RC10Talk - The Net's Largest Vintage R/C Community

About eight years ago my Parents bought me a second hand MRC Thunder King. The truck is amazing. It has two drive motors that allow the truck to traverse almost any obstacle. But I'm having an issue with battery life, or lack there of. The truck came with a mechanical speed controller, and I did fix a short that existed between the soldered joints. That almost doubled the battery life. Where the other short is I don't know. In the meantime I have found that a couple people have a Nitro version of the Thunder king and was thinking about converting the truck from electric motors to a nitro engine. I was wondering if anyone had any ideas as to where to begin, as well as what all I would need.

That’s an obscure truck to try to find conversion parts for. Nitro is pretty dead these days. You would really be looking for a parts truck to rob from, as finding all the needed parts on a shelf somewhere would be unrealistic.

Honestly, updating to modern power would be the best option. It would only need one brushless motor and speed control to help the efficiency a ton and have a lot more power than your two stock motors. Going to a lipo battery and matching charger will be life changing for you.

I will let others comment on what motor and speed control you would want as well as battery and charger. I would probably go for a 1:8 scale brushless motor and carve out the motor plate to fit.

I did recently purchase a 5000 mAh LiPO and charger and I'm just waiting for the battery and charger to come in.

if you were to replace the speed controller for a newer electronic speed controller, and use the lipo battery, as long as the rest of the drivetrain is nice and free, ie, no binding or damaged parts, it will act like a completely new vehicle. if they are stock motors, you can use something like a traxxas EVX2, which can handle dual motors, and dual batteries (I'd only use a single pack if possible.)

2 old stock motors and a mechanical speed control will drain most any battery pretty quickly. Moving to an ESC would be your best bet and I probably wouldn't run a LiPo with the mechanical speed control. The ESC jwscab mentioned would be a great choice as you can run either a single or dual motors. EVX-2 has LiPo shut-off, waterproof, plenty on eBay, etc.

My son and I both have Thunder King runners. Well, mine is technically a Baja King, but they are the same truck as far as the chassis and running gear. The body-off shots show mine with the brushless. My son wanted twin motors on his, so he used the brushed Trinity Midnights. They both have the same Novak ESC, although I don't recall offhand which one it is (The trucks are not with me right now). I run a 3S LiPo on mine and it's ridiculous and an absolute terror to drive. It's way too fast and handles like a turd due to me locking the diff.

The diffs are a potential problem area on the World Scale trucks. They are tough to keep tight if you run them for any amount of time and / or with any sort of power. On mine at first, with the brushless/3S setup, I ended up having to use JB Weld to lock the diff. I then found a product made by RC4WD that is a 1-peice steel diff gear. This was years go and they no longer make them. My son's doesn't suffer as much from this since he's running stock-ish motors and 6-cell/2S batteries.

Those ESCs look a lot like the Novak HV-Maxx. I've got one in an Emaxx and so far, its great. Didn't realize it would also run brushed motors, though?

I am looking at upgrading to an ESC. As of right now I am still running the mechanical speed controller with a LiPo that I picked up for $15. Once I made that switch, I went from about one and a half minutes to 25. I cut it off at 25 minutes to prevent from ruining the LiPo.