jeff91C2T

I'm looking into a transmission overhaul on my G50/52 (C2 Turbo) transmission and was considering going to the 964 C2 2-5 gear set. Does anybody have the gear ratio's available from a 964? Also, any recommendations where to by the gears (and syncro's)?

Thanks

Cupcar

Firtst two gears are lower than a Turbo's and are 3.5:1 and 2.059:1 in the normal gearbox, otherwise ratios 3, 4, 5 are the same as your turbo.

Turbo= 3.154 > 1.695 > 1.407 > 1.086 > .868

C2/C4= 3.500 > 2.059 > " > " > "

joey bagadonuts

Here's a link to some useful information. I couldn't find a link to Guard Transmissions, though, which comes highly recommended.

What are you trying to accomplish with the change? I think shortening the whole package would be nice ... I mean, how often do you need to get to 160mph?

Tom W

I have a spreadsheet that contains the info from the factor repair manuals for the gear ratios of most, if not all, G50 transmissions. It includes a sheet that converts rpm to mph at various rpms and has a plot of rpm vs speed if you want to look at different options. I created it when I had my 993 regeared to shorter gears. Send me PM if you want a copy (include the email address where you want it sent).

jeff91C2T

Thanks Tom...just sent you a PM!

Joey, I'm looking to shorten the gears. I'm not sure swapping out the dif would work for me. How often do I go 160...every lap (when I'm brave enough)!

Cup Car, the gear ratio's for the turbo trans are (1st 3.154, 2nd 1.789, 3rd 1.269, 4th .976, and 5th .756). Took this right out of the 965 factory manual. What I'm after for the change is to improve autocrossing (ie...better 2nd gear top speed) and more fun at the track. My 5th gear puts me at around 188 at 6500 rpm. Don't need or want to go that fast!

It sounds like the C2 2-5 gear sets might be a reasonable cost effective choice (if there is such a thing) for what I'm after. Does anyone recommend a way to source these (ie...used or new). I saw the prices for custom gears and the price scared me away.

Tom W

New gears are not cheap! The simplistic estimator is $1000 to drop the transmission and $1000 per gear. If you want steel synchros, it's more as the 2nd gear synchro is about $1200 (others are cheaper).

When I changed 2-5 in my 993 with the stock brass synchros and added a LSD, the final bill was about $11k. Mine was more than the estimate above as it needed some other repairs, forks were replaced and the new 2nd gear required a new main shaft as the original transmission had both 1st and 2nd fixed to it. It also had shipping to/from the shop that did the gear work.

Cupcar

Sorry about the memory fade on the ratios.

What I was trying to say was perhaps keeping your 1 and 2 then using the 3 to 5 from a normal C2 may be an OK box.

jeff91C2T

Yep...$11K is out of my budget.

Tom, do you still have your old 964 gears laying around? Want to sell them??

Tom W

Jeff,

They are 993 gears. Yes, they are sitting on a shelf in the garage. I don't have the old main shaft so 2nd wouldn't help, but have the rest of the gears from a G50/20 for 3rd, 4th and 6th. I used the 'old' 5th gear as 6th in the revised transmission.

It does make an incredible difference in quickness (especially with an RS-LWF, I forgot to mention that as another mod done with the gear change that added another $2k to the mix and helped get the total up to the silly level it was). I've often toyed with the idea of swapping the transmissions on my two cars - nice tight, quick 6-spped for the track and big, lazy 5-speed for the daily driver.