pete95zhn

Thanks Matt, I'll return to this later this week!

pete95zhn

I've looked through some of my datalogs and it seems that I would get a big benefit from longer 2nd and some from longer 3rd on those local tracks I usually run. There's espacially one uphill section (LH-RH-LH-RH) where I now hit the limiter in 2nd, but the part is so short and steep that changing to 3rd is not an option. Occasional Nordschleife visits would too benefit from longer 2nd and 3rd.

Videos from those tracks (not by me though...):



Now the questions, if you care to answer:
-if keeping my present main shaft I can use 2nd gear from Cup's selection, can I? But where to get the longer (like 1.333) 3rd?
-What's the benefit of changing to GT2 RS's mainshaft, beefier axle, wider gears or wider bearings?
-Any sense of straight cut gears, 2nd-4th? Noise is no problem, not anymore, but how about durability in long term and cost?
-Steel syncros, for which gears?

JarmoL

Aren't the 1. and 2. machined into the mainshaft? So those can't be altered unless you buy a Cup mainshaft?

Some sloppy driving at Ahvenisto too..

pete95zhn

Looking again through several GT3 & Cup PETs you seem to be correct...damn.

rbahr

2nd gear on the 996 tt is a bit longer than what comes on the GT3. When I redid my tranny, based on Matt's suggestion, I used the TT main-shaft

996 GT3 gear ratios:

1st gear: 3.82
2nd gear: 2.15
3rd gear: 1.56 (steel synchro)
4th gear: 1.21 (steel synchro)
5th gear: 1.00 (steel synchro)
6th gear: 0.85

Ring and pinion: 3.44

996 TT Gear ratios:

1st gear: 3.82
2nd gear: 2.05
3rd gear: 1.41
4th gear: 1.12
5th gear: 0.92
6th gear: 0.75

Ring and pinion: 3.44

Ray

GTgears

As you have verified, all of the street car shafts have 2nd gear integral to the mainshaft. This is why the GT2 RS mainshaft is such a popular option. It runs a taller 1.89. If you wanted something other than that, you would need a Cup shaft or one of our 3 piece versions along with another 2nd gear.

Furthermore, it uses a slightly wider 3rd gear than the stock 996 turbo gear. The stock ratio is still a 1.41. Bill Rader commissioned me to make some custom. They are 1.364 and straight cut. I do not believe that he will just sell them and that you would need to have him rebuild the gearbox for you, which isn't necessarily a bad thing. He's among the best of the best when it comes to builders.

powdrhound

I had the 997GT2RS 1-3 mainshaft installed this past spring. It's a great mod especially with running the taller rear 997GT3 tire sizes. I get 54mph in 1st, 91mph in 2nd and 123mph in third. 3rd gear is also wider that beefier.

pete95zhn

What's the part# for GT2 main shaft? The PDF-PET doesn't tell...
Shipping the 'box 5417 miles one way for a rebuild is unfortunately not an option.

996FLT6

Had my box shipped by my Indy in a big ice cooler to Brian Copans for a shorter r/p. It's been awhile but I remember turnaround time was 4 weeks. Mike

GTgears

I can offer more assistance if you actually tell me where you are located. I am a solution oriented guy...

pete95zhn

PM'd.

GTgears

Got it. Busy day for end of the season but I will get back to you.

rbahr

Part numbers & Ratios for GT2, GT3, and TT trannys

99730290188 1st/2nd gear
1st gear Z = 41 : 13
2nd gear Z = 34 : 18
99730295388 3rd gear Z = 35 : 25
99730295488 4th speed Z = 35 : 32
99730295588 5th gear Z = 33 : 37
99730295688 6th gear Z = 33 : 45
99730290788 reverse gear
95030291171 ring gear and pinion shaft 31 : 9

99630290150 1st/2nd gear
1st gear Z = 42 : 11
2nd gear Z = 43 : 21

99630204250 2nd gear Z = 43 : 21
99630295302 3rd gear Z = 38 : 27
99630209393 3rd gear Z = 38 : 27
99630295402 4th speed Z = 38 : 34
99630295551 5th gear Z = 34 : 37
99630207551 5th gear Z = 34 : 37
99630295650 6th gear Z = 30 : 40
99630207650 6th gear Z = 30 : 40
99630291155 ring gear and pinion shaft 31 : 9

99630295303 3rd gear Z = 38 : 27
99630295403 4th speed Z = 38 : 34
99630295550 5th gear Z = 34 : 37
99630290750 reverse gear

99630290110 1st/2nd gear
1st gear Z = 42 : 11
2nd gear Z = 43 : 20
99630295350 3rd gear Z = 39 : 25
99630295330 3rd gear Z = 39 : 25
99630295455 4th speed Z = 40 : 33
99630295430 4th speed Z = 40 : 33
95030295587 5th gear Z = 36 : 37
99630295530 5th gear Z = 36 : 37
99630295531 5th gear Z = 36 : 36
99630295600 6th gear Z = 32 : 39
99630295675 6th gear Z = 35 : 41
99630291171 ring gear and pinion shaft 31 : 9

99730290190 1st/2nd gear
1st gear Z = 42 : 11
2nd gear Z = 43 : 19

99730290191 1st/2nd gear
1st gear Z = 42 : 11
2nd gear Z = 43 : 19

99730295390 3rd gear Z = 41 : 25
99730295490 4th speed Z = 40 : 31
99730295590 5th gear Z = 34 : 32
99730295690 6th gear Z = 36 : 41
99730291190 ring gear and pinion shaft 35 : 9

pete95zhn

I just bought a slightly used set of 997 GT2 mainshaft and I-II gears.
I: 3.15 / 41:13
II: 1.89 / 34/18

Now the question is the longer third. Something around 1.3.

rbahr

I see a tranny rebuild in your future :-)

Whatever you budget for gears, do the same for synchros and then again for bearings...

Ray