Dan_s_young

iTrader: (1)

Well i have done searches and am thinking about getting 4.444 gears... Some people said that its possible to get them from a front diff of a toyota 4x4 is this true? Im wondering how much of a difference in the 0-60 time this would make, and if theres a way to fix the discrepincy in the speedo. I have been price checking different spots, someone mentioned in another thread that he saw 4.444 ring and pinon gears at mazdatrix for 285 bucks now it appears there over 500: http://www.mazdatrix.com/getprice.as...m=27-110A-M054 So im looking at racing beat again there 4.444 gear set is for $381 http://www.racingbeat.com/resultset....rtNumber=13005

So another question i have is does anyone have a before and after video showing the difference the gearing makes? Thanks

Boswoj

There are some interesting ring and pinion sets from the front of Kia Sportage's that are supposed to fit. 4.625's in the New Zealand model, and 4.778's in the US model. That's what I read elsewhere on the web, so verify that before making any "expensive" decisions.

Dan_s_young

iTrader: (1)

I think thats a little too much low end for me im looking at the 4.444 cause this is for a daily driver, i want the car to still go over 60 mph at less than 4000 rpm's I drive the car mostly in town and sometimes on the highway... I think anything over 4.444's might be too much for what im looking for (a want a good mix between quick yet drivable) thanks

Boswoj

Heck, depending on the wheel and tire combo some guys are running 5.12's on their racecars! There are some good rpm calculators on the internet that give you rev's at a specific speed with a known rear ggear and wheel tire diameter. I'll try to find you a link.

peejay

Dude.

Just drive around without using Fifth gear.

Note the difference in RPM between 4th and 5th. About halfway between is where 5th will be with the 4.44's.

Lots of RX-7s were sold with 4-speed transmissions. Their high gear was the same as a 5-speed using 4.78 gearing. The world managed to not end for people with 4-speeds.

Besides, it's a rotary, it likes to spin. I would get better MPG avoiding 5th below about 75-80mph than using it, when it was stock. My friend's '79 (which has a 4-speed) shows that this is not a fluke, he gets about 22mpg despite turning 3500 to go 60mpg.

- Pete ("OMG WTF my truck turns 1200rpm to go 70 how come my RX-7 doesn't ????//")

puntorotary

Actually the rear kia sportage gears are the ones you want,they have different gears for different years,from 98-02,call the junkyards and ask them .

Dan_s_young

iTrader: (1)

What makes you say these are the ones i want? Is this for best performance at the best price?

RotorMotorDriver

iTrader: (1)

Has anyone thought about direction of cut and hardening of the teeth on these gears from the front ends? In my experiance, gears cut to run in the front end dont like to be used in the rear end, and vice versa. I dunno though, I just play with 4x4s a lot too, lol

~T.J.

peejay

NO!

NEGATORY!

WRONG ON ALL COUNTS!

Firstly, you want the FRONT gears. The rear differential has the weirdball Mazda "7.5 inch" gearset. These gears WILL NOT work in your diff. The FRONT diff, on the other hand, has the correct gears.

ALL, repeat, ALL, US spec Sportages have 4.78 gears. (New Zealand had 4.675's)

Dan_s_young

iTrader: (1)

has anyone here had 4.444 gears and had 4.88 gears? Im wondering which would be better for a daily driver where i will be going 60 mph+ often.... Im just wondering if the 4.88 is to unpractical. Which one would you guys recommend for a street car?
Thanks

hornbm

blake quailey really seems to like the 4.88's and doesnt seem to mind them at all for what ever driving he does.

Personally I think 4.88's are a bit much on a daily driver, so Im choosing to go with 4.44's myself

31rx7

I would agree that 4.88 gears are way too much for street driving. I used to autocross my IT car with 4.88 gears, and would have to shift out of first within 100 feet of the start. Plus, constantly doing the 2nd - 3rd upshift / downshift was a drag while having to turn our slow manual steering. Driving one on the street would have to be painful.

SS124A

I use a 4.375 ratio in mine and it does really well.

2nd gear is long enough for most autoX courses, and short enough to help my stock 12A (gay class rules) accelerate the car reasonably

You need to figure out for your own how much time you spent with the car autoXing/on track vs. daily driving/ highway driving.

Dan_s_young

iTrader: (1)

how about fixing speedo discepency is there a way? I would like the speedo to be as close as possible, just seems kinda lame if your always trying to calculate how fast your going...

Dan_s_young

iTrader: (1)

bump for answer... Anyone?

peejay

Look on the solomiata website. (http://www.solomiata.com or http://members.aol.com/solomiata ) In the drivetrain section there is a list of different speedo gears for the "smoothcase" transmission.

Calculating what gear you need is easy. Divide your new gear ratio by your old one, then multiply the answer by the number of teeth on your old speedo gear.

For example, you're replacing 3.91's with 4.44's. 4.44 divided by 3.91 is 1.1355(etc), times 17 (IIRC that's stock 12A) is 19.3. Find out what application (if any) used a 19 tooth gear and you're done.

If you're *really* over-toilet-trained, or you're changing your tire diameter as well, there's another way. Take your tire's revs per mile (869.4 for a 185/70-13), multiply by rearend ratio (3.91 for stock 12A) for driveshaft revs/mile: 3398.6. At 60mph this is also your driveshaft revs per minute, and thus your engine RPM in 4th gear. (4.78's would be around this number in 5th gear, you wussy!)

Why do we care about RPM at 60? Because, almost universally, speedometers are calibrated so that 1000 cable RPM = 60mph. Our trannies have 5 tooth speedo drive gears and 17 tooth speedo driven gears. 3398.6 times five, divided by 17, equals... eeequals... 999.59!

So just for arbitrary numbers, we put some taller tires on that have only 825 revs per mile, and we put some fat nasty 4.78 gears back there. That's 3943 driveshaft RPM (under 4k at 60... in FOURTH gear!) and to figure the best gear, we multiply by the speedo drive gear's teeth (five) for 19717.5, divide by 1000 (rpm we want to break it down to) and we find we need a 19.7 tooth gear. Since we don't have the technology for fractional tooth sizes, we'd use a 20 tooth speedo gear. No muss no fuss!

Dan_s_young

iTrader: (1)

wow thats the most confusing explaination ive ever seen lol! Thanks

SS124A

you're *really* UNDER-toilet-trained,

Dan_s_young

iTrader: (1)

wow either im really dumb or i just suck at math... But seriously I didnt realize there was so much math involved and i also didn't realize that you could calculate everything out like that thanks. And for the under-toilet trained part, im still learning... You cant just be born knowing these things!

hornbm

thats some really helpfull information so from what I gather, if we decide to put 4.44 gears in the rear, the 87-91 convertable rx7s speedo gear witch is 19 teeth, will keep the spedometer accurate.

awesome!