2006 C6 ratios?
Burning Brakes
Joined: Mar 2003
Posts: 1,030
Likes: 0
From: Pittsburgh PA
Originally Posted by jreediii
Why change to 2.56 ratio ( GM8 ) for 6 speed w/ paddle shift automatic?
How will it effect 0-60 performance and/or top end relative to 2005 automatic or 6 speed manual ( 3.42 ratio )?
How will it effect 0-60 performance and/or top end relative to 2005 automatic or 6 speed manual ( 3.42 ratio )?
Melting Slicks
Joined: Nov 2004
Posts: 2,514
Likes: 1
From: Orwigsburg Pa.
Originally Posted by haljensen
The new A6 gears and differential ratio make it much closer in performance to the manual 6spd than the A4 was with any factory rear ratio.
Race Director
Joined: Mar 2005
Posts: 10,399
Likes: 25
From: Austin Texas
Originally Posted by SHOOTER 49
With all due respect I doubt that. The a6 is more about enticing those potential buyers that NEED ''help'' in deciding between MB/BMW/etc. and an American ICON then it is about matching up with a 6 speed stick.
6 speed standard...............6 speed Z51............................A6.....
...................Final Ratio................Final Ratio..................Final Ratio
1st; 2.66X3.42= 9.10........2.97X3.42= 10.16.......4.027X2.56= 10.31
2nd;1.78X3.42= 6.09........2.07X3.42= 7.08.........2.364X2.56= 6.05
3rd; 1.30X3.42= 4.45........1.43X3.42= 4.89.........1.532X2.56= 3.92
4th; 1.00X3.42= 3.42........1.00X3.42= 3.42.........1.152X2.56= 2.95
5th; 0.74X3.42= 2.53........0.71X3.42= 2.43.........0.852X2.56= 2.18
6th; 0.50X3.42= 1.71........0.57X3.42= 1.95.........0.667X2.56= 1.71
Look at 1st gear; Z51 is 10.16:1, A6 is 10.31:1.
Look at 6th gear; Base Mn6 and A6 are the same final ratio.
Team Owner
Joined: Jun 2001
Posts: 26,714
Likes: 344
From: Houston, TX
Originally Posted by SHOOTER 49
With all due respect I doubt that. The a6 is more about enticing those potential buyers that NEED ''help'' in deciding between MB/BMW/etc. and an American ICON then it is about matching up with a 6 speed stick.
Certainly being able to market the six speed auto as a "world class" transmission can't hurt - but is more likely to be a selling point in cars like the Cadillac STS which goes head to head against a variety of premium European and Japanese sedans. Truthfully, the A6 is just a gift to the Corvette. No way would they have developed it for the small numbers that the Corvette will use.
The biggest benefits will be realized next year when the new Tahoes, Suburbans (and their "twins") come out with the A6 - followed by the new pickup trucks a year later. That will make a huge difference in GM's ability to meet new CAFE requirements for trucks and truck classified SUVs.
Team Owner
Joined: Sep 2000
Posts: 25,002
Likes: 2,704
From: Far NW 'burbs of Chicago
St. Jude Donor '13
shopdog pointed out that the ratios on the A6 are ideal for a truck to carry/tow a heavy load and still get good acceleration at low speed combined with good economy on the highway.
He's probably right, the ratios we get are for a tranny that will be used in many applications; not ideal for us. Bummer.
He's probably right, the ratios we get are for a tranny that will be used in many applications; not ideal for us. Bummer.
Race Director
Joined: Oct 2004
Posts: 10,089
Likes: 14
Originally Posted by Gearhead Jim
shopdog pointed out that the ratios on the A6 are ideal for a truck to carry/tow a heavy load and still get good acceleration at low speed combined with good economy on the highway.
He's probably right, the ratios we get are for a tranny that will be used in many applications; not ideal for us. Bummer.
He's probably right, the ratios we get are for a tranny that will be used in many applications; not ideal for us. Bummer.
All it'd do in a light Corvette with TC turned off is smoke the tires, and we don't need the extra torque multiplication to do that. We have enough trouble getting off the line quickly without smoking the tires as it is.
The other gears, after the torque converter locks up at 1:1, are all taller than either MN6 or the A4 with a 3.15 rear, so the A6 won't pull harder once rolling than the manuals or the old auto. The GM Powertrain hook graph was right.
Note that this also explains why, in sport mode, the A6 will start off in second unless you force it down to first. In second, with the torque converter multiplication, you still have a final ratio of 12.1. Once the revs come up enough for the torque converter to lock up, of course, you're down to 6.05 in second, and the following gears also offer less multiplication than the corresponding MN6 gear.
