Fellow AT 08'ers,

At what road speeds do you redline 1st, 2nd and 3rd? (Assuming a redline of 7500 rpm). And how fast are you going at 3k rpm in 5th?

I have a feeling my GCC Spec 08 has a 3.357 rear end rather than a 3.692.

Thanks for your help.

 

hey Sam
since you swapped a RB25 gearbox, wouldn't that affect your overall gear ratios and resulting in different speeds through each gear?
Did you have the same redline speed before the swap?

 

You are correct Indyn. I want to compare peoples numbers to mine before I did the swap.

My tuner who has an RB30'd 350Z (RB25 Tranny + 3.5 diff ratio) says that my gears are much taller than on his Z. That is why I am suspecting my diff is not a 3.692.

 

Sam - There is a way you can determine your gear ratio by jacking the rear of the car up and counting the rotations of the driveshaft as you turn one of the rear wheels. I forgot exactly how you do it but I'm sure Google would help lol.

 

Your car came stock with an AT, right?
It's a 3.357.

Stock MTs came with a 3.692.

According to the 2008 FSM.

 

Correction, 5AT in 2008 came with 3.692. There was no 3.357 option.

Hmmmm??

 

Put it on a hoist, mark the driveshaft at 6 o'clock, ,ark the ale shaft at 6 o'clock, turn the driveshaft, and count the turns of the axle shaft.

 

I tried that and it wasn't very successful. It's not easy to turn the driveshaft LOL. And when tried turning one wheel, the other one also started turning (at least I got an LSD though )

Can anyone reply to my first question though?
At what road speeds do you redline 1st, 2nd and 3rd? (Assuming a redline of 7500 rpm). And how fast are you going at 3k rpm in 5th?

 

Sam, when I watch my drag vid below, I shift TO 4th JUST after the eighth mile markers (1:38" on the vid). I'm going exactly 99mph at the eighth, and I'm shifting at 8000rpm.

3150 is my current 80 MPH RPM.

How are you measuring speed? Is your speedo accurate?

Coop

 

70 km/h in 2nd at 5k rpm.
100 km/h in 3rd at 5k rpm.

my km/h might be off little bit as my speedo is in miles.

 

2008 final drive is 3.692

 

Confirmed via GPS that my speedo is working fine. Yet every gear ratio calculator indicates that there is no way I'm on a 3.69 ratio. There must be some sort of hidden coupler somewhere in my drivetrain lol

 

I finally pulled my OEM Ring & Pinion out. My fellow 5 speeders, I got some bad news for you:



This was pulled out of my OEM diff. It shows that the Ring has 47 teeth, and the Pinion has 14 teeth. If you do the math, that's a ratio of 3.357:1. Every online resource I came across showed 3.69:1 just like the MT but that is clearly not the case. I double checked with Nissan's technical department here and they have confirmed that it's a 3.357:1 not 3.69:1.

Luckily, this bad boy is going to replace it

 

Oh no it cant be! Thanks for clearing that up Sam.

 

OK! Well, it all makes sense even if the specs don't. At least you WILL get the increase you wish.

IS that the 4.08 set in the second photo? And.... what are you learning about jamming that in there.

Coop