Driving impressions for the NISMO 4.3 and 4.6 final drives

[nlzmo400r]

I searched and found nothing but how gears work etc. What im looking for is driving impressions from people who have driven with different than the stock 4.083 final drive the 240's come with. My ka will soon be boosted, and am curious if it is actually beneficial to purchase a shorter final drive (such as the 4.364 or the 4.636). Obviously it will be harder to build boost in the lower gears this way, however it still may be faster. The car is mostly autoX and occasional roadrace used. Anyone boosted driven on these gears? Opinions welcomed

- Rob

[g6civcx]

Shorter (numerically higher) final reduction drive gear decreases top speed in each gear, and increases cruising RPM.

You may lose some ability to build boost, and that depends on your turbo setup (it may actually help spool up huge turbos), but you'll be able to rev up so much more quickly so that more than makes up for it. Your optimal shift points will also change with the final drive gear.

You'll need a dyno plot to accurately evaluate what's the best gearing. I don't know if you're roadracing, but if you do you'll lose some top speed as well.

But in general gearing has to be selected to match the engine and the application. You can't just randomly slap on gears and expect it to work well with your car.

[s13coupedrfter]

I'm running the 4.63 on my sr20det powered s13 coupe and I love it!!! The car has a exedy stage2 clutch with an exedy lightweight flywheel. Boost is at 12psi. At cruz there is about 200-250 RPM increase in each gear from the 4.08. Before I changed it I logged down RPM, speed and gear info. For instance in 2nd gear at 25 mph I was at about 2500 RPM with stock(I'm doing this from memory so bare with me). Now just add 200-250 RPM on that and it will give you an idea with the 4.63. The shift between gears is improved too. When I used to hit up the local canyon I was always 2nd-3rd-2nd-3rd. With the 4.63 its 3rd-barely 4th-3rd-barely 4th on the same canyon. As far as drifting that canyon I feel the 4.08 would be better because the turns are really tight and 2nd on the 4.08 is geared better. The 4.63 is almost pushing me to clutch kick in 3rd but its to high for the same turns. Of course this is only 1 canyon/layout. Your decision is all about prefrence. If this gear sounds like a bit much go with the 4.3 but its for sure a kickass mod for anyone looking for more acceleration, but not for people trying to save gas!

[g6civcx]

Going from a 4.08 final to 4.63 gives you a 13% increase in reduction ratio. For any given speed, you would rev 13% higher in each gear as compared to the old ratio, and your top speed in each gear decreases by 13%. Not a huge deal, but if you still have your speed governor you will bump into it at a lower speed on the roadcourse (ECU reads speed at the gearbox and calculates road speed, it doesn't know if you changed final drive). Gas mileage on the freeway will also decrease a little bit as you'll be revving 13% higher.

200-250 RPM is not an accurate range because it's different for each gear and speed. For example, if you were revving 6,000 RPM on the old gear, you would now be revving 6,800 RPM on the new gear.

Plus I wouldn't use the stock tachometer. They're notoriously inaccurate, especially in the top quadrant of the rev range (probably worse as the car gets older). Better go with a good aftermarket unit if you need more precision and response.

[nlzmo400r]

well as I said the set up will be:

ka24de in s13 hatch (safcII for tach)
precision 3071R turbo, fmic, 3" piping etc etc @ 10lbs.

The vehicle will be autoX atleast once a month, and roadraced about 2 times every 6months or so. Im not really worried about top speed, but gas I guess will be considered (its my daily driver). With stock gearing, the turbo [I]should[I] hit 10lbs by 3000rpm or so. I shift around 6500 (according to the afc) and have done the 248/240 cam setup (gives more power up top w/out much sacrifice down low).

Thanks for the information, if anyone has anything else to add, feel free, more correct info= better

- Rob

[broken240sx]

installing 4.3 gear w/ s15 helical next weekend, ill let you know how it works out

s13 w/ sr

[Dousan_PG]

4.3 for way to long
best upgrade ever
4.6 equal gas hog. haha

[s13coupedrfter]

The 200-250 RPM increase was measured at low RPM. I measured each gear at about the same RPM (2000-3000RPM). g6civcx is right though, at 13% vs. stock the RPM will have a greater increase the higher you rev.

[qhatherly]

Has anyone had any experience with higher gearing than 4.6?

I'm using a supra rear end with my sr20det (w/gt30r) so my options are 4.56 or 4.88. I was hoping 4.88 might help keep the turbo spooled but i'm a little worried it's overkill. Anyone have any input?

[qhatherly]

(edit) sory, double post

[NIK90s13]

Has anyone had any experience with higher gearing than 4.6?

I'm using a supra rear end with my sr20det (w/gt30r) so my options are 4.56 or 4.88. I was hoping 4.88 might help keep the turbo spooled but i'm a little worried it's overkill. Anyone have any input?


Like every one said in reverse. You will gain boost, and have a higher topend at lower rpm's. Less ware on your motor at higher speeds.

[KrazyZenki]

where can u buy the nismo gears??? very interested

[Dousan_PG]

courtesy nissan, jspec can get them, for slae forums.

its not always 'nismo' gearing
4.3 came stock in some R32s
my R/P are both from R32s.. i have 2 4.3 drives.

[2_fast_240]

Does this 4.6 fd make the car accelerate any faster? if so how much faster

[nlzmo400r]

well see, one thing im worried about is having too short of a final drive. One of my close friends has been ka-t for a little over a year, and he runs a turbonetics t3t04e on about 9lbs. He doesnt even really spin much in 2nd gear (hankook rs2 235/40/17) from a dig. I would think that if the gears were shorter, it would be harder for the turbo to build boost in the lower gears, and may create more wheelspin (making the gearing useless). However with the low end and fat powerband of the KA, would it be wiser to use a taller than stock final drive (allowing the turbo to stay on full boil for longer?).