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Thread Starter
2nd Gear
Joined: Oct 2005
Posts: 2
Likes: 0
Originally Posted by jreediii
Why change to 2.56 ratio ( GM8 ) for 6 speed w/ paddle shift automatic?
How will it effect 0-60 performance and/or top end relative to 2005 automatic or 6 speed manual ( 3.42 ratio )?
How will it effect 0-60 performance and/or top end relative to 2005 automatic or 6 speed manual ( 3.42 ratio )?
Race Director
Joined: Oct 2004
Posts: 10,089
Likes: 14
Originally Posted by jreediii
Is there an answer to the original question?
Burning Brakes
Joined: May 2004
Posts: 996
Likes: 13
From: Dallas TX
Originally Posted by shopdog
GM Powertrain says 2% slower than an A4 with 3.15 rear, but with 2% better fuel economy than an A4 with the 2.73 rear.
Drifting
Joined: Feb 2005
Posts: 1,321
Likes: 0
From: Catonsville MD
Well, I should be placing my order for my A6 tomorrow, and I'll be glad to tell you what it does at the track when I get it.
I don't see it being too hard to launch these cars, granted, I've never had one. But my truck put down over 600ft lb of torque to the wheels, and I manged to get it out of the hole with a 1.79 60'....on Goodyear f1's on a consistant basis.
I'm looking forward to seeing what I can do in a vette.
I don't see it being too hard to launch these cars, granted, I've never had one. But my truck put down over 600ft lb of torque to the wheels, and I manged to get it out of the hole with a 1.79 60'....on Goodyear f1's on a consistant basis.
I'm looking forward to seeing what I can do in a vette.
Burning Brakes
Joined: May 2004
Posts: 996
Likes: 13
From: Dallas TX
Originally Posted by shopdog
Remember to add the torque multiplication of the torque converter to the chart shown above. That gives a final ratio in low of 20.62. That's a real granny gear to pull a boat out of the water, or start off a big fifth wheel trailer.
All it'd do in a light Corvette with TC turned off is smoke the tires, and we don't need the extra torque multiplication to do that. We have enough trouble getting off the line quickly without smoking the tires as it is.
All it'd do in a light Corvette with TC turned off is smoke the tires, and we don't need the extra torque multiplication to do that. We have enough trouble getting off the line quickly without smoking the tires as it is.
Originally Posted by shopdog
The other gears, after the torque converter locks up at 1:1, are all taller than either MN6 or the A4 with a 3.15 rear, so the A6 won't pull harder once rolling than the manuals or the old auto. The GM Powertrain hook graph was right.
A4 315 | 9.64 5.13 3.15 2.21
A6 256 | 10.3 6.05 3.92 2.95 2.18 1.71
Considering a locked TC, all of the A6 gears are actually shorter than their respective A4 gears with either 2.73 or 3.15 rearend by a significant margin. It should pull harder than either A4 in any gear.
Last edited by Black04Vert; Oct 19, 2005 at 12:17 PM.
Burning Brakes
Joined: May 2004
Posts: 996
Likes: 13
From: Dallas TX
Originally Posted by Gearhead Jim
shopdog pointed out that the ratios on the A6 are ideal for a truck to carry/tow a heavy load and still get good acceleration at low speed combined with good economy on the highway.
He's probably right, the ratios we get are for a tranny that will be used in many applications; not ideal for us. Bummer.
He's probably right, the ratios we get are for a tranny that will be used in many applications; not ideal for us. Bummer.
Team Owner
Joined: Sep 2000
Posts: 25,002
Likes: 2,704
From: Far NW 'burbs of Chicago
St. Jude Donor '13
BTW, does anyone know if the A6 TC will lock up while accelerating full throttle? I get the impression from other posts that many TCs do not. On my C5 the 3-4 shift would come 10-15 mph below the calculated speed, and at that point the acceleration was slow enough that it wasn't speedometer lag. Too bad i never looked at the tach...
Le Mans Master
Joined: Nov 2004
Posts: 6,566
Likes: 2
From: Goleta CA
Cruise-In VIII Veteran
Originally Posted by jreediii
Is there an answer to the original question?
Burning Brakes
Joined: May 2004
Posts: 996
Likes: 13
From: Dallas TX
Originally Posted by Gearhead Jim
BTW, does anyone know if the A6 TC will lock up while accelerating full throttle? I get the impression from other posts that many TCs do not. On my C5 the 3-4 shift would come 10-15 mph below the calculated speed, and at that point the acceleration was slow enough that it wasn't speedometer lag. Too bad i never looked at the tach...