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Old 03-06-2009, 06:42 AM   #1
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Exclamation Gearing????

Ok my electric 1/10 evader has a 18 pinion/88 spur. The internal gear ratio is 2.4:1. I have tires with 3.8" diameter and 4.75" diameter. The gear ratio with the 3.8" tires is 3.6% max speed and the ratio with the 4.75" tires is 29.5% max speed. How close do you need to stay to the 1:1 ratio for you motor? Plus what temps should your motor not peak over? Thanks for any help in advance!!!
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Old 03-06-2009, 06:56 AM   #2
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No idea where you're coming up with those percentage of max speed numbers or what they mean, also no idea what you're referring to when you say the 1:1 ratio for your motor... where are you getting this stuff from?

Also, the gear ratio is the same gear ratio regardless of tire size, so you really need to point me to whatever source of info you're quoting from so I can see what they're talking about... it really makes little to no sense to me the way I'm reading your post.

Not trying to be a smartass here or put you down in any way... I just need a little help to help you.
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Old 03-06-2009, 07:18 AM   #3
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So does it matter what gears you put in it then? or do you base your gearing off of if you want more speed or acceleration but you are limited to if your motor over heats?
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Old 03-06-2009, 07:36 AM   #4
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It definitely does matter what gearing you put in. I'd start with the stock gearing that comes with the vehicle, or if it's a kit look for gearing recommendations in the manual for different motors and pick the one closest to the motor you have.

Generally, a bigger pinion gear gives you more top speed, but slower acceleration off the line and vice versa.

FOr onroad, we gear based on lap times, keep gearing up until the lap times stop improving,l or the temerature of the motor gets unacceptably high. For offraod, the same considerations apply, but you also need to look at jumps and obstacles and run a gearing that doesn't make it too difficult to achieve consistent laps...
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Old 03-06-2009, 07:55 AM   #5
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[QUOTE=Trips;5518169]It definitely does matter what gearing you put in. I'd start with the stock gearing that comes with the vehicle, or if it's a kit look for gearing recommendations in the manual for different motors and pick the one closest to the motor you have.

Generally, a bigger pinion gear gives you more top speed, but slower acceleration off the line and vice versa.

FOr onroad, we gear based on lap times, keep gearing up until the lap times stop improving,l or the temerature of the motor gets unacceptably high. For offraod, the same considerations apply, but you also need to look at jumps and obstacles and run a gearing that doesn't make it too difficult to achieve consistent laps...[/QUOT

How would you know if you motor is getting to warm? Is there a temp that it should stay under? If it does get to hot you just gear it down correct?
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Old 03-06-2009, 08:15 AM   #6
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For brushed motors I used the simple method of touching the motor after the run. If I could keep my finger on it without discomfort, I felt I had room to gear up if I wanted to. If I could keep my finger on it but it was uncomfortable I was getting close to as much gear as I wanted to run. If I couldn't keep my finger on it, I'd back off a tooth or so.

With brushless, cooking a motor is too expensive, so I use a temp gun after the run. Anythign below 170 is okay to me, between 170 and 180 is too much, anything beyond thast is definitely bad. Seems when I'm getting my best lap times, the motor is coming off the track at 140-150 lately.
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Old 03-06-2009, 08:21 AM   #7
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Ok thanks. one more question what is the point of changing the spur gear up or down? Is it just to give you more gear ratios then just changing the pinion gear?
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Old 03-06-2009, 08:31 AM   #8
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Sometimes you can't get the exact ratio you need, the ratio you want might fall halfway between two pinion sizes... a change of spur will sometimes get you there.

Also, brushless motors typically require MUCH taller gearing than their brushed equivalents... for stock racing, we typically ran a 96 spur and a 32 pinion in a 1/12 car. To get the right ratio for a brushless, you'd need a much bigger pinion than would fit in the car. Dropping all the way down to a 76 spur lets us get to the ratios we need for 17.5 brushless motors and still have the spur/pinion combo fit in the car...
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Old 03-06-2009, 08:40 AM   #9
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Quote:
Originally Posted by Trips View Post
Sometimes you can't get the exact ratio you need, the ratio you want might fall halfway between two pinion sizes... a change of spur will sometimes get you there.

Also, brushless motors typically require MUCH taller gearing than their brushed equivalents... for stock racing, we typically ran a 96 spur and a 32 pinion in a 1/12 car. To get the right ratio for a brushless, you'd need a much bigger pinion than would fit in the car. Dropping all the way down to a 76 spur lets us get to the ratios we need for 17.5 brushless motors and still have the spur/pinion combo fit in the car...
I take it that faster the motor is you will need to go up in gears?
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Old 03-07-2009, 01:55 AM   #10
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I have a 4.5 LRp BL motor, the spur is a 87 tooth and i think i need pinions from 18 to 22.
Correct?
I used gearchart.com and thats what it said anyway.
Are those pinions okay or do i need different ones?
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Old 03-07-2009, 09:29 AM   #11
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Quote:
Originally Posted by neekcotrack View Post
I take it that faster the motor is you will need to go up in gears?
Typically, the faster the motor gets, the smaller the pinion needs to be.
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Old 03-07-2009, 09:31 AM   #12
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Quote:
Originally Posted by Tucker101 View Post
I have a 4.5 LRp BL motor, the spur is a 87 tooth and i think i need pinions from 18 to 22.
Correct?
I used gearchart.com and thats what it said anyway.
Are those pinions okay or do i need different ones?
If you know the rollout or ratio you need, then gearchart can tell you what pinions you need. If you don't know the rollout or ratio you need, then gearchart can't help you.
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