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Discussion Starter #1
Anyone know what the gear ratio is for each gear of the 6-speed manual, M6 trans?

I thought is was the close ratio Tremec T56, but if that were the case, we would be able to go the speeds below according to my calculations @6200rpm for 1st, 2nd, 3rd:

1st = 51mph
2nd = 77mph
3rd = 105mph
 

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kn7671 said:
Anyone know what the gear ratio is for each gear of the 6-speed manual, M6 trans?

I thought is was the close ratio Tremec T56, but if that were the case, we would be able to go the speeds below according to my calculations @6200rpm for 1st, 2nd, 3rd:

1st = 51mph
2nd = 77mph
3rd = 105mph
Yep:

1st 2.97:1 @6000rpm = 44 mph
2nd 2.07:1 @6000rpm = 63 mph
3rd 1.43:1 @6000rpm = 91 mph
4th 1.00:1 @6000rpm = 131 mph
5th 0.84:1 @6000rpm = 155 (speed limited)
6th 0.57:1 @6000rpm = 155 (speed limited)

Courtesy of Road and Track Magazine

EDIT: Oh yeah....rear diff is 3.46:1, so just multiply that by the ratio of whatever gear you're in to get overall ratio.
 

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Discussion Starter #3
Not that I would shift at redline, but isn't the GTO's 5.7L LS1 engines redline 6200rpm?

Or is 6000rpm the redline, and 6200rpm the fuel cut-off?
 

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I read those somewhere else on here. With those ratios, it's *almost* the equivalent gearing of my old '99 SS with the M6 and 4.10s. :)
 

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So which one do you want the MN6 or the M12? The GTO uses the M12 which is the ratios that are posted, the MN6 uses different first second and third gears, which do you want? :)
 

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GTPprix said:
So which one do you want the MN6 or the M12? The GTO uses the M12 which is the ratios that are posted, the MN6 uses different first second and third gears, which do you want? :)
Are you sure? According to the build sheets of the '04 M6's on our lot, they are built w/MN6. Where did you get this information?
 

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kn7671 said:
Not that I would shift at redline, but isn't the GTO's 5.7L LS1 engines redline 6200rpm?

Or is 6000rpm the redline, and 6200rpm the fuel cut-off?
I just copied the specification chart from R&T's road test of the GTO. I don't know why they used 6000rpm.
 

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HRJ said:
Are you sure? According to the build sheets of the '04 M6's on our lot, they are built w/MN6. Where did you get this information?
open the hood of a car and you will see M12!
 

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MN6 was an RPO. Perhaps they did away with that combo as the RPO and replaced it with M12. Nothing more, nothing less.
 

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ANd the rev limiter is 6,250 rpm. But since our tachs may be a tad slow, it may show 6,000 when it hits.
 

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You're right. I'll see if i can post the build sheet.
 

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Here is a build sheet from one of our lot vehicles:

***Vehicle Build***



Home - Summary - Claim History - Vehicle Build - Vehicle Component - Delivery Information - Dealer Information - Service Contract - Warranty Block - Branded Title


VIN 6G2VX12G34L297536
VEHICLE BUILD
Merchandising Model : 2VX37 -2004 GTO COUPE
Gross Vehicle Weight Rating : N/A Order Number : HFQQST
Build Date : 08/13/2004 Build Plant : 64LV
OPTION CODES
AH5 - FRT PWR DRIVER SEAT,8-WAY
AH8 - FRT PASS POWER SEAT,8-WAY
AK3 - FRT SEAT HEAD RESTRAINT
AK5 - DUAL FRONTAL AIR BAGS
AQ9 - CUSTOM BUCKET STS
A88 - SEAT HEADREST
B58 - FLOOR MATS
C60 - AIR CONDITIONING, CUSTOM
C95 - LAMP, ROOF COURTESY & READING
DL5 - DECAL ROADSIDE SERVICE
DL6 - MIRROR O/S REMOTE CONTROL,ELEC
EF7 - UNITED STATES OF AMERICA
FE2 - SUSPENSION SYSTEM, HANDLING
FE9 - 50 STATE EMISSIONS
GH4 - EQUIPMENT ADD'L USA
GS9 - AXLE REAR 3.46 RATIO
G80 - LIMITED SLIP TORSEN REAR DIFFERENTIAL
JL9 - ANTILOCK BRAKES - FRT & RR DISC
K30 - CRUISE CONTROL AUTOMATIC
LHD - VEHICLE DRIVE LEFTHAND
LS1 - ENGINE,8CYL 5.7L SFI
MN6 - TRANSMISSION, 6-SPEED MANUAL
M12 - TRANSMISSION, MAN 6 SPD
NP5 - LTHR WRAP STEERING W/RAD CNTRLS
NT9 - FED EMIS SYS, TIER 2 PHASE-OUT
N40 - POWER STEERING
PZ9 - WHEEL, 17 X 8, ALUMINUM
QWZ - P245/45ZR17 W-RATED TIRES
R6J - CUSTOMER DIALOG NETWORK
R9U - GM ACCESS - AUTOBOOK IDENTIFIER
SLM - SALES STOCK ORDERS
T43 - SPOILER, REAR DECK LID
T82 - HEADLAMPS AUTO ON-OFF
U1X - RADIO, AM/FM STEREO, SEEK/SCAN MULTI CD,CLOCK,ETR HPS
U77 - REAR WINDOW ANTENNA
VM5 - LABEL INFOR BMP IMP STD FRT/RR
V5Z - PLATE SAFETY COMPLIANCE-DELETE
V73 - VEHICLE CERTIFICATION U.S.
W62 - EQUIPMENT GTO PERFORMANCE PKG
1SZ - OPTION PACKAGE DISCOUNT
24U - IMPULSE BLUE METALLIC
81I - INTERIOR TRIM ANTHRACITE
812 - ANTHRACITE,LEATHER TRIM COMB


