JXD Drift King Just Spins: How I ALMOST Fixed Mine!

So, as I mentioned in a previous article, my sister bought me a JXD Drift King for my birthday. This was extra cool because I had just received my green Syma S107G the day before. I was a little extra excited about the JXD Drift King because it is a four channel helicopter unlike the Syma, which is just a three channel helicopter.

Sadly, after just a handful of crashes, my Drift King we just spin wildly about a millimeter off of the floor — even at full throttle. I could tell that the lower rotor spinning much faster than the upper rotor. In fact, the upper rotor was barely spinning at all, and this is why the helicopter was spinning wildly.

The Problem: A Slipping Gear

Close-up of the problem gear.Before I explain the problem, let me orient you a little bit with all the relevant parts.

On the Drift King, the upper and lower rotors are powered by two different motors. One motor, which I will call the “front” motor is positioned towards the nose of the helicopter and drives the lower rotor. The other motor, which is positioned more towards the rear of the fuselage, drives the upper rotor. For lack of a better term, I’ll refer to this motor as the “rear” motor. But please don’t confuse it with the completely separate motor that drives the small rear rotor, which has nothing to do with this issue.

What turned out to be the problem, was that the drive gear on the rear motor had slipped so that it was making contact with the circuit board. Below I have an animated diagram which might help clarify everything.

Animation of gear slipping.

The friction between the drive gear and circuit board was apparently causing the motor’s shaft to slip quite a bit inside the gear. So, even though the drive gear was still making contact with the giant gear that turns the upper rotor, it simply wasn’t spinning very much because the motor’s shaft was just slipping inside of the little drive gear.

What Almost Worked

I found that I could wedge the tip of a really small screwdriver between the drive gear and circuit board and slide the gear back into the proper position. The helicopter would work again, but the gear would just slip back out of place after a crash or two. In fact, after doing this a bunch of times, the gear would slide down the shaft simply by activating the throttle.

Tip: The smallest screw driver I could find still had trouble getting in between the gear and circuit board. So, later I made a little tool by straightening out a paper clip and filing one tip of the wire to a sharp edge.

What Did Also Almost Worked

Update: Originally I thought my fix was permanent, but it merely lasted longer than earlier attempts. It stayed fixed for about a week. But the gear finally slipped again. It’s back to just spinning wildly on the ground. >:(

Now, before I show you what I did, let me say here that, if you follow these instructions, you are probably going to make the helicopter where it won’t be returnable. So, make sure you want to do this instead of just returning or exchanging it (if those are options for you).

Basically what I did was take the helicopter completely apart so I could more easily access the drive gear. I then slid the drive gear up the shaft until the shaft began to protrude just a tiny bit on the other side of the gear. I then mixed up some two-part epoxy and, using the tip of another paperclip that I bent out straight, I put a small dab of the epoxy over the end of the shaft so that it completely covered the tip of the shaft and also some (but not all) of the gear. Just reading that sounds confusing to me, so hopefully the images below will make it more clear.

How to apply the epoxy to the gear.

After the expoxy has been applied, I set the helicopter parts aside and let it set for 24 hours. At that point, I put the helicopter back together. And the gear has held just fine even though I’ve crashed it numerous times since then.

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4 Responses to JXD Drift King Just Spins: How I ALMOST Fixed Mine!

  1. KusH says:

    I had the same problem as you. I took the thing apart enough to get a vise-grip on the motor shaft and crush it enough to make some dents in the steel shaft which is not easy but after that I put some CA in the teeth marks from the vice-grip, slid the gear back on. It was so tight I had to slightly tap with a small hammer to drive the gear back on. It will never slip again in this man’s life. I also allowed the tip of the shaft to slightly protrude as you did and put ca on that side as well. I am now cleaning up the gear teeth as I slightly damaged them tapping the gear back on but the machine works well now as you also made a good repair also. I consider mine very difficult to do because it needs a lot of strength to force the vice-grip very tightly closed to make dents in the steel shaft of the little motor. I did not have enough room for a large vice-grip so I was forced to use a smaller one. But it will never slip again. I am curious to know did you see the spline teeth on the upper gear shaft that the culprit gear drives? The shaft is splined so the gear can never slip. Why did they not do this to the motor shafts? Good artice on your part and diagrams are EXCELLENT!

    • admin says:

      Hi, Kush.

      Glad you liked the diagrams. I made them with a free 3D graphics program called blender (which you can download from blender.org). It’s complicated software, but there are tons of instructional videos on youtube.

      No, I didn’t notice the splines…I didn’t even know what splines were until just now after I read about them in your comment and after I googled that word. LOL.

      Anyway, thanks for sharing your experience. I found it very interesting and helpful. Cool to see how other people approach problems like this. Sounds like your fix is much more durable than mine. Unfortunately, my fix here failed after about a week. I’m going to try a slightly different approach later.

      I’ve got a friend who recently bought this model off amazon.com and, so far, he hasn’t had this problem. So maybe the newer ones don’t have this issue. {shrug}

      Thanks for stopping by!

      (Follow us on Facebook or twitter.)

  2. Dustin says:

    I have had the same problem and fixed it with glue. It broke again and the little gear that is slipping broke in half when I was adjusting it. Do you know where I can buy some of these gears?

    • admin says:

      Hi Dustin, I’m sorry to hear that. The most complete selection of replacement parts for the JXD that I was able to find (after a quick Google search) was here. But they didn’t have the particular gear you need.

      If you have a facebook account, “like” my facebook page. Who knows, I might run a giveaway soon. Also, I try to keep my page’s fans alerted to other RC helicopter giveaways.