What Differential / Final Drive ratios are available?
 

Hi all,

Does anyone know what diff or final drive ratio's are available for the RX-8?

Many thanks.

.ps Did a search and didn't have much luck.

mazdausa.com look for specs there.

What about Aftermarket?

FEED makes an aftermarket set of the final drive. I want to get it, but I'm afraid of how high my rpm will be when cruising on the freeway.

I believe it is a 4.77 ratio.

Some FEED stuff here: http://www.pac-gate.co.jp/feed/rx8.html

68,250 yen = 631.13 USD

Not too pricey, I suppose.

I can't even figure out how to navigate those type of sites. Maybe I need some type of plug in.

I would be interested if something would affect the ratios from 1st thru 4th, but the 6th gear on this car is already too short. I am at around 4000 rpm already when I am cruising on the freeway in 6th.

It's really not that short when you consider it has a 9k rpm redline. I am sure it's capable of cruising at 4500 with no problem. And to reply to any responses regarding fuel mileage, I hate to say it but if you're looking for gas mileage, you bought the wrong car. You could always buy a cheap hatch and drive to and from work if fuel economy is an issue.

I don't feel that way. Why would I want a car that is using up half it's revs at cruising speed ? I would rather have a longer 6th gear. My previous car was at about 1/3 of it's revs at 70-75 mph. You can say something about not caring about fuel economy, but it is part of this car. There are times when I like the handling & acceleration, but there are other times when I want it as an everyday driver & hence a usuable 6th gear. This is not a Lotus Elise we are talking about. It is a practical car, just with a marginal 5th & 6th gear. No reason for it. We are not using those gears (especially 6th) to accelerate.

maybe you aren't . . . . .

Even with the turbo & going 100 mph I wouldn't be using 6th to accelerate, just drop it down a gear or two is how most RX8 drivers accelerate. 6th gear is a fuel saving/cruising gear, as such it should be longer. I would rather have a taller 6th gear & be able to save 1 or 2 mpg & shift down a gear or two for much better acceleration vs. having shorter gearing overall.

Mazda Motorsports offers a 5.12:1 ratio, you don't want to know how much it costs, if you have to ask you can't afford it

Excellent, can you get a hold of these? rough idea on price?? (have to work to some sort of budget! :) ) thanks.

$3600 just for the ring & pinion

Hmmmm.....no response from 4rotor. Think he had a heart attack?

i well instal next wheek the FEED final gear, you must change sam oil seal and other parts for the instal, consult with your woorkshoop
i well post to scoment the change.

I will be very interested in hearing your impressions after the install as I have been very seriously considering the Feed final gear. Will be interesting to hear your impression on what the difference feels like going from 4.4 to 4.7.

Contrarian
 

I would be interested in a numerically lower (taller) rear axle ratio. It would yield better highway gas mileage and make the car more driveable by making 1st gear more useful.

...some of the best 1/4 mile times are done by revving the engine, dumping the clutch, getting wheelspin, and taking off in second gear. The logic of this is you lose more time shifting from 1st to 2nd than you get from the mechanical advantage of the 'stump puller' 1st gear.

the shorter 245/35-18 Kumho V710 tires we're using (24.8" OD) yield an effective 4.66 gear ratio relative to the taller OE 225/45-18 tire and 4.44 actual gear ratio

A 4.7 gear will help, but it's not going to be all that big of an improvement IMO. Highway RPMS will still be reasonable though

What I'd like to do is get a shorter rear with a taller 6th. More acceleration in the lower gears and better freeway cruising. Anyone know of a swap for 6th gear?

~ Matt

Need For Speed, have you installed the FEED final gear? Would be great if you can share with us on how it has improved the car's performance. Thanks.

i did not instal it, i well instal it on friday.
i did not install it befor , because we need to chage sam apex seal and other parts so we have to wait for it.

wen its install i well send pics and let you now the diference.

Mazdaspeed charges $3600 for a ring and pinion? That's insane.

it's probably a custom, low volume, high quality racing part

What about for turbo folks? I imagine with a turbo torque curve you would want to change out the differential to make the most of the new power with a taller gear ratio.

japanparts sell two Mazdaspeed LSDs: one 'mechanical 2 way' and one 'selective LSD, initial torque: 3grade adjustable' has anyone tried these?

