maybe a jeriko straight cut racing trans for that kind of power. 
MN12 vs MN6
Thread Starter
Burning Brakes
Joined: Mar 2003
Posts: 874
Likes: 0
From: Bonita CA
MN12 vs MN6
I'm about to do an A4 to six speed conversion. What are the differences between the MN12 and the MN6? Will a stock LS1 benifet from the different gear ratios that the MN12 has? I have a ZO6 3:42 rear.
I have future plans after this conversion to upgrade to a forged LS2 shortblock moderate flowing heads and ultimately F/I.
I will be selling a complete A4 setup for those who are looking to do a six speed to A4 conversion. Includes TC, TQ tube, 4L60E tranny, 3:15 rear end, brake pedal and shifter. I have a very maintained So. California Garage Queen Vert now with 46K miles on her. No leaks, no slipping, no dragracing or track time on this setup. If interested I will be doing this swap within the next 30 days.
I have future plans after this conversion to upgrade to a forged LS2 shortblock moderate flowing heads and ultimately F/I.
I will be selling a complete A4 setup for those who are looking to do a six speed to A4 conversion. Includes TC, TQ tube, 4L60E tranny, 3:15 rear end, brake pedal and shifter. I have a very maintained So. California Garage Queen Vert now with 46K miles on her. No leaks, no slipping, no dragracing or track time on this setup. If interested I will be doing this swap within the next 30 days.
Last edited by DJMRTS; Sep 27, 2005 at 10:26 AM.
Night Owl for life
Joined: Nov 2003
Posts: 24,721
Likes: 4,560
From: Bugs Bunny should'a made a left turn here
yes it will benefit from a Z06 tranny. shorter ratios mean quicker accelleration.
some of the hard core racers on the forum say that the MN6 is actually better for racing, though because of the spacing between gears...
some of the hard core racers on the forum say that the MN6 is actually better for racing, though because of the spacing between gears...
Burning Brakes
Joined: Oct 2003
Posts: 959
Likes: 12
From: California CA
The MN6 is by far the better gearbox. I own both a 400RWHP 2001 Coupe and a stock 2003 Z06. The MN12 gearbox is good for stock HP as the lower gears are closer, but this advantage disappears very quickly as you increase HP. I think my coupe would actually be slower with the MN12 as I would be forever shifting...
For a high HP (bigger cubes or FI) application, go with a MN6 and a 3.42 diff with hardened output shaft. Stay away from the MN12...
For a high HP (bigger cubes or FI) application, go with a MN6 and a 3.42 diff with hardened output shaft. Stay away from the MN12...
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
Originally Posted by DJMRTS
Is the MN12 stronger than the MN6? Is the stock MN6 reliable to 600 rwhp?
Yes, an M6 is stronger than an M12.
As far as "how much HP will it hold", that's all relative.
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Burning Brakes
Joined: Oct 2002
Posts: 797
Likes: 1
From: Sunny Earthquake Country, USA On the Left Coast (which is becoming more Right!)
Ditto...
Originally Posted by Dan_the_C5_Man
Everyone is telling you the real story.. M6 and a set of 3.90's is superior to an M12 w/ 3.42's
Yes, an M6 is stronger than an M12.
As far as "how much HP will it hold", that's all relative.
Yes, an M6 is stronger than an M12.
As far as "how much HP will it hold", that's all relative.
MN6 w/3.90 rear has same overall reduction in 1st as MN12 w/3.42 gear and the other ratios are better and you have a .5 overdrive in 6th!
As far as strength, the pinion (smaller gear) of the MN6 1st gear should be stronger but the pinion of the 3.90 rear gear will be weaker. These are very fine distinctions and in the overall scheme may not be real significant.
May the BOOST br with you!
Roy
Team Owner
Joined: Jul 2003
Posts: 20,474
Likes: 2
From: Detroit
Originally Posted by DJMRTS
Is the stock MN6 reliable to 600 rwhp?
Originally Posted by Dan_the_C5_Man
... an M6 is stronger than an M12 ...
Mark
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
with 600 rwhp you need a racing transmission. Neither of the NM12 or MN6 are built for that kind of punishment.
GM does make a racing transmisson and differential which is much stronger and built for those numbers. Gearing is closer to the MN 12 gears ( but is custom to your needs) and the rear end of choice are the 3.73 and occationally the 3.90.
I have driven lots of both transmissions. I prefer the MN6 gearing, espessially the 3rd to 4th.
MN6 - 3.42 & 18x335/30 tire
rpm on top, gear down left - speed in each gear
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6300 6500
1st 8 13 17 21 25 30 34 38 42 46 51 53 55
2nd 13 19 25 32 38 44 51 57 63 69 76 80 82
3rd 17 26 35 43 52 61 69 78 86 95 104 109 112
4th 22 34 45 56 67 79 90 101 112 124 135 142 146
5th 30 46 61 76 91 106 121 137 152 167 182
mn12 - 3.42 & 18x335/30 tire
rpm on top, gear down left - speed in each gear
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6300 6500 6750
1st 8 12 16 19 23 27 31 35 39 43 47 49 51 53
2nd 11 17 22 28 34 39 45 50 56 61 67 70 73 75
3rd 16 24 32 40 49 57 65 73 81 89 97 102 105 109
4th 23 35 46 58 69 81 93 104 116 127 139 146 150 156
5th 28 41 55 69 83 96 110 124 138 152 165 174
GM does make a racing transmisson and differential which is much stronger and built for those numbers. Gearing is closer to the MN 12 gears ( but is custom to your needs) and the rear end of choice are the 3.73 and occationally the 3.90.
I have driven lots of both transmissions. I prefer the MN6 gearing, espessially the 3rd to 4th.
MN6 - 3.42 & 18x335/30 tire
rpm on top, gear down left - speed in each gear
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6300 6500
1st 8 13 17 21 25 30 34 38 42 46 51 53 55
2nd 13 19 25 32 38 44 51 57 63 69 76 80 82
3rd 17 26 35 43 52 61 69 78 86 95 104 109 112
4th 22 34 45 56 67 79 90 101 112 124 135 142 146
5th 30 46 61 76 91 106 121 137 152 167 182
mn12 - 3.42 & 18x335/30 tire
rpm on top, gear down left - speed in each gear
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6300 6500 6750
1st 8 12 16 19 23 27 31 35 39 43 47 49 51 53
2nd 11 17 22 28 34 39 45 50 56 61 67 70 73 75
3rd 16 24 32 40 49 57 65 73 81 89 97 102 105 109
4th 23 35 46 58 69 81 93 104 116 127 139 146 150 156
5th 28 41 55 69 83 96 110 124 138 152 165 174
Safety Car
Joined: Jun 2004
Posts: 4,921
Likes: 1
From: Minburn Ia
Originally Posted by DJMRTS
So why did the factory put the MN12 in the Z06 if the LS6 has more HP & TQ than the LS1?
Who can give answer to his question? What is the history of use of MN12 and M6 trannys in vettes ... over the C5 model years?
Melting Slicks
Joined: Jul 2005
Posts: 2,572
Likes: 3
From: Rehoboth MA . . . NRA Life Member
St. Jude Donor '06-'07
I wonder how one is supposed to be stronger than the other when their are both rated by the factory for 450 horsepower, 425 ft lbs of torque. 
I think their slightly different based on their intended application.
Bob
I think their slightly different based on their intended application.
Bob
