brucec59

+1

okindao

current 5th to 6th
new 3rd, 4th and 5th........1st and 2nd leave alone and are fine on track......

SMF

Hello,
interesting topic which sudenly finished. I PM few of you - thanks for all answer but what about C4 gearbox - precisly g64 20 - may I re-gear it if I get 950 302 901 21 (or if99330290116) mainshaft?
based on post " GT2 Gearbox shaft part number? " posted by 993 RS - YES

I am not a mechanic so I can be wrong which shaft is which but I took quick look diagram of the C4 gearbox and torque in converted forward via "lower" - secondary shaft - which is longer than in C2
Is it correct?
hard time of winter projects....
thanks

Bill Verburg

any of the g50/20, 21, 30, 31, 32, 33 mainshafts can be interchanged, only the g50/3x mainshafts have all 6 gears loose or changeable at will. You will only be concerned about that if you want to change 1 & 2. Some of the early '94/95 mainshafts do have loose 1 and/or 2 which can be changed.

your concern is w/ the layshaft, all of them have a layshaft w/ pinion gears at the back end that mesh w/ the large crown gear in the diff. But the g64 versions of the layshaft are also splined at the front end to connect to the awd viscous coupler. If you wish to retain the awd mechanism you must use a g64 layshaft. If you can live w/o awd then you can use any g50 layshaft that suits

993GT2 was 2wd and its layshaft is not splined at the front

trophy

Hi Bill, i didn't realize some of the early 94/95 trans had both 1st and 2nd removable. Do you happen to know when the change occured or was it/is it the luck of the draw. ie. any way of knowing without opening the trans up?

Bill Verburg

they are all fixed 1 only the early 94/95 have a swapable 2

I believe that the changeover was
G50.20 - 02693
G50.20 - 02174 (M220)
G50.21 - 05072
G50.21 - 03094 (M220)

guardsredcab

Thanks for the education everyone. Not sure I fully understand Bill's graphs, but I'm working on it. Here's my complaint... for street the stock gearing works fine, but on the track, I have a big problem shifting from 2nd to 3rd... seems to drop way out of the power band. I suppose solving this problem could create a similar problem shifting from 3rd to 4th. Most of the tracks I run on (haven't been to VIR yet) I stay in 2, 3 and 4 anyway. So, I don't know how big of a problem this would be. I have a 95... Thoughts on a cost effective solution?

Red9

I posted this before - you raise the question again.
Simple cheapest solution --- move existing 3 to 4 ---- existing 5 to 6
Get new 3rd at about 1.65 approx . Get 5th at about 1,117.
Still leaves 6th cruising gear revs ok, but makes it usable on the track.
Getting new 3rd & 5th brings the ratios 2nd, 3rd,4th,5th ,6thcloser and much more user friendly on both the track and the road.

cgfen

indeed, for street drving, regearing has very little appeal to me.
The only time i ever really realize that our standard gear ratios are less-than-optimal is when i'm doing a "track day", that's when i realize that second gear is oddly chosen and the gaps from 2-3 and 3-4 leave a bit to be desired.
Yes, i drive like a "*****" on the street

hmmmmmm sounds like you are a forward thinking DIY kind of guy.
Nice.
Next time i see you at an OC event, please prepare to have your brain picked a bit.

and thank you for doing so AND sharing the wealth.

cheers

Craig

cgfen

bump
more discussion please

wasatch1

Thanks for the education everyone. Not sure I fully understand Bill's graphs, but I'm working on it. Here's my complaint... for street the stock gearing works fine, but on the track, I have a big problem shifting from 2nd to 3rd... seems to drop way out of the power band. I suppose solving this problem could create a similar problem shifting from 3rd to 4th. Most of the tracks I run on (haven't been to VIR yet) I stay in 2, 3 and 4 anyway. So, I don't know how big of a problem this would be. I have a 95... Thoughts on a cost effective solution?

I am in the same boat, only I have a 96'. I feel on the track, on long sweeping turns, I either hold 2nd at 6000+ rpm or go into third and have low power. Also on the freeway, I ride 5th a lot for the sound and ability to let the revs slow me down. (drama or police). Maybe a lower 3rd, 4th and 5th are the answer?

guardsredcab

I switched to a shorter 3rd, 4th and 5th. Great for the track and haven't noticed a problem on the street.

Aircooled Dave

I think this is the right answer for most people. Changin 1 & 2 is just too expensive and in reality, isn't really solving a major issue other than the 1-2 shift. You typically would spend 90% of your time in 2/3/4/5 so making those behave nicely together seems like the best investment. Personally, i actually like a long 2nd gear as long as subsequent shifts are spaced correctly.

NP993

I changed to RS ratios for 3, 4, and 5. Kept 1, 2, 6 stock. Absolutely fantastic gearbox. Really wouldn't want 5th gear in 6th position -- terrible for modern highway travel. And there is no discernible difference in 2nd gear ratio between the /20 (stock U.S.) and /31 (RS) boxes.

No-brainer, IMHO, to do it this way -- great bang for the buck.

JM993

That's an improvement, but there remains a too tall 6th and the big gap between 1st and 2nd. The RS 1st is taller than the g50/20 version. The latter is very annoying on the street and the former makes 6th much less useful.

Just my .02.