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Done: 4.08 gears in a 2012 AT Coupe. But wait....

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Old 09-05-2014, 05:10 PM
  #16  
NBE-ON'D
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Originally Posted by SlateBlueG
Have to give props to SharpByCoop and ivoidwarranties (Jim and Kevin). Thought long and hard about doing this after swearing I wasn't going to do anything else to the G for a good while. Ok, a few months maybe. Followed their threads since both had 08 5ATs like me and suddenly the lightbulb burned bright. Damn -- had to do it! I bought Kevin's 6MT 4.08 VLSD and rear portion of the 6MT driveshaft. Bolted right in. The 3.69 diff is sitting in the garage having a pity party. Performance of the 4.08 gear ratio? Pure sex! It's like the G popped Viagra.....schwing! Again, thanks guys!


Wicked to hear the 4.08's compliment that 5spd's gearing, bet that woke her right up.


That 3.69:1 diff would be a nice bump for a 7AT, mostly helping 4th gear, likely wouldn't cause any grief either. Bet you can sell that easy and recover some cost, or extra beer money!!
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Old 09-05-2014, 08:05 PM
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Solidus
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With Sam's diff there was some question as to whether the 5AT actually had a 3.69. I got a bit iffy and stayed with the 6MT I bought so there was no question. Is there no one else that's done the 7AT swap to 3.69 or will I be the first here? I'd like to hear about it if someone else is out there.
Old 09-07-2014, 08:55 PM
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SlateBlueG
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Originally Posted by Solidus
Dang, I'm happy for you. All my stuff is still camouflaged throughout the house. I need to set a hard install date so that I'm in time for a nice cool first time at the track. More on just how it felt.


Unless I'm sadly mistaken you'll be happy you did. I've held on to my 5AT 3.69 diff in case I ever need to go back (sell the car) but have no regrets.
Old 09-07-2014, 08:59 PM
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SlateBlueG
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Originally Posted by NBE-ON'D
Wicked to hear the 4.08's compliment that 5spd's gearing, bet that woke her right up.


That 3.69:1 diff would be a nice bump for a 7AT, mostly helping 4th gear, likely wouldn't cause any grief either. Bet you can sell that easy and recover some cost, or extra beer money!!


Woke her up is right! Shot of adrenalin in her veins. Now, about my relationship with local law enforcement........
Torn about offloading the 3.69. If I ever sell the car I'd want to pull and pass along the goodies that made this mate up to a 5AT.
Old 09-08-2014, 07:37 PM
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Ivoidwarranties
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Glad it's working out for you. You're car is looking awesome!
Old 09-14-2014, 12:25 PM
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NBE-ON'D
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Originally Posted by SlateBlueG
Woke her up is right! Shot of adrenalin in her veins. Now, about my relationship with local law enforcement........
Torn about offloading the 3.69. If I ever sell the car I'd want to pull and pass along the goodies that made this mate up to a 5AT.


LOL Im sure them tax collectors will love you hahahaha
I actually just got a PM from someone who's considering the 3.69's for his car. I bet he would love to purchase your diff, plus who ever buys your car will just sell that diff on you and that would just be a shame, soooooooo..... How about I get him to PM ya and you guys can think it out??
Old 07-30-2015, 05:17 PM
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Gwhizz
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Is there somewhere that this is completely broken down the exact parts and what needs to be done to do this on a 5 AT? Sounds like something that I would like to do to m 2008.
I know people ask a ton of questions but I don't want to piece info together and get something wrong.


Thanks Guys
Old 04-06-2016, 09:15 PM
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oakroadsteve
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G37 Convertible Gears

Originally Posted by eddiejoe
SharpByCoop: yes, your posts helped me get this mod done! I think I've got a solution after reading RPG11's post. I had my uprev tune done by Church's here in SoCal and after talking with them they can update the ECU to keep the P0500 code from triggering. I'm off to see them tomorrow for the fix.

One thing that did occur to me was that the convertible G37's employ a 3.9 final drive gear, and that there must be a way to get some of that software into my car!
I was looking into 3.91 or 4.08 gears for my 2011 G37 AT Convertible. Can you confirm for sure they already have 3.91gears??
Old 04-06-2016, 11:24 PM
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PongSanity
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Originally Posted by oakroadsteve
I was looking into 3.91 or 4.08 gears for my 2011 G37 AT Convertible. Can you confirm for sure they already have 3.91gears??

This chart should help you out.

https://www.z1motorsports.com/transm...36-p-4523.html
Old 04-07-2016, 07:28 AM
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oakroadsteve
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Higher Gears in my G37 AT Conv

This chart was extremely helpful. Many thanks for the assist....
Old 04-09-2016, 01:12 AM
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Kris9884
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Originally Posted by SlateBlueG
Have to give props to SharpByCoop and ivoidwarranties (Jim and Kevin). Thought long and hard about doing this after swearing I wasn't going to do anything else to the G for a good while. Ok, a few months maybe. Followed their threads since both had 08 5ATs like me and suddenly the lightbulb burned bright. Damn -- had to do it! I bought Kevin's 6MT 4.08 VLSD and rear portion of the 6MT driveshaft. Bolted right in. The 3.69 diff is sitting in the garage having a pity party. Performance of the 4.08 gear ratio? Pure sex! It's like the G popped Viagra.....schwing! Again, thanks guys!
Besides this and the bearing/seal kit, what else is needed? I already sourced these for my manual swap but if I can enjoy the 4.08 gears while I'm still auto, I'm going to lol.
Old 04-09-2016, 08:39 PM
  #27  
PongSanity
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Limited Slip Differential 1.5 way
Old 04-12-2016, 08:17 PM
  #28  
oakroadsteve
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08 Differential has 3.69 gears?

Originally Posted by PongSanity
Limited Slip Differential 1.5 way
Pong,

I picked up an 08 G35 differential that I have been told will bolt right in to my 2011 G37. I've also seen posts here that it has 3.69 gears. I got it on Ebay and the parts supplier references it as an 08 diff...I sure would hate to have it installed and find out that it's not really an 08. Is there a way to eyeball the differential to ensure it's a 2008 diff that has 3.69 gears??

I would be grateful for your sage advice.....
Old 04-13-2016, 06:34 AM
  #29  
PongSanity
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If it's out of the 2008 g35 sedan, it's 3.7... Look up the part number on the diff.
Old 04-13-2016, 07:59 AM
  #30  
chuckie311
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Originally Posted by oakroadsteve
Pong,

I picked up an 08 G35 differential that I have been told will bolt right in to my 2011 G37. I've also seen posts here that it has 3.69 gears. I got it on Ebay and the parts supplier references it as an 08 diff...I sure would hate to have it installed and find out that it's not really an 08. Is there a way to eyeball the differential to ensure it's a 2008 diff that has 3.69 gears??

I would be grateful for your sage advice.....
It will not bolt right in You will have to change out the flange and more than likely the axle flanges as well. All of mine had to be change out because the axle side on the auto were threaded and the Manuel's were not


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