How to Build A Better
and Micro RC are all the rage these days.
You’ve probably read this a dozen times in as many articles,
and there’s a reason for it.
These little beasts are a lot more fun to play with than their
full size counterparts. I
don’t have to tell you why, if you’re reading this it’s because you’re
interested in a TLT-1, which is one of the best mini trucks on the
market. It’s a full function
all terrain machine, built as solid as a block of steel with all the
rock crawling potential one could hope for.
However, it’s not without its flaws.
every RC enthusiast that sees the TLT-1 for the first time has the
same thought…what a great little truck, but it looks ridiculous and
the ground clearance under the chassis is a joke.
When deciding whether to purchase one, I too was frustrated
by the apparent design flaws that the engineers at Tamiya built in
to an otherwise fantastic kit. The TLT-1 managed to win me over in
the end, though, with its extensive use of metal parts, high quality
components and what I believed to great promise.
I had this inescapable feeling that I could build it better right
out of the box. As it
turns out, I was right, and that’s what this article is about.
0 - Lock the Diffs
fool put a center diff in this thing?”
call this part 0 rather than part 1 because a monster truck
or rock crawler with three open differentials is just plain
silly. It’s not like it has electronic traction control or “gerotor”
the center diff is easy.
Don’t put in the diff balls and use JB weld to seal it
shut. Do this first,
so that it will be dry by the time you finish building the kit.
If you’re a fan of perfection, you can shim it to keep
it steady, or JB weld it with the balls in place (without the
balls it’s a little thinner).
There is no reason to ever undo this.
have JB weld? No
problem. Use a
pair of screws to screw the two halves together…you might have
to drill a couple of holes. I found it easier to go to the hardware store and pick up JB
Weld. In case you
like the screw idea, here is a picture:
axle diffs are a little more tricky. If you look online, you’ll
see a lot of different answers about some kind of goo that you
can put in there to lock them.
Some of these can even be undone.
Well, forget about all that.
There is a much better way that is easy to undo.
it comes time to build the axle differentials, you will be given
three small bevel gears and a little “Y” on which to mount them
(all illustrated clearly in the instruction manual).
These little bevel gears rest between the two large bevel
gears that connect to the output shafts, or “half shafts”.
Instead of mounting all three of them on the little Y,
mount only two. Then take the third and wedge it between them, making sure
they sit flush (they sit perfectly flush when properly positioned).
This will make it impossible for the large bevel gears
to rotate at different speeds, locking the diff up tight.
carefully at the picture below…see the third bevel gear wedged
between the other two?
It’s a perfect fit and a perfect diff lock.
first two images appear courtesy of rc-whirlybird, who saved
me the trouble
of disassembling my truck - thanks!)
you want to unlock the diff, just take the third one out from
between the other two and mount it on the “Y”.
in mind, though, that locking both axle diffs is only for dedicated
who like to drive around their house should leave both open
or just lock the rear, as locking one axle diff will hurt your
turn radius, locking both will make it hard to turn around in
an empty parking lot.
Also, if you lock an axle diff, you will need to put
a high torque servo on that axle.
With an open axle diff, a regular servo is sufficient.
1- All Stock Mods
instruction designers hate you... "
is really no other way to explain why the assembly instructions
contain all the steps you need to build a really bad truck with
under an inch of ground clearance.
Nevertheless, I followed them to the letter, and wound
up with exactly what I thought I’d get when I first looked at
the kit…a neat truck with a ridiculously high disposition and
a ground clearance that would make it hard to crawl over a salt
I could even stand to look at it, the body had to come down.
Sitting as high as it was, it looked like some absurd
child’s toy designed by a madman with a crack habit.
I had the MaxClimber kit, that was simple enough.
All it took was lowering the little rubber tubing that
determines where the body rests, maneuvering the body as low
as it would go.
The outer fenders required a little trimming for wheel
clearance, but all in all, it looked great.
That, of course, brought up the first question.
Why does Tamiya have you build it to look, well, dumb…when
you can build it to look better with the same parts?
the absurd body problem was taken care of, the next major issue
had to be addressed…ground clearance.
Like a lot of people, my first choice was to run out
and get 2.2” stadium truck wheels and some stadium truck tires.
