1/16 Megaldon Nitro Monster Truck final specs and build guide

I lost count of the months it took to complete this(it’s been 8 actually), and while it wasn’t a steady work pace, and there were times I shelved it to work on other projects, this build was probably the most difficult challenge for me yet simply because nobody had done it before (that I’m aware of) and because I’m going to go on the record and say it here – that working on a 1/16 monster truck is way more difficult than working on a 1/8-10 scale truck. Aside from the fact that everything is just so dang tiny, it’s also more difficult to find examples, parts, and the logistics are difficult. I’m also going to go on the record to say this was also one of the most satisfying builds, and I absolutely love how this thing came out!

My choice of chassis was not too hard after scouring the interwebs for some ideas. There really just aren’t many good 1/16 solid axle chassis choices out there. Most of them are dedicated rock crawler types, and really don’t look very scale, and also don’t really provide much that is useful besides the links and axles. I did see a great little 1/24 chassis made by HBX, but simply too small for a nitro project. Of course this was going to be a nitro project! Then I stumbled upon the aftermarket WPL C14 metal upgrade chassis. I didn’t know much about WPL, but some research showed that it was a pretty popular platform with a lot of aftermarket support.

This chassis is perfectly suited for a monster truck. It has very beefy metal axles with metal gearing, driveshafts, and transmission. It uses carbon fiber sideplates, adjustable links, and metal brackets for just about everything. There are metal platform braces that are good for mounting radios, batteries, etc. All in all it’s of very great quality, and I’m starting to see some other people using this chassis as a starting point. It should be noted that you can also buy many of these parts separately, in different colors, on EBay.

So let’s get started on what you’ll need. It’s a long list.

WPL C14 metal upgrade chassis: $165 – Wpl c14 c24 1/16 metal rc car chassis upgrade parts rc vehicle models Sale – Banggood.com

SH .07 Engine(w/ slide carb): $85 – SH .07 Nitro RC Engine | Nitrotek

Flywheel: $7 – Engine FlyWheel 51C00-86038 (nitrorcx.com)

Pilot shaft: $3 – Engine Pilot Shaft/with one Clip 51C00-86036 (nitrorcx.com)

Clutch: $13 – Clutch Shoes(w/Spring) 51C00-86040 (nitrorcx.com) or 86640 Clutch Shoes Al. – [286008] – RC Nitro Gas Powered Car Buggy Truggy Truck (rcwholesales.com)

Throttle linkage: $6 – Throttle Linkage Assembly 51C00-86050 (nitrorcx.com)

Spur gear: $8 – Main Spur Gear Complete(52T) For Nitro 51C00-86063 (nitrorcx.com)

Nitro tubing: $5 – Fuel Tubes 2P 51C00-02058 (nitrorcx.com)

Clutch bell: $6 – Clutch Bell Assembly(13T) 51C00-86035 (nitrorcx.com)

Cone: $2 – Cone – 07 Engine (hobbyking.com)

Brake cam: $2 – Brake Cam/with one grub screw 51C00-86048 (nitrorcx.com)

Brake disc: $2 – Brake Disc 51C00-86044 (nitrorcx.com)

Brake pads: $2 – Bake Pad Assembly 51C00-86045 (nitrorcx.com)

Brake u-joint: $4 – Universal Joint Cup/with one grub screw(For Brake System) 51C00-86021 (nitrorcx.com)

Tuned pipe and manifold: $5 – Tuned Pipe for .07 Engine – Turnigy 1/16 4wd Nitro Racing Buggy, A3011 (hobbyking.com)

Air filter: $12 – Amazon.com: Hobbypark RC Air Filter Aluminum Capped w/Element Sponge 04104 Nitro Engine Parts for 1:10 Monster Truck Off Road Buggy Redcat HSP Exceed (Blue): Toys & Games

12mm wheel extension/adaptors: $15 – Amazon.com: 1 Set Blue Aluminum 12mm Wheel Hex Hub Extension Adapter 30mm for 1:10 RC Model Car: Toys & Games

