GBX

Been researching a regear obsessively. Came acrosss this option with my local shop using 997 GT3 RS gears in 3-6. Trying to stay with oem to avoid the gear whine associate with aftermarket gears. 1&2 stay stock since I have a 96.

1st - 3.154
2nd - 2.05
3rd - 1.640
4th - 1.290
5th - 1.063
6th - 0.912

My car is used mainly on the street. Any thoughts, comments, opinions would be greatly appreciated as I’m a total noob when it comes to choosing the right ratios.

phoneyman

I might be mis-remembering, but isnt one of the main reasons to do a re-gear to tighten up the gap/RPM drop between 1 and 2? What is the reasoning for only doing 3-6?

911LeeN

friend who did a regear of 3-6 only on his 993 said it made sense on the track where he is rarely in 1-2. The 3-6 was cheaper (no replacing mainshaft) and helped him shave seconds.

Spyder_Man

Others who are more knowledgeable than me will certainly chime in here, but it is my understanding that for most US 993s the first two gears are linked so that you cannot replace one without replacing the other along with more parts. Only early '95 993s have a separate second gear.

So early '95 993s can easily have gears 2-6 re-geared. Most US 993s can only have gears 3-6 re-geared without significant additional parts and costs.

I've wondered as well about the point of regearing for street use if you cannot adjust the gap between 1st and 2nd. To me that's the most annoying (most RPM dropping) shift.

For the OP, I've read cases of people reusing their 5th gear as their 6th gear (i.e. top gear) so that they have to purchase one less gear during the re-gear work.

I don't know about you, but I rarely shift all the way to 6th gear because I have to be on a very flat road traveling well above freeway legal speeds for it to not feel like my engine is lugging some. I could be quite happy having my top gear be what is presently my 5th gear. Perhaps with a bunch more HP and torque that might change.


One more thing, I linked to this site in another thread regarding engine rebuild options, but it also has a great spreadsheet resource for transmission gearing:

http://www.instant-g.com/data-and-in...s-915g50g64g96

Download the file linked as "G50/G64/G96/G97 6 speed Gearboxes (993, 996turbo and 996/997 GT3 Street and Cup)" and enjoy playing around with the numbers.

Tlaloc75

Looking at these charts, it appears the changes to 2nd and 3rd are pretty minimal. 72mph vs 69mph in second and 105mph vs 95mph in 3rd.

Given that 2nd and 3rd are what you will be using for just about any spirited street driving, does it make sense to re-gear? I like the idea of a little more acceleration with the shorter gears but also like the fact that the longer gears means I can hold 2nd longer in a corner and won't need to shift as soon on exit.

For those who have experienced a re-gear, what do you think? Is it primarily useful for track work?

JM993

IMHO you need to address 1st and 2nd if you want to do this right. 1st is too short and the gap between 1st and 2nd is way too large. I would recommend patterning your regear after a g50/31. I have one and let me tell you it's fantastic for street driving. 1st gear becomes a usable gear.

Spyder_Man

Great info here:

https://rennlist.com/forums/993-foru...-31-box-2.html

GTgears

I'll let you guys debate the relative merits of it, but one thing you need to be sure to do is get a GT3 3/4 shift sleeve assembly as well. 993 use symmetrical 3rd gear dog teeth and gt3 uses asym. Be sure to get a new one if you go this route. You will also need to update the bearings under 3-4. Currently they are 50mm and GT3 gears are 47mm. I'm the only one who makes the one for 3rd because it was never in any factory car anywhere, so no doubt your shop will reach out when the time comes.

sander97C2

Exactly!! Stock G50/20 1st to 2nd gap always bothered me, but thats just me being picky and its honestly ok and does work just fine. Regardless, I changed every gear so that required a new mainshaft etc, but I was able to use a 3.50 ratio which makes big big difference.

These are the gears I went with. All gears and lsd purchased from Matt Monson at GTgears (thanks again sir!!), and then built by Robert Overholser at Lufteknic in Richmond VA. Make sure the work is done by Porsche pros, don't skimp on this or you may run into some serious headaches. I've been running the rebuilt trans since spring of last year with no issues. Runs very strong. End result, the car absolutely rips in every gear. Ride the torque curve every where. Its just so easy now. If you don't like shifting a lot then space the gears out more but I personally love it for how I drive which is good because it was expensive

Gear Ratio Mph
1st. 3.50 0 - 41
2nd. 2.294 41-63
3rd. 1.650 63-88
4th. 1.286 88-112
5th. 1.040 112-139
6th. 0.854 139-169

Gbx, if you find yourself in the area drop a line and I'll let you drive the car.

GBX

Thanks Matt. Appreciate the advise. My goal is to avoid gear noise but maybe it’s not worth the sacrifice. Do you recommend an option using oem gears?

Sounds awesome! Will def take you up in that if I’m ever in the area. Any chance you’ll be at the Palmer Motorsports event in a few weeks?

GTgears

Nothing wrong with the ratios you are considering. You will want a new 3/4 slider regardless of how you do it so you just need the right one.

You could also use 993 turbo gears. They are very similar to 996 GT3 ratios but are 50mm. No idea on current cost or availability through Porsche.

Bill Verburg

you don't have 3.154 1st unless you have a /3x gearbox

didn't we go through this a while ago w/ your car?

GBX

Don’t think so. This is the first I’m asking about specific ratios. What is the ratio for g50/20 stock 1st? Is 2nd correct? Shop I’m speaking with must have made a mistake or maybe these are the ratios he’s recommending if I change out 1-6. Thanks Bill.

Spyder_Man

Here is a table that Bill V posted in the thread that I linked above. Very useful info therein:

Bill Verburg

Here's an updated summary including yours, the /30 is the gold standard for track /30 w/ a bit taller 6 would be the gold standard for a more street oriented trans(see Cervelli custom). Engine torque curves would also affect the optimal gear choices

these have all been standardized for comparison purposes for rpm and tire, actual rev limit and tire may be different and thus have slightly different results