3.42 to a 3.73
TECH Enthusiast
Joined: Jun 2013
Posts: 513
Likes: 1
From: Moose Jaw SK, Canada
Don't even bother with that swap IMO
4.10 is a nice ratio with a 6 speed. I definitely wouldn't go any higher ratio than 4.10, and any lower 4.30, 4.56 etc with a 10 bolt, as you lose pinion contact area and in turn lose strength.
But it all depends what you're wanting to do with the car.
If the highway rpm scares you, don't let it lol. With a 26" tall tire and 4.10 gears it's like 76mph at 2000 rpm. I've been in these cars with varying gear sets, and they seem to cruise happier around 2k anyways. Best of luck making a decision.
4.10 is a nice ratio with a 6 speed. I definitely wouldn't go any higher ratio than 4.10, and any lower 4.30, 4.56 etc with a 10 bolt, as you lose pinion contact area and in turn lose strength.
But it all depends what you're wanting to do with the car.
If the highway rpm scares you, don't let it lol. With a 26" tall tire and 4.10 gears it's like 76mph at 2000 rpm. I've been in these cars with varying gear sets, and they seem to cruise happier around 2k anyways. Best of luck making a decision.
FWIW, a 4.11 is a bit stronger ring gear than the 4.10, cause it has 37 teeth instead of 41, so they're a bit thicker. Splitting hairs maybe, but every little bit helps.
Also, FWIW, I put 4.11 on my car with 26" tires. Went to 28" tires and the car got faster. I'd suggest a 3.9 gear personally.
Also, FWIW, I put 4.11 on my car with 26" tires. Went to 28" tires and the car got faster. I'd suggest a 3.9 gear personally.
3.90 is a very good gear with the MN6. For a 10-bolt, I think it may be stronger too because it's manufactured in Italy vs Asia. Or at least it was. That's why it costs more.
3.73 won't be very noticeable.
3.73 won't be very noticeable.
TECH Apprentice
Joined: May 2010
Posts: 303
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I went from 3.42 to 3.73 motive orange box and Ive noticed a big improvement and a much more enjoyable ride. With the 3.42s, I wouldnt even think of using 6th gear unless I was going 75mph+. With 3.73s, you can shift into 6th at 40mph with plenty of torque still on tap. I went with 3.73s for 10 bolt longevity and because I run street tires. The new gears got rid of my low rpm dead spot below the power band, I am happy with my new gears. If I had a stronger rear, i would go with 4.10s or 3.90s. I have lid, full exhaust and tune to give you an idea on power.
Joined: Aug 2007
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From: Turnin' Wrenches Infractions: 005
One of the best things about gear swaps is the ability to do a rebuild while you have it apart. You reset tolerances tighter then they were from the factory AND every single m6 car Ive done has had driver carrier bearing wear/damage, so you get the chance to undo that.
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Teching In
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I went from 3.42 to 3.73 motive orange box and Ive noticed a big improvement and a much more enjoyable ride. With the 3.42s, I wouldnt even think of using 6th gear unless I was going 75mph+. With 3.73s, you can shift into 6th at 40mph with plenty of torque still on tap. I went with 3.73s for 10 bolt longevity and because I run street tires. The new gears got rid of my low rpm dead spot below the power band, I am happy with my new gears. If I had a stronger rear, i would go with 4.10s or 3.90s. I have lid, full exhaust and tune to give you an idea on power.
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Teching In
Joined: Jun 2016
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One of the best things about gear swaps is the ability to do a rebuild while you have it apart. You reset tolerances tighter then they were from the factory AND every single m6 car Ive done has had driver carrier bearing wear/damage, so you get the chance to undo that.
2002(1999-2002) had Torsen 'posi' which had a 'gearset' posi arrangement. 1998 and earlier had Auburn 'posi' which had cone clutches and those were not rebuildable.
the reference to 'did you also replace the clutches in the carrier??' applies to Eaton positraction carriers.
the reference to 'did you also replace the clutches in the carrier??' applies to Eaton positraction carriers.
TECH Apprentice
Joined: May 2010
Posts: 303
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I used motive 3.73 orange box which are part number G875373. They have a little whine to them on slight accel from 45-70 but they are a little stronger than the blue box motive which should be silent as stock and are part number GM-7.5-373.
Does anyone have an opinion about 3.73 for Autocross? I'm seriously considering it- seems like a small boost in low end launch, and missing a few MPH top end in 2nd might not matter. I'm rarely at max rpm in 2nd on most courses.