NX Highway Cruisin'...

[Greg Amy]

Back when I bought my brandy-new 1984 Rabbit GTi, I thought I was in heaven. For those of you who were still suckin' your mammy's teet back then, that car was a breath of fresh air in the stale environment of post-emissions and -safety automotive dregs. Bigger engine, more torque, close-ratio gearbox. Car only had one annoying downside: buzzy at highway speeds. But, back then they had an excuse: the NHMSL of 55 mph. After all, why optimize a car for 70 mph cruising when you can only do 55? Hell, they even had speedometers that ended at 85mph...

Cut to 10 years later, and Nissan offers a nice improvement on the theme, with the SR20-powered B13/B14s. But, similar problem: 3500 at 70 mph? Why?? Nissan can't even lay back on the old "55 mph excuse" as the NHMSL was repealed. Let's move forward another 15 years, and I'm playing with my NX2000, installing an even more-torquey and -flexible engine, so I *really* don't need to be pulling a noisy 3500 RPM at highway speeds.

So, what to do about it?

Well, I'm looking to take the same tactic as we did in the Rabbit GTi. Back then, the big trick was to replace the GTi's fifth gear (0.91) with one from either the convertible (0.76) or the diesel Rabbit (0.71). It was an easy in-the-car swap and brought the revs down to reasonable speeds while cruising. It didn't really hurt performance, because if you were racing or doing best accel (or drag racing) you'd never used fifth anyway. Yeah, the 4th-to-5th shift was a tad annoying, but that annoyance was quickly eclipsed by the fact you were turning <3000 RPM on the highway. And, you got used to it. Like, the second time you shifted.

So, what are my options with the RS5F32V? Are there parts in the "family" to let me do this?

The 5th gear in my NX is 0.756:1, giving me about 3500 RPM at 75 mph. Optimally, I'd like to find something that will drop the revs to 3000 or below, which would require a ratio around .65; nothing I can find in the RS5F32V family has that. Closest I found was the RS5F31A trans which had a .733 fifth, but that only drops the revs 100 or so, hardly worth the effort. In fact, the ONLY gear I found that was in the range was the sixth gear from the SpecV/Altima trans (RS6F51H) and it's 0.63 (~2900 RPM in fifth). I'm perfectly OK with that jump from 4th to 5th; again it's all about maintaining acceleration from 1-4 then dropping the revs for cruising. But will that gear fit? Are the shaft sizes the same, are the gear centers the same? Of course I have no clue.

Then again, if it DID fit, then I could even consider dropping in the Suny Lucino 4.437 final drive, IMPROVING acceleration in 1-4 *and* improving cruising RPMs on the highway (~3100)!

So....what's the chances ANYONE would have a clue on the physical specs for that sixth gearset (or even one they could send to me)? Are they even close enough where I could modify/broach the splines to make it work?

Alternatively, I suppose I could install the SE-R 6-speed in my NX, but that just seems like overkill. I'm guessing it's neither cheap nor easy...

Thoughts appreciated.

GA