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1/25 King Hauler - Nikko rebuild

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Well, I've finally got a Nikko to match my forum name, a Nikko Road Express.

Released a few years after the Tamiya, the Road Express was Nikko's toy version of the Tamiya King Hauler. At 1/25 scale it's much smaller and much more basic but does have some pretty nice features, including working headlights and a third channel that can detach the trailer. The car runs on a 9.6v pack, but also includes an 8 x AA adaptor, which means I can use up some AA batteries. 

The  two speed 280 motor gearbox is attached with a pendulum suspension which helps with small bits of gravel, but it's not an off roader.

However it's not proportional (which makes reversing with a trailer really tricky) and could be sped up a little.

The full plan is:

  • Clean it up completely
  • Restore a few broken pieces of chrome work, and then repaint these as best I can
  • Replace the missing cab roof spoiler
  • Add modern steering servo, esc and a mini servo to operate the trailer release
  • get a hotter motor if I can

On arrival the car was much more dirty than I had thought.



After giving a good clean I removed the steering magnets and installed a regular servo. I probably should have used a smaller servo, but this one just about squeezed in. The servo is attached with bolts which run though to the underside of the car. Testing it it seems to work fine, although due to the geometry servo horn is quite long, meaning that I'll have to dial down the steering EPA. I'll loose some torque, but given the small wheels this won't be an issue.


Next job is going to be adding the servo for the trailer release mechanism.


then it'll be a case of the motor, esc and chrome.

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Intriguing project! This one should clean up nicely - best of luck!

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So, I've got a few more updates that I'll add pictures tonight. I was able to get a nice solution for the trailer locking mechanism that I'm quite happy with. Opens with a single press, then when released it springs shut again, just like the original.


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So, the pictures.

The trailer release really reminds me of the old board game mousetrap. Usually the arm is pulled back with a spring which keeps the trailer release in place. When you press the third channel the micro servo rotates 90 degrees anti clockwise. The servo horn hits the lever, which in turn rotates clockwise and pushes the arm forwards which then drops down the flap, releasing the trailer. 


The arm is sprung, so the second you let go of the channel 3 button the arm springs back at the trailer locks into place. Here is another picture, but missing the lever arm.


I also painted a little of the chrome, which is more of an patina steel or aluminium than mirror chrome, but looks ok.


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I was able to complete this last night.

First impressions. The performance increase is somewhat lower than I thought it might be. It's got more power than stock (in particular in high gear under load or on carpet) but where as the Tandy Off Roader (same size motor, same ESC, battery) really jumped up a notch when I took out the old electronics, this is more of subtle improvement, probably because the stock electronics were already pretty good. I've bought a cheapish 280 motor rated for 6 - 12V, so we'll see if that makes a difference. 

That being said having proportional steering and throttle makes a huge difference to running it. The LED lights are really bright and look great, and the trailer release works really well too.  It can't carry much, but I was able to take a 2l bottle of coke in the trailer and drive around. I quite like loading it up and seeing what it will do. 

Anyway onto the photos and build.

This was the final step, fitting in all the electronics. There wasn't enough space in the chassis, so I used a aluminium bar to make a second level, using the posts that would have held the original pcb to lift the bar up. The bar also sits over the micro servo and helps hold that in place.


I also cut a small hole to take the Tamiya connector into the battery bay. I could have drilled a smaller hole pushed wires through and resoldered, but I didn't want to get the soldering iron out every time I wanted to change the ESC. 

With that all done it was time to fit it all together and enjoy in all it's tiny, epic glory.


Look, really bright lights! Shiny things!


You can see here that I mended the smoke stack, using aluminium tubing. I also used JB weld to fix the horn, filling in the gap and filling down to shape.


I went for a dull or weathered chrome look. I can't do full shiny. It looks like it's got a few miles on it to say the least.


Overall thoughts are that it's quite fun and it looks great. I had a similar truck to this as a kid (with a wire control) and remember driving it around my house as a kid, so this brings a smile to my face. I have got to remind myself that this was 1/30 of the price of a Tamiya model, but I like the way it turned out.





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