The autocross comments above, and my experiences on the street, seem to indicate that it really is. And I do rate fuel efficiency and comfortable cruising as two more areas of performance. I'm willing to compromise on both (else I would not have a GT4), but it seems kinda dumb to compromise on these areas for no benefit.

The same engineer told me that a 997 GT3 (RS?) gearbox in a 996 GT2 was transformative, so he's clearly one of us. Loopy.

sunnyr

Info on the Ehresmann final drive (from another thread) -

Speeds at redline with a 4.75 final drive -
39.85
67.64
93.55
116.73
138.84
162.84

@stout, Curious if you thinks this will address the 2-5 being too long issue (obviously, it won't help your 6th not long enough complaint)? For comparison, 1-5 speeds with 911S ratios mated to stock GT4 3.89 final drive -
41.19
70.33
103.91
123.89
149.13

Alan C.

I could be happy with those gears.

BillC3

I could also be happy with those gears, at least for 1-5. I could live with it for 6, but would much rather have a taller 6th, preferably tall enough to be a little taller than the original 6th gear overall ratio. The odds of me taking my car on the Autobahn are worse than winning the lottery, and improved highway cruising would be nice. Since they'd have to open the trans to install the new R&P, might as well install a new 6 while they're in there.

BTW, 8:36 is actually a ratio of 4.5, not 4.75. So, that would make 2nd gear top out at 72 mph, not 67. Either way, a big improvement over 84 mph. A 4.75 ratio would be 8:38 (not 36). Could there have been a typo in the original thread?

neanicu

Reading this thread,I can totally see why a manufacturer has to choose a certain set up from their engineering and cost standpoint. Sure,the gears are long,but as you can see,it is impossible to satisfy everyone. We all have our uses,our roads,our corners,our track,our entry speed,our highway and our own vision on how we want the car to behave in a certain gear. There is no perfect car and the GT4 is far from it. People talk about the " parts bin ",but disassemble your GT4(at least on a computer screen) and see how much the sum of its parts cost : I'll tell you right now,it's a heck of a lot more than what the car sells for! I'm not defending it blindly,those that know me sure realize I'm far from the average Kool-Aid drinker,but we have to be realistic here : something has to give! We've been complaining for years that we want a Cayman that is not held back : well what do you know! They've made a step in the right direction but held it back once AGAIN! Surprising?! NO. Patience I say...it will come in time even better.
The aftermarket will most likely come true if the demand is there,for those that need that every last bit of performance,just like they've managed to come true to fix quirks and complaints in other Porsches and/or other makes/models.

Manifold

^ I don't really buy the argument that the gearing seems unsatisfactory in some circumstances due to tradeoffs. I've driven other manual Porsches on road and track, and the gearing was good in both settings, to the extent that I never noticed the gearing, it just worked.

My thinking is that the gearing of the GT4 is somewhat mismatched with the engine precisely because of the parts bin aspect. Again, it's less of an issue on the track than the road, and it doesn't ruin the car on the road, but the pairing of the gearing/engine could have been better if Porsche put more effort into the development.

The GT4 should feel muscular on the road, or at least peppy. But it doesn't. It feels like something is missing, or holding it back.

Accel Junky

I could totally live with these shift points.

The thing is...the same gearing is in the 981 GTS and S and those have even less power. The gearing mis-match is even worse in those cars.

stout

Agreed. I think it's two things:

1. The 3.8 as installed in the GT4 is not breathing (and thus outputting) like it can and should be.

2. Gear ratios—I cannot think of a single other modern Porsche where I felt the gearing was anything other than acceptable or even brilliant; EVO complained about the 981-1 S/GTS gears before, and I did take note of it—but it didn't bother me in those cars the way it does in the GT4. I think that has something to do with the GT4's chassis and mechanical grip as well as the 3.8 feeling strangled and soft, at least here in CA on CA gas.

stout

Really nice contribution to the discussion. Thanks for this.

I think those 991S ratios for 1-5 with the stock GT4 final drive is the magic ticket—especially if you could get the 991S 7th to work as a 6th. Given Matt's comments on R&P longevity, I also like the idea of sticking with the GT4's stock R&P.

I like the ratios with the R&P change 1-5, but it requires an aftermarket R&P and exacerbates the 6th gear problem, which is already borderline. Might have to stop for gas twice on the way to LA...

Raghu

There is so much information one can get from reading these posts. It is amazing to see all the angles covered on the GT4.
It is easy to understand why every person can have a unique opinion about the GT4. All arguments are valid.
The GT4 is an awesome track/street car.
Perhaps we can request Porsche to make a non-GT car for milder performance and more economical gas mileage. Well, there is already the Cayman and the GTS. for just that.

Yargk

I'm sure you already know this, but just for the discussion, a final drive change just lowers all the gears which doesn't change the rpm drop when shifting. One might respond "well that's what we want, 2nd is too tall!" However, what we really want is a smaller rpm drop when shifting gears and from reading the posts above, usable gears at low speeds (street and auto-x) is also something people care about. If you just lower all the gears with a final drive change, the rpm drops when shifting would be unchanged.

Since only the 1-2 shift really has a big-ish rpm drop, what you really want is to keep 1st the same, shorten 2nd a little (top speed in the 70s, not 82) and then lower 3-5 to keep the same gaps they have now, so that also the 2->3 gap is still okay after you lowered 2nd. I like all my gears progressively spaced so I'd lower 6th as well, but if you're not in that crowd you could leave 6th.

mooty

if you are only changing R&P, dont bother. you killed one bug and created another. we did this in bmw (god forbid) and in 996gt3.

change 3-6 really helps. and those who find the car lacks punch on street. have guards do 3-5, you will be surprised. many who drove my car thoguht i had turbo linked to 3rd gear. even ppl who know nothing about cars, they hit 3rd gear, and look at me like they saw ghost.

to really get it write, cut a large check to matt at guards, get new main shaft with 1-6 redone. then you will smile.

gulf911

I know the old addage if you have to ask cost... but do you have a ballpark
to replace 3-5 all in?

Thanks Mooty
Dan

mooty

each gear is approx. 1100
then add labor

sharkwerks done several