Click here

From the FeedRX8 site it says the LSD they have is made from Kaaz. From what I read on the internet Kaaz and Cusco make the best differentials. Any comments on this?

So did you install it Need for Speed???

neither of those LSD's show up in the USA Motorsports parts listings

We have a 5.125 final drive+LSD diff @ 1500€.
:)

Yeah, if we could get @75 the RPM's under 3K that would be great...heck or at 3K.

Can someone explain to me (it can be via PM if they wish) what is final drive ratio? I thought the tranny had something to do with that but always suspected it was the rear axel that everyone was talking about. Maybe I'm talking crazy here but I just want to understand this.

Going higher means what (or going lower)? Can a tranny help save gas (I think it can) or does it have more to do with the final drive ratio?

While I like the tranny in my 8 I wish they sold something smoother...is that common in the car world for aftermarket companies to build replacement tranny's for performance, fuel economy, etc.

Sorry I know I'm all over the place but I'm trying to understand some of your advanced car talk...lol, thanks in advance!

bump bump bump

Was it installed???

Was it installed?

Does Mrs. ILIV48 knows about this? :p

Haha...

Hey do you reckon you have to recalibrate the speedo after this or you guys think it is ok. It did not say anywhere in all the books that you have to... I guess you don't :)

I guess the final gear is on my list of future mods, but I wonder how it is going to change the 4th gear that I passionately hate so much, especially on the track.

My understanding of the term final drive ratio:

You have two gear ratios working in series in your drivetrain. The transmission gear ratio of revolutions of the eccentric shaft coming out of the motor to revolutions of the drive shaft coming out of the back of the tranny. The second gear ratio is from the differential in the rear axle. It is the ratio of revolutions of the drive shaft to revolutions of the rear axle driving the rear wheels. Your final drive ratio is the comparision of revolutions of the e-shaft coming out of the motor to the revolutions of the rear axle driving the rear wheels when the car is in top gear.

Changing the rear differential gear ratio will effectively change the drive ratio of all your gears. This also will have an impact on the performance of your car since mazda selected this ratio for a balance between performance and fuel economy.

Correct, which is why a lot of us want the new final drive ratios, and at the same time, replace the 6th gear with a longer one. If I could have a perfect set up, and I'd have a new lightweight flywheel, stronger clutch, FEED final drive, and longer 6th gear. I'm sure that won't be cheap though :dunno:

FEED makes some

So say that someone crazy like me is interested in doing this...

which of those are avail in the market? (I know the lightweight flywheel and clutch are)

how much would it cost me?

where would I go to get it?

-jc

As far as I know, everything but the longer 6th gear is available. Flywheel/clutch will probably run you ~$800, and the final drive ratio I heard somewhere is about $600-700 (base price w/o importing fees). I'm not sure if a new 6th gear is available, but if you are really serious, you can do some homework and see if one from another car will fit. Don't forget to factor in how much all this will cost to install.

I don't know that much about cars... I just got started. I've done all of my mods in my sig, but those are nothing compared to say dropping the tranny and doing my flywheel, etc. (which I plan to do once I order it); anyhow, I don't know where to even being to find out how can I find taller 6th from another car that'll fit mine. Lol.. I don't even know what they look like! Is it possible to mix and match gears?? -- For instance, say I buy a shorter set, but I want to keep the stock 6th. Is that possible? (thx)

To be honest, I'm no expert at this either. I've picked up a few things over the last year, and thats about all I know. Would anyone with some knowledge about this stuff car to chime in???

when you say keep teh stock 6th? you mean in the tranny..i'd say no..it's only set up for 6 gears..not enough room to make it 7.

if you are looking for gear swaps...try miata gears out of there 6sp...i hear they are compatable ...although i can't remember where i heard that....but it'll give you a place to start looking at least ;)

haha sorry i can' tbe more helpful......i haven't really cheacked out any of this too indepth....and i only really do things to other rx-8's haha not ofther mazdas......and we only get toyota's at work :( oh well guess this weekend i'll look into everything. but by the tiem i figure it out rotarygod would've chimed in with the answer hahaha

Looks like they recently revised the price down from $3600 to $1285

Kaaz has a new LSD out called the "Solid", it is redesigned with a fully machined housing and 50% more disc plates, numerous setup options, best of all it's available for the RX-8

MAzda probally keeps 6th gear at its ratio because so many mags and reports that use speed tests test out acceleration speeds in 6th