Gearing Mechanics: Torque/HP & Gear Ratio Explained

[aliaze1]

anybody know the mechanics of gearing, like on a bicycle, motorcycle, or car?

what is the relationship between gear ratio and torque/hp? i mean we all know that starting the car in higher gears isn't as easy as first, same goes for a bicycle...anybody know the details?

 

[rcgldr]

Gearing multiplies the torque and divides the rate of rotation. If the gearing is a 3 to 1 reduction, then the torque applied at the pedals (bicycle) or from the engine (vehicle) is multiplied by 3, and the rate of rotation is divided by 3 (the driven wheel(s) turns at 1/3rd the rate).

As mentioned torque is multipled, but power remains the same, because the increase in torque is offset by the decrease in rate of rotation.

 

[aliaze1]

hmmm

a fellow classmate told me about a car his friend had (this guy is in his 40s btw, which will make sense as u read further)...he told me his friend had a Pontiac GTO, with a 400ci+ engine (he doesn't remember exactly, but it was huge), and a special transmission that had the following result:

Engine: V8, more than 400ci, he said mayb 440 or something, but not sure 100%

Trans type: 4 speed manual

Speeds @ gears (redline)

1st - 65mph
2nd - 95mph
3rd - 120mph
4th - he got to 140, but decided not to go further, but said that the pedel had a lot of room left

so basically we can do crazy stuff like this?!? i mean would that be a custom trans? i mean that isn't stock, but u guys think its custom built or an trans swap from something crazier/aftermarket trans?

 

[Danger]

That sounds reasonable to me. The shift points for my Roadrunner are 65, 85, & 115. That's shifting at 6,500rpm, which is 1,000 higher than the factory redline.
I'm not a GM guy, and I'm not going to bother looking anything up, but the 2 main large engines for that car were the 396 tri-power and the 455. He must have had the latter. The gearbox was probably a Muncie M-22 'rock crusher' feeding a Posi-Trac 10-bolt with about 3:1 gears.
'How Stuff Works' has a section on musclecars that can probably help, as well as checking different GTO owners groups.

 

[aliaze1]

allright thanks, yea i was just wonderin how reasonable it was u kno

damn roadrunner...niiiice

looks like u kno your parts haha, i thought this was custom...

so your roadrunner is a 3spd manual? or a 3spd auto with a shift kit?

 

[Danger]

No. Full race 440 (.030 overbored to 446), A833 4-speed with a long-throw Hurst shifter (4th gear is 0.73:1 overdrive), with a 3.23 geared Dana 60 rear. About 650hp.

 

[aliaze1]

damn...im going to need some time to absorb that lol jk

that is one sick ride...how much it cost? like drivetrain and chassis, not the accessories lol

 

[Danger]

I bought her in '75 for $2,500. New, it listed at $8,500. (For comparison, a fully-loaded 'Vette went for $8,000.)
The engine rebuild was $1,500. As it sits right now, rotting away in my back yard, it'll cost somewhere between $30-50,000 to get it going again.

 

[aliaze1]

oh man that sucks..so she don't even run? turn over?!?? lol that sucks...

yea haha i want a muscle car...i was originally going to swap something into a 80s camaro, but its unibody so idk if it can take it u kno

so what's the 0-60 time on yours? 6sec?

 

[Danger]

It ran when I parked it, but that was over 20 years ago. The engine will have to be stripped down and cleaned. Most of the expense will be body work and upholstery; there's not much left of either.
0-60 varied with the surface conditions. On a good dry road, from the time it stopped spinning and started moving, about 3.5 seconds. I usually had to let it spin for at least a second or so first in order to get a decent launch. Quarter mile was 12 seconds @ 115mph, but it got headers after the last time that I tried that. It seriously needs a different cam, though, which should pull it down to 10 or 11 seconds.
As mentioned in another thread, I've designed an entirely new motor for it (which I'll never be able to afford) that would put out a good 2,000 hp.
As for a camaro, the first thing that you should always do with overpowering any car like that (including mine) is to weld connecting tubes between the front and rear sub-frames.

 

[edmondng]

if you are running 1000rpm, and you gear it down 10:1 so that it runs 100rpm on other side, the torque will increase 10 times.

1000rpm with 100oz-in = 100rpm with 1000oz-in with a 100% 10:1 gear down transfer

Horsepower = Torque x Speed

Hope this helps

 

[aliaze1]

lol

why would u leave it like that? i assume u are married..but still lol...why just let it rot away? i mean u could put it n your garage and run it once a month...

damn 3.5? that's crazy...

yea i doubt i can afford such stuff, maybe i'll just get a camaro with a 350 and fine tune it, maybe add the corvette intake, that should add some punch to it...

so if i get an old muscle car, and assuming the body is in good shape, i could just drop a new drivetrain in with a crazy trans like that and it should run decent? (yea I'm over simplyfying it haha)

btw u could make some good $$$ on ebay...