M3 internally threaded tubing: $12 – Amazon.com: uxcell 10Pcs M3 x 60mm Round Aluminum Column Alloy Standoff Spacer Stud Fastener for Quadcopter Black: Home Improvement

2 mm carbon fiber sheet: $21 – Carbon Fiber Sheet 300 x 200 x 2mm (hobbyking.com)

Fuel tank: $8 – Fuel Tank 51C00-86061 (nitrorcx.com)

Hobbypark shocks: $20 – Amazon.com: Hobbypark 4pcs Aluminum Shock Absorber Assembled Replacement A949-55 For 1/18 WLtoys A959 RC Car A969 A979 K929 Upgrade Parts: Toys & Games

Steering servo mount: $22 – Amazon.com: Dilwe RC Servo Mount Set, 5T Steering Gear Modification Mount Parts Fit for WPL C14 C24 B14 B24 B16 17G 9G Model Car Accessory(Titanium): Toys & Games

Micro servos(2): $36 – Amazon.com: AGFrc Sub-Micro Servo Motor – Upgrade Metal Case Titanium Geared 13g 3.8kg Mini Servo for 1/14 1/18 1/24 RC Cars RC Planes: Toys & Games

4×7 flanged bearings(1): $6 – DuraTrax Bearing 4x7mm Flanged (2) (DTXC1509) | RC Planet

4×8 bearing(1): $4 – Rolling Bearing 8*4*3 4P 51C00-86082 (nitrorcx.com)

Traxxas 1/16 Gravedigger tires/wheels: $44 – Amazon.com: Traxxas 7265 Dual-Profile (1.5″ outer, 2.2″ inner) Monster Truck Tires Pre-Glued on Grey Wheels (pair): Toys & Games

Body: $20 – Amazon.com: J Concepts Inc. 1/16 1982 GMC K10 Clear Body: 1/16 E-Revo, JCO0382: Toys & Games

Optional – link upgrade: $22 – DIY Upgrade Metal Suspension Toe Link Rod Set Op Kit for WPL B14 B16 B24 C24 C14 for sale online | eBay or DIY Upgrade Metal Suspension Toe Link Rod Set Op Kit for WPL B14 B16 B24 C24 C14 for sale online | eBay

The first step is getting the chassis disassembled and the transmission rebuilt to use for nitro. You’ll likely find that the chassis is assembled, poorly, and probably wrong as well. After getting the electric motor off, you’ll also need to make sure they put the cv joints on the correct output shafts. Both drive shafts should be mounted to the bottom output shaft, not the top! Getting these off without stripping the set screws can be rather traumatic. You may need brute force. This goes for getting the gear off of the input shaft for the electric motor. Take that input gear and put aside. Leave the front and rear main braces in place, but use blue Loctite on the screws.

Once you have this done, and the transmission opened up, you’ll note that the electric engine used a 3×7 bushing instead of a bearing. Replace the bushing with a 3×7 flanged bearing, then insert the spur gear/shaft assembly and put on the original gear you put aside. Insert the e-clips that hold everything in place, put in some bearing/gear grease, and bolt it all back up, using blue loctite. Meanwhile, download the file to 3D print the bracket (link) that will serve as a chassis/engine plate brace, as well as house the 3×8 bearing for the output shaft’s long end.

Using my templates(link), cut out the two plates from the 2 mm carbon fiber sheets and drill the holes for the braces and the engine, as well as the body mount posts and gas tank. Mount the plates to the supplied metal braces, but not to the printed brace just yet.

3D printed brace with 8x4mm bearing inserted.

