NJ-GT

996 GT3
R&P: 3.44:1
Stock Michelin Pilot Sport 2 295/30R18 (25.0" tall). 5th and 6th gear redline at 8,000rpm

Gear Ratio -------- Max Seed -------- RPM on upshift
=======================================
1st: 3.82 -------- 46 mph
2nd: 2.15 -------- 82 mph -------- 4600 rpm
3rd: 1.56 -------- 114 mph -------- 5900 rpm
4th: 1.21 -------- 147 mph -------- 6400 rpm
5th: 1.00 -------- 173 mph -------- 6800 rpm
6th: 0.85 -------- 203 mph -------- 6800 rpm

997 GT3
R&P: 3.44:1
Stock Michelin Pilot Sport 2 305/30R19 (26.3" tall). 5th and 6th gear redline at 8,200rpm

Gear Ratio -------- Max Seed -------- RPM on upshift
=======================================
1st: 3.82 -------- 50 mph --------
2nd: 2.26 -------- 85 mph -------- 5000 rpm
3rd: 1.64 -------- 116 mph -------- 6100 rpm
4th: 1.29 -------- 148 mph -------- 6600 rpm
5th: 1.06 -------- 176 mph -------- 6900 rpm
6th: 0.92 -------- 203 mph -------- 7100 rpm

997 GT3
R&P: 4.00:1 (GT3 Cup/RSR ring and pinion)
Hoosier R6 335/30R18 (25.6" tall). 5th and 6th gear redline at 8,200rpm

Gear Ratio -------- Max Seed -------- RPM on upshift
=======================================
1st: 3.82 -------- 42 mph --------
2nd: 2.26 -------- 71 mph -------- 5000 rpm
3rd: 1.64 -------- 98 mph -------- 6100 rpm
4th: 1.29 -------- 124 mph -------- 6600 rpm
5th: 1.06 -------- 151 mph -------- 6900 rpm
6th: 0.92 -------- 174 mph -------- 7100 rpm

On a typical track, there is not downshift to 1st gear. Most of the time the car is in 2nd, 3rd and 4th, and 5th on very fast tracks.

From 2nd gear and up the 997 GT3 still has long gears, with just a 200rpm increase when upshifting most likely related to the new 8,400rpm redline, compared to the 996 GT3. The spacing between 5th and 6th is great, but unfortunately, I don't know of any road course where I can get a GT3 over 176mph.

The 997 GT3/GT3 RS with the RSR R&P should be really fun.

krC2S

that would be nice..how much?

grussell

As usual, you are a wealth of valuable info!!!!

Thanks!

Unitah

Very interesting information, thank you!!

Any ideas or speculations on how that would decrease 0-60 and 0-120 times (not like those matter), or more importantly gear to gear acceleration out of 2nd gear or 3rd gear corners for instance?

Thanks guys! Great information!

grussell

About 6k including all parts and labor

fapena

Is it 6K for re doing the gearbox or to change the diff. I remeber talking about this before on a different thread and my recollection is the NJ-GT suggested to go with redoing the gears as a better option than the diff change. But I may be wrong.

My question is which way is the most reasonable one to go and how much is it. It looks to me that the spacing between 1st and 4th is quite equal, so why to mess with the gears? Again speaking from a very ignorant point of view.

Thanks

03-turbo911

Thank you for this valuable information NJ-GT.

Nordschleife

on the Nürburgring, the car spends a lot of time in 3/4/5 and does use 6th. The most important test track in Germany (Europe/World?) is very high speed and does not make great demands on brakes, once you know your way round, FYI Fangio set a record when racing a car in which the brake system had failed, Moss (who developed trail braking here, reckoned there are only six places you need to brake).

In moderm cars, with some form of stability management (like PSM), I find it pays dividends to drive in as high a gear as possible, as the stability management is less intrusive in higher gears, and I have to drive more smoothly to hold a fast line in a higher gear than I might in a lower gear.

It is very enlightening to drive a car at race pace as if you were the fastest chauffeur in the world. Its also nice to lap faster than the other guys in the car and use less tyres, less brakes, less fuel. One of my colleagues successfully modified the PSM system in a Daytona car so it was used in the race, reliably.

R+C

Jean

Great points R+C.

Changing the R&P will not reduce your RPM drops (see NJ-GT's data ), but will shorten your overall ratios, all by the same amount. I don't know about labour rates in the US but I don't expect more than 10 hours to fit it. A gear change is better since it will do both (shorten the ratios and reduce RPM drops) and you can customize each gear according to your needs depending on your target top speed or corner exits etc...

As far as acceleration goes, for some fun, expect something along these lines with a 4.0R&P and stock tires.

*Assuming* the stock 997GT3 does (in mph):

0 -60--4.8s
0 -70--5.6s
0 -80--6.5s
0 -100--9.4s

Then the 4:0 R&P will give you this:
0 -60--4.5s
0 -70--5.3s
0 -80--6.7s
0 -100--9.4s

Gear changes are what make the 80mph look worse.

In-gear acceleration is more important:

3rd. Gear with 4:0 R&P
30-50mph: 2.6s
50-70mph; 2.1s
70-90mph: 2.1s

3rd gear with 3:44 R&P
30-50mph: 3.3s
50-70mph; 2.6s
70-90mph: 2.5s

Jean

Sun Ra

is there an R&P > 4.00, to deliver even lower speeds at redline, or better to change down 2-4th? Is 2nd welded on in the 997 GT3? TIA

TTRob

Why does Porsche gear the GT3 so high? 85 mph in second gear, 116 in third, etc... why? Is this gearing the best compromise for most track designs? The car doesn't have an excess of torque and isn't exactly a lightweight. Why not gear the car for more snap? TIA

Nordschleife

See my post above -

So the car is developed on a high speed track. In Germany, most GT3s used as daily drivers will be driven at over 150 mph every day. When in Munich I do over 185mph most days, on the Munich ring road, moving between offices.

High speed is natural in Germany, which is one reason why German cars are tough. There are a lot of cars around that can drive past P cars on the Autobahn, I can't see PAG willingly increasing this phenomenon.

R+C

cgomez

I disagree with Nordschleife, as it will always be faster to use the lower gear possible at any point on the track so you get the maximu torque to the wheels possible all the time. The only exceptions are when there's not enough grip (rain?) or under braking (when little power is needed)

A fast driver that's shortshifting and driving in higher gears that is faster than all others that are redlining will always be even faster if he uses all the power band.

However, I agree with Nordschleife view as to why the gears in the 997GT3 are still very high. Lower gearing (via R&P) is not necessarily always better. It all depends on the each track characteristics. For example, from NJGT's numbers, if you are at a track where most of the acceleration time is spent in the 60-90mph I would prefer to run the OEM stup where you will be most of the time in 2nd gear. with the 4.0R&P you are most of the time in 3rd and that gear "total" ratio is higher than OEMR&P 2nd.

Lower is not always better, as tracks are not unlimited straights. The 4.0R&P is only an obvious choice for things like autoxing where you will always be in 2nd gear and rarely above 70.

Sun Ra

garret's given me some leads

but anyone on here know of or are you a ready source of the cupcar R&P? i need one asap. tia.

NJ-GT

Watt,

Call Brian Copans. There are a few versions of the 4.00:1 R&P. Mine is a forged one from the 996 GT3RSR.

BMC&G
6207 Central Park Drive, West Chester, Ohio 45061
Brian or Pam Copans
(513) 779-3302

Brian is the guru for our transmissions. Lots of good feeback.