Does anyone have hard before and after numbers on the 0-60 & 1/4 mile times for the 3.9 gear with a stock engine?

Is it worth the dinero?

JET

 

i think it'd b a bettar mod than cams.

 

https://my350z.com/forum/showthread....l+drive+review

https://my350z.com/forum/showthread....l+drive+review

 

I swapped diffs with louzer (6MT) mine is a (5AT)
He can now hit 60mph in 2nd gear and I am turning 13's instead of 14.1's.

I think changing diff ratios is a very good way to get more punch out of the Z....or any other car for that matter.

zillinois.....so the speedo is not effected by the diff swaps???

 

Correct.

 

This is a nice mod, where are you folks getting the parts for this?

Thanks,

Chris

 

I exchanged my diff with a fellow who had a 6MT I have a 5AT. We just switched the diffs.

zillinois Can you tell me why the speedo is not affected? I believe you I'm just curious to find out why. Walt

 

The wheel speed sensor measures actual rotational speed. The measurement is not mathmatically calculated, but sampled, I believe. Either that or the sensor is (spatially) located after the gear and therefore does not effect it. I'm not sure exactly which one is it, but I'm pretty sure its one or both of them. I just know it doesn't because the shop that installed it verified the accuracy of my speedo with a radar gun.

For the other guy, I got the 3.9 at www.350evo.com.

 

Thanks, glad I don't have to worry about speedo error.

 

My $0.02....doesn't the wheel speed get measured from the serrated thingies outboard of the rear axel stub axels?

 

I would suspect that the same wheel sensors used for ABS, TC, and VDC are used to measure speed. They're located at all four wheels, routed around the shock absorber, and bolted into place. I had to remove it temporarily when I yanked my shocks out. So, only wheel diameter should affect speedo.

 

If you don't care about speedo error, just get smaller diameter tires. It'll have the same effect as the shorter final drive (actual it'll improve acceleration even more since it'll lower rotating mass) but it costs a lot less. I run 275/40-17 as track tires which gives a 2.2% reduction from the stock tires. You could use a 245/45-17 for a 2.2% reduction or a 245/40-17 on the stock enthusiast wheels for a 5.8% reduction in gearing. Plus it lowers the car too! Of course, if you have the money to spend, not having to worry about speedo accuracy would be nice. Don't forget to upgrade the limited slip as long as you're in there.

 

So you switched for the faster acceleration, and he switched for the longer gears(forced induction i'm assuming then). Did you just post, WTT my 5AT diff for a 6MT diff?

 

There are some folks in the FI forum with a 6MT thinking about switching to the 5AT final drive... you could try and swap with one of them.

 

Hmm, switching to taller gears? they must really have the power...

 

I switched with louzer who has 415 rwhp and could not hit 60 in second gear until we switched diffs. It gave me more out of the hole with my 5AT. Didn't cost anything except labor for us.

 

i would be willing to switch with someone who has a 6mt and wants the 5at final drive, if anyone wants to pm me