Insert the 4×7 bearing into the printed brace, and then the input shaft of the transmission into the bearing. Assemble the clutch and pinion on the engine, and bolt the engine directly to the plate. You will not need an engine mount, use the bottom block mounts instead. Now take the transmission and brace and hold them in place to get a nice, tight mesh between the pinion and spur, and if all is right, you should note where the brace needs to be placed(it should be centered on the chassis plates vertically, and in the gaps cut out of the CF engine plate. Mark the drill points in the brace and side plates and drill out for 3m bolts to the CF engine plate, and then for 2mm self tapping sheet metal screws for the side plates. The holes in the side plates should be 3mm.

Final position should look like this.

Now you can probably see that the stock holes to mount the transmission may not be in a good place because the transmission is going to be flipped in reverse to accommodate the engine being in the rear. You’ll need to mark and drill new holes in the sideplates to move it to the right spot. Take GREAT care in getting those holes perfectly aligned. If all of this is done correctly, you will have a tight mesh with the pinion and spur gears, if it’s too tight you can add washers under the engine to lift it a little, if it’s too loose, you’ll need to probably get new sideplates, so make sure to get it right! I would recommend doing this with the axles mounted so that you get the position correct where it’s not going to cause driveshaft binding.

With the drivetrain in place now you’ll need to mount the throttle servo. Cut a piece of .080 poly using my template. Drill one hole where the rear upper link is(and it needs to be large enough for the mount to go through), and one where the screw for the chassis brace is. Using the included servo mounts from the chassis kit, mount the servo as high up as you can to get clearance, and to line it up somewhat with the throttle. Next put on a servo arm(I used the stock “X” arm), and now comes a fun part (not really!). You’re going to need to come up with a good way to make a linkage work. What I did is bend the linkage both up and laterally to get the smoothest, correct action.

Once you have all of this done, bolt up your tank, exhaust, and now your drivetrain is complete! The next phase is working on the links and steering. This part is not much easier…

I would strongly suggest attaching the links and mocking things up first. Getting the links right so that nothing binds, or falls out, is tricky. You need to test with the suspension fully compressed, and extended. In fact, since you’re going to need to roll the truck around a bit, I’d suggest mounting the wheels that come with the truck to test. After you get those done, take it all back apart, and put the links together using blue loctite. In my case, I did go for an upgraded color matched set of links, they are a little better than the stock ones, though technically they should be the same. I would also mock up how you want your body to sit, and for this you may want to trim your body posts to proper length.

While you have the axles off, take them apart, grease the gears, and put them back together using Loctite. Now comes some real fun – putting on the wheel extenders/hub adapters. Now maybe there are some out there that are designed right, but I couldn’t find any hex-to-hex adapters that extended enough, so these were the best I could do. This will require some careful drilling for sure. First your going to need to drill a perfectly centered 2mm hole though the existing spindle. I would strongly suggest using a vice and drill press for that! Now, also using a drill press, you need to make the holes in the adapters larger, using a 7mm bit. I do not know if there is a version of these adapters that is the exact size, but I’ll do some research. Next slide the adapters onto the spindle, insert the lock pin, and rubber o-ring retainer. Lastly, put the steering servo mount on and your steering servo.

Retainer hole for extender/adapters.
Rear axle, ready to attach to chassis.
Completed chassis! I cut pieces of .020 poly for the sponsor decal plates.

Put it all back together now, using blue Loctite where you’re not using locknuts, and put your shocks together using oil of choice. At this point you should have a functional roller chassis. Next, find two points, one in front, and one behind the transmission to mount braces using the 3m aluminum threaded tubes for the rear brace, and 3d print out the front brace/brake cam bracket. Cut the threaded tube to the 2 inches, and bolt it in. Install the bracket/brace for the brake cam, as well as the u-joint cup in the upper output shaft of the transmission. All you need to do now is install the battery pack, radio, and align/tune everything up. I used double sided servo tape to attach the radio receiver, and a zip tie for the hump pack.

The finished product!
View from below.
Front view of steering servo and mount.
With lighting added.

Next article I will show how I build a working brake system! That was a serious challenge.

Published by John Diamond

RC Racer - chassis designer - all around nutcase

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