Pinion Gears for New HH Motors

[Redharris]

SCX10.3.
There seems to be some confusion on what Pitch (32P or 48P) is correct for this truck.

I did some searching here and found a thread confirming that 32P is correct, and that the manual and certain online stores still have 48P listed as correct.

Originally Posted by GA Dawg

Definitely 32p. I can't believe they haven't fixed the manual yet.

Originally Posted by The Bug

Not only the manual but Tower Hobbies and Horizon says the same thing.

I knew it wasn’t 48, glad to see that I’m not loosing my mind.
Now let’s just hope that Tower sends me the correct part.

I just ordered Holmes Hobbies Crawlmaster Sport motors in 10T and 15T.
I would like to order some various size pinions to have on hand, but not sure what tooth sizes are likely to be most useful. The range that will fit in the truck is 11 -18T.

I have 14 T now...... Should I go Higher or Lower?

[durok]

Taken from this link:

https://www.horizonhobby.com/product.../AXI03014.html

(Horizon Hobby owns Axial)

At the very bottom it states:

Product Specifications
Power Type Electric
Gear Pitch 32-Pitch

A smaller pinion or larger spur gear will cause the vehicle's top speed to slow down, but you should get better low speed grunt and response.

A common saying with R/C crawlers is "Voltage up, gear down" - many enthusiasts run a higher-voltage (more cells in the LiPo pack) battery and then use a smaller pinion to offset the speed increase.

Running 3S, with a slightly higher kv (faster) motor than stock, gearing down (smaller pinion by a tooth or 2) can be a good idea.

Or, if you think you can deal with the extra speed and power, run the stock pinion on your new higher-kv motor and check your motor temps after running for a few minutes, if it is too hot to touch then gear down some more.

Pinions are cheap, and on a crawler they tend to last a very long time.

[Fallen]

I'll assume you aren't shooting for higher speed. If that's not correct, let us know.

That said, both of your new motors will be noticeably faster than your current motor.

I'd probably buy 11t , 12t & 13t pinions. If the truck proves too fast still, you can try changing batteries too. If you're currently running 3S, going down to 2S will result in a noticeably slower truck. So much so that you might need to gear back up.

[Traulus]

32 pitch. They are not making a 48 pitch for many years now

[SCX10 JK]

Like the others have said depends on what you want to do with it. I run a 10t in my 10.3 JLU and I do have it geared with a 12t pinion. It has great crawling and decent speed on 3s (not using the 2speed trans). I do run a HW1080 esc though so its pretty smooth vs the Firma 2-1 esc. I typically like my top speed around 5 to 6 mph for trails this still gives me very good low end for crawling as well.


Short list of comparisons using same batteries 3s (2s is about 33% slower than 3s)


stock 35t - 1400kv equivalent
HH 550 10t - 1850kv equivalent - faster
HH 550 15t - 1250kv equivalent - slower
HH 550 13t - 1450kv - slightly faster than stock but smoother and more torque.



All speeds based on the Stock gearing for the SCX10.3 Kit (speeds will be different if using a bronco or basecamp)


stock 35t - 14p = 4.8 mph (1st gear) 7.02 mph (2nd gear)


10t - 18p = 70% faster than stock (8.16 mph 1st - 11.92 mph 2nd)

10t - 15p = 42% faster than stock (6.8 mph 1st - 9.93 mph 2nd)
10t - 14p = 32% faster than stock (6.35 mph 1st - 9.27 mph 2nd)
10t - 13p = 23% faster than stock (5.89 mph 1st - 8.61 mph 2nd)
10t - 12p = 13% faster than stock (5.44 mph 1st - 7.95 mph 2nd)
10t - 11p = 4% faster than stock (4.99 mph 1st - 7.28 mph 2nd)


15t - 18p = 14% faster than stock (5.51 mph 1st - 8.05 mph 2nd)

15t - 15p = 4% slower than stock (4.6 mph 1st - 6.71 mph 2nd)
15t - 14p = 11% slower than stock (4.29 mph 1st - 6.26 mph 2nd)
15t - 13p = 17% slower than stock (3.98 mph 1st - 5.82 mph 2nd)
15t - 12p = 23% slower than stock (3.86 mph 1st - 5.37 mph 2nd)
15t - 11p = 30% slower than stock (3.37 mph 1st - 4.92 mph 2nd)

In all reality the 15t CMS motor is probably slight closer to stock speed due to better quality over the stock motor. I have run the HH trailmaster sport 35t 540 cans against the stock 35t axial/dynamite motors and there is a difference. All of these numbers were based though off of Holmes Hobbies motor chart KV ratings for their motors.

[tonered]

Good info here.

Thanks!


While I like the really good scale stuff if the 10.3 and with the hood thankfully not opening for strength purposes, I deleted the engine cover. The motor would get too hot. Now, it seems to stay a lot cooler.

[durok]

The manual states 14t stock.

Part number is AXIAL AX30725 Pinion Gear 32P 14T Steel for 3mm Motor Shafts.

The 550 can will fit.