RCM Available gears
 

I'm trying to figure out what gear set I want to use on my E-Jato project. I'm not sure if I want to go with Mod 1 or stay with 0.8 pitch. Mod 1 has thicker teeth for durability, but the Jato is so light, I don't think that will be an issue.

Anyway, the problem I can see is that the transmission doesn't leave much room for a variety of gearing options. So, I need a fairly large spur. The Revo spurs go as high as 40T, but are not very big around. So, I need a large pinion to give me the room I need. Besides, I want a spur-to-pinion ratio of about 2.2:1 or 2.3:1. At 40T, that's an 18T pinion, which aren't available for Mod 1.

Soooo, I figure I'll stick with 32p. If I stay with the 54T spur, I need a 23T or 24T pinion, which also aren't available.

I can't go with a smaller spur because then I get tranny clearance issues between the motor and tranny.

Argg. Any other ideas?

Mike sells 18t Mod 1 pinions, and they're in stock.

You can run a 32pitch pinion on the .8m pitch spur. If that helps you out any.

mike might be able to make you something:032:

Brian, are we talking 1/8th inch shaft? If so, that shouldn't be much of a problem. Even then, contact Mike, he can get larger pinions than are in the store.

Aah, now I see; they weren't in numerical order. My bad. So it looks like I'll be going with mod 1 gearing., as long as the motor I select uses a 5mm bore. That negates the use of the Mamba Max systems because there are no 1.8" bore Mod1 pinions above 15T, and I would need 18T. I also have to watch the size of the gears to make sure they are big enough so the motor will clear the tranny.

Edit I took so long to post my response that two oither posts came in! I guess I'll have to figure out what motor/ESC I'm gonna use and then pick my gearing based on that. Once I decide, I might have to ask Mike if he can make/get the right size. Thanks guys.

You may have to make sure the spur gear will fit on the trans as well. I think my jato has a 40 tooth jato spur on it. It was run with a 32 pitch pinion with no wear. 15 tooth pinion with 40 tooth spur 40000 rpm 2 speed trans is like 50 mph. That is not fast enough. Or you want faster?

The Jato has a 54T, 56T, and 58T spurs available in 32p. If you use Revo spurs, which are Mod 1, you have 36T, 38T, and 40T. Revo spurs do fit.

I'll list a few gears and their diameters to make my next argument easier:

Mod1
- 40T = 42.67mmD
- 38T = 40.53mmD
- 36T = 38.40mmD
- 20T = 21.33mmD
- 18T = 19.20mmD
- 16T = 17.07mmD
- 14T = 14.93mmD

32p
- 58T = 48.33mmD
- 56T = 46.66mmD
- 54T = 45.00mmD
- 22T = 18.33mmD
- 18T = 15.00mmD

Purely for sizing purposes, I lined up an 8XL motor (just to guage the clearance between the motor and the tranny using real parts) with a 14T mod1 pinion with a 54T 32p spur. The clearance is VERY close, but do-able. So, I added the two diameters together and divided by two to get the distance from the tranny shaft to the motor shaft, which is about 31mm. So, no matter which gear set I choose, I have to have at least 31mm between the two shafts or the motor will hit the tranny.

Now, a little info about my Jato. I did the single speed conversion, which has a ratio in between 1st and 2nd. If I use the stock spur/clutchbell ratio, 3s Li batts, and the BK 10S motor, I get about 45mph. A little slow, but I didn't factor a couple things. So, I want to keep the spur/pinion ratio the same or lower for equal or more speed. 54T/22T is 2.45:1. Using a 40T, that means I would need to use at least 18T to get the same ratio and keep a safe diameter. I can't use anything larger than a 54T 32p spur because the rear a-arm could conceivably hit the spur under certain conditions (although unlikely).

So, long story short:
Using 32p, I need 54T spur and 22T+ pinion.
Using Mod 1, I need 40T spur and 18T+ pinion.

Then, aside from all of this, I have to make sure the pinion I select is available in the shaft bore I need. Ugg.

Sorry I have a 58 tooth spur.
But the .8m pitch and 32 pitch will work together if you worried. May help may not.

Brian, If I were you, I would choose the Mamba Maxx controller with a different motor depending on what shaft you want.

CHC: Actually that does help. I wonder what the "32" in 32p stands for? I know the "0.8" is metric (in mm), but it doesn't mean anything if I convert it to standard...

Squee: Yeah, that controller seems like it will fit the bill. I especially like the fact you can program your desired torque curve! That will save the tranny and diff and help runtime! Plus, I'm using 3s e-molis and I want to keep the current down somewhat.

I was thinking about the BK 10s. Does the S series have enough torque to get a 5lb truck moving without going over 130 degrees?

I would think it should. Just remember, its got a 5mm shaft. My personal choice would be a Lehner 1920.

Here's a good link for seeing the equivalents, if not how they actually convert. I don't understand most of the terminology, however :003:

http://www.engineersedge.com/gear_pitch_chart.htm

Joe is the one that hooked me up on the info. He should know. :D

The "32" in a standard 32 pitch gear is known as the diametral pitch. Pretty sure this means there are 32 teeth per inch(diameter). 48 pitch would have 48 teeth around a 1 inch diameter. Same idea as the metric sizes, just uses inches (mod1 - tooth count = mm pitch diameter, so a 51 tooth mod1 one gear has a 51mm pitch diameter). This is handy information of you are drawing a part that needs gears to mesh.

I am quite sure the Castle controller will perform quite well. They obviously spent a lot of time developing it. ;)

The BK10s has plenty of snot, but pretty much all the Feigao based motors will run on the warm side in a car. I agree with Squee on this one - Go Lehner or go home. :) The "s" motors have a 1/8" shaft unless otherwise noted.
Th Neu motors are quite nice as well, though the ends are open(good for cooling-bad for harsh environments).