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Old 07-13-2003, 08:33 PM   #1
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Default Gear ratio formula

hi, any1 can teach me how to calculate (formula) the gear ratio? i got a tb01 and the manual shown that the gear ratio for using a 16T pinion and 61T spur gear is 1:9.91. how to come out the gear ratio??

glad that any1 can show me in details.... thz....
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Old 07-13-2003, 08:48 PM   #2
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and does anyone know how to work out the rollout of your car.

thanks
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Old 07-13-2003, 09:03 PM   #3
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Try Here to calculate roll out


To work out final drive ratio blixelX, i work mine out by dividing the spur gear by the pinion and then time's it by the transmition ratio

Example for a TC3:

A 27tooth pinion and a 72 tooth spur on a tc3 the final ratio formula would look like this, 72/27*2.5= 6.666 repeter.

It isnt rocket science
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Old 07-13-2003, 09:03 PM   #4
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Default Re: Gear ratio formula

Quote:
Originally posted by blixelX
i got a tb01 and the manual shown that the gear ratio for using a 16T pinion and 61T spur gear is 1:9.91. how to come out the gear ratio??
Formula is:

(spur / pinion) X (diff gear / bevel pinion)


on TB01, I think you've got:

( 61 / 16 ) X ( 39 / 15 ) = 9.9125


For "rollout", just divide the circumference of your tyre (pi x diameter) by the 9.9125.
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Old 07-13-2003, 09:04 PM   #5
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You simply divide the spur teeth amount by the pinion teeth amount then times it by the internal gear ratio which should be in your manual. To get the rollout I'm not exactly sure but there's this site I'll find it in a little bit. You need to know how many mm your tires are.


Zach
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Old 07-13-2003, 09:04 PM   #6
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Just beat ya WC
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Old 07-13-2003, 09:17 PM   #7
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... mine was TB01 specific...
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Old 07-13-2003, 09:32 PM   #8
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thz WC.... very clear now...

another question is, the manual had shown that it supports 3 spur gears (61T, 58T & 55T) with pinion (16T - 25T), r these setting/ ratio can use on the stock motor??
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Old 07-13-2003, 09:37 PM   #9
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With a stock motor make sure your final gear ratio is pretty high. Too low and you'll work the motor way too hard.

Zach
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Old 07-13-2003, 09:40 PM   #10
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Default Gear Ratio Program

Heres A Cool Gear Ratio Program Called Gear Finder:

Gear Ratio Program


Last edited by Fully Hopped; 07-13-2003 at 09:56 PM.
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Old 07-13-2003, 09:59 PM   #11
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Quote:
Originally posted by zachzachz
With a stock motor make sure your final gear ratio is pretty high. Too low and you'll work the motor way too hard.

Zach
hi, the gearing ratio shown in manual is from 9.9125 to 5.28, can i use all the ratio by using the stock motor?

can i hav use a gearing ratio that is lower than the manual shown with a better motor? or what ever motor i use, thats the gearing ratio i can only use?
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Old 07-13-2003, 10:03 PM   #12
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Default Re: Gear Ratio Program

Quote:
Originally posted by Fully Hopped
Heres A Cool Gear Ratio Program Called Gear Finder:

Gear Ratio Program

That's awesome. That makes it too easy.
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Old 07-13-2003, 10:03 PM   #13
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Quote:
Originally posted by zachzachz
With a stock motor make sure your final gear ratio is pretty high. Too low and you'll work the motor way too hard.
Haha, 10:1 on a TB01 is slow as a turtle... Tamiya gives 16t pinion in the rally TB01s as they are supplied with knobbly rally tyres. On the road TB01s, they get 19t... which is slightly better.


Stock RS540 motors can pull a pretty high gearing; they don't rev very high so the only way to get good speed is to use their good torque. So you gear Up (motor turns less for each wheel turn).

On a smaller track, can try about 7:1. (gearing "Up")

On a larger track, can go closer towards 5:1 (gearing "very Up").


On the weekend, was at our local track (very large) running 4.8:1 (gearing "stratospherically sky high"!! ) and it had pretty good speed. It was a pretty spot on gearing for this particular track as the motor wound out (reached top revs) on about 50% of the lap, and was singing by 1/3 down the straight. Good fun! Motor was not very hot on this cold day, I ran it 4 packs in a row without resting longer than a battery-swap.

If motor is "overgeared", it will bog down and get very hot.

Don't try it with your stock and mod motors. You will kill them fast.
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Old 07-13-2003, 10:04 PM   #14
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Yeah it would be safe to use all of the ratios in the manual. But once you go below 5:1 with a stock motor I think you might want to get a new motor or gear higher or you may have a cooked motor. You can use whatever gear ratio you want, but it would be smart to stick with what your manual says. Keep in mind your manual is telling you what ratio is good for the stock motor. If you want some more top speed gear lower and/or get a lower turn mod motor. Opposite for better acceleration. Also the higher your rollout better top speed and vice versa. I'm pretty sure everything i said is right, I might have screwed up and if so please correct me.


Zach
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Old 07-13-2003, 10:14 PM   #15
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so that means i can hav lower ratio (lower than the lowest in the manual) if i hav a better motor, rite?

i just bought 20T & 21T pinion, and had tried the 20T pinion, really can see the diff by comparing with the 16T pinion...
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