What Lower Gears for C6 Paddle Shift?
Race Director
Joined: Mar 2005
Posts: 10,399
Likes: 26
From: Austin Texas
Other than "S" mode it downshifts to First every time.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,108
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
So the thinking is to gear the car so as to not use 4th gear at all in the 1/4? That almost makes nonsense of having a 4th underdrive gear. Clearly folks like subfloor have the 3.42 working for them, and, at the end of the day, if it makes the car more responsive and feel more powerful, that's certainly worth something, isn't it?
I'm not entirely convinced on the argument about extra engine wear and better gas mileage and certainly bigger trans breakage risk. If, like me, you spend most of your time lugging around in 5 & 6th at ~ 1000-1200 RPM with a 2.73, I certainly don't see the sense in using a 2.56 and I can't see how going from either of those 2 ratios to a 3.42 would make a significant change in engine wear (since the transmission will simply up shift into a higher gear quicker) or lose mileage either, certainly not as much as a cam or high stall converter.
As for breaking the transmission, I don't know how going to a higher (numerically) gear will place more load on the drivetrain? I think it's the other way around, especially considering that you will need more converter (higher STR) to get a 2.56 geared car off the line vs. a 3.42 geared car, with the consequent increase in drivetrain load. All of the cars that I've seen that perform well with 2.56 gears have something like a Yank 4000. That must result in higher drivetrain load than, say, a 3200 and a 3.42?
I've seen seen this discussion before about 3.42s only being worth a tenth in ET, but I can't say I've actually seen a back to back test that establishes that. From all of the discussion I've seen on here, most folks have changed a bunch of other stuff, particularly converters at the same time or at least before testing the car after the gear change. I would actually like to find such a back to back test, so if someone has done this, please post your findings.
In any event, the OP asked specifically about gear ratios and so I thought I would share those tables with him, and, in so doing, I only proffered my personal opinion about using a Z06 diff with a 3.42 gear. This is clearly a drivetrain upgrade and I think - like Subfloor pointed out to me on another thread - that must be, in and of itself, worth the extra money.
I'm not entirely convinced on the argument about extra engine wear and better gas mileage and certainly bigger trans breakage risk. If, like me, you spend most of your time lugging around in 5 & 6th at ~ 1000-1200 RPM with a 2.73, I certainly don't see the sense in using a 2.56 and I can't see how going from either of those 2 ratios to a 3.42 would make a significant change in engine wear (since the transmission will simply up shift into a higher gear quicker) or lose mileage either, certainly not as much as a cam or high stall converter.
As for breaking the transmission, I don't know how going to a higher (numerically) gear will place more load on the drivetrain? I think it's the other way around, especially considering that you will need more converter (higher STR) to get a 2.56 geared car off the line vs. a 3.42 geared car, with the consequent increase in drivetrain load. All of the cars that I've seen that perform well with 2.56 gears have something like a Yank 4000. That must result in higher drivetrain load than, say, a 3200 and a 3.42?
I've seen seen this discussion before about 3.42s only being worth a tenth in ET, but I can't say I've actually seen a back to back test that establishes that. From all of the discussion I've seen on here, most folks have changed a bunch of other stuff, particularly converters at the same time or at least before testing the car after the gear change. I would actually like to find such a back to back test, so if someone has done this, please post your findings.
In any event, the OP asked specifically about gear ratios and so I thought I would share those tables with him, and, in so doing, I only proffered my personal opinion about using a Z06 diff with a 3.42 gear. This is clearly a drivetrain upgrade and I think - like Subfloor pointed out to me on another thread - that must be, in and of itself, worth the extra money.
I have a concern about gas mileage and engine wear, because my car is a DD and I go on long road trips with lots of 6th gear cruising time. Out of the 119K miles so far, about 45K is on trips of 2500 miles or more. If I never left the county or state, it wouldn't be a big deal, but that's not the case.
How the car actually performs is more important to me than how it feels. I don't relate to things like carnival rides, but dig numbers on timeslips. Fun to me is winning the challenge to go faster than before and doing more with less.
As far as the 3.42 being worth a tenth over the 2.56, subfloor is the authority on that subject. He's also right up there with personally acquired experience and data about what stuff breaks on the A6 and why. His insight and information has helped develop better parts. So far, I've been fortunate and probably conservative enough to have no transmission breakage. Never needing the WOT 3-4 shift may have contributed to the longevity.
If you don't currently run above 123-124 and don't twist it tighter than 6500-6600, the 2.73 is probably fine. Just get a converter so you can launch harder and you'll be quicker than a gear change.
Le Mans Master
Joined: Apr 2013
Posts: 5,376
Likes: 1,118
I wasn't arguing a point, but merely providing additional data for consideration and voicing how I personally handle it.
I have a concern about gas mileage and engine wear, because my car is a DD and I go on long road trips with lots of 6th gear cruising time. Out of the 119K miles so far, about 45K is on trips of 2500 miles or more. If I never left the county or state, it wouldn't be a big deal, but that's not the case.
