Why didn't Chevy Revise Gear Ratios on 7sp?
#21
Drifting
At least 6th should have been revised. I have the 'Z51' tranny on my '12 GS, and even though it has closer ratios than the base car, 6th is almost too tall already at 83 mph at 2K rpm. Leaving the ratios the same and just adding 7th was pretty stupid IMO. Since the biggest jump is from 5th to 6th, at least 6th should have been made closer, and 7th just a hair taller than the current 6th. But the GS has some weird ratios, to be honest, so a full revision would have been warranted, especially when the damn car lasts 9 or more years.
Besides, now at 83mph in a z51 you'll be a tick UNDER the rpms a base car's 6th gear are/will be. GS with the m12 gearset(is that what they are called still?) have great gears. Just enough added umph over base 6 speed gears but not gas guzzling.
If I had a choice of a non... Zxx model, a 2008 z51 would be my choice, between the lighter weight and z51 trans its gotta be a blast.
#22
Burning Brakes
Thread Starter
So at no time did the engineers explain the ratios of the new 7sp? I would love to hear from Chevy their explanation. I thought they may have at the bash, 60th ann, etc.
#24
Drifting
AMEN!! No more accidentally bumping into reverse when the lock out solenoid fails
#25
The 7th gear is for when you're crossing middle America at 75mph. The car will barely be idling. I approve.
All of you folks who think having a 5th gear 1:1 is great, it really isn't. I end up skipping gears a lot. I have that in my Mustang paired with 3.73s, and honestly, I wish I had less gear. Also, the ratios in the Tremec are naturally stepped. For me, 5th to 6th goes 1:1 to .65. That's a big drop. A set of 3.31s would do me nicely, but I don't want to crack open my pumpkin to do it.
All of you folks who think having a 5th gear 1:1 is great, it really isn't. I end up skipping gears a lot. I have that in my Mustang paired with 3.73s, and honestly, I wish I had less gear. Also, the ratios in the Tremec are naturally stepped. For me, 5th to 6th goes 1:1 to .65. That's a big drop. A set of 3.31s would do me nicely, but I don't want to crack open my pumpkin to do it.
#26
I think it'd be fun to have a lower first gear instead of a higher highway gear.
I'm not sure if the tires could take a lot more torque, but doing rolling digs up to a 30 or 35 mph speed limit and actually getting into the power band would be fun.
My C5 does 50+ in first gear (and I believe the C6/C7 do more), which means it's rare for me to even have a chance to hit the power band or do a 1-2 shift on my commute without being obnoxious and/or illegal.
I'm not sure if the tires could take a lot more torque, but doing rolling digs up to a 30 or 35 mph speed limit and actually getting into the power band would be fun.
My C5 does 50+ in first gear (and I believe the C6/C7 do more), which means it's rare for me to even have a chance to hit the power band or do a 1-2 shift on my commute without being obnoxious and/or illegal.
#27
The gearing is really nonsensical. 7 speeds. 1st gear will go 60. The car almost certainly tops out in 5th. It will finish the quarter in 3rd probably. Yet the car is still overreved cruising at 99-100, which is not speeding in many jurisdictions.
The base car should have at least grand sport gearing in the 1st 3, and if youre going to spin the extra 11 pounds all day long for a 7th gear, it ought to be a taller od.
The base car should have at least grand sport gearing in the 1st 3, and if youre going to spin the extra 11 pounds all day long for a 7th gear, it ought to be a taller od.
#28
Race Director
GM has other factors to consider while building cars. The most notable is CAFE. For each 0.1 MPG they fall under the standard they have to pay a fine of $5.50 on every car sold. GM builds millions of vehicles so this isn't exactly chump change. I don't know if it is brand specific (i.e. Chevy) or GM total but regardless the fine could really add up.
#29
The gearing is really nonsensical. 7 speeds. 1st gear will go 60. The car almost certainly tops out in 5th. It will finish the quarter in 3rd probably. Yet the car is still overreved cruising at 99-100, which is not speeding in many jurisdictions.
