Interesting question, Ratio Effects?

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DadGum_Teen

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After learning a bit more about "hopping up" electric r/c cars, I've seen that two different Pinion and Spur gear combinations, with the exact same final drive ratio can actually have a major difference on the motor temperature and performance during runs.

Well, how does this all come into play in full scaled, gasoline cars? Let me explain my question...

If you had a car with a low rear end ratio but big tires, with an overall ratio of 1:1 (Tire rotates once for every rpm, [just to make it easy] :???:)

And you had another car with a tall rear end ratio, but little tires, with an overall ratio of 1:1 (And do they have a name for this? For the overall ratio after adding every factor?)

And can this same rule be applied to matching tall transmission gears to low rear gears, and vise-versa?

Both will cruise simultaneously, but what would the pros and cons be of each? There has to be some kind of performance difference dealing with rolling resistance or torque multiplication of some sort, but I just don't know enough about physics to put all the peices together. Has anyone ever read about or discussed this before?
 
I have been having this discussion with my self allot recently, if that counts. :)

Higher driveshaft rpm / lower = adjust final drive ratio in trans to rear end ratio to yield total vehicle speed or same vehicle speed / same engine rpm (assuming same tire diameter)
I have some theories about advantages and disadvantages.. I cannot see how the engine would care though. The mechanical resistance essentially is the same on the engine if the total mechanical leverage calculates out the same given a different approach to reach the same overall gear ratio. I say essentially because in my opinion an overdrive transmission may yield more more load because it is an additional process prior to tailshaft. My opinions..

After learning a bit more about "hopping up" electric r/c cars, I've seen that two different Pinion and Spur gear combinations, with the exact same final drive ratio can actually have a major difference on the motor temperature and performance during runs.

Well, how does this all come into play in full scaled, gasoline cars? Let me explain my question...

If you had a car with a low rear end ratio but big tires, with an overall ratio of 1:1 (Tire rotates once for every rpm, [just to make it easy] :???:)

And you had another car with a tall rear end ratio, but little tires, with an overall ratio of 1:1 (And do they have a name for this? For the overall ratio after adding every factor?)

And can this same rule be applied to matching tall transmission gears to low rear gears, and vise-versa?

Both will cruise simultaneously, but what would the pros and cons be of each? There has to be some kind of performance difference dealing with rolling resistance or torque multiplication of some sort, but I just don't know enough about physics to put all the peices together. Has anyone ever read about or discussed this before?
 
With electrics its heat and I'm guessing eventual increase of resistance thru the motor and loss of battery and overall power. In a car, it's use of fuel and response. The difference is an electric motor develops full power immediately. It's 1 or 5 or 30hp within several degrees of it starting to spin and it doesnt get more powerful unless more power is run thru it. A gasoline engine, because of the physics involved, does not have a linear power level. It's a curve. So for any given engine, there will be a perfect final drive ratio that gives the most economy and the most response. However, that perfect ratio... Will be different for every driver that uses the car... It's personal taste you're trying to match unless you remove variables like snappiness, economy, and power.
 
This calculator is decent. I have used 20 or so varieties of these calculators. It would be preferable to manually select (key in) each gear ratio of your transmission. I see in the right side you can edit the numbers to skew your results.

Here is also a good calculator that will generate you a spread.

http://www.atmotorsport.com/drive-calculator/

Neither of these give you feedback on engine / clutch system loading, transmission stress, drive shaft stress, rear end stress, axle stress, rolling resistance. Albeit those variables are impossible to quantify exactly, they can be assigned baseline numbers that could then be conversely reported based on changes to drive train variables. This would give more helpful feedback on the true mechanical effects of gearing changes.


here play around here.. it should answer your questions... http://www.bigblockdart.com/techpages/speedtire.shtml
 
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