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Upgrading LOSI XXX SCT to Brushless

Old 08-19-2022, 02:18 PM
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ncostes
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Default Upgrading LOSI XXX SCT to Brushless

Hi All,
My old LOSI XXX SCT w/stock brushed motor & ESC - the motor fried. Can anyone offer any suggestions for upgrading to brushless (ESC/motor combos) and any other parts that would need to be upgraded to prevent damage from the new motor?
I'm not looking for speed, the brushed motor/ESC was fast enough for my kids. Just want it to be smooth and fun / low maintenance.
Thanks!
Old 08-26-2022, 04:53 PM
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suburban_hooligan
 
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idk what motor came with your truck stock, but im guessing a 17.5 is good for kids. punchy but not really fast.
idk how good it is iv yet to run a hobbywing esc. but i do have a couple hobbywing motors and like them.
https://www.amainhobbies.com/hobbywi...20321/p1331138

Last edited by suburban_hooligan; 08-26-2022 at 04:56 PM.
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Old 08-29-2022, 01:57 PM
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Thanks for replying, Hooligan. This is what it came with: https://www.spektrumrc.com/Products/...rodId=LOSB9999

Brushed 14 turn motor.
Here's the brushed ESC: https://www.spektrumrc.com/Products/...rodID=LOSB9522

I measured my motor, seems to be the same outer diameter as the one you linked.
The shaft diameter seems is .125 same as yours.
My motor is about 1.9" long.
So physically it seems like it should fit.

I can't get the pinion gear off - the grub screw is rounded out inside.

The manual lists 48 pitch 14T and 18T pinion gears and the spur gear is 84T.

When converting to brushless do I stick with the same # of teeth on the pinion?

Any concerns with the transmission getting bashed by the more powerful motor?

Thanks!
Nick


Old 08-29-2022, 04:28 PM
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suburban_hooligan
 
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oh wow it's a 14 turn. that's faster than i was expecting (figured maybe 17 turn), battery pending that's still comparable to about a 17.5 brushless. are you running a lipo battery or a nimh battery? cause that'll matter, it'll also have an effect on gearing. (info shared here is for lipo battery)
iv got a XXXT i used to have a 17.5 set up in (Tekin motor with LRP ESC) gearing i think i was running 18/88 and it was a bit under geared. i think i went 20/88 and that worked better but was still under geared, i don't really remember, that combo wasn't in that truck for very long. gearing with brushless is a little different than brushed, the 84 tooth spur is fine. id be tempted to use a 20t pinion just to get a base. just keep a close eye on motor and ESC temps and adjust if necessary.

no concern with the transmission as long as the diff is in good shape. your truck have a ball or gear diff? and the slipper clutch is adjusted properly.

im starting to wonder if a 13.5 wouldn't be better for your truck... cause a short course truck is a little bigger and heavier than a stadium truck. how old are your kids and how well can they drive? how much space have you got and what kind of terrain are you driving on?
they make that same system i posted earlier in a 13.5 https://www.amainhobbies.com/hobbywi...20320/p1331137

Last edited by suburban_hooligan; 08-29-2022 at 04:32 PM.
Old 08-29-2022, 04:33 PM
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suburban_hooligan
 
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here's a couple videos of my XXXT running a 17.5 motor with a 2 cell lipo battery. believe this is the 20/88 gearing

Old 08-29-2022, 06:04 PM
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ncostes
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Wow you're literally jumping at a brick wall in that first video That's gutsy

* I'm using 2S 5200mAh lipos.
* The pinion is 16T and the spur is 88T. These are stock.
* Diff is geared. Stock part.https://www.hobbytown.com/losi-gear-...osa2930/p25168
* The kids that are enjoying driving this are 8 and 10 yrs old now. It's a little fast for the 8 yr old, she prefers a rock crawler right now. They're not great drivers, just starting out.
* We have about as much room on grass as you do in the 2nd video at your cabin (I mean just the area you're driving in, not all that you have available)
* We have a nice quiet street too but my son says its not fun on the street, he likes driving on the grass and in the dirt.

My son burned the XXX-SCT brushed motor up running it in the yard in grass. He ran in yelling "Daddy daddy daddy" and there was smoke coming from it, I thought it was the lipo, but it was the insulation on the inductors connected to the motor burning up.

I figure he just ran it too long and too fast in the grass. When I first got it used, I ran it with a 3000mAh NiMh, so it wouldn't run very long. These 5200mAh and 6000mAh lipos let it run forever, and it was hot out that day. I didn't warn him about motor temps and taking breaks, honestly I had forgotten all this stuff, it's been a while.

So a more reasonable speed motor is fine. I'm actually thinking of just replacing it with a brushed motor, I can get one for like $18 but maybe it's worth just going brushless since it'll run cooler and I don't need to worry about brushes.

I do have a Ruslter VXL for speed so I'm ok with this one being slower.

BTW I bought all my RC cars used ages ago, it was always more affordable.

Thanks again for taking the time to ready and reply. I'm considering the combos you linked.


Last edited by ncostes; 08-29-2022 at 06:06 PM.
Old 08-29-2022, 07:03 PM
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yeah, 17.5 is probably fine for them and that truck then. having a gear diff is probably more beneficial in this application. if anything it's less maintenance and less wear. and i did melt a worn out ball diff once... get the gearing right and you can run a whole pack in grass with no issues.


if you think jumping at a wall is gutsy, how about jumping off the wall? (truck was still brushed in this video)

Last edited by suburban_hooligan; 08-29-2022 at 07:06 PM.
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