Capra Gear ratio

[Hondarider94]

I am potentially wanting to use capra axles in my next build, but i am trying to figure out the gear ratio of capa axles, vs scx10.2 axles. If they were both hooked to the same tranny, how much lower geared ( slower) are capra axles then scx10.2?

[twade984]

Stock form the Capra ring and pinion is 3.75:1, portal gears are 1.91:1,
Total axle ratio about 7.1:1

Scx10.2 also has a 3.75:1 ring and pinion ratio.

Most people determine overall final drive on a rig that they like the gearing in and work from there. Anywhere from 35:1-65:1 seems to be common.

Assuming a 13/56 pinion/spur : 4.3:1
Stock 3 gear trans ratio of : 2.6:1
Standard ring and pinion : 3.75:1
A stock ish 10.2 would be 42:1

Swap in Capra axles and you have,

4.3x2.6x3.75x1.91= 80:1. Basically cutting your top speed in half.

From there you can run a higher kv/lower turn count motor, smaller spur gear and larger pinion, add o/d ring and pinion, and/or o/d portal gears.


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[Hondarider94]

Originally Posted by twade984

Stock form the Capra ring and pinion is 3.75:1, portal gears are 1.91:1,
Total axle ratio about 7.1:1

Scx10.2 also has a 3.75:1 ring and pinion ratio.

Most people determine overall final drive on a rig that they like the gearing in and work from there. Anywhere from 35:1-65:1 seems to be common.

Assuming a 13/56 pinion/spur : 4.3:1
Stock 3 gear trans ratio of : 2.6:1
Standard ring and pinion : 3.75:1
A stock ish 10.2 would be 42:1

Swap in Capra axles and you have,

4.3x2.6x3.75x1.91= 80:1. Basically cutting your top speed in half.

From there you can run a higher kv/lower turn count motor, smaller spur gear and larger pinion, add o/d ring and pinion, and/or o/d portal gears.


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Thank you! i dont think these will work for my application

[chilly]

Originally Posted by twade984

Stock form the Capra ring and pinion is 3.75:1

I was just wondering this myself. I can find the part number but not the gearing for the life of me. AXI232003 is the stock part number but they don't list the gear sizes specifically. Is that part the 3.75 do you know?

I've already geared my pinion down to the minimum 11T for the stock trans, but I wanted a bit of overdrive, so was considering putting in a vanquish rear end that is a 33/8. If all that is correct, then I'm thinking:

Stock: 3.75
Vanquish: 33/8 -> 4.125
(4.125 - 3.75)/3.75 = 10%
or maybe this is technically more accurate:
(4.125 - 3.75)/4.125 = 9%

So if I'm understanding right this would be effectively be a 9-10%. Is that even noticeable? It's like $40....

[twade984]

Originally Posted by chilly

I was just wondering this myself. I can find the part number but not the gearing for the life of me. AXI232003 is the stock part number but they don't list the gear sizes specifically. Is that part the 3.75 do you know?

I've already geared my pinion down to the minimum 11T for the stock trans, but I wanted a bit of overdrive, so was considering putting in a vanquish rear end that is a 33/8. If all that is correct, then I'm thinking:

Stock: 3.75
Vanquish: 33/8 -> 4.125
(4.125 - 3.75)/3.75 = 10%
or maybe this is technically more accurate:
(4.125 - 3.75)/4.125 = 9%

So if I'm understanding right this would be effectively be a 9-10%. Is that even noticeable? It's like $40....

I use this Omni percentage difference calculator as recommended by Josh aka Harley.



In my experience around 10 percent over/underdrive is very noticeable, and usually what I like to run.

Using a vp underdrive ring and pinion would be my recommendation to help offset the high FDR of the stock Capra drivetrain.


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[meatmonkey]

Most transmissions have plenty of room for a much !larger pinion gear to help offset the reduction I the portals.

Im running the Vanquish under drive gears in the back and can recommend them. 9% is a subtle but noticeable amount of overdrive. I did eventually get mild OD portal gears up front to go with the UD out back. Seems like the sweet spot for my usage. There is no perfect amount of OD, it varies for tire diameter, driving style, and terrain.

[OSRC]

Originally Posted by chilly

I was just wondering this myself. I can find the part number but not the gearing for the life of me. AXI232003 is the stock part number but they don't list the gear sizes specifically. Is that part the 3.75 do you know?

Ring and pinion are 8/30.