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Which Gears?

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Old Dec 28, 2008 | 11:14 PM
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Default Which Gears?

I plan on upgrading my trans and rear soon. I'm going with the RPM mn6 with G-force 5th and 6th for better top end. I'm torn between staying with 3.42's in the rear or switching to 3.73's.
The car is just a fun street car that I'd like to be able to hit 200mph in at 7k rpm or less.
I think the 3.73's would get me there but cause traction problems in the lower gears. The 3.42's I'm guessing would be great up top but not drive so hot in 1st. I will be running Hoosier R6 tires in 345/30/19. I appreciate any input or experience.
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Old Dec 29, 2008 | 09:56 AM
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3:73 with the M6... the C5 Z06 comes with the M12 tranny, lower gear ratio in 1st thru 3rd.

HAVE FUN !!!
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Old Dec 29, 2008 | 12:42 PM
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You are going to be able to spin your tires in first gear (and probably second too) no matter what gear you have in there, so that's not really a criteria. you just have to learn to hook them up. On that basis, I would go to 3.73s and enjoy the lower gearing.

However, with 3.42s, you be'll just about 200 mph in 5th gear at 7k, assuming you can pull to 7k at that speed (minimal tire growth). 3.73s only get to about 180 mph at 7k at which point you drop to about 4800 rpm in 6th, not so ideal.
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Old Dec 29, 2008 | 02:25 PM
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Originally Posted by Ragtop 99
You are going to be able to spin your tires in first gear (and probably second too) no matter what gear you have in there, so that's not really a criteria. you just have to learn to hook them up. On that basis, I would go to 3.73s and enjoy the lower gearing.

However, with 3.42s, you be'll just about 200 mph in 5th gear at 7k, assuming you can pull to 7k at that speed (minimal tire growth). 3.73s only get to about 180 mph at 7k at which point you drop to about 4800 rpm in 6th, not so ideal.
I think your numbers are with the stock gears. My 5th and 6th are currently .84 and .56. The new gears will change that to .83 5th and .70 6th. Right now the party is over when you shift into 6th, but I believe I'll be able to pull 6th with the new trans.
I will also be moving from the m12 to the mn6 changing 1st from 2.97 to 2.66, I just don't know how much of a difference that will make. Thanks to those that took time to post.
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Old Dec 29, 2008 | 03:41 PM
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Your car is just a fun street car??? Your car is a beast!!!! a fun street car is a stock LS1 thru 6! WOW!! But if you want to get to the 200MPH stay with the 3.42's that motor should get you there. and you might even want to flirt with the idea of getting 3.23's too. you obviously have the power to push it from go and its not a drag car, so that might be an option for you too.
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Old Dec 30, 2008 | 09:20 AM
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Originally Posted by MPM IV
I think your numbers are with the stock gears. My 5th and 6th are currently .84 and .56. The new gears will change that to .83 5th and .70 6th. Right now the party is over when you shift into 6th, but I believe I'll be able to pull 6th with the new trans.
I will also be moving from the m12 to the mn6 changing 1st from 2.97 to 2.66, I just don't know how much of a difference that will make. Thanks to those that took time to post.
My numbers are based upon the Z06 tranny for 2004. If you are changing out your tranny to the base M6 than 5th gear becomes .74 and .5 for 6th. With 3.73s and the base tranny you would just make 200 mph in 5th gear assuming you can pull to redline.

3.73s with the base tranny will put first gear back to being about the same as your current Z06 tranny with 3.42s.
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Old Dec 30, 2008 | 02:03 PM
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i also switched to the mm6 and it is great. i went with 3.90s but if 200 is your goal i would do the 3.73s. when are you going give me a ride in that beast?
Attached Thumbnails Which Gears?-dsc00130.jpg  

Last edited by algws6; Dec 30, 2008 at 02:09 PM.
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Old Dec 30, 2008 | 09:19 PM
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Originally Posted by Ragtop 99
My numbers are based upon the Z06 tranny for 2004. If you are changing out your tranny to the base M6 than 5th gear becomes .74 and .5 for 6th. With 3.73s and the base tranny you would just make 200 mph in 5th gear assuming you can pull to redline.