That helped with ground clearance, going from about an
inch to just under an inch and a half, but I just didn’t like
the look. The
tires were too big and the truck tended to roll over more than
it had without them, so I put the stock tires back on.
was time for plan B.
took a good long look a the chassis, and decided that the cantilever
links, the links that connect the cantilevers to the axle, control
the ground clearance.
So I made them longer by unscrewing the rod ends.
Measuring between the ends of the rod ends (the metal
parts only), I extended them to 14mm.
You can use the gold wrench that came with the kit as
a guide…the end of the wrench with two openings should just
be able to squeeze between the plastic parts.
I put the wheels back on and put the truck on the table,
only to discover that there was very little difference.
After a moment of frustration, I realized that the shocks
needed to be adjusted.
Using the thicker shock clip in the kit (an unused part)
remedied the situation.
result was nothing short of amazing.
Almost 1.5 inches of ground clearance with the stock
tires, just as much as was gained by switching to the ungainly
stadium truck wheels!
as most mods do, this one affected something else. There was now a slight clicking coming from the drivetrain…the
stock dogbones were binding.
again, this called for a long hard look at the chassis. There are three links that connect the axles to the chassis:
the cantilever links, the upper links, and the lower
lower links control the distance of the axle from the chassis,
and together with the upper links, they control the angle of
the axle relative to the chassis.
In essence, making the lower links longer (while keeping
the upper links the same) rotates the axle down, so that the
outdrive points at the ground.
Decreasing their length relative to the upper links rotates
the axle up. The
opposite is true of the upper links.
some tinkering, I increased the length of all the links to the
following measurements (once again, measure the metal part of
the rod between the rod ends only):
increased articulation significantly, as you can see. The stock setup can barely clear a spray paint can (the small
lower links: 45mm
upper links: 34mm
(cantilever shock links stay at 14mm)
(there it goes again), the dog bone is not long enough and falls
There are two ways to remedy this: find a slightly longer
dog bone, or be stubborn and refuse to give up on the idea that
this kit could be built better out of the box.
I called this section “all stock”, but you will need something
not found in the kit…foam.
Just about any foam will do.
Cut out some small pieces and stick them in the outdrives,
both axle and center diff.
the foam behind the dogbone?
takes some patience, as you may or may not get it right the
first time. What
you want is a dogbone that stays in the cups (on both ends)
throughout the entire articulation range.
Too much foam on one end or too little on the other will
push that end out too much and the dog bone will drop.
I got one of them right the first time, but dropped the
other one during testing.
A little more foam on one end and all was good.
end result is a truck with a ton of articulation and a respectable
ground clearance, using all stock parts (and some foam). It really makes you wonder how much money Tamiya lost
in sales by marketing the truck with the limited clearance and
came very close to not buying it for those reasons, I’m sure
many decided not to.
2 - Not So Stock Mods
throw anything away…”
least in RC. If
you follow this tenet in your daily life you will be featured
on a Discovery channel show about crazy people.
items that I’m glad I didn’t throw away are the cheap plastic
shocks from the Losi Mini-T.
Most people buy the aluminum shocks right away and toss
the old plastic ones away (hopefully not in the trash).
Some people sell the old ones on EBay for a couple of
dollars (usually about $3.00).
I happen to own a Mini-T with aluminum shocks, and had
the plastic ones lying around somewhere.
If you have multiple sets, use the back (longer shocks).
If you only have one set, buy another set on EBay.
Until then, you can use the shorter ones on one side
(I put them on the front…my other set is in the mail)…just don’t
mix them up.
read a topic in the RC Universe rock crawling forum in which a
poster named garynjr put a set of these shocks in place of the
cantilever links. He
claimed this gave him great articulation.
I tried it, and he was right, the difference in articulation
was fantastic, and there was a big boost in ground clearance (which
required further adjustment of the upper and lower links to prevent
the stock dogbone from binding).
attaching the shocks, do not remove the ball ends on the cantilevers,
even though they look like they’re too big.
The shocks are made of soft plastic that will easily
stretch its way on there.