 

[studda]

the 2 main large engines for that car were the 396 tri-power and the 455

Sorry, buy I'm a big Pontiac guy and couldn't help but chime in. There was a 389 tri-power(396 is chevy). A 440 is possible with a Pontiac 428 block bored .060 over. They are actually very strong motors. They don't tend to throw the rods as easily as a 455 because of its shorter stroke and they have the same bore as a 455 so you can actually put just as big of a cam without the low end hesitation. I do think that could be possible without too much modification, considering Pontiac cast iron rods are only rated for 5500 rpm(I've taken mine to 6000+ no rod failure yet).

 

[Danger]

Yeah... I caught that 396 error myself, but didn't get around to fixing it. A guy I know has a 389 Goat and a 396 Chevelle. I got the two mixed up.

 

[aliaze1]

?

That sounds reasonable to me. The shift points for my Roadrunner are 65, 85, & 115. That's shifting at 6,500rpm, which is 1,000 higher than the factory redline.
I'm not a GM guy, and I'm not going to bother looking anything up, but the 2 main large engines for that car were the 396 tri-power and the 455. He must have had the latter. The gearbox was probably a Muncie M-22 'rock crusher' feeding a Posi-Trac 10-bolt with about 3:1 gears.
'How Stuff Works' has a section on musclecars that can probably help, as well as checking different GTO owners groups.

btw, what transmission does your roadrunner have? and what engine?

 

[Danger]

That's covered in post #6. Sorry I didn't respond to the question about why I left it as is, but it's too complicated to get into just now.

 

[aliaze1]

o ok...no prob...i was just curious...

 

[aliaze1]

No. Full race 440 (.030 overbored to 446), A833 4-speed with a long-throw Hurst shifter (4th gear is 0.73:1 overdrive), with a 3.23 geared Dana 60 rear. About 650hp.

yea i was just wondering if u had an estimate about the torque output

0.73:1...thats crazy, i thought that M-22 was crazy as it is but damn...

 

[aliaze1]

yea i was just wondering if u had an estimate about the torque output

0.73:1...thats crazy, i thought that M-22 was crazy as it is but damn...

actually, wouldn't you want a short throw shifter?

 

[Danger]

A short-throw is probably a bit more practical for most people, since it goes from one gear to the next with less movement. I find it preferable to have something that's easy to reach without disrupting my posture. Anyhow, my shifting is faster than my leg and the clutch can react, so I'm not losing time that way. It takes me about 50 milliseconds to change gears, and a lot longer than that to get the pedal down and back up.
Besides which, the long pistol-grip Hurst is rarer than the short one, so it adds to the value of the car.
I can't give you a torque figure. Despite it being a big-block, though, I don't think of it as a 'torquey' motor. It doesn't really start making power until over 4,000 rpm. Torque is probably maxed out at about 5,000 while hp is better around 5,500-6,000. If I had to estimate, probably around 500 ft/lbs max.

 

[aliaze1]

ah ic

yea i looked @ a similar one on ebay, actually it isn't as long as i was thinking, and yea it has a pistol grip as opposed to the ball grip, nice haha

lol when u said long throw i was thinking like from a pickup truck

and yea, 500lf-ft is a lot haha

btw i was checkin out those gear ratios of that M-22, no wonder it was so fast, the ratio is like 2.2 :1 on first gear...a toyota matrix (i figure that's your average type of car) has a ratio of 4.xx:1...not to mention the M22 is direct in 4th...but yea...the one u got is crazy...0.73:1 DAMN

 

[Danger]

I think that we have a really serious generation gap here.
Back in the day, my car was something of a joke on the street scene. The rule pretty much was, 'if you have less than 1,000 hp, don't bother showing up'.
If Hypatia shows up in this thread, she can probably tune you in a lot better than I can. That woman knows racing.

 

[aliaze1]

lol well its not all horsepower...bec some cars got tons of power but they are heavy ... i mean a big block is a lot of weight

have u seen the edmunds comparissons between the new GTO and a subaru WRX STi?

subaru wrx STi

300hp flat-4, turbocharged
~300ft-lb torque
6spd manual
AWD

GTO
400hp (at least) 6.0L LS2 V8
6 speed manual
RWD
but weighs a lot more..

conclusion:

GTO is faster on a drag strip
STi is faster in the slalom

http://www.edmunds.com/insideline/do/Drives/Comparos/articleId=105773

haha yea...sometimes i wish they still had cars like the ones in your day haha...

 

[Danger]

Yes... well, the two are not comparable because of being designed for different purposes. By the same token, I'd beat the living snot out of a Porsche up to 160 mph on a straight road; if there were turns involved, I wouldn't have a chance. It's like comparing a top-fuel dragster to a NASCAR racer, or an F-16 to a Pitts Special.
I got to log out now; my shift is over. I'll get back on when I get home.