Gear Ratios Options

[BonzaiCelica]

I was wondering what the purpose of the final drive gear ratio?

also what is this? http://auctions.nengun.com/item/k113042803

[BonzaiCelica]

I got the information from this link : http://www.rubydist.com/Family/Power.html

A second way to improve acceleration is to put a higher (numerically) ratio final drive in the vehicle. The torque available at the drive wheels is the engine torque multiplied by the transmission ratio multiplied by the final drive ratio.
Let's just use some hypothetical numbers to make the math easy. Let's say for an example that the engine has 200 lb-ft of torque all across the usable speed range (a gross oversimplification); let's have a final drive ratio of 3:1, a rolling radius of 1.25' (15" radius, 30" diameter tire); and let's say that the transmission ratios are 3:1 (1st), 2:1 (2nd), 1.5:1 (3rd), 1:1 (4th), and .75:1 (5th).
-So, the torque available at drive wheels in first gear is 200 (engine torque) x 3 (first gear ratio) x 3 (final drive ratio) = 1800 lb-ft. (The force at the point where the drive wheels contact the road is a total of 1800 lb-ft / 1.25 ft (rolling radius) = 1440 lb.) If we change the final drive ratio to 4:1, the first gear torque will be 200 x 3 (first gear ratio) x 4 (final drive ratio) = 2400 lb-ft.
This is a 33% increase in drive wheel torque, and it will result in dramatically improved acceleration. (It will also increase engine speed on the highway, resulting in lower fuel mileage, increased noise & engine wear, and a lowered top speed of the vehicle.) The final drive ratio has no effect on the horsepower of the vehicle, but it does affect the torque available to the drive wheels.

Stock S54 Gear Ratios:

1st : 3.285
2nd: 1.960
3rd: 1.322
4th: 1.028
5th: .820
Final Drive: 4.176

Using this equation, (engine torque) x (first gear ratio) x (final drive ratio) = # of pounds. Then # of pounds / rolling tire radius in feet = gives you # of wheel torque.

I am using my current 215/45R17 tire size = 2.06 ft in diameter.

Final Drive 4.176 (Stock S54) = 1012.21 pounds

Final Drive 4.562 (96-2000 Rav4 E250) = 1105.78 pounds

Final Drive 4.933 (96-2000 Rav4 E250F) = 1195.70 pounds

Increase in torque from 4.176 - 4.529 is 9.24%.
Increase in torque from 4.562 - 4.933 is 8.92%
Increase in torque from 4.176 - 4.933 is 18.14%

Which means a 4.933 final drive in your s54 transmission will gain 27 ft lb torque + 152 = 179 ft lb tq


This post has been edited by BonzaiCelica: Oct 16, 2017 - 5:32 AM

[sir_smeghed]

Does anyone know if the ring and pinion from the 4.933 Final Drive out of the E250F transmission has a suitable ring and pinion for the S54 box?

I would dearly love it if this is the case!

I came up with these calculations can anybody back this up?? I got the information from this link : http://www.rubydist.com/Family/Power.html

this is what I read from the link, and how I came up with the calculations:

A second way to improve acceleration is to put a higher (numerically) ratio final drive in the vehicle. The torque available at the drive wheels is the engine torque multiplied by the transmission ratio multiplied by the final drive ratio.
Let's just use some hypothetical numbers to make the math easy. Let's say for an example that the engine has 200 lb-ft of torque all across the usable speed range (a gross oversimplification); let's have a final drive ratio of 3:1, a rolling radius of 1.25' (15" radius, 30" diameter tire); and let's say that the transmission ratios are 3:1 (1st), 2:1 (2nd), 1.5:1 (3rd), 1:1 (4th), and .75:1 (5th).
-So, the torque available at drive wheels in first gear is 200 (engine torque) x 3 (first gear ratio) x 3 (final drive ratio) = 1800 lb-ft. (The force at the point where the drive wheels contact the road is a total of 1800 lb-ft / 1.25 ft (rolling radius) = 1440 lb.) If we change the final drive ratio to 4:1, the first gear torque will be 200 x 3 (first gear ratio) x 4 (final drive ratio) = 2400 lb-ft.
This is a 33% increase in drive wheel torque, and it will result in dramatically improved acceleration. (It will also increase engine speed on the highway, resulting in lower fuel mileage, increased noise & engine wear, and a lowered top speed of the vehicle.) The final drive ratio has no effect on the horsepower of the vehicle, but it does affect the torque available to the drive wheels.

