9 Tooth driver vs. 12 tooth driver for short track?

Actually, if the gear ratio is the same, there is no mechanical advantage whether you have a 10 tooth or 15 tooth on the engine. 10/40, and 15/60 are both 4.0 – 1 ratio. Where's the mechanical advantage?

Wikipedia has a good explanation of what the term "mechanical advantage" means.

Now the argument has been made that bigger drivers and sprockets are better (sometimes), but that argument has been going on for years with no settlement insight. lolIn
The argument over the years is that a ratio is a ratio.
There was a rule in place for years that limited the stocker guys on how low a rear gear we could use, that has changed.
 

"J'-remy

Member
Actually, if the gear ratio is the same, there is no mechanical advantage whether you have a 10 tooth or 15 tooth on the engine. 10/40, and 15/60 are both 4.0 – 1 ratio. Where's the mechanical advantage?

Wikipedia has a good explanation of what the term "mechanical advantage" means.

Now the argument has been made that bigger drivers and sprockets are better (sometimes), but that argument has been going on for years with no settlement insight. lolIn
Nope there is less tension on the chain if you were to imagine every tooth as a lever the longer the lever (distance from the center of rotation) force X distance= torque hence the better the mechanical advantage. the chain also bends less to get around a larger driver = less friction
these are laws of physics not hypothesis
 

sundog

Member
Well the longer from center, the less mechanical advantage you have but, what ever it is, it is equal and opposite in the rear gear for the same ratio.
 

alvin l nunley

Premium User
Nope there is less tension on the chain if you were to imagine every tooth as a lever the longer the lever (distance from the center of rotation) force X distance= torque hence the better the mechanical advantage. the chain also bends less to get around a larger driver = less friction
these are laws of physics not hypothesis
The difference between your understanding and my understanding of the term "mechanical advantage" is different. I believe you're talking about efficiency.

I believe you can calculate mechanical advantage, but you have to test for efficiency. Efficiency would probably change with speed" and the load, but the mechanical advantage would never change.
 
You guys saying run the biggest driver you can have absolutely no idea what you are talking about or don’t read the racers post at all..... long straights, hair pin turns..... you go ahead and try and run that bigger driver I will run the smaller 11t with a 56ish rear gear and beat you off the corner and get to the 4800-5000 rpm range quicker while you burn up your clutch not being able to pull that bigger front driver.
What Earl is saying is correct. It’s all about the rotating mass when you are able to get low enough on the front and the rear gears...... why do you think most of the bigger top dogs now run it? There is a reason also why the keep running it. I’d like for you to show up to a race of top caliber and try your physics ratio out...
 

"J'-remy

Member
I will put this in easy terms because you people can't get your heads out of the sand and are too interested stating YOUR OPINION that understanding strait up facts is beyond you if you have NO power steering in your car you want a big steering wheel because its a mechanical advantage same as using a wrench with a longer handle to take off a stubborn nut, a larger diameter driver is the same as the bigger steering wheel, longer handle wrench. this is day one of physics class. please keep telling me i'm wrong its funny to me

and yes i did read the post he wanted to know 9 vs 12 and i told them the best option and why don't worry if you can't comprehend
 

racing promotor

Moderator
You can debate driver size till the cows come home, for the average karter you cannot go wrong keeping the rear gear between a 56 and 62 for clones and predator, what separates to hot shoes is TIRES .
 

jaymancds

Premium User
The governor is at 5500.
They fall off around 5100,5200
You want to run them 4800-4900 rpm
Preditors are momentum engines.
Do you have a tach? Whats your average RPM drop?
Your turning it to much now, leave the 12 on and lower the rear to a 64 try it if it's better than lower rear even more 62.
box stock looses power @4600 . 4900 is too far out of range
Must be on treads if it's 38/41 . I would do as Racing Promoter said , 12 driver and target rear gear to get 4900 or so . I might even try an 11 driver and target the 4900 rpm's
"Losing power 4600 RPM and." But that doesn't mean there's not enough horsepower above 4600 RPM to keep accelerating. The acceleration rate may be a little slower, depending on the horsepower, but it can keep accelerating after peak HP, just at a slower rate.

