Project: XL-1

[Michael.mt2k]

After performing several mods on my Monster Herbie crawler, I wanted to address a couple of issues that I had discovered in the course of my tinkering.

The result: XL-1

(Sorry about the poor quality of my camera.)

[Michael.mt2k]

The main issues I addressed were these:

1) My first 4-gear geardown was performed using a screw, and although it works great, I didn't like how much slop was present in the additional gear, nor did I like using a wheel washer as a means to stabilize it.

XL-1 uses a front wheel pin from an old Zip Zap, requiring a smaller hole in the gear and a cleaner, tighter install while still allowing for proper play in the gears.
The pin was easy to trim for length, easy to find, and keeps the hardware in the ZZ family.

2) All crawlers now get the orange upgrade motor.
It's well worth the additional speed to get the additional power.

3) The Half-Lego wheelset I was playing with was pissing me off because the ridge of rubber inside the Lego tire keeps it from sliding onto the MT wheel as far as it can go.
I fixed this by turning the tire inside-out and cutting away the ridge. When I experimented with putting the cut Lego wheel caps in backwards, I discovered that not only did it fit flush for a futuristic look, but flattened out the tapering effect on the Lego tire from the MT wheels!
(Sorry they look rough, but they are prototypes.

XL-1's new hybrid MT/Lego wheels are super grippy, raise the overall clearance, widen the stance, and are heavier for better crawling performance.

4) The steering motor I installed in my first crawler, while clearly stronger than the original and a clean install, is an unknown quantity.

XL-1 uses a modern-day yellow ZZ motor which throws the heavier wheelset with a positive action and keeps the hardware "in the family", as does the gear pin mentioned earlier.

5) Almost all of the these modifications require more power, which reduces the running time to less than half of a stock MT.

XL-1 features an additional MT battery pack wired in parallel for double the capacity and glued to the PCB in a forward position in an attempt to keep the weight to the front.
Connecting the battery in this manner also means simply doing multiple charges on an unmodified controller!

The overall effect of all these mods makes XL-1 look a bit larger than a regular MT, thus the name XL-1 (xtra large)

[Michael.mt2k]

The motor clip screw is spaced with four wheel washers.
Motor spacer is a trimmed and cut green MT idler gear.

I removed the PCB cover to mount the battery as low as I could and keep it as compatible with ZZ bodies as possible, but it doesn't work with most of the cars because of the low hood clearance.

I thought this Mustang body looked pretty cool on there, and the headlights don't hurt.

Here are the official specs:

XL-1
-----
49Mhz
Cat5 Antenna
Dual Parallel-Wired Battery Packs
Orange Upgrade Motor W/ZZ Pinion
4-Gear Geardown W/ZZ Blue Gear and ZZ Front Wheel Pin
Hybrid MT/Lego Wheelset
Suspension Drillouts
Athearn Springs
Yellow ZZ Steering Motor Upgrade

[chilli_mp138]

Michael--

So much for keeping the hardware "in the family"? The tires and wheels would have to go, too, if that's your goal. You're probably the first I've heard of to parallel batteries, something I've always thought better than celling in series. Your work looks really good.

Several questions: (1) Do you think it might be possible to redesign the MT chassis itself to maintain the ground clearance and yet have a lower center of gravity, e.g., batteries on the front and back? (2) Does removing the steering's center-return spring improve steering? (3) Would a FWD-only with a split rear axle yield a tighter steering radius? Or, has someone already designed a small differential? (4) Would a single digital joystick be a good replacement for the two buttons on the controller? (5) Why not kitbash two controllers, one of each frequency, into one box, with a switch to select one of the frequencies, an antenna jack with the option of plugging in one of two tuned antennas, no charger, and a single 9-volt battery with a 6-volt regulator to replace the batteries, and maybe even a power jack to supply a rechargeable 9-volt battery? (6) How about a stand-alone charger that uses the electronic guts of a controller, powered by any adequate external source then regulated to 6-volts before it hits the circuit board? (7) Have you noticed how an endloader steers--could it be done with an MT? Maybe the controller's steering button could be rotated 90 degrees--there are pads for it on the PCB.

Just stuff in the pipeline of my imagination. So many mods, so little energy. There is a downside to being old enough to get senior citizen discounts!

I'll breadboard number 5 above and let you know how it turns out. Number 6 is in process already. Number 4 will be incorporated into number 5. Someday.

chilli

[Michael.mt2k]

Wow you're right, the Lego stuff blows that whole ZZ hardware concept away doesn't it? I wasn't thinking about that!
It wasn't a goal, just a desire to show parts that another enthusiast might have access to. Plus they work a little better! ZZs have excelent quality for the most part.

The stupid bogey wheels are mounted too high, so I've removed them. I saw some guy made a really cool wheelie thing online somewhere...

I know that when I really discovered how cool these MTs are, "regular" ZZs/MS/Bit/clones ceased to be of interest to me. (Great supply of components though!)

Extending the chassis would be helpful for crawling, and by default you'd get more room for additional batteries to be mounted low and internally.
The challenge there is finding some fine rod stock to make the extended drive shaft that's required.

I think the steering return spring is fine. It does help make front end assembly a big pain in the butt.
If anything I was thinking to add one to help throw the heavier wheelset back to center.

Additional stuff like diffs and such would require making the vehicle into something else entirely.

Building these things up is an interesting idea, but as you replace each existing component you will eventually have built a new vehicle!

I don't know how much further my personal explorations will go with these little trucks. I really don't know if I'll be doing any radical chassis mods.

-
The idea of using the circuit boards for other RC applications isn't lost on me at all.
I love non-standard RC applications too!
(Google "Probe II SG")

Combining several frequencies of PCB is something I've considered in the past as well.
I have a bunch of old bitclones that spread across quite a few frequencies.
(As long as you don't mind a custom controller with mutliple antennas! )

[Michael.mt2k]

The more I play with XL-1 the more I see that the build-ups have made this a very solid performing, no-nonsense MT.

Heck, it still pulls decent wheelies despite the weight and gearing!

The mods weren't super hard, the materials were available, and I ended up with a better MT when it was finished.


Now maybe a series-wired speedy version...