Project Acura NSX Final Drive Install - When You Can't Make Power, Change Gears

Even with a tighter-than-NSX-R final drive ratio, the OS final drive is very usable for daily driving and lets the engine hang around 3700 rpm while cruising at 80 mph compared to about 3500 rpm with the stock gears.

Even with a tighter-than-NSX-R final drive ratio, the OS final drive is very usable for da

Testing
Even before getting to the track, one thing is apparent: The new 4.44:1 final drive does wonders for the 5-speed NSX. The shorter final now makes the NSX feel more like driving a zippy, high-strung S2000 that likes to stay at higher engine speeds. Taking off from a stop, the lethargic feel of waiting for VTEC to kick in at 6000 rpm is nearly gone and the gear spacing us now perfect without the gaping hole between first and second gear. The engine also revs much faster due in part to the better power band and lighter flywheel. Clutch engagement is strong, but not so immediate so as to make the car undriveable. Compared to many other multi-plate clutch systems, the OS STR clutch much easier to use in traffic and requires just a slight bit more pedal effort than the stock hardware.

At the quarter-mile, we picked off a tenth from our time even though the trap speed was a little slower. The quarter-mile with the new gears and final also required a shift from third to fourth gear to complete the pass whereas the OEM gear set could finish the pass in third gear, meaning some time was lost in the additional shift. More importantly, we took off three-tenths of a second from our 0-60 times on account of the tighter final drive.

We lost some time on the figure-8. The car was far easier to drive, but because of the dimensions of the figure-8, our new gear set would bang the engine against the rev limiter a bit before the braking point for the turn in. The distance was small enough that upshifting for a split second and then downshifting for the turn would have lost more time, so we had to sit on the limiter for a short time unlike before. This cost us some top speed and thus time, but if the dimensions were just a little bit different, we're sure the new gear seat would have performed better.

In the turns, the car generated the same average 1.0 g lateral acceleration because we're on the same Yokohama Advan Neova AD07 tires, but the feel was definitely different. The higher revs through the turn and better LSD mean the car was much easier to drive and control as it oversteered at the corner exit. The transition between understeer and oversteer was much easier to balance due to the smooth but responsive transition between lock under power and release as the gas was feathered.

Lap times aside, the OS Giken hardware along with JDM gear set is probably the most noticeable and practical improvement we've made to an already great car. If you want to retain the stock Honda reliability and trackability while keeping your car streetable, this drivetrain upgrade is probably the best investment you can make.