We are looking into the possibility of running the car in other forms of competition, and would possibly consider changing the gearing to match whatever we do (Solo I, drifting, etc.). This is just in the talking stage, but I could have SWORN that I saw a site, somewhere, that already had a ring and pinion set for the RX-8 somewhere.

Does anyone remember (or know) ANYTHING about this???

I have looked everywhere I can remember, but no luck.

 

Are you referring to the Fujita Engineering final gear set? The link is here.

http://www.pac-gate.co.jp/feed/rx8.html

Scroll down, somewhere near the bottom of the page.

 

will the that shorten the final gear?

 

Yes, its a 4.7 final drive, compared to stock 4.44

 

That's what I remember - appreciate the help.

 

Has anyone seen info on taller gears? The 4.44's cause a real traction problem for me. I would like to swap to something like 3.9's or so.

Charles

 

I think the rx8 gears are too tall. Well since you're runnin n/o it would sense I guess. How can I get my hands on the final gear set?

 

btw correct me if i'm wrong but wouldn't shortening the final gear improves accleration but limit top speed? I think it would be a good idea, i don't drive 148 mph all day.

 

Yes, it will, but not enough. It's a (approx.) 15% increase (numerically), which in second gear translates to about a 500 rpm difference at the same speed.

Not sure if that's worth $600.

 

its actually 750 not including shipping :D

 

so basically you're saying its a waste of $$$. Hrm I guess we wouldn't know until we try one out.

 

go with smaller wheels and tires... It's cheaper :D

 

I wonder what sort of times will we see with the FEED shorter final gear set? Would it be like half a second faster to 60? Or are we looking at something insignificant like 0.1 to 0.2 seconds??

 

Well there's a video where the feed rx8 goes up against the autoexe 8 i think on the 200m and lost about a half of second. Not sure what the autoexe had but I know both of them got a good launch off the stage. I paid attention to the shifting the feed 8 definetly hit the higher rpms faster but still didn't manage to beat it. It was pulling around 10.4 on the 200 and the other was like 9.9.

 

um... Got a link to that video?

Regardless, I would LOVE to see that :D

 

I thought it was the other way around. But I guess it depends on how you define "shorter" or "taller" gears.

I know that back when I was building drag racers in the late '70s, we usually put in rear end gears that were higher numerically than the current ones. We often went from 3.XXs to 4.11s or so to improve 1/4 mile acceleration. Of course, this resulted in more wheelspin, but definitely improved times.

So I believe the higher the numerical value, the better the 0-whatever acceleration will be, but the lower your top speed.

 

My understanding is final gear ratio is expressed in terms of wheel revolutions to driveshaft revolutions. So a 1:4 gear turns the wheel once for every four driveshaft revolutions. Change that to 1:6 and for a given engine RPM it takes less work to turn the rear wheel but the rear wheel turns less. Think of a rope and pulley system as a good analogy. Adding an extra pulley reduces work (ie effort) by half but doubles the amount of rope you need to pull to lift the object the same distance.

I always thought a tall gear meant lower ratio which translates to a longer time/speed range spent in gear before hitting redline. Likewise a short gear means narrower speed range and requires quicker shifts. So if you're racing from a moving start you want a tall first gear (since you don't care about acceleration from a stop) but shorter gears for 2-6 so you can keep the revs in the powerband.
________
Cheap airsoft gamo

 

Yea that's what I meant. So wouldn't going from 4.44 to 4.7 improve 1/4 mile acceleration? But wouldn't this terminate the 6th gear intentions on being an overdrive?

 

if I was to get a shorter final gear how would I adjust the speedometer to match the actual rate of speed?

 

Would that really change? As long as the speedometer is running off actual wheel speed sensors, (rather than doing math with a transmission gear trigger or crank sensor) I don't think that would be a problem.

 

i thought the speedometer reads off the tranny?

 

I wonder about that, myself. When I did my flywheel swap I saw two connectors. One was for the reverse light circuit and the other might have been a speedo or gear position circuit. Since I have read that the maps are different depending on the gear selected, I assumed it was for the gear position.

Charles

 

since the maps are different, what adjustments should be made to accomadate the shorter gearing?

 

Some people have posted that the ignition timing changes not only with regard to rpm but also with regard to the gear selected and load placed on the engine. I would assume the load is detected via the vacuum signal. I cannot remember if it was specifically stated that the PCM monitors all of this and is responsible for the adjustments or if it was merely implied. I am sorry I cannot provide any more details other than that.

Charles