For instance, a KT100 reaches peak HP at about 11,400 RPM, but they can't easily turn 15,000 and be accelerating all the way.
You guys must not understand how well these things run with the 10.8 springs and jetting to match. This magic "48-4900" is absolute BS. He told you it isn't stock. With the 10.8 springs and jetting to match, at 4800 you aren't event close to where you make power. It might be there for stock, but the springs and jets change that significantly.

I have the same setup that the OP does. I target mine to be 54-5500 topping out, and I have twisted it up to right at 5700. This idea that he is over turning this thing is nonsense. It would be great if you guys would realize this. Not everyone running predator is running them out of the box. If you show up to my local track turning 4900, I will blow your doors off all day long.
 

OVALTECH1

Premium User
You guys must not understand how well these things run with the 10.8 springs and jetting to match. This magic "48-4900" is absolute BS. He told you it isn't stock. With the 10.8 springs and jetting to match, at 4800 you aren't event close to where you make power. It might be there for stock, but the springs and jets change that significantly.

I have the same setup that the OP does. I target mine to be 54-5500 topping out, and I have twisted it up to right at 5700. This idea that he is over turning this thing is nonsense. It would be great if you guys would realize this. Not everyone running predator is running them out of the box. If you show up to my local track turning 4900, I will blow your doors off all day long.
I see it every other Sunday... that’s why I bowed out. I watched people get 1/2 tracked and a few lapped in predator... just this weekend
 

jaymancds

Premium User
I see it every other Sunday... that’s why I bowed out. I watched people get 1/2 tracked and a few lapped in predator... just this weekend
Are you saying they shouldn't be lapped? We were also lapping people this week. Getting caught with a lapper actually cost me 3rd yesterday.
 

OVALTECH1

Premium User
no.... I’m saying with a gutted muffler(which you can hear plain as day) the spring change and blueprinted carb it’s 800 more usable rpm that is really noticeable on track. I see it a lot. You can hear the rpm difference as well.
 

OVALTECH1

Premium User
I personally am box stock and wish they would of kept it that way governor and all. It’s 3 rocket ships and 12 in the way now by lap 6 of a feature 😂
 
I will put this in easy terms because you people can't get your heads out of the sand and are too interested stating YOUR OPINION that understanding strait up facts is beyond you if you have NO power steering in your car you want a big steering wheel because its a mechanical advantage same as using a wrench with a longer handle to take off a stubborn nut, a larger diameter driver is the same as the bigger steering wheel, longer handle wrench. this is day one of physics class. please keep telling me i'm wrong its funny to me

and yes i did read the post he wanted to know 9 vs 12 and i told them the best option and why don't worry if you can't comprehend
Yeah YOUR best option.......I comprehend very well actually. Go tell all the top motor builders in the country whose drivers and motors are up front every weekend your “theory”

One reason I stay off bobs anymore due to the fact that someone thinks their opinion is an actual fact without ever trying another’s “opinion”......
 

shiftyag

Member
J'-remy said:
I will put this in easy terms because you people can't get your heads out of the sand and are too interested stating YOUR OPINION that understanding strait up facts is beyond you if you have NO power steering in your car you want a big steering wheel because its a mechanical advantage same as using a wrench with a longer handle to take off a stubborn nut, a larger diameter driver is the same as the bigger steering wheel, longer handle wrench. this is day one of physics class. please keep telling me i'm wrong its funny to me

and yes i did read the post he wanted to know 9 vs 12 and i told them the best option and why don't worry if you can't comprehend.

The Steering Wheel would be the Flywheel and Pitman Arm would be the driver 9 -12 ......think about it............... does a longer pitman arm make it easier to steer?
 

jaymancds

Premium User
I personally am box stock and wish they would of kept it that way governor and all. It’s 3 rocket ships and 12 in the way now by lap 6 of a feature 😂
You're right. There is definitely 4 or 5 of us with the engines to the limit of the rules, and then there are the guys who we lap every race.
 

"J'-remy

Member
LOL what he does wins so he's right so your provable scientific facts are wrong!. guitar players and kart racers the most gullible people on the planet
 

GClary

Member
Still wondering about those tire sizes 38/41 ( L38 / R41 = 3 inches stagger ? Got to be treads )and hairpin corners ? Stocker springs are better than 10.8's from what an engine builder tells me , and not sure what jet or jets were changed to . Could he be on a backyard mud bog or a nice prepped track that you other guys race on that lap everyone under the sun . Who knows , but my money is on torq and not HP .
 
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