My Mathematics skills says:

Stock S54 Gear Ratios:

1st : 3.285
2nd: 1.960
3rd: 1.322
4th: 1.028
5th: .820
Final Drive: 4.176

Using this equation, (engine torque) x (first gear ratio) x (final drive ratio) = # of pounds. Then # of pounds / rolling tire radius in feet = gives you # of wheel torque.

I am using my current 215/45R17 tire size = 2.06 ft in diameter. So here is the difference in torque.

Final Drive 4.176 (Stock S54) = 1012.21 pounds

Final Drive 4.562 (96-2000 Rav4 E250) = 1105.78 pounds

Final Drive 4.933 (96-2000 Rav4 E250F) = 1195.70 pounds

Increase in torque from 4.176 - 4.529 is 9.24%.
Increase in torque from 4.562 - 4.933 is 8.92%
Increase in torque from 4.176 - 4.933 is 18.14%

Which means a 4.933 final drive in your s54 transmission will gain 27 ft lb torque + 152 = 179 ft lb tq

http://www.youtube.com/watch?v=rTLPZ1bVgHs

the beams sounds even better revving up past 8000rpm, its pretty interesting but in japan they raced the ss3 celica's in n1 endurance racing and you cant modify the engine for that, they used a 8400rpm rev limit, the heads will produce peak power at 8600 rpm with no modifications, but due to piston speed at that point its better to keep it to 8000rpm, its an engine with great potential, as soon as you fit an aftermarket ecu to them they come alive. If i'd kept mine any longer i'd have matched the increased rev limit to an e56 gearbox with 4.9 final drive which would have given the same top speed in each gear as the stock car, but nearly 20% more torque at the wheels, eat your heart out v6 owners muahahahaha

see even EDOPHUS thought the same thing i did 2 years before i even posted this.

This post has been edited by sir_smeghed: Jun 9, 2017 - 6:30 AM

[sir_smeghed]

PLEASE! Someone.....

I have an SW20 with an F20C engine (honda S2000) so it's got a 9000 rpm redline with Vtec kicking in at 6000 rpm. For this power to be usable on the track I will need something closer to a 4.9 final gear, I want to keep the S54 box as it is lighter, handles the power well and has nice gearing and I can't really afford to re-engineer the entire setup.

Does the ring gear from the E250F (4.933) transfer directly into the S54????



This post has been edited by sir_smeghed: Jun 9, 2017 - 6:44 AM

[slavie]

PLEASE! Someone.....

I have an SW20 with an F20C engine (honda S2000) so it's got a 9000 rpm redline with Vtec kicking in at 6000 rpm. For this power to be usable on the track I will need something closer to a 4.9 final gear, I want to keep the S54 box as it is lighter, handles the power well and has nice gearing and I can't really afford to re-engineer the entire setup.

Does the ring gear from the E250F (4.933) transfer directly into the S54????

You can't replace just the ring, you have to replace the pinion as well. The pinion is part of the output shaft, and replacing it involves pressing off and back on all the gears on the output shaft. In other words, you're pretty much rebuilding the gearbox. Or, maybe you can, but then you need to measure the gear backlash to make sure it'll work - I don't have the answer here.
Decent info here, but looks like Bonzai has already read that:
http://www.mr2.com/forums/threads/7966-In-...s-transmissions

With that said, it is highly unlikely that the ring and pinion from E box will go onto an S box. E-series differential is much beefier.
If I were you, I'd research into the newer C series boxes - at least C boxes had the same exact differential as S boxes. Ring will fit, but the output shaft is a big unknown.

I actually have a space S54 output shaft with all the gears already removed. If anybody has C-series shaft and want to exchange the measurements, I'm down for that.
Hope this helps.

This post has been edited by slavie: Jun 9, 2017 - 10:15 AM

[sir_smeghed]

That helps a lot, thanks.

Since I left my last post I found that Bonzai has put out a call for a group buy....

Getting a new C series box doesn't seem to be a very good option, a great idea but just soooooo expensive! I found one that had a damaged casing and was only good for parts and they still wanted $1300 for it.



Can't really afford to experiment at those prices.