3.73s with the base tranny will put first gear back to being about the same as your current Z06 tranny with 3.42s.
Thanks. I wasn't sure where the new 1st with 3.73 would put me.

I will be getting the Mn6 but not the stock 5th and 6th. The G-force gears should allow me to pull 6th. There isn't much point in a gas saving gear with this motor .
Algws6, we need to get togeather some time. I'd like to check your car out, and the weather is great right now.

It also looks like I need to look at the tire size input in my tune. At 7k rpm in 5th my spedo is showing 170 mph. I was told today that I should be around 195 mph on my 19's.
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Old Jan 3, 2009 | 03:01 AM
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what ratio will your 5th and 6th be? I run 4.10's in a MN6 and love it. People who care about traction havent bought a tire yet. granted in this cold weather i still spin them at 130mph plus, but in the summer my Nittos hook great
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Old Jan 3, 2009 | 10:09 PM
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Fastvet, thanks for the compliment. I just wanted people to know I wasn't building it for any single purpose.
The 5th will be .83 and 6th will become .70. Aparently my tire dia. was input at 25.x and should be 27.x, so the car is already breaking 200mph. I'm leaning toward the 3.73's.
Now that the car is running faster than I realized I'm not sure what my priority is.
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Old Jan 4, 2009 | 01:25 PM
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guys, i had a chance to take a ride in this car on friday, and dam it is ****** insane!!!!!!!!!!!! nothing like breaking the tires loose at 70 all motor in 3rd gear.
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Old Jan 5, 2009 | 07:01 PM
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Originally Posted by algws6
guys, i had a chance to take a ride in this car on friday, and dam it is ****** insane!!!!!!!!!!!! nothing like breaking the tires loose at 70 all motor in 3rd gear.
Glad you enjoyed it man. Great looking car you have. Made me want to go home and polish my wheels .
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Old Jan 6, 2009 | 09:03 AM
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You can look up all of the different combinations here.

http://www.f-body.org/gears/
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Old Jan 6, 2009 | 09:30 AM
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I swapped from a MN12 +3.90 gears to a MN6 with 3.73 gears. I prefer the MN6 & 3.73s. However if you want top end then the 3.42s are the way to go.
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Old Jan 9, 2009 | 09:15 PM
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Thanks to everyone for their input. I went ahead and ordered the MN6 with 3.73s today. I'll post up what I think once they're installed.
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Old Jan 9, 2009 | 09:33 PM
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i thought about switching gears to 3.73's but i'm happy with my stocker 3.42's and base transmission
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Old Jan 9, 2009 | 11:41 PM
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Your Vette is a roach. You should just trade me cars and be done with it.

That new tranny and rear should make it a blast all around though. One of these days I'll catch up. Take care man and tell the wife that we said hello.

Originally Posted by ColeTrains'96Z28
i thought about switching gears to 3.73's but i'm happy with my stocker 3.42's and base transmission
He's a good frind of mine and I will just say that until just starting his car would cause instant death, he will not be happy. He's had some pretty killer cars and this one just tops all of them.
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Old Jan 10, 2009 | 12:36 AM
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haha sounds like my friend with his '03 Cobra. He's always changing, never happy haha
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Old Jan 10, 2009 | 03:01 PM
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Originally Posted by ColeTrains'96Z28
i thought about switching gears to 3.73's but i'm happy with my stocker 3.42's and base transmission
Just trying to go a little faster. I'm actualy changing to the trans you currently have. I think the close ratio box I have now was designed to get the car moving quicker with substantialy less power than it now has. In the past I've always changed the rear gears, but kept the tranny the same. Hopefully this will work out the way I think it will.

And now you all know I hang out with a trouble maker!
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Old Jan 10, 2009 | 10:49 PM
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I went with 4.10's c5 Z06 on my set up, cant describe what a 402 Ci with 4.10's feels like..... It is a beautiful thing...
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