Gear ratios?

[Maelfyn]

I don't understand how to read gear ratios. Help :) What does 3.73 gears mean or whatever? I see it in video games too where it has a ratio for each gear. I don't get it :rolleyes:

[Deaks2]

its a ratio dummy :p

ex: 3.73:1 = 3.73 revs for each 1 rev of the other side...

real world: engine @ 4000 rpm, in 1st gear (lets say 6:1)

therefore the input shaft will be spinning @ 4000 rpm and the output shaft @ 24000 rpm...

multiply!!!

[Maelfyn]

hee hee hee you said input shaft :eek:

[Deaks2]

Umm wait a sec, I reversed them...
int shaft spins @ 6000 rpm, output shaft spins @ 1000 rpm...

hehe, i'm such a goof.

of course the above is example is only with a 1:6 ratio...

[bickley]

Okay I'm just a newbish user so flame on if you must....but would there be any way to get a different set of gears made? I want something to help me stay in Lift on the 1-2 shift.

[Maelfyn]

I don't see why not. You could get tighter gearing and sacrifice top speed.

[bickley]

Well with enuff money anything is possible, the question is who can I get to do this for me?

[DannyBoy]

Originally posted by bickley
Okay I'm just a newbish user so flame on if you must....but would there be any way to get a different set of gears made? I want something to help me stay in Lift on the 1-2 shift.

I heard that the gearbox in the '02 celicas does this. I've also heard that the '02 ECUs have a fuel cutoff of 7800 RPM instead of 8300. I can't confirm any of these, so you should double check before trying to do swaps of any kind...

Also, don't forget the final gear ratio in any calculations you do... I think its close to 3.5:1 for the celica (does anyone know it exactly?). So the output shaft spinning at 1000 RPM works out to the tires spinning at just under 300 RPM.

dan

[Raw Iron 1]

Hello.

I don't know about sticks but there is a company out west that does gear changes for front drive GM transaxle automatics. If there is not someone doing it now I am sure there will be. The company's name I believe is Hydromatic Specialties or Hydromatic Specialists. Anyway, their latest project was changing the "final drive" ratio in a late model Bonneville SSEi for the top speed competition on the Bonneville Salt Flats. They had to raise the gears from 2.93 to 2.73 in order to break the 200mph top speed barrier. They topped out at 201mph. Not bad for a 50 state legal 4-door full size sedan.

Things to remember about gears...

Lower gears mean you go faster at low speeds and eat more gas.

Higher gears mean that you go faster at high speeds and use less gas.

Higher gears have lower numbers and lower gears have higher numbers. Example: 4.00 to 1 or lower gears (higher numerically) are considered "racing gears". 3.00 to 1 or higher (lower numnerically) are considered "highway gears" or "fuel economy gears". Anything in between 3.00 to 1 and 4.00 to 1 are considered "performance highway gears" or "performance gears" These give you a combination of fuel economy and performance. Confused yet?

More examples: 2.56 to 1, 2.73 to 1, and 2.89 to 1 would be examples of highway/fuel economy gears. 3.08 to 1, 3.36 to 1, and 3.94 to 1 would be performance gears. 4.10 to 1, 4.56 to 1 (some Celicas have this gearing), 5.56 to 1 would be racing gears.

If you go too far to the extreme for your application it can hurt what ever performance you are looking for. If you go too high in search of fuel economy it can actually kill you accelleration. Too high a gears on a very non-aerodynamic car can kill your top speed instead of actually increasing it. Too low a gearing can actually hurt your 1/4 instead of increasing it. A guy in one of the car clubs I am in went from highway gears to racing gears and shaved about 1.5 seconds off his 1/4 mile. However, he was advised to go a little back twards the highway end because he had overgeared or geared his car too low. When he made the change he shaved about another 1/2 a second off his 1/4 mile. His problem was than with the super low gears he was almost at his redline when he crossed the finish line in 3rd gear in a 3-speed manual car. The slightly higher gears put him back down to where he was making max horsepower when he crossed the finish line.

Too good of a thing can actually be bad.

Jason

[bickley]

Thanks for the info Raw Iron:) I just wanna change the gears just alittle bit so we can stay in lift thru the 1-2 shift :tongue: Anyone know what that ratio should be? We need taller gears right? So the question is how tall :confused:

[Slant]

I think it would be easier to just learn to stay in lift(which many people have no problem with) or just change the final ratio.

[t2000gts]

does that company only make final drive gears (ring and pinion) or can they fabricate custom gearsets (i dunno how you'd do this in an auto...an entirely new planetary gearset just swapped in?)?

[2nsane]

You could also see if there is another tranny with better ratios for what you want that is compatible to the celicas engine, Don't know if there is one but it would be worth looking into.

[erok]

This was discussed a long time ago. I couldn't find the thread though. How long do threads stay in the database befor they're deleted? Fortunately, I happened to save the thread as a text file which I could post if anyone is really interested.

You could make 2nd shorter to help with the 1-2 shift, but then you'd have the same problem with the 2-3 shift and so on unless you changed all the gears.

Rather than do this, you could make 1st gear taller than stock. The ratio we came up with back then was 2.84:1 which would go up to like 45 mph. When you'd shift the car would be moving fast enough to stay in lift in 2nd gear. It'd probably be harder on the clutch in daily driving, but might improve things once you got rolling. The stock 1st gear ratio is 3.17:1.

[Kit99bar]

I think lowering 2 3 4 and 5 would be better than raising 1st :)

[M SPEC]

I'm a newbie at gear ratio's as well but check out this graph from C-One company from Japan.

http://www.c-one.co.jp/images/cross_graph.jpg


Comparsion chart of gear ratio's for the 6 speed from the 2ZZ-GE engined Celica.

1st. 2nd. 3rd. 4th. 5th. 6th.
Stock 3.166 2.05 1.481 1.166 0.916 0.725
C-ONE 2.929 2.176 1.70 1.364 1.167 0.916

Jason

[GTS LAID]

looks like with their 2nd gear set you'd be able to hit 62mph in second without any problems.

[erok]

Interesting how they went with a taller 1st and shorter 2nd gear. I think that would be a fun car to drive.

6th gear with the C-ONE is the same as stock 5th gear. I could live with the changes in the first four gears, but taller 5th & 6th is key for commuting on the highway.

[NSX_GTR_LM]

Is it just me, or do I see some ENGRISH?!?!?!?! :) thats funny stuff. Intead of 2nd 3rd 4th 5th and 6th, it has 1st 2st 3st 4st 5st and 6st. check out engrish.com for some better engrish than that.

[Auto[BoT]_GTS]

In my 02 its definitey harder to stay in lift....cuz my 00 I had little /no problem staying in lift.

[Tikked Again]

What's the ratio on first gear on the GT.....I test drove both the GT and GTS and I believe the GT 's have a taller first gear which might be a good replacement if you want to stay in lift. Of course you'd be more likely to bog if you try to take off hard, but you can always get some kind of LSD to fix that.....just rev and dump eh...yeah right