For the 5AT, it is best to go with the 6MT 3.5 ring and pinion. You will need to use the VLSD from a 6MT. The easiest way for install is to swap the whole pumpkin like it stated in this thread. We have done a few here and all the customers were happy with the improved acceleration.

 

I dun quite understand....

what's the disadvantage of installing 3.9 final drive into 5AT car??

btw.. does the final drive void the warranty?

 

I think that driveability will be sacrificed by going with the 3.9s in a 5AT. I think that the RPMs will be really high for everyday driving. I would suspect cruising RPMs will be several hundred or a thousand or more with the 3.9.

I think the warranty void question is all subjective to whichever dealership you go to. According to the Moss Magnussen (sp?) Act, a dealer can not deny warranty service unless the aftermarket mod led directly to the failure.

 

Here is a picture someone added of the difference
https://my350z.com/forum/showthread....10#post1667510

Im going to order the 3.5 pre-assembled unit to swap out.

 

cannot void warranty other then for the pumpkin, doesnt affect engine or drive line warranty. the difference would be night and day, had gears in my old mustang and my sc400 lex,, it makes it alot more aggressive through out the whole rpm, its like driveing a auto and turnning off over/drive. you will notice rpm will rise about 100 rpm more while cruising, putting you in to the sweet spot of the power band. best mod for the money. 3.9 with a torque converter would be the ultimate mod for the money, no other mod will give you such gains. these mods dont add HP , but it will make your car act like its on roids.

 

must you tease?

i have the torque converter mod. and i saw big gains in the 1/4 from it (.6 seconds). you try doing both on your z, the TC and 3.9?

however, i still dont think its worth the money for a 3.3 to 3.5 upgrade. you wont see enough gains to make the mod cost effective.

 

How much are we talking for the TQ Mod and the 3.9 Gearset, Parts only?

 

the TC mod was a little over $400 in parts including the tranny cooler plus shipping both ways. about 1k in including labor.