Ambitious Brushless Conversion
 

Hi all,

Just recently I have been bitten by the rc bug and purchased a HSP Nokier Pro 1/8 truck, absolutely love it. Using this has given me a good idea of how the modern hobby grade rc's work.

I also have an early 00's Radioshack Monster Patrol which was my first full on rc car. 4wd grip, servicable parts, nicad batteries, the lot. Pity the thing now (compared to the hsp) is as slow as a wet week, not to mention the battery life is sub par.

I was thinking, would it be possible to rip out all of the old electronics in the monster patrol and fit a modern brushless setup with some nimh or 2s lipo? I have done some measurements and the old brushless motor is the same size as a 1/10 brushless type, so it should be a nice fit. The old front steering servo is a little different, but i think i should be able to rig a standard servo in its place. There's loads of room in the old chassis, so a new esc and receiver and some double sided tape should do the trick.

The only issue is, as most of the drivetrain consists of plastic cogs, i need a motor that isn't hugely powerful. What sort of esc and motor kv should i be aiming for? I'll probably buy off hobbyking.
My guess is this esc (Hobby King 35A Sensored/Sensorless Car ESC (1:10/1:12)) and this motor (XK3650-B-3900KV Brushless Inrunner (11.5T))


Would this be suitable? I'm not looking to thrash it, and i know it probably wont be half as fast the HSP (that's ok), but just want to know if it is possible?

Thanks

That 3900kv will shred that tranny to pieces imho..

Ok, so what should i be aiming for? Would the 5000kv 9t or 6500kv 6t version be better?
Yes the trans is plastic. but it does seem rather robust. It doesn't seem to be of cheap quality.

Any more answers would be much appreciated.

It's tedious, but I'd honestly go through the trans, count all the teeth on each gear and figure out the total reduction ratio. Once you know that, set a reasonable top speed goal and use a gear calculator to find the Kv that'll get you there. Most toy grade cars don't have adjustable motor mounts so you're probably stuck using the same size pinion as on the old motor. So unless you find a way to make the mount adjustable you can't use gearing to adjust top speed, you'll have to use motor Kv.

I haven't seen the gears like you have, but I'm pretty sure a modern brushless motor will shred the gears of a radio shack toy. Going 2s is a smart choice, finding an esc with punch control would be wise as well.

Well i havent counted the teeth, but it is quite a large main gear (67ish mm), around the size of a helicopter's main gear im guessing around 70/80 teeth

You will absolutely destroy that truck in one battery pack with a brushless system.

The idea is fun, I have thought about little projects like that is the past. In all honesty, it will be fun for the 3 mins it lasts before it disintegrates everything in the transmission.

Not worth the time my man.

I can understand, and it honestly sounds like fun. I'm always trying to find a way to save old RC's.

I bought my kids a New Bright 1/12 scale Corvette racecar years ago that no longer holds a charge in the battery pack, and the pack itself is somewhat elusive to find. Been thinking somewhat along the same lines of gutting it and making some form of a brushless version out of it since I have tons of RC stuff laying around. It actually has a lot of room under the shell, and a hard enough plastic lower bottom that I can probably drill and dremel out stuff so that things fit.

I do love a good project and hearing about how others turned out.

Agreed.

Well i'm going for it anyway, ive ordered the parts and we'll see how it goes :cool:
All up It's only costing me about $70aud and if it doesn't work I can get a cheap 1:10 chassis kit off ebay and throw the parts in there.

I'll let you know how things get on.