Just use a pair of pliers to force them on, then push
them past the center of the ball and they will move freely.
extra articulation comes from the fact that the cantilever links
(the Mini-T shocks) can expand or contract as needed.
When a wheel is lifted, its cantilever connector can
contract, and the opposite wheel’s connector can expand, allowing
the axle to articulate outside the boundaries of its suspension
geometry. In other
words, it can move
more than the length of the suspension links allow.
only problem with using the Mini-T shocks was that the truck
became very “tweaky”.
When driving, even slowly, the chassis would move left
and right a lot, twisting or tweaking as the truck moved.
This is present to some small extent in the stock configuration
as well, but the truck almost immediately rights itself.
Not so with the Mini-T shocks.
annoyed at this, I realized that while I wanted the extra articulation
of a flexible cantilever link, using an extra shock and getting
all sorts of freaky tweaky action was uncalled for.
So, off came the springs, solving all my problems.
When driving flat, the TLT rested on the fully closed
Mini-T shocks and drove like stock.
When articulating, the opposing link expanded as necessary,
greatly increasing the motion.
Some ground clearance is lost when removing the
springs (as that reduces the length of the cantilever link),
but a couple of zip ties used as spacers remedies this.
Raise the spring-less shock and wrap zip tie around the
metal shaft, pulling it tight and clipping off the excess.
I used two zip ties with the bottom one wrapped around
a small block of foam (because I was in the mood to cushion
zip ties is the quickest way to shim the shock…feel free to
come up with a more elegant solution.
end result was a ground clearance just a little less than I had
with the springs (maybe 2mm).
The trade off, for me, is worth it.
If you don’t mind how tweaky it is with the springs, by
all means leave them on.
3 - Center of Gravity
who puts battery on top of chassis will roll down hill…”
of these mods did nothing to improve the truck’s performance.
All they did was give me some online bragging rights.
at my awesome TLT! Behold
the articulation in its stock form!
That’s more that you have and you stretched it by five
feet! I’m better
than you! Muhahahahahaha!”
What I did not post was that this silly truck flipped
over every time I tried to climb anything.
Raising the ground clearance raised the center of gravity,
and extra articulation made it easier for the top of the chassis
to pivot to rollover position every time I crossed an obstacle.
was ready to cry. All
that work, for nothing.
Instead of crying, however, I decided to do something
about it. The
first step was to go from six cells to four.
That helped. It
did cut down on top end (oh no, you mean I can’t race my rock
crawler??) and a little run time, but it was nothing to write
home about. I mean
the gains, as well as the losses. The truck still rolled over.
realized that the batteries had to come down, but the chassis
is so small there isn’t much room.
I looked at putting them on the axles as some crawling
enthusiasts suggest, but that would mean I’d have to run 2 cells.
I decided to make a saddle style pack and place the cells on either
side of the chassis, attached with some hook-and-loop Superlock
fasteners (available at Radio Shack).
The wire that connects the pack holds the batteries up,
the hook-and-loop fasteners just keep the cells from swinging
Here is the pack:
And here is how it’s mounted:
I had to cut away a part of the plastic gear cover
to make the batteries sit flush.
4 - Conclusion
how it all comes together…”
a difference! The
low center of gravity allowed the extra ground clearance and
articulation to work in the truck's favor.
I could now climb things that previously were unapproachable.
In short, I had a real rock crawler that from a distance
looked like a stock TLT-1 MaxClimber. I
have an E-Maxx tire worth of articulation (that’s 1.2 soda cans
for those who need precise measurements), 1.2 540 motors worth
of ground clearance, a center of gravity so low I can climb
on the ceiling (but only when I’m sleeping), and the only non-stock
parts are a pair of three dollar Mini-T shocks.
didn’t the engineers in Tamiya do this to begin with?
I don’t know. Maybe
because they are evil and want us to suffer.
Or, maybe because it feels so much better to do it yourself,
and this is, after all, a hobby.
luck with your own TLT, and I hope you enjoy these mods as much
as I do. There’s no limit to where you go from here; stretches, custom
chassis, etc. Just
remember that you bought the TLT because you liked the size,
and that a bigger crawler isn’t necessarily better, it’s just
bigger (rocks come in all sizes).