- Yes these are the stock 997gt3/rs gears - no changes.
- Yes overall ratio changes when you change from the stock 9/31 (pinion shaft teeth / ring gear teeth) to the 8/32 (pinion shaft / ring gear).
- My first 2 trackdays are at VIR in the 3rd week of april so I will do a write up after this event - I then do 4 days in mid may at Watkins Glen.
- Given that these are 2 of the greatest tracks in america I can't think of a better test.
- I did VIR last year so I will use my memory for comparison
- at Watkins Glen there will undoubtedly be a few 997gt3s/rs so skill aside, it should be a very good opportunity to compare the gearing

- compared to last year I have also just changed to the 997gt2 rear sway bar and I changed out my broken stock LSD (28/40) for a Paul Guard (50/80) unit - i will do my very best to try and separate the handling affects from the gearing affects (shouldn't be difficult but given VIR wil be the first event for me, I'm just hoping the new bar/lsd setup allows me to drive 9/10s with a neutral handling car

Paul

 

the only drawback on shorter r and p is the added wear value of the setup. they do wear more rapidly.

 

I had 50/80 and found the car had to much understeer in tight corners. I switched the ramps to 40/60 which is what the 6-cups use and it was much better. Pretty easy to do as well.

 

Actually that's not the only drawback in my eyes. Look at the breakout on the previous page of this thread and one thing becomes obvious. While the shorter FD ratio does make every gear ratio multiplication shorter and gives you more thrust force and mechanical advantage in each gear, it does not decrease the RPM drop between shifts.

What I am saying is that it doesn't change where on the engine's powerband you enter each gear. Personally, I advise our customers to go with the 3rd, 4th 5th gear change (with either 5th in 6th or a new shorter 6th depending on needs) more often for a car that is not a dedicated track car.

Not only does is keep you away from the issue you bring up, but it avoids dropping 1st and 2nd gear down as shorter. It lets you tighten up 3rd and 4th in particular, where an improvement of 500-800 rpms of drop putting you higher up in the powerband has real effects on acceleration. It doesn't just increase horsepower in every gear. It actually increases horsepower to the wheels at a given speed over where the R/P swap would be at the same speed.

It's about a zero sum game with respect to cost. The R/P set is a cheaper part but installation is more expensive. 3 gears cost more partswise but the labor is less. I really only market the 4.0 r/p (or our proprietary 4.125 r/p) sets for racecars or serious trackday junkies who are ALSO doing gears at the same time. Basically, if a guy wants to build a 996 GT3 Cup replica gearbox then a short ratio r/p is a must. But for most trackday junkies it doesn't offer as much advantage IMO as doing a few gearsets.

 

Very good information as usual, not just trying to push product (since you guys sell the 8:33 R&P)..

 

Yes, too bad Porsche just changed 6th gear on the RS. Same gaps..

 

when ever you have gear sets that are evenly divisible you get a resonance that accelerates wear. When ever possible use hunting gears that do no exhibit this characteristic.

here's a stock 2007 GT3 w/ 9:31


2007Gt3 w/ 8:32


2008 Cup w/ 8:32, this one is most similar to the g50/30 993Cup trans I use. It;s a great track setup and also acceptable for street use


2002 Cup w/ 8:32, this one gives you more flexibility(more speed in a given gear can be very useful if it eliminates a shift at an inconvenient place) and is still a great all round trans


A nice thing about the Cup g-boxes besides the smaller drops is the tall first

 

I really need to research and learn about gearing and R&P...

I have no clue on the subject

 

Just follow Bill around. He'll get you all edumacated on the subject. There's a couple of really detailed threads on the subject over in the 993 forum.

 

^ Thanks for the info!

I hope I can keep myself from going crazy with the new car, but I certainly will need an LSD rebuild from you guys soon

 

yes, yes....with all the gear changes we do at FM, it becomes a better choice for the gears rather than R&P. AND the shorter R&P's that a greater beating. When I did the earlier turbo's they would go "south" much sooner. FORGET 935's, NEVER TOLERATE THE SHORT R&P. Most factory race gearbox setups will use sets with most teeth on the pinion for durability.
Most GT3's we service need gearbox work anyway. hasta - Mark