Tamiya 1/16 R/C Tank
Transmission Modifications
No one
would disagree; Tamiya tank transmissions are light years ahead of the Bandai
units.
Still,
in stock form they are prone to failure from just normal use. The problem is one
of materials and under-design. The side plates of the Tamiya units may look
sturdy however the design allows for torsional bending. The bending under load
leads to misalignment of parts and excessive wear. Gear failures have led some
R/C tankers to search out replacement gears in brass or steel to replace the
nylon ones. This ‘fix’ is reported to cost $50 in parts. There have not been any reported gear
failures from those who installed the metal gears, but that is not a
commendation. Adding stiffer parts
without addressing the underlying cause just means one is relocating the
stresses to other components. It may take longer but at some point something
else will fail.
The
value of using nylon gears is that they cost less than brass or steel, nylon is
quieter than all metal-to-metal and has some anti-vibration qualities. It is
however more susceptible to fracture from a given level of stress than steel.
If the side loads and bending can be eliminated then the Nylon gears can be
reliable and do the job quietly. Armour Concepts proposes that they have the
solution.
Armour Concepts Trans Mod Kit
Kit installed in a Tiger I Display
Model.
Review
by Kevin Savage
Garnik
Ghaloostian is the owner of Armour Concepts.
He calls his first product the Trans Mod Kit. The kit’s function
is to stiffen and maintain alignment of the Tamiya transmission components.
“What
qualifies Garnik to second-guess Tamiya’s engineers?”
Garnik
designs miniature power transfer systems as part of this ‘REAL’ job. Garnik is
president CopterWorks. His company
supplies R/C helicopter movie-camera platforms for the Hollywood movie
industry. Generally, his company is commissioned to design/build one-off custom
creations. Garnik’s creations are his livelihood. His products must work.
REALLY big money is at stake when a movie crew is filming. They cannot sit
waiting for a ‘toy’ helicopter.
Garnik
investigated the 1/16th Tamiya Tiger’s transmissions and DMD units
for possible adaptation to his ‘copter business. Being a technical
perfectionist, (we R/C’rs are lucky that he is) Garnik measured the
transmissions while running and under various loads. He discovered what we R/C
tankers already know; these transmissions need additional work.
Example:
holding your tank securely, try to move the drive sprocket for ‘play’. You’ll
find that the entire transmission can be flexed.
Garnik’s
kit eliminates trans frame flex and thereby any misalignment/binding of the
final output shaft and track drive sprocket. The kit is a pure bolt on and
requires no drilling or butchering of the transmission. The parts are all
hi-tensile aluminum CNC machined to guarantee a perfect fit. It also provides
one stainless steel gear to replace one brass gear in each gearbox. While the red
anodizing is an eye-popper, it is purely cosmetic. The anodizing does seem to follow Garnik’s penchant to deliver a
‘finished’ product.
For the
Tiger he includes a cross-member that ties both transmissions together over the
top. The transmissions are already tied together across the bottom i.e., being
bolted to a common hull pan.
This
added cross-member creates a box-section. Any hot-rodder knows that boxing the
frame is key to power delivery and to decrease breakage from flex. For the
Tamiya Sherman, no such cross-member is offered. Not that the Sherman would not
benefit. Garnik states there just isn’t room to fit one under the forward hull
shell. Even without the cross-member the Sherman transmissions benefit greatly
from the CNC made stiffener/bearing blocks.
The kit
is available for the Tamiya Sherman, King Tiger and Tiger I Early Production
equipped with dual transmissions. Cost at the time of this review is $ 75.00
for the Tigers, $70.00 for the Sherman.
K.S.
ZAGI 400 Replacement Motor by Trick R/C
6 Volt Zagi-400 balanced Speed 400
motor with built in capacitors.
Review
by Dick Bernier
The Zagi
Speed 400 motor from Trick R/C has been wound to obtain low RPM (somewhere in the
6500 to 7000 RPM range) and higher torque than the 380's. Pat Matthews has
tested them electronically and I have tested them on the battlefield. When you
run two Tigers side by side, one modified with just a change to Zagi motors,
and one “straight out of the box”, the speed differential is very noticeable.
We found the real value of the Zagi’s through some assessment and a lot of
luck. Understand there was no "Genius" on my part involved in this
discovery. (I wish there was)
I then
swapped out the stock Nylon gear at the final-drive shaft for a metal
replacement gear. I decided to add the Nylon gear back to the transmission to slow
the Tiger down. (I was targeting 14 in/sec for a scale like cross country
speed.) The Nylon gear was installed using a new brass bushing and short steel
shaft just off the motor end of the transmission gears. I did some very
SIMPLE fixes to accomplish this. I
did have to push the motor pinion on up to the bell housing of the motor. The
motor stays in the same mounting holes. The entire conversion took two or three
hrs. I also converted Kevin Rimrodt's Tiger and
Mike Gregoreus's Sturmgeschütz. Both tanks have Kenny Kong replacement metal
tracks do very well on the battlefield with the full Tamiya modified set-up.
