qmantran

Can someone with 3.692 gears in a 7at G37 tell me what your RPM is while cruising at

60
70
80

or any speed in between?

I recently installed what I thought was a 3.692 rear end but now I'm starting to think I installed a 07 G35 Coupe diff which is 3.538.

stealthee

Just based on the math alone

3.69 would be 2864 at 80, 2506 at 70, and 2148 at 60 in 7th.
3.538 would be 2748 at 80, 2404 at 70, and 2061 at 60 in 7th.

qmantran

Thanks a lot stealthee. So with my factory 3.357 I took pictures of the rpm before I swapped it out. Here are what they were vs new diff.

3.357 2011 G37S 7AT RWD

• 60mph - 1950rpm
• 70mph - 2300rpm
• 80mph - 2600rpm

Swapped diff from a 07 G35 "KG" stamped + labeled (3-bolt pinion flange)

• 60mph -2150rpm
• 70mph - 2550rpm
• 80mph - 2850rpm

So I may indeed have 3.692 FD.

krazyfiend

was just able to get up to 60 in 7th on my commute into work this AM. 2150rpm is right on and coordinates with stealthees mechanical leverage against speed, rpm calculation.