The base car should have at least grand sport gearing in the 1st 3, and if youre going to spin the extra 11 pounds all day long for a 7th gear, it ought to be a taller od.
The base car should have at least grand sport gearing in the 1st 3, and if youre going to spin the extra 11 pounds all day long for a 7th gear, it ought to be a taller od.
1st Gear will go 60. Yes. That is correct.
The car will probably be aero limited with top speed in 5th. And then this is where you lose me.
99-100mph is DEFINITELY speeding in all jurisdictions. And in 7th, it'll be virtually idling, not overrevving.
7th IS a taller overdrive.
#30
Drifting
The gearing is really nonsensical. 7 speeds. 1st gear will go 60. The car almost certainly tops out in 5th. It will finish the quarter in 3rd probably. Yet the car is still overreved cruising at 99-100, which is not speeding in many jurisdictions.
The base car should have at least grand sport gearing in the 1st 3, and if youre going to spin the extra 11 pounds all day long for a 7th gear, it ought to be a taller od.
The base car should have at least grand sport gearing in the 1st 3, and if youre going to spin the extra 11 pounds all day long for a 7th gear, it ought to be a taller od.
New rule. If you havent bothered to look up/compare the ratios, dont bother posting in this transmission related threads...
#31
Safety Car
Base C6s feel a bit sluggish with the 2.66 first compared with the C6 Z51 cars' 2.97 first. But a C6 Z06 with the same 2.66 first gear feels really strong! Because of all its torque it doesn't really need more gear than the 2.66. The C7 on takeoff has almost the same torque as a Z06 so it's very likely that it too will feel quite strong even without the more aggressive gearing.
I always wonder how the Z51 2.97 gearing is now sometimes referred to as "close ratio" when the overall ratio spread is obviously wider than the 2.66 trans. Why don't they call it a "wide ratio"? With the old Muncie 4-speeds, 2.20 first gear was close ratio and 2.56 was wide ratio.
.
Last edited by ZL-1; 07-12-2013 at 12:51 AM.
#32
Le Mans Master
Member Since: Jul 2009
Location: Los Angeles California
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I just realized after the fuel economy numbers came out that on the new 7sp manual, chevy left the ratios exactly the same except added the 7th gear. Why wouldn't they revise 1-6 to make them closer and lower now that they have an extra gear? 7th should now be the highway fuel econ gear and 1-6 performance gearing. Did they explain it at all at the bash or 60th anniversary or any other time?
The distance between each gear up until 5th gear is actually further than the standard ratios. They seem like they're closer, however, because they're actually shorter gears (larger ratios). Meaning you can't be in them as long.
To give you an example of what I'm talking about:
Z51 Ratios (first 6 speeds)
2.97:1 <-31%-> 2.07:1 <-31%-> 1.43:1 <-30%-> 1.00:1 <-16%-> 0.84:1 <-33%-> 0.56:1
Non Z51 Ratios (first 6 speeds)
2.66:1 <-33%-> 1.78:1 <-27%-> 1.30:1 <-24%-> 1.00:1 <-26%-> 0.74:1 <-32%-> 0.50:1
As you can see, the only time the ratio is closer for the Z51 gearing is 1st to 2nd, but the distance isn't that different from the other ratio. However, you can see from 2nd to 3rd and 3rd to 4th, the ratios for the non-Z51 are actually closer and the spread for the Z51 maintains about even and still wider.
#33
Race Director
The corvette team got the gear ratios correct on the c6 and just added 7th gear to improve fuel efficiency for the c7.
Rev matching is a cool new feature.
Rev matching is a cool new feature.
#35
Safety Car
The current Z51 gearing has 2nd too short to use at most tracks and the drop off in acceleration between 3rd and 4th is too much.
The base gearing allows the car to use 2nd in more areas as it's taller and the drop from 3rd to 4th is less so the car is in the power band when you enter 4th.
#38
Safety Car
When I sell my base 1YY07 Stingray in a few years I'll advertise that it has the "close-ratio 7-speed trans"
#39
Instructor
Would you please show the gearing for the Auto?
Thanks
Last edited by Al77Vette; 07-12-2013 at 11:28 AM.