TorchRedRocket

Have these been released yet? I'm curious whether they are gonna be the same ratios as the M6 with another even steeper overdrive, or if 1st-5th will be closer and shorter?

Bucknut2006

5 and 6 have always been OD gears on the C6 so I bet that 5-7 will all be OD with 7th being slightly steeper and 5-6 being a little less.

glhs386

This was posted in another thread:



I hope this info is wrong, because this chart looks like a total mess. Basically it's the current six speed box with an additional gear tacked on top. Top speed still reached in fifth. Not only is having two fuel economy gears inexplicable, but why are they closer together than first through fifth? Driving the car in GT5 you can see how the car bogs hard going into fourth and fifth. The "close ratio" Z51 box is actually wider first through fifth, but with a shorter sixth and seventh. What for? There's no performance advantage, it just guzzles extra fuel on the highway. Compared with the ratios in Porsche's ZF sourced 7 speed, it seems like Tremec pulled numbers out of a hat.

Raitzi

Seems like they messed up fifth between base and Z51. GM guy actually said that top three gears are overdrives and was proud of that. Porsche only has one overdrive on 7-speed
Also car won't accelerate in 6th or 7th in any case(when 5th is topped) so there is no point making them shorter with z51.

glhs386

Number of overdrives doesn't really mean anything, that's just a math game. My point is that the Porsche has six well spaced performance gears with no yawning ratio gaps and one fuel economy gear. The C7 should be the same way. Of course the actual physical ratios will be different, they have different engines, final drives, etc.

You must have misread what I typed, because I just said that. They're unnecessarily short for no reason.

SCM_Crash

In the MN12 I have now, every now and then I think "Gosh, I wish I had another OD gear."

I swear on it, that's what I'm thinking. I'm not thinking "I wish I had another gear to pull speed out of."

You know why? Because the car hauls @ss as it is. I'm obviously in the minority here.

That being said, I don't know if I like these gear ratios. I almost think they should have skipped the 1:1 ratio all together. 2 OD gears is honestly something I like. But there should have been maybe 6 gears that are closer together and all could be acceleration gears. I'm thinking that the gears should have looked like this:

1: 2.99
2: 2.20
3: 1.80
4: 1.15
5: 0.90
6: 0.65
7: 0.50

To me this would make more sense. I'm not sure why a 1:1 has to be there at all. Notice how there's still 3 over drive gears. This achieves both goals, as far as I see.

Raitzi

Has GM released ratios for the automatic transmission?(for base and Z51)

dclafleur

Looks like they're trying to hit higher fuel efficiency numbers. Anyone compare the size increase in wheelbase and track width and see if it bumps the corvette up a CAFE class too?

GOLD72

The extra overdrive with ratio below 0.50 is another device to raise the EPA Highway MPG. Just as CAGS has done for over 20 years for the 6-speed.

dclafleur

Yeah, I've got a Doug Nash 4+3 sitting on my workbench that says GM is willing to use screwy gear ratios and experimental transmissions to try to hit fuel economy numbers.

Thud

Assuming that the C7 prototype in GT5 has the correct gear ratios, 7th is really tall. Like 1500rpm at 75mph. Top speed is still attained in 5th gear.

JoesC5

The only way to change the Tremec 6070 to a 1.15 4th gear is to completey redesign it as 4th gear is straight through. A better approach is to make the car think it has a 1.15 4th gear by changing the rear axle ratio.

If they would have installed the 2.29 ZR1 transimssion with the .67 6th gear and added a .37 7th gear(who cares what the drop off in RPM is between 6th and 7th gears as 7th is strictly for highway gas mileage) and then made a simple change to the rear end by inatalling a 3.9 gear instead of the current 3.42, we would basically the same 1st through 3rd gears for city gas mileage, a much better 4th, 5th and 6 th gears(for performance) and still end up with the same final ratio in 7th gear for highway gas mileage.

current C7 base TR6070 with 3.42 read end.....

2.66 X 3.42 =9.10
1.78 X 3.42 =6.09
1.21 X 3.42 =4.45
1.00 X 3.42 =3.42
0.74 X 3.42 =2.53
0.50 X 3.42 =1.71
0.42 X 3.42 =1.44

With my gear ratios....and a 3.90 rear gear....

2.29 X 3.90 =8.93
1.61 x 3.90 =6.24
1.21 X 3.90 =4.72
1.00 X 3.90 =3.90
0.81 x 3.90 =3.16
0.67 X 3.90 =2.61
0.37 X 3.90 = 1.44


Because of the additional 25 lbs-ft of torque with the LT1, having a slighty higher gear ratio in 1st gear would help from blowing the tires away.

In 2nd and 3rd, where traction isn't as big of a problem, the lower gearing would help acceleration.

In 4th and 5th gears, my gearing would mean wonders. No falling on it's face.

6th gear really dosen't mean much as it becomes a new "5"th gear, but it would allow a 197 MPH top speed, and 7th would still have the same final ratio as the C7's current gearing for gas mileage. Not only could they get buy with an extisting transmission 9other then add the 7th gear. It's possible that the new 3.90 ring gear and pinon would fit the C6 Z06/ZR1/GS differential. which would make those guys really happy.

SCM_Crash

Yeah. This all makes perfect sense to me.

DJackman

To me this is a disappointment. I was hoping that C7 will top out on 6th gear or even better 7th gear. I know some will take the MPG over the close-ratio but this is a Vette not a Buick. At least give some of us the option to have the close ratio gears rather than the gas saving gears as I call it. I like what GM did to the ZR1 ratios but this is not acceptable to me. Oh well.

SCM_Crash

Change the diff gears out with 4.10's. Problem solved.