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ChrisRx718

Mad Hopper

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So I have been getting back into the hobby lately and one of the last cars I built before taking a break was this Grasshopper.

I actually only built it because I'd purchase the incorrect aluminium wheel covers (I meant to get ones for an FAV) I couldn't sell the wheel covers so I bought a Grasshopper instead :lol:

The intention was to have something "tame" that the nephew's could drive when they visit. Stock, with the 380 motor. 

Only that didn't happen. I put a Hobbywing 16BL30 ESC in it coupled with a 4-pole motor - still 380 in size but rather a lot faster than the stock can. Especially, it turns out, on 3S!

2018-03-22_07-24-19

Trouble is, I think I've reached the limits of the chassis with the power available. The thing is completely mad.

So to fellow Hornet / Grasshopper owners...

Should I lock the diff? Will it be easier to handle? 

If yes, how do I go about locking the diff?

The gearbox is making some odd noises. Kinda like a drill? Far louder than any of my other RCs. Is that normal? 

My little Chinese 2435 BL motor got really hot. Brushed motors always used to get hot; but I've never had a brushless one get this hot before. Again, is that normal?

Sorry for all the questions, that's why I started a new thread rather than clog somewhere else up.

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There's not a whole lot you can do for the handling, the gearbox by design rotates and pulls the shocks open under throttle and stops them from working properly. You can convert to hornet pivots and at least gain some side to side articulation but the lock out is pretty much impossible to defeat. I've seen people add a weighted spare wheel on the roof and use feather soft springs which seems to have some affect but at the end of the day you can even take the shocks off entirely and the back end will stay up under throttle so you'll never fix it completely.  Adding oil dampers definitely helps the ride at the front and at the rear too but only when you're not on the throttle.

Even if you managed to solve that one, you still have a buggy that traction rolls with incredible ease. I have a brushless in my Grasshopper but I pretty much exclusively use it at the beach or on grass etc where the shell won't get ruined as much when it inevitably flips.

Locking the diff only really helps in situations where the car stalls out with the wheels spinning such as on grass etc. Because it has a solid axle, it's easy for one wheel to end up in the air and you lose all forward motion. The problem if you lock it is that the car would be more prone to spinning out on tarmac etc and it would make it more jittery when cornering on such surfaces.

Grasshopper gearboxes definitely have a distinctive noise, I can only suggest listening to some youtube videos and seeing if they sound similar to yours.

A 2435 motor is actually 280 size and not 380 so it's definitely going to get hot pushing a 1/10 buggy around on 3S. The fact that it can manage it at all is a testament to how good brushless motors are but I would stick to 2s for such a small motor. I have seen people use them before with the intention of lowering the unsprung mass at the rear but 3s is really pushing it. The Grasshopper is light but it's still a 1/10 class buggy and that's a 1/16-1/14 class motor. The smaller you go with the motor the more you negate the cooler running of brushless until you end up with the same or worse thermal characteristics. 

You can get slightly longer 2445 motors that run somewhat cooler if you wanted to stick to 24mm diameter motors.

Have you mounted the motor in the same place as the stock 380? Are you using the pinion from the 380 motor? In my experience, 2435 motors have a 2mm shaft but the stock 380 has a 2.3mm shaft.

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