[Z06] MN12 Gear spacing?
Thread Starter
Racer
Joined: Aug 2001
Posts: 321
Likes: 0
From: Houston TX
M12 Gear spacing?
I believe it is 2.97,2.07.1.30,1.00,0.84,0.56.
Doesn't it seem like 3rd gear should be closer to second? I'm thinking 1.4 - 1.5 range. Any thoughts on this?
[Modified by 03QSZ06, 12:14 AM 9/30/2001]
Doesn't it seem like 3rd gear should be closer to second? I'm thinking 1.4 - 1.5 range. Any thoughts on this?
[Modified by 03QSZ06, 12:14 AM 9/30/2001]
Race Director
Joined: May 2000
Posts: 12,712
Likes: 2,271
Re: MN12 Gear spacing? (03QSZ06)
Third gear is quoted wrong. It's more like 1.40 or 1.44 (can't remember it exactly), but the price you pay is a big gap between third and four that I don't like.
One of the mags quoted the gearset you list, but they mistakingly included the third gear ratio of the MN6 box, not the M12 box.
Duke
One of the mags quoted the gearset you list, but they mistakingly included the third gear ratio of the MN6 box, not the M12 box.
Duke
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
Re: MN12 Gear spacing? (03QSZ06)
When shifted at redline, M12 gear ratios yield 4500 in the next gear. This is nearly perfect as the torque peak is at 4800. So gears are just right.
Ranger
[Modified by Ranger, 11:50 PM 9/29/2001]
Ranger
[Modified by Ranger, 11:50 PM 9/29/2001]
Thread Starter
Racer
Joined: Aug 2001
Posts: 321
Likes: 0
From: Houston TX
Re: MN12 Gear spacing? (Ranger)
That would make more sense in being just right if the gear is 1.43 or so.
I thought in a mag it was 1.43 I read, but recently I saw 1.30. Thanks for the input guys.
:cheers:
[Modified by 03QSZ06, 11:05 PM 9/29/2001]
I thought in a mag it was 1.43 I read, but recently I saw 1.30. Thanks for the input guys.
:cheers:
[Modified by 03QSZ06, 11:05 PM 9/29/2001]
Drifting
Joined: Jun 1999
Posts: 1,582
Likes: 2
From: Colorado Springs CO
Re: MN12 Gear spacing? (03QSZ06)
Thank R&T (Aug 2000) for that confusion! 
Gear.......Ratio..........RPM after Shift
1...........2.97...........N/A
2...........2.07...........4530
3...........1.43...........4490
4...........1.00...........4545
5...........0.84...........5460
6...........0.56...........4333
Ideally, 4th should've been 1.10-1.12 to make the 3-4 gap shorter and the 4-5 gap wider.
Gear.......Ratio..........RPM after Shift
1...........2.97...........N/A
2...........2.07...........4530
3...........1.43...........4490
4...........1.00...........4545
5...........0.84...........5460
6...........0.56...........4333
Ideally, 4th should've been 1.10-1.12 to make the 3-4 gap shorter and the 4-5 gap wider.
Race Director
Joined: May 2000
Posts: 12,712
Likes: 2,271
Re: MN12 Gear spacing? (raj)
Your're correct, but the gearbox design architecture includes a direct drive fourth, so there is no other choice for fourth other than 1.00:1.
A gearbox should have progressively closer ratios as you move up through the gears, to yield greater revs/power as you pick up in the next higher gear. This is because as the car travels faster, more power is required to overcome drag. Any surplus is available to accelerate the car, so the closer the ratio spacing, the better the car accelerates.
If the spacing is to wide, the car feels like it "falls on it's face" when you shift to a higher gear. The LS6' broad torque curve masks this tendency, but relatively speaking, the Z06 does fall down on the 3/4 shift.
Duke
[Modified by SWCDuke, 11:30 AM 9/30/2001]
A gearbox should have progressively closer ratios as you move up through the gears, to yield greater revs/power as you pick up in the next higher gear. This is because as the car travels faster, more power is required to overcome drag. Any surplus is available to accelerate the car, so the closer the ratio spacing, the better the car accelerates.
If the spacing is to wide, the car feels like it "falls on it's face" when you shift to a higher gear. The LS6' broad torque curve masks this tendency, but relatively speaking, the Z06 does fall down on the 3/4 shift.
Duke
[Modified by SWCDuke, 11:30 AM 9/30/2001]
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