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internal ratio vs. spur gear size

internal ratio vs. spur gear size

Old 05-03-2004, 06:40 PM
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Default internal ratio vs. spur gear size

ok someone help me out, is there a "perferred" spur gear size for different internal gear ratios? does it make a difference on shaft drive cars vs belt drive cars? stock motors vs. mods?
different brands of mods?
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Old 05-04-2004, 02:03 AM
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Not sure what you are asking about....

First: You need the proper gearing. There's no buttom line, it depends track layout, driving style and motor. The general rule of thumb, is that your car should reach top end speed, when it's 2/3-3/4 down of the longest straight. On tighter tracks, you might want one tooth less on the pinion. On more open tracks, one more tooth on the pinion.

Assuming you found the right ratio: Now you can use a larger pinion and a smaller spur and still have the same ratio. Which is best? Derpending on the car, the motor might sit lower with a larger spur. That will give you a lower center of gravity - which you'll like
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Old 05-04-2004, 06:51 AM
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also for the same ratio of pinion and spur..

the larger spur and smaller pinion will give more grunt and low end power, good for tight tracks

the smaller spur and larger pinion will suffer a little on the grunt but have a better handle on higher speeds... more for open tracks

the ratio is the same, but the power outputs of each scenerio can impact your car's speed.

correct me if i am wrong, this is how i always envisioned it.
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Old 05-04-2004, 03:50 PM
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run the biggest 64 pitch gear you can put on your car and go from there...with a larger spur theres a smaller "jump" of final drive ratios when you change pinions
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