© 1998-2004 General Motors Corporation. All Rights Reserved.


The only thing that shows up on the stock reports is MN6. Since I currently own an A4, this is not what I see when I pop the hood. So I guess this actually both an MN6 and an M12 based on this build sheet, and it's the same tranny, so the gear ratios won't be different. Right? So I still don't understand why there are two tranny codes assigned to one car. Anyone?
 

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And I believe my tag does say MN6 under the hood.

So either one can be used interchangibly.

No reason to fret guys. :D
 

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Thats actually not true, the MN6 has different first second and third and is still the RPO in the base C6 six speed, the M12 is the uplevel C6 Z51 trans also found in the GTO. They are still seperate entities for now. M12 is considered an upgrade over the MN6 so the MN6 gets keyed into build first and then replaced by M12 which is why they both show up.
 

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GTPprix said:
Thats actually not true, the MN6 has different first second and third and is still the RPO in the base C6 six speed, the M12 is the uplevel C6 Z51 trans also found in the GTO. They are still seperate entities for now. M12 is considered an upgrade over the MN6 so the MN6 gets keyed into build first and then replaced by M12 which is why they both show up.
I still want to know where you are getting this info from....
 

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I just called GM. They say that the actual trans is an M12. MN6 is the merchandising code for the same transmission. So they are one and the same. He also warned me not to mix it up with MM6, because according to him many people do, so I thought I'd pass that along too.
 

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Double checked in the GM Service Manual and it definetly is an M12...
 

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CMNTMXR57 said:
ANd the rev limiter is 6,250 rpm. But since our tachs may be a tad slow, it may show 6,000 when it hits.
According to what LS1 Edit hacked out of my computer, my rev limit was factory set at 6200 rpm.
 

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GM Service Information
Document ID# 1338233
2004 Pontiac GTO
Manual Transmission Description and Operation
Manual transmissions are identified by the number of forward gears and the measured distance between the centerline of the output shaft and the counter gear.

The 6-speed manual transmission (RPO M12), incorporates the following features:

An aluminum case
Fully synchronized gearing with an enhanced synchronizer cone arrangement:
Triple-cone: FIRST, SECOND
Double-cone: THIRD, FOURTH, FIFTH, SIXTH
Single-cone: REVERSE
An internal shift rail mechanism
A remote transmission shift control mounted forward of the transmission
An external transmission shift rod enabling the forward mount location of the transmission shift control
An extended-length transmission output shaft mating directly to the rear axle drive pinion, in the rear of the differential housing
Tapered roller bearings supporting the mainshaft and countershaft
Caged roller bearings under all speed gears
Solenoid inhibit of SECOND and THIRD gears
Solenoid inhibit of REVERSE gear during predefined forward motion
These features combine to yield a rugged, reliable system capable of handling input torques of up to 610 N·m (450 lb ft) for the M12.

The gear ratios are as follows:

Gear M12 Ratio :)1)

FIRST 2.97
SECOND 2.07
THIRD 1.43
FOURTH 1.00
FIFTH 0.84
SIXTH 0.57
REVERSE 3.28
 
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