re-gearing just 1st and 2nd
#1
Thread Starter
Rennlist Member
re-gearing just 1st and 2nd
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?
Casual shifts at 5K and Redline shifts at 7.4k
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?
Casual shifts at 5K and Redline shifts at 7.4k
Last edited by MarinS4; 12-04-2016 at 01:21 PM.
#4
Race Car
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.
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.
#5
Rennlist Member
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.
Here's my gear chart:
Here's my gear chart:
#6
Rennlist Member
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
#7
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.
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.
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#8
Thread Starter
Rennlist Member
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.
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.
Last edited by MarinS4; 12-06-2016 at 09:29 PM.
#10
Thread Starter
Rennlist Member
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.
#11
Rennlist Member
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
great graphs!
Mk
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?
Casual shifts at 5K and Redline shifts at 7.4k
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?
Casual shifts at 5K and Redline shifts at 7.4k
#12
Thread Starter
Rennlist Member
Yes that's with the new 1st and 2nd. Here is what stock looks like.
Thanks! They really helped me visualize the changes. Here is the link for the calculator http://www.gearboxman.co.uk/inforatios.html
I've seen you around Mark and I believe we spoke at TFB years back. I hope to run with you on track one of these days!
.......
Thanks! They really helped me visualize the changes. Here is the link for the calculator http://www.gearboxman.co.uk/inforatios.html
I've seen you around Mark and I believe we spoke at TFB years back. I hope to run with you on track one of these days!
.......
#13
Race Car
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.
#14
Nordschleife Master
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.
#15
Race Car
So you can make a 3.167 for the G50 Transmission? Is there an upcharge for these custom ratios?