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  1. #1
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    What pinion for onyx 4000kv brushless setup?

    Like the title asks, what pinion tooth should I start with on me and my sons stampede's?
    I'm going to install the onyx 4000kv setup we had in our smt10's I sold. Trucks are stock xl5 4x4's with the undersized 9T pinion

  2. #2
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    We will be running the trucks on a sod yard, soccer/baseball fields, and a huge course sand pit next to our house. In south Jersey we run year round so winter can be snow at 5* or no snow and 30* and summer can be 85* up to 95*. We run lectron pro 2S 5200mah 35C batteries
    I'm a put the battery in and A) full throttle the entire time bashing or B) mess around with a donut, then hit a small jump or two. Maybe dona speed run then slow down and climb a hill or do another donut
    My son is new to the whole "speed" thing (weve had crawlers his entire career so far) so hes more of a no throttle or full throttle driver LOL

  3. #3
    RC Turnbuckle Jr. olds97_lss's Avatar
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    4000kv is kind of high for a stampede's weight, but if you keep the gearing low, you should be fine. I'm not sure the physical size of that motor either.

    The XL5 stampede has lower gearing in the diffs as well, so keep that in mind for future repairs/updates. You may need the aluminum center shaft to deal with brushless power as the XL5 comes with a plastic center.

    When I ran my vxl 4pede with a castle sct sv3/3800kv (3654 motor) on 2S, I was fine running 13/52 gearing with a motor fan on it and 2.8" trenchers. I was running 7200mah 2S packs at the time without issue and little to no cool down time in grass, dirt, concrete.

    I believe the sct sv3 is a 75-80A esc, but the 3800kv motor will pull less amps than a higher kv motor. Looking at the specs of the onyx (70A), you may have to stay pretty conservative even with lower gearing in the diffs. I'd try the 9T and see how it does, but you may be able to get away with 13-14.
    https://www.youtube.com/c/olds97lss

  4. #4
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    Too high of a kv?
    I only say this because the hobby shop suggested this setup for the smt10 grave diggers we had, with the axial trans 16T is as bog as you can fit with stock spur and with the same battery they were so so....dropping to a 13T pinion helped with the low end so we could do some backflips off skate board jumps I bough off Amazon. Problem with the 13T was top end was HORRIBLE! Then the dang trucks broke steering servos/four links like crazy...and we weren't even hitting 35mph! So I sold the SMT10's and my buddy talked me into these stampede's.
    Weight of the stampede-4x4 is less than the SMT10 we had also

  5. #5
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    I found a 12T pinion in my crawler truck parts, that should be a happy medium no?

  6. #6
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    I still have my xl-5 diffs that came with the Stampede unassembled 4x4 kit, running a 14t pinion with a 3200kv motor, on 2s.

  7. #7
    RC Turnbuckle Jr. olds97_lss's Avatar
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    Since your sticking with 2S, it's probably ok, but 3S on a 4000kv motor is a lot of RPM's/heat/amps. At least from what I've experienced.

    I went from the stock 3660 3500kv to a 3654 3800kv, then 3660 3200kv, then a 3665 3100kv. For the first 2, I only ran 2S. I ran 3S for a bit with the 3800kv, but broke the motor shaft, so not sure how it would have really done. I ran it on 2S for a year or so. Instead of replacing the motor, I got a max10 sct/3200kv combo. It was ok, but still ran on the warm side on 3S and I went to the 3665 3100kv (longer motor for more torque).

    I now run a 4074 2050kv in it with a 6S 150A esc on 4S... it's silly fast now and nothing runs hot.
    https://www.youtube.com/c/olds97lss

  8. #8
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    Well my truck is all swapped, I'll see how it runs with the 12T pinion and the 4000kv system

  9. #9
    RC Turnbuckle Jr. olds97_lss's Avatar
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    I'll be curious how it does for you.
    https://www.youtube.com/c/olds97lss

  10. #10
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    Came home on my lunch to run the truck for one battery. In my opinion the truck is set up perfect for what I want from it. It will pull standing wheelies in the grass or street, and I can feather the trigger just right to ride a wheelie without dragging the back bumper. In the grass or the cleared out woods behind my house I keep clean the truck rips again in my opinion PERFECT for a basher. The torque and tip speed is just right for the way I have the suspension dialed in. I can hit uneven terrain/ small roots/etc and the truck stays straight and settled. Hit some small dirt Juno's and the truck flys level and most importantly lands level and stays straight. I have a hill off the one side of the house and I can easily jump it sideways and again the truck will land and straight and settled. Ripping off the street and back into the yard you can get a little kick out of the rear but the motor isnt over powering the chassis so it settles and just keeps going. I'll take it to a old sand pit we drive in and hit real jumps and climb some hills to see how the motor/esc handles it. So far today the battery/esc are very cool, the motor was only slightly warm to the touch. I'll use my infrared red gun on the electronics later to get real temperatures but I do not see a issue occurring

  11. #11
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    Mind the spelling, talk to text sucks on my phone and I need to get back to service calls for the day before customers start calling the office

  12. #12
    RC Turnbuckle Jr. olds97_lss's Avatar
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    Good to hear.

    I know I pushed mine near it's fastest limit for gearing/weight/tires and where I drive. In the end, I just couldn't gear it for as fast as I wanted to run in the grass without cooking the motor or esc. Which is why I went 4S with a 1/8th system. The BMX track I run at is public and fully grass covered. They keep it pretty well mowed, but the jumps are tall and wide, so clearing them consistently takes speed.
    https://www.youtube.com/c/olds97lss

  13. #13
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    I didnt get to run it at the sand pit we go too yesterday but I ran another battery around my yard and street. I think its spot on for what I need, if anything to keep the motor just a tad cooler (again it's not hot and I can hold it with no problems) I might go up one or two teeth on the pinion. That should ease the low end torque slightly/lower the motor temp slightly/get me a few more mph for street use

  14. #14
    RC Turnbuckle Jr. olds97_lss's Avatar
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    Taller gearing will pull more amps, so it may actually heat up the motor, as well as the esc. But if you can keep your hand on it, it's not that hot yet. 125F+ is uncomfortable to touch for long.
    https://www.youtube.com/c/olds97lss

  15. #15
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    I didnt get to run it at the sand pit we go too yesterday but I ran another battery around my yard and street. I think its spot on for what I need, if anything to keep the motor just a tad cooler (again it's not hot and I can hold it with no problems) I might go up one or two teeth on the pinion. That should ease the low end torque slightly/lower the motor temp slightly/get me a few more mph for street use

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