The Zagi
motors alone reduce the Tigers overall top speed by about 35%. Even so, you
still need a gear reduction. We found that at our last tank run the Zagi
motor/gear-down combo achieved a good 14 in/sec which is in line with the 1:1
Tigers 20 Km/h cross country speed. The
Applied effects Speed Reduction Unit (above) will be a God send to the guys
because we need to control the speed in the tank battle contests. It is most
likely that speed limits will end up in the contest rules.
D.B.
(My Tamiya Tiger came supplied with 380 size
motors. Tamiya supplied Mabuchi knock-offs made by Johnson Electric. The motors
had very sloppy armature fore/aft play. In the course of installing the Applied
Effects kit I discovered one of the Tamiya motor armatures fore/aft movement was
5/64”. The pinion gear could move forward and contact both the A.E. gear
reduction unit and the big nylon gear at the same time. A lock up of the big
transmission gear resulted. I could not test the Applied Effects kit using the
defective stock motors. I had to swap out the Tamiya’s for Zagi’s. Zagi’s
Mabuchi-built motor is a much better product, even without the chrome. K.S.)
Applied Effects Speed Reduction Unit
Prototype installed in a Tamiya Tiger I
full option model. Arrow points to a potential pinion lock–up problem. If your
motor’s armature has too much forward play, it can ride onto the big nylon
gear. Check your motor!!
Kit contents, penny is to show
relative size if components.
Review
by Justin Day and Kevin Savage
The
first thing you’ll notice when you open the package is the smell and stain of
machine shop oil. Yeah! Here is the real deal boys... no namby-pamby stamped
metal... this stuff IS MILLED! The Applied
Effects kit has that ‘industrial’ look. Sure it lacks a jazzy polished
finish but that is not to say the parts are rough. To the contrary, all the
finishing effort is spent where it counts. The cut edges are smoothed, the
corners are rounded and the holes are champhered. The consumer may not notice
these touches but the attention to such details says Hi-grade work.
A
two-page instruction sheet is included in the kit. You’ll find the reference photos helpful as the written
instructions could use some fine-tuning for general readability.
The
reduction unit consists of a steel double-gear in an aluminum frame. This frame
mounts into the Tamiya transmission replacing the rear most brass tube spacer.
A donut shaped aluminum spacer is supplied. The spacer is fitted between the
electric motor and the transmission frame. This machined donut spacer moves the
motor away from the frame to align the pinion with the big-end gear of the
reduction unit. The original Tamiya motor mount screws are re-used to mount the
motor to the spacer. Additional 2-56 machine screws are included to mount the
spacer (with motor) back onto the transmission frame.
When
installing the reduction unit you must first remove a brass rod frame-spacer
located at the top/rear of the transmission. I urge you to grip the rod with a
pair of vise grips, clamping down gently with just a touch of ‘bite’. The
screws that hold the brass rod in place are secured with thread-lock compound.
Without the vise-grips, you run a good chance of hurting yourself or the
transmission. Attempting to break the screw’s hold risks slipping off the screw
slot and impaling something (like a hand). Believe me on this… without
vise-grips the screw will win!!
After
inserting the reduction unit and securing with button head screws you must ‘set
the gear lash’ (amount of space between the gear teeth). For the purpose of
adjusting the gear lash, paper strips are supplied to use as a feeler
gauge. No recommendation is given to recheck
the gear lash after running in the transmission. If you subscribe to “Murphy’s
Law” you may want to recheck after some extended running in to ensure that the
lash remains stable. The final modification is to reverse the wires on the
motor so that the motors run the opposite way of stock. That’s correct. The
extra gear you just added makes the whole transmission run backwards. You
correct this by flipping the motor leads or using the channel reverse feature
(if your transmitter has that option).
There
should be no increase in noise level from your transmissions after kit
installation. If one of your transmissions is louder than the other check that
the quieter transmission is not binding anywhere when you rotate it by hand. If
the quieter transmission has any tight spots, readjust it first and then repeat
the sound level check of both transmissions. If the other transmission is still
louder it needs the gear-lash set a bit closer.
As with
the Armour Concepts kit above, no butchering of your expensive transmission is
expected. The Applied Effects kit is a drop in installation taking about 90
minutes.
