Hi,
I was just wondering what exactly this would do:
http://www.toms-trd.com.hk/eng/main_...contentid=7693

it looks like a rear differential gear or something.


has anyone seen something like this for an is350 before?

 

From what I understand, adding a taller gear would "increase" fuel economy. I don't think it would add performance to your 350. The gearing in our 350's is already super aggressive.

First Gear Ratio (:1): 3.52
Second Gear Ratio (:1): 2.04
Third Gear Ratio (:1): 1.40
Fourth Gear Ratio (:1): 1.00
Fifth Gear Ratio (:1): 0.72
Sixth Gear Ratio (:1): 0.59
Reverse Ratio (:1): 3.22
Final Drive Axle Ratio (:1): 4.08

Kurtz or carLx could probably shed some light on/explain this better than I could

*On a side note, Infiniti G owners like to swap out their pumpkins for Z ones because the gearing is "better" (off the line acceleration, but you lose top end speed)

 

4.08 is the relevant number in the IS350... that's the gear set in the stock diff from the factory.

4.60s (which is an odd ratio to see...) would theoretically reduce mileage a touch (and the top speed in each gear) and increase acceleration a bit (though you'd have an even tougher time launching without wheel spin with tc/vsc off).... it'd also confuse the speedometer and possibly other systems since there's no way to change the computer to compensate for what it thinks the ratio should be....

Gernby and others have mucked with overall gearing a bit by changing their tire sizes with decent results, but mainly at the track I think.

 

The stock final gearing for the IS is PERFECT, best leave it alone. The LSD would help at the track but not needed for street use. Spend the money on coilovers and/or sway bars.

Koz