My 4.08 install...
07-02-2013, 06:06 PM
#1
My 4.08 install...
Here’s my story in pictures:
I had been wanting to do this mod for years and ironically the day I get my rearend with 4.08 gears delivered, I also received a Getrag rearend with 3.55’s for my dad’s SRT8. Two modded 3rd members delivered the same day... yeah, that’s how we roll.
I bought mine used and got it for a steal. It looked pretty rough and weathered but it was now mine.
I helped my dad install the Getrag with 3.55’s in his SRT8 and then started to tackle my install. First thing to go was the solid bushings.
It took some elbow grease but they came out.
Then I started to really clean the thing up.
Got up close and personal with it on the bench.
Cleaned up real nice like. I planned on repainting the thing when I first opened the box but it just needed a good cleaning. I used the Whiteline bushings and there is no axle hop now.
Finally got my hands on a driveshaft from a manual (only used the rear half).
Then I started pulling parts off the car.
The stock unit fell right out.
My two rearends next to each other for comparison. The stock one will clean up just as well if not better once I get to it.
I used the rear half of the manual drive shaft and the front half of my auto drive shaft and put the new 4.08 diff in. It fit perfect.
All back together and ready to launch.
It drives like a different car now, how it should have from the factory. I did lose cruise control as expected. I’d like to get an idea of gas mileage but I can’t keep my foot off the gas. The car just flat out moves now.
I had been wanting to do this mod for years and ironically the day I get my rearend with 4.08 gears delivered, I also received a Getrag rearend with 3.55’s for my dad’s SRT8. Two modded 3rd members delivered the same day... yeah, that’s how we roll.
I bought mine used and got it for a steal. It looked pretty rough and weathered but it was now mine.
I helped my dad install the Getrag with 3.55’s in his SRT8 and then started to tackle my install. First thing to go was the solid bushings.
It took some elbow grease but they came out.
Then I started to really clean the thing up.
Got up close and personal with it on the bench.
Cleaned up real nice like. I planned on repainting the thing when I first opened the box but it just needed a good cleaning. I used the Whiteline bushings and there is no axle hop now.
Finally got my hands on a driveshaft from a manual (only used the rear half).
Then I started pulling parts off the car.
The stock unit fell right out.
My two rearends next to each other for comparison. The stock one will clean up just as well if not better once I get to it.
I used the rear half of the manual drive shaft and the front half of my auto drive shaft and put the new 4.08 diff in. It fit perfect.
All back together and ready to launch.
It drives like a different car now, how it should have from the factory. I did lose cruise control as expected. I’d like to get an idea of gas mileage but I can’t keep my foot off the gas. The car just flat out moves now.
The following users liked this post:
SharpByCoop (07-03-2013)
07-02-2013, 06:37 PM
#2
Dude I forgot your from the 402. 
Nice job on the 4.08s.
Nice job on the 4.08s.
07-03-2013, 05:21 PM
#6
Registered User
Fantastic post with good clear photos.
To the users who may not have followed our other thread on this conversion: THe 4.08's HAVE to be installed in a MT VLSD diff housing from any year G35/G37/350Z/370Z.
With the auto trans you NEED to use a manual transmission back half from a 2007+ G35 or G37. The 4.08 gearset pinion does not have that finger which aligns and centers the AT rubber coupling.
^^^ This is the best method.
I also did the conversion in my 5AT, and BOY is it responsive. Just like he said: It makes it right.
Great job, Kevin!
Coop
To the users who may not have followed our other thread on this conversion: THe 4.08's HAVE to be installed in a MT VLSD diff housing from any year G35/G37/350Z/370Z.
With the auto trans you NEED to use a manual transmission back half from a 2007+ G35 or G37. The 4.08 gearset pinion does not have that finger which aligns and centers the AT rubber coupling.
^^^ This is the best method.
I also did the conversion in my 5AT, and BOY is it responsive. Just like he said: It makes it right.
Great job, Kevin!
Coop
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