“So how
did the kit alter Tiger I performance?”
Justin
Day reports to us as follows…
“I ran
the time trial 3 times. The results were the same on every run…
120'/min=
7200'/hr=1.36mph----> scale speed 21.76 mph (pre-measured, running start,
and checked twice)
The A.E. kit also improves the performance. The tank can now climb about 5
degrees more of an incline without sitting and spinning its tracks as it did
before (tested on a packed dirt hill).
This
gear-down makes slow driving easier especially turning. The speed of the turn
and where the turn stops is more controllable. When I would creep the tank
along it would speed up significantly if I were to try to turn hard, with the
gear-down it speeds up a little, but it is a much more controlled turn. I rate
controllability is the greatest benefit after installation of the A.E. kit. The
kit allows you sufficient but not excessive speed and makes the tank easier to
drive at slower speeds when you have to creep around buildings and stuff.
I think it is perfect. Given the simple installation, and the low cost, I would
suggest is as a method of slowing down the Tiger to anyone.
In
factory performance tests the Tiger attained a top speed of 23.61 MPH. One particular Tiger test vehicle recorded
an absolute
top speed of 27.96 MPH. Actual sustained speed on the highway was 12.4
MPH,
while cross-country performance was 9.32 MPH. These Tiger MPH stats were speeds
that were determined to be the best speed for the Tiger in conditions that were
for saving gas and for minimizing wear on the tanks (from the book “Germany's
Panzers in WWII” by author Jentz). I am sure that in combat there were
some tankers that found ways to balls out run. Now, that is not to say
that in a city or town, you would be running that fast at all. Most of
the time, I find that in a tight spot, I drive VERY slow, that 88 gets hung up
all of the time if you fly around!
I am
using hot batteries. My Tiger was faster than some of the others due to the
good batteries. I theorize the gear-down will reduce the speed advantage
of hot batteries so that you can present a more level ‘playing field’ for
battle-tank competitions. The hotter batteries will still give you the extended
running time, just not as much speed advantage. J.D.
The test was performed using Justin’s full
option Tiger I and Kevin’s R/C’d display Tiger I as test vehicles. Here are the results…
Test Course: Level
Asphalt Time: Wide-open run for 10
seconds.
Stock transmissions and
motors Applied Effects
kit
A.E. kit and Zagi motors
51.5 Feet 20.00
Feet 18.5 Feet
(scale 56.18 MPH, 238% of 1:1
speed) (scale 21.76 MPH, 93% of 1:1
speed) (scale 20.16 MPH, 86% of 1:1
speed)
Summary:
So, if
you want scale speed and good controllability, the Applied Effects kit is the
way to go. The cost is $69.95 +$5 S&H +tax if your in Ca. This is money
well spent for the control and low-end grunt you'll gain.
The Zagi
motors act as an additional gear-down. With the kit and the Zagi’s you gain
maximum pulling power and low speed controllability at a sacrifice in top end
scale speeds.
I
foresee that these results could spark a further debate. Just how does the additional controllability
of the A.E./Zagi combination offer increased accuracy and scores at battle-tank
competitions? Considering how successful
these tests have been, we’ll soon be seeing the result! K.S.
Follow
up 12/05/02:
Here is
an interesting email I received from a reader. k.s.
Dear
Kevin,
I finally received my Applied Effects Tiger1 gear-down kit last Friday. Spent
the w/e fitting, testing and comparing the set-up between the Zagi 400s vs.
Perkins 480s mentioned below.
I used the Perkins 480s first. These fitted fine. The Applied FX ‘donut’ slotted
in well despite motors being 8mm longer. Endplay same as the Zagi’s so no
problems with gear crunch. Set-up good control at low revs but overly powerful
on throttle - plenty of low-end grunt yet top speed far too high with excessive
and biting acceleration on slow turns if not careful with the stick (much the
same as the stock kit).
Then I tried the Zagi/Applied FX/Garnik combination. Much better but not as underpowered
as the 86% suggested. Indeed, it seemed to me that the set-up provides a
max speed that is still over the top. My set-up (includes Kenny Kong's metal
tracks) seems on the fast side - maybe it’s my imagination. I tested it against
the scale down distance mentioned which came out the same. I guess we are all
victims of our own experience. Mine is 28 years on Chieftain tank, which has
left me with a fair feel for how a 56-ton tank feels and performs between 0-30
mph! This is not to say that Chieftain's performance was the same as the
Tiger's, simply that I know how a big tank handles at these speeds, on road and
off.
But to sum up, the set up is great and I'm very happy with the scale speed.
Charles Roskelly
