help building a very slow crawler

[sfort]

I'm trying to build a very very slow 1/24 scale crawler, on the scale of 1 mph. I'm trying to get the driveline in order. I bought this brushless outrunner. It's 1000 kv, so at 14.8 volts, that's 14,800 rpm. And plan to put a flat spot on the prop adapter shaft and connect this worm gear and worm wheel to it. The worm wheel will be attached to a Hot Racing spool with 5 mm outputs with flats on both sides of the shaft.

I was thinking to achieve a 60:1 ratio here, to take the rpms down to 247, then take it down again with a differential pinion with a 3:1 ratio for a final drive ratio of something like 82 rpm at WOT. I was going to make a custom bearing carrier out of hardwood and use flange bearings to support it in the center, then use some Traxxas (?) driveshafts to get the power to both front and rear axles.

I was thinking of connecting a diff output yoke, Traxxas p/n 6828X on both ends of the spool in the center. Then, from there, connect that to Traxxas p/n 6850X. See this - https://traxxas.com/explodedviews/67...ampede-4X4-VXL - for the exploded view of the Stampede 4x4 VXL driveshafts.

From there, I need to somehow get the driveshafts connected to a differential pinion. The one for the Slash 4x4 and Stampede 4x4 VXL is a 6 mm and just seems overkill, plus it doesn't fit my driveline since I'm using 5mm parts elsewhere. The rear Slash/Stampede differential pinion connects to the 5mm side of the slipper shaft - p/n 6893, per this diagram. But it won't work because the differential pinion gear just slides over the big end of the slipper shaft. I need to connect a differential pinion with a 5mm shaft to the sliding driveshafts coming from the spool in the center.

I bought this 1/10 HSP differential pinion gear with a 5mm shaft, but it only has a single flat side of the shaft. I could also get this differential gear to go with the differential pinion, if we can come up with a way to get everything connected. I also have this differential gear but it's for a 1/16 scale truck and the gear pitch is smaller than the above mentioned differential pinion gear.

I realize I'm mixing and matching parts from different manufacturers, but just trying to keep everything ultra-light because I have weight constraints and need to keep it light as possible. I need to also make this truck with a straight shaft on the back, so no true differential is needed, but I do need to somehow transfer the power from the center driveshaft to the front and rear axles and I was thinking of securing the differential gear to a set screw hub.

I'm sure this probably a much easier way to get the power transferred to the front and rear axles with a center transmission. Maybe something like the E-Revo - https://traxxas.com/explodedviews/E-...ssion-Assembly - but I really need crawler type speed that's probably slower than most of you use so I can pull it. Thanks in advance for any help!

EDIT: I do have several of these differentials for the slash/E-Revo - https://www.amazon.com/Traxxas-5379X...288237&sr=8-30 - so I could pull the differential pinion and differential from those and just use those two parts, but it's pretty heavy. I'd also need some way to connect the center drive shaft to the 6mm ends of the differential pinion. Maybe that's workable? The problem is that if I used that differential, I'd need to use the 6 mm drive yokes like these - https://www.amazon.com/Traxxas-Brush.../dp/B01JF6O80W. Then I'd need a way to connect those to a 6 mm spool. I assume this is a 6mm shaft spool - https://traxxas.com/products/parts/5381X?

[Voodoobrew]

You can drop the voltage since outrunners have so much torque. Try a forward mounted motor, also 48 or 64 pitch gears if it's that small and light, they have smaller pinions usualy.

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[sfort]

Can't - our 1/24 event has constraints that the truck can't be over 4 1/2 inches wide. Need a simple driveline that is only about 1/2 inch wide to work with the wheels I have.

[Voodoobrew]

Originally Posted by sfort

Can't - our 1/24 event has constraints that the truck can't be over 4 1/2 inches wide. Need a simple driveline that is only about 1/2 inch wide to work with the wheels I have.

Worm drives have a bunch of reduction. They also make the planetary gearboxes for a variety of motor sizes that just increase the motor length.

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[Voodoobrew]

Tamiya 72001 Planetary Gear Box Set
https://rover.ebay.com/rover/0/0/0?m...2F391882032783

Up to 400:1 you go a need moar kv's

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[sfort]

Had seen this before, but was afraid to order since it has plastic gears. Just bought one to look into it though - thanks for the suggestion.