How the car actually performs is more important to me than how it feels. I don't relate to things like carnival rides, but dig numbers on timeslips. Fun to me is winning the challenge to go faster than before and doing more with less.
As far as the 3.42 being worth a tenth over the 2.56, subfloor is the authority on that subject. He's also right up there with personally acquired experience and data about what stuff breaks on the A6 and why. His insight and information has helped develop better parts. So far, I've been fortunate and probably conservative enough to have no transmission breakage. Never needing the WOT 3-4 shift may have contributed to the longevity.
If you don't currently run above 123-124 and don't twist it tighter than 6500-6600, the 2.73 is probably fine. Just get a converter so you can launch harder and you'll be quicker than a gear change.
I have a concern about gas mileage and engine wear, because my car is a DD and I go on long road trips with lots of 6th gear cruising time. Out of the 119K miles so far, about 45K is on trips of 2500 miles or more. If I never left the county or state, it wouldn't be a big deal, but that's not the case.
How the car actually performs is more important to me than how it feels. I don't relate to things like carnival rides, but dig numbers on timeslips. Fun to me is winning the challenge to go faster than before and doing more with less.
As far as the 3.42 being worth a tenth over the 2.56, subfloor is the authority on that subject. He's also right up there with personally acquired experience and data about what stuff breaks on the A6 and why. His insight and information has helped develop better parts. So far, I've been fortunate and probably conservative enough to have no transmission breakage. Never needing the WOT 3-4 shift may have contributed to the longevity.
If you don't currently run above 123-124 and don't twist it tighter than 6500-6600, the 2.73 is probably fine. Just get a converter so you can launch harder and you'll be quicker than a gear change.
I am definitely going to change the converter, but keep wondering if I should do the Z06 diff at the same time, since I'll have to drop the rear end to change the converter anyhow and I'm a bit concerned about the stock differential's strength. My car is annoyingly lazy out of the hole, even with the 2.73s. We currently don't have a race track here and this is my weekend street car, so I'm not overly concerned about extracting every bit of ET. I just want the car to feel as good off the line as it does once it starts to pull in first gear.
I have a whole list of things that I want to do to the car and I'm going to get started on it as soon as I can get my garage finished. I will probably go with a Yank PAS 3400 (that's what Dave @ Yank has recommended) as Im going to supercharge it. I intend to change the cam as well.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,108
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
No worries, I'm wasn't trying to make an argument either, just wanted to clarify my thinking on this discussion. I've learned a lot on here from guys like yourself and Subfloor and I value your input, so apologies if I came across as being argumentative.
I am definitely going to change the converter, but keep wondering if I should do the Z06 diff at the same time, since I'll have to drop the rear end to change the converter anyhow and I'm a bit concerned about the stock differential's strength. My car is annoyingly lazy out of the hole, even with the 2.73s. We currently don't have a race track here and this is my weekend street car, so I'm not overly concerned about extracting every bit of ET. I just want the car to feel as good off the line as it does once it starts to pull in first gear.
I have a whole list of things that I want to do to the car and I'm going to get started on it as soon as I can get my garage finished. I will probably go with a Yank PAS 3400 (that's what Dave @ Yank has recommended) as Im going to supercharge it. I intend to change the cam as well.
I am definitely going to change the converter, but keep wondering if I should do the Z06 diff at the same time, since I'll have to drop the rear end to change the converter anyhow and I'm a bit concerned about the stock differential's strength. My car is annoyingly lazy out of the hole, even with the 2.73s. We currently don't have a race track here and this is my weekend street car, so I'm not overly concerned about extracting every bit of ET. I just want the car to feel as good off the line as it does once it starts to pull in first gear.
I have a whole list of things that I want to do to the car and I'm going to get started on it as soon as I can get my garage finished. I will probably go with a Yank PAS 3400 (that's what Dave @ Yank has recommended) as Im going to supercharge it. I intend to change the cam as well.
The converter will make a difference, especially after you add the cam and SC. Since you're not going to the track, I wouldn't bother with the gear at this time. Doing it in stages is more fun, because each one brings noticeable improvements. Converter, then cam, then SC. If you decide to change gears, you can do it as the last thing. You don't need to pull the whole back end just for the gear change either.
I know what you mean about the garage thing. I've been stuck with minimal space for over 2 years while trying to get my new house built.
Team Owner
Joined: Feb 2001
Posts: 27,254
Likes: 136
From: Short Hills, NJ
A good converter along with those 2.73s and the right tire choice can make for a stellar combo. 
Le Mans Master
Joined: Apr 2013
Posts: 5,376
Likes: 1,118
I just did a couple of quick 0-60mph tests with my car on the G-tech, which illustrate what I'm saying about how lazy my car is out of the hole:
Both runs were identical @ 4.03 seconds. This was foot-braking to 1200 and launching from there.
This was with an 88 degree outside temp and my IAT was 90 degrees on the launch of first run and 107 degrees (on DashLogic) on the second.
The second run was literally within a couple of minutes of the first run.
My car can hardly bark the tires off the line, but rips them violently on the 1-2 shift.
