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I know quite a few of you have played around with the gearing on these cars.
If one is to fit a cup car 4:1 final drive to a 996 GT3, does this make the gearing taller, shorter or the same as the 996 cup car? I understand the 996 cup has a close ratio box. On the weekend I ran a circuit in my cup car for the first time but when comparing this weekend’s in car footage to previous footage of my 996 GT3 (with 4:1 R&P fitted) at the same track, the gearing in the street car appears to be noticably shorter than the cup car. I do not know for sure what is in my cup car but I’d like to assume it retains the factory cup gearing.
Any pointers on this topic of which I have limited understanding would be great.
996.2 GT3 with 4:1 final drive: 1st-34mph,...2nd-63mph,...3rd-83mph,...4th-106mph,...5th-130mph,...6th-152mph
So the 4:1 swap makes the 996 GT3s 1st, 2nd and 3rd gears significantly shorter than the 996 cup with 4th, 5th and 6th being quite similar to the cup car.
I dont have the specifics on rpm drop between gears for each scenario but in my experience of driving both 996 GT3 (4:1) and 996 cup on track, there doesn’t seem to be a huge difference in rpm drop between the two cars. The ring and pinion change closens up the ratios quite nicely in the street car. I’ve got to say I prefer the shorter gearing that the street car + 4:1 change offers. The cup car gearing feels too long by comparison!
There’s a mistake in your numbers/ratios. 3rd gear on both a street car and a cup car was 1.56 25:29 for 996. Only 1st and 2nd will be shorter on the street car once you fit a 4.0.
There’s a mistake in your numbers/ratios. 3rd gear on both a street car and a cup car was 1.56 25:29 for 996. Only 1st and 2nd will be shorter on the street car once you fit a 4.0.
So the speeds in 3rd should be the same between the two? Interesting as the footage I have of the two cars is fairly representative of the numbers I came across.
So the speeds in 3rd should be the same between the two? Interesting as the footage I have of the two cars is fairly representative of the numbers I came across.
I figured it out. It's the delta in tire size. It's the only possible answer if those numbers are based on 7000rpms like mentioned on Pistonheads.
I figured it out. It's the delta in tire size. It's the only possible answer if those numbers are based on 7000rpms like mentioned on Pistonheads.
Ah yes, that makes sense now! I was only a few tenths quicker in the cup car than I was my street car (old rubber on the cup probably did not help) but the car just felt like a dog getting off the really slow corners compared to my experience 2 years earlier.
This may help. I ended up changing my gear set as opposed to the Final.
Ray
What have you done ray, fitted the cup gear set to your road car? I suspect it would be quite nice with the small street tyre on the back but with the 680 slick on the rear of a cup car I feel it’s a touch too long. Porsche wanted something that would work well everywhere though so it’s always a compromise. The layout on the weekend was far from the norm so not going to get too caught up on it. I just wanted to see if there was some “sense” to what I was feeling out on track.
1st gear: 3.82 996 TT
2nd gear: 2.05 996 TT
3rd gear: 1.56 996 GT3
4th Gear: 1.308 Cup
5th Gear: 1.094 Cup
6th Gear: .912 Cup
R&P stock
Ray
Interesting that you stuck with the stock GT3 3rd gear...At this point in my "track journey" I find that 3rd gear is too low, especially on an uphill exit when I am carrying too much speed for 2nd, in 3rd it bogs a little and I don't feel like i have the torque I'd like in 3rd. If there's a single gear I would want to change on the car it would be 3rd. Maybe I just need to carry more speed to get higher RPM's in 3rd...LOL...Like I said - At this point in my track journey - Always learning and trying to get faster and smoother.
Let me say that my 3rd selection was not made after much deliberation. But then, because 2nd gear is a bit longer than stock - I am using the TT mainshaft, 3rd is never a problem for me. My biggest problems were 4th, 5th, and 6th, which I replaced. I had considered the R&P, but could only afford the gear set or the R&P, and decided to go for the gears. It would be easier to change the R&P later. I was also concerned about the accelerated wear of the 4.0 R&P
Interesting that you stuck with the stock GT3 3rd gear...At this point in my "track journey" I find that 3rd gear is too low, especially on an uphill exit when I am carrying too much speed for 2nd, in 3rd it bogs a little and I don't feel like i have the torque I'd like in 3rd. If there's a single gear I would want to change on the car it would be 3rd. Maybe I just need to carry more speed to get higher RPM's in 3rd...LOL...Like I said - At this point in my track journey - Always learning and trying to get faster and smoother.
Watching this thread with interest.
I have never experienced a 996 GT3 with stock gearing as my road car had the 4.0 fitted by the previous owner. But, comparing it to my cup car and based on the numbers I posted above, I can see how you would find 3rd to be too long as the cup car is too long (2nd is too IMO) and the street car is longer yet again. It takes forever to rev out to 8, so much so that I get impatient and shift at 7500 lol. This gearing is not at all suited to tight tracks. It bogs down out of slow corners and you’re just waiting waiting waiting. Yes, these are momentum cars and the revs need to be kept up at all times but there is only so much of that you can do when you’re running slicks with 15+ heat cycles on the rear and there are multiple 25 mph turns . My advice is to fit the 4.0 R&P and not mess with the stock gearing otherwise. It’s cheaper and easier and it really livens up the car. It’s not a perfect set up but it beats the heck out of stock.
i will see if I can do an overlay video of my fastest lap
in the road car with the 4.0 upgrade versus the cup car.
I lack the skills for overlay but the top video is my 996.2 GT3 with the 4:1 final drive change. The bottom video is my 996 cup with factory cup car gearing.
12-03-2018, 06:34 AM
Question about gearing.
. My advice is to fit the 4.0 R&P and not mess with the stock gearing otherwise. It’s cheaper and easier and it really livens up the car. It’s not a perfect set up but it beats the heck out of stock.
