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I want to start by saying thanks to all of those (Mostly Bill) who have contributed to the subject of re-gearing over the years. The archives serve us all well. I try and keep that in mind when I post something.
I have my own gear calculator and played with all kinds of combos. I also spent time thinking about what I really want to change every time I drive the car. I've come to the conclusion I just want to change 1st and 2nd gears. I like 3rd gear on and just want to make second closer to third to lesson RPM drop and make first taller to bring it closer to second.
My setup is different than just about eveyone's here. I have a turbocharged high compression VRAM engine. With the broad powe-rband it likes most of the current ratios. Loading the motor more in 1st and 2nd will help build boost and bring everything closer together.
That all being said I wanted to run these ratios by those in the know and see if this will give me a good overall 1-2-3 RPM drop without feeling goofy with the rest. 3.154 1st, 1.938 2nd.
I also would like to get some feed back from those who run the 3.154 1st on the street with LWFW. How bad is it in traffic or hills? I am sure I got enough torque to pull the gears but how is initial slippage etc?
I have always thought that the taller 1st and 2nd from the G50-3x transmissions is the way to go, 3 4 and 5 are not so bad after that and 6th gives a good highway cruise, especially if you are looking at street performance.
I have driven a number of 993 RSCS's over the years and really didn't notice the tall gearing that much from a starting perspective. Was not around a place like San Fran, but plenty of hills and hill starts no issue.
3 4 and 5 are not so bad after that and 6th gives a good highway cruise
Preserving this was the strategy for how I went about my re-gearing project. We used a taller 1st gear to help close up the large RPM drop going into 2nd gear, then shorten everything up with a shorter final drive. We went shorter than I was hoping for at first, but the manic rush of rowing through the gears is pretty awesome. 6th ended up being a bit shorter as well, but I'm personally not looking to be too strictly economical on the freeway.
Oh sorry, worth mentioning that I started with a G50/21 gearbox instead of the /20, so the ratios were shorter overall than the North American boxes. We found this out *after* the transmission arrived at the shop :P
I have always thought that the taller 1st and 2nd from the G50-3x transmissions is the way to go, 3 4 and 5 are not so bad after that and 6th gives a good highway cruise, especially if you are looking at street performance.
I have driven a number of 993 RSCS's over the years and really didn't notice the tall gearing that much from a starting perspective. Was not around a place like San Fran, but plenty of hills and hill starts no issue.
Spot on. I have a g50/31 and the taller first gear is wonderful everywhere -even on SF hills. As a bonus, 1st much more useable.
Thanks guys this really helps! JM your comments are especially helpful. I rarely get into SF with the 993 but it's good to know I won't be stuck if I do.
It seems everyone agrees the 3.154 1st gear is ideal. How do you guys feel about my second gear choice? There is a 2.00 available but quite frankly I thought the 1.938 work better with stock third.
I think the 1.938 is a much better choice than the 2, really stacks up the rest of the gears nicely.
That was my thought as well.
I am thinking of a slightly different first gear of 3.167, this along with the 1.938 and stronger main shaft can be sourced through GT gears. They don't offer the 3.154 ratio. I ran the math and it's pretty darn close.
So, is the graphs what you want to propose moving toward? if so, its interesting, because that is the exact ratio spacing and speeds in gear, as i have in the race car. seems to work very well on the street and race track. compared to my pure street car with a 6speed, the 1st gear is much lower (12.5:1 vs 8.5:1 of the race car) but RPM vs MPH is the same. the difference is that the shorter first is much easier to drive in traffic. easier on the clutch as you can imagine.... even though redline speeds are the same.... the 6 speed brings 3rd , 4th and 5th much closer together to keep the engine in the max HP range, which is the goal at the track . 55mph, 80mph, 115mph, and 150mph is what i have 1st through 4, with my overdrive going to 225mph, vs yours at 177. but the point here is that your 10.8:1 proposed 1st gear is a go between from stock to what i have... but with your higher engine RPM , it works out to be the same... better in traffic on your side due to the lower speeds to synch up clutch and speed/gear for 1st, but same net max speed in each gear. i think its near optimal. however if i was going to make a pure race car. i would closen the gears and sacrifice the hyway top gear.
great graphs!
Mk
Originally Posted by MarinS4
I want to start by saying thanks to all of those (Mostly Bill) who have contributed to the subject of re-gearing over the years. The archives serve us all well. I try and keep that in mind when I post something.
I have my own gear calculator and played with all kinds of combos. I also spent time thinking about what I really want to change every time I drive the car. I've come to the conclusion I just want to change 1st and 2nd gears. I like 3rd gear on and just want to make second closer to third to lesson RPM drop and make first taller to bring it closer to second.
My setup is different than just about eveyone's here. I have a turbocharged high compression VRAM engine. With the broad powe-rband it likes most of the current ratios. Loading the motor more in 1st and 2nd will help build boost and bring everything closer together.
That all being said I wanted to run these ratios by those in the know and see if this will give me a good overall 1-2-3 RPM drop without feeling goofy with the rest. 3.154 1st, 1.938 2nd.
I also would like to get some feed back from those who run the 3.154 1st on the street with LWFW. How bad is it in traffic or hills? I am sure I got enough torque to pull the gears but how is initial slippage etc?
I am thinking of a slightly different first gear of 3.167, this along with the 1.938 and stronger main shaft can be sourced through GT gears. They don't offer the 3.154 ratio. I ran the math and it's pretty darn close.
You have the same advantage as I do with revs, revving to 7400 does make the stock ratios feel better normal...
a 3.167 and a 1.938 looks great on the graphs shifting at 7400, and even at a shorter shift still shows some urgency.
I am thinking of a slightly different first gear of 3.167, this along with the 1.938 and stronger main shaft can be sourced through GT gears. They don't offer the 3.154 ratio. I ran the math and it's pretty darn close.
What we keep on the shelf these days is 3.00 and 3.50, but I can make any of them. 3.154 was the 993 Cup ratio, 3.167 is the GT3 Cup ratio. Same basic gearboxes with some changes, the biggest being the move from rod shift to cable shift after 1999.
What we keep on the shelf these days is 3.00 and 3.50, but I can make any of them. 3.154 was the 993 Cup ratio, 3.167 is the GT3 Cup ratio. Same basic gearboxes with some changes, the biggest being the move from rod shift to cable shift after 1999.
Boy a 3 is tall.... That would be a tough one one on the streets... What would you then match this to for a 2nd ratio?
So you can make a 3.167 for the G50 Transmission? Is there an upcharge for these custom ratios?
12-03-2016, 01:52 PM
re-gearing just 1st and 2nd
but the point here is that your 10.8:1 proposed 1st gear is a go between from stock to what i have... but with your higher engine RPM , it works out to be the same... better in traffic on your side due to the lower speeds to synch up clutch and speed/gear for 1st, but same net max speed in each gear. i think its near optimal. however if i was going to make a pure race car. i would closen the gears and sacrifice the hyway top gear.