My 60' times are usually like ~ 2.15 seconds, which really sucks. This is one serious POS converter that GM has in these cars.
BTW: My best ever recorded 0-60 has been a 3.92, which is barely better than what GM advertised for the GS (4.0).
But, I can't help but think on a stock converter car like mine, the 3.42s would make a big difference with the 0-60 (and 1/8) ET, whereas with a good converter the difference would be much less. This is probably, IMV, because a converter tends to stall higher and multiplies torque better with a taller rear gear.
Put another way, for the guys that don't want to change their converter (NOT me, I'm dying to throw mine in the trash!), the 3.42 gear must still be a worthwhile mod that will give them the SOTP performance that these A6 cars seem to lack, especially from a standstill.
However, Im going to take the sage advice proffered on here and go the converter route. I've done that with every vehicle I've ever owned, so why stop now...
Both runs were identical @ 4.03 seconds. This was foot-braking to 1200 and launching from there.
This was with an 88 degree outside temp and my IAT was 90 degrees on the launch of first run and 107 degrees (on DashLogic) on the second.
The second run was literally within a couple of minutes of the first run.
My car can hardly bark the tires off the line, but rips them violently on the 1-2 shift.
My 60' times are usually like ~ 2.15 seconds, which really sucks. This is one serious POS converter that GM has in these cars.
BTW: My best ever recorded 0-60 has been a 3.92, which is barely better than what GM advertised for the GS (4.0).
But, I can't help but think on a stock converter car like mine, the 3.42s would make a big difference with the 0-60 (and 1/8) ET, whereas with a good converter the difference would be much less. This is probably, IMV, because a converter tends to stall higher and multiplies torque better with a taller rear gear.
Put another way, for the guys that don't want to change their converter (NOT me, I'm dying to throw mine in the trash!), the 3.42 gear must still be a worthwhile mod that will give them the SOTP performance that these A6 cars seem to lack, especially from a standstill.
However, Im going to take the sage advice proffered on here and go the converter route. I've done that with every vehicle I've ever owned, so why stop now...
Last edited by CI GS; Aug 11, 2014 at 12:01 AM.
Supporting Vendor
Joined: Feb 2011
Posts: 3,523
Likes: 885
2024 C6 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (track prepared)
2019 C6 of Year Winner (track prepared)
I just did a couple of quick 0-60mph tests with my car on the G-tech, which illustrate what I'm saying about how lazy my car is out of the hole:
Both runs were identical @ 4.03 seconds. This was foot-braking to 1200 and launching from there.
This was with an 86 degree outside temp and my IAT was 90 degrees on the launch of first run and 107 degrees (on DashLogic) on the second.
The second run was literally within a couple of minutes of the first run.
My car can hardly bark the tires off the line, but rips them violently on the 1-2 shift.
My 60' times are usually like ~ 2.15 seconds, which really sucks. This is one serious POS converter that GM has in these cars.
BTW: My best ever recorded 0-60 has been a 3.92, which is barely better than what GM advertised for the GS (4.0).
But, I can't help but think on a stock converter car like mine, the 3.42s would make a big difference with the 0-60 (and 1/8) ET, whereas with a good converter the difference would be much less. This is probably, IMV, because a converter tends to stall higher and multiplies torque better with a taller rear gear.
Put another way, for the guys that don't want to change their converter (NOT me, I'm dying to throw mine in the trash!), the 3.42 gear must still be a worthwhile mod that will give them the SOTP performance that these A6 cars seem to lack, especially from a standstill.
However, Im going to take the sage advice proffered on here and go the converter route. I've done that with every vehicle I've ever owned, so why stop now...
Both runs were identical @ 4.03 seconds. This was foot-braking to 1200 and launching from there.
This was with an 86 degree outside temp and my IAT was 90 degrees on the launch of first run and 107 degrees (on DashLogic) on the second.
The second run was literally within a couple of minutes of the first run.
My car can hardly bark the tires off the line, but rips them violently on the 1-2 shift.
My 60' times are usually like ~ 2.15 seconds, which really sucks. This is one serious POS converter that GM has in these cars.
BTW: My best ever recorded 0-60 has been a 3.92, which is barely better than what GM advertised for the GS (4.0).
But, I can't help but think on a stock converter car like mine, the 3.42s would make a big difference with the 0-60 (and 1/8) ET, whereas with a good converter the difference would be much less. This is probably, IMV, because a converter tends to stall higher and multiplies torque better with a taller rear gear.
Put another way, for the guys that don't want to change their converter (NOT me, I'm dying to throw mine in the trash!), the 3.42 gear must still be a worthwhile mod that will give them the SOTP performance that these A6 cars seem to lack, especially from a standstill.
However, Im going to take the sage advice proffered on here and go the converter route. I've done that with every vehicle I've ever owned, so why stop now...
Le Mans Master
Joined: Apr 2013
Posts: 5,376
Likes: 1,118
In fact, I think that's how I got the 3.92, although that was on a different day.
But, I don't just want a better 0-60 time, I want my front wheels to dangle like yours does!
