Gruber
HobbyMasters
M.L. Toys
KidsWheels
Gruber
HobbyMasters
M.L. Toys
KidsWheels
HobbyMasters M.L. Toys
Gruber
KidsWheels
Need new motors? Grind a gearbox? Adding teeth to a pinion?
#146278
Upgraded the kiddo's dune racer to 18v which made a huge difference in speed. Now I'm sort of stuck at which direction to go next. He rides it in the back yard on grass and there are a few inclines, but nothing too huge. Usually just him @ 35lbs. From what I've read 550s are great speed on driveways/roads, but have less torque than the stockers. The 775s are torque monsters, but I'd definitely see a reduction in top end speed.

My goal is to make it just a tad faster mph-wise(keeping in mind this is 99% grass driven), add a little more torque for when the brother gets in(combined 65lbs), but keep it reliable from a maintenance standpoint. I run bmx traction strips and plan on doing the metal first gear upgrade. Oddly enough hes been running for 2 months now on the plastic one with no issues(knock on wood). Wiring is upgraded with a 40A circuit breaker. If I go 775s I'll upgrade to 10-12g wiring.

Plan A:
Stock gearbox(16t) and the HPI 550s - figured doing a 19t box upgrade with the 550s would be a huge loss of torque, but I'm concerned this will still result in a noticeable loss of tq.

Plan B:
19t gearbox upgrade with 775s - figure the gearbox would offset the speed loss and the combo would net me a little more positive torque.

Plan C:
stock box with 775s - I think this would end up making me slower, which is a no go.

Plan D:
19t box upgrade with 550s - This would be a rocket on hard surface, but seems would be a dud in the grass/inclines.
#146504
Maybe take a look at the budget 775 I posted in the motor database sticky. $16 gets you four Nichibo 775-7013F shipped to your door. Buy two 16T pinions and then make a replacement shim out of 1/2" PVC (if you have the right size drill -- the OD is perfect, ID needs to be drilled to 11/16".

This should net you 33% more torque and the same speed as stock, with only about 10% more current draw (vs. a "higher speed" 550 which will pull more current but without any torque improvement). They should handle 18V though I haven't run them there yet.

You could do a 19T gearbox with that and still get a torque improvement combined with the extra speed (~20% more speed, 15% more torque).

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