Kraton Big block (780KV) and what pinion for K8s

[lbenton]

About to swap the motor mount and drop a Spektrum 780KV in my K8s, It still has the stock 1250KV and 17T pinion on it. Have not yet gotten the pinion to go with this conversion yet but was leaning towards a 30t and 35t to feel things out with.

My habit is to run a full pack and enjoy open spaces and try not to walk too far to right it back on the wheels again. I am not doing speed runs, but just enjoy running it a pack at time with a little cool down between runs for a few minutes. I do not want to fight battles on heat, and it is still 90 degrees F outside here.

Am I in the right ballpark to get continuous runs on a full pack without a huge worry on heat and no loss in top end if I go 30/35T pinions? Looking for any real first hand experience out there. Reading back on some old threads is where I cooked up the 30/35T in my head, but there was not a definite "aha" thread on this motor for normal bashing/running. The motor mount is PracticalProto and will go up to 44T.

 

[DoNoHarm]

Never ran that setup in the K8s, but going by the factory gearing, 30T sounds perfect. 32T if you can push it a little less on hotter days.

Edit guy pretty far below corrected me in a very civilized and called for way (especially because if you took my advice you would’ve completely killed your kraton ???)

Edit2 he fixed his reply and now it’s a lot more humane. Good stuff!

 

[KevinC]

Ya I never saw much, if anything on that Spektrum motor here on the forum. If it helps, I run a similar sized motor with a 39T pinion, stock spur. It kills.
@bicketybam and @Primarrma among others are running similar (non-Spektrum) setups I think.
Perhaps they will chime in.

cheers,
kev

ps.
i still take a break mid pack, but my temps are never above 155......I’m a soft basher.

 

[Rcproponent]

I have the 2028 castle 800kv stock spur and 39t pinion, no heat issues yet, and I don’t even have a fan on my motor ??‍ This is with the mmx8s esc as well. I think youd be more than good with the 30 for sure...

 

[bicketybam]

You don't want a 30t pinion with that setup. I suspect the person who made that comment doesn't realize there is a reduction gear in the gearbox. 30t would be geared to about 40mph. I understand not wanting a speed demon but you want to go faster than that. I run a 44t on an 800kv motor I thinks that's about the sweet spot. If you want to be conservative, try a 38 or so. Forget the 30.

 

[DoNoHarm]

I have the 2028 castle 800kv stock spur and 39t pinion, no heat issues yet, and I don’t even have a fan on my motor ??‍ This is with the mmx8s esc as well. I think your good with the 30 for sure...

Damn those 800 castles are way more of a beast than I ever thought they’d be. Words of the wise right here^^

 

[gotnitro]

You don't want a 30t pinion with that setup. I suspect the person who made that comment doesn't realize there is a reduction gear in the gearbox. 30t would be geared to about 40mph. I understand not wanting a speed demon but you want to go faster than that. I run a 44t on an 800kv motor I thinks that's about the sweet spot. If you want to be conservative, try a 38 or so. Forget the 30.

THAT!^^

You made a thread in the supporting members section a while ago. Some of these posts are exactly what you are talking about!

 

[IRONWORKER]

I run a 38 (Castle 2028 XLX combo) & it’s perfect, very fast but no heat issues even in tall, thick grass.