(Click any picture to enlarge it)
The completed car with all electronics installed.
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Yokomo MR4-TC Special (reviewed by Speedo)
Product:
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Kit Cost:
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MR4-TC Special
1/10 Scale 4WD Electric Touring Car
Yokomo
MSRP $495 / Street Price $265
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Introduction
When Yokomo first announced the MR-4 touring car in 1999, it was defined as an
"entry level" kit and aimed at people with a lower budget. Still, the car had
a long list of features that easily rivaled some of the more successful racing
designs of the time. It came equipped with full bearings, a molded "low-CG"
(center of gravity) chassis, ball differentials, lightweight nylon diff outdrives,
and more. As a marketing ploy, Yokomo equipped a few of their Team drivers
with the car to show off at several large races. Surprisingly, Barry Baker and
Masami Hirosaka did very well with it and reported that it was just as capable
as Yokomo's purebred racing platform, the soon-to-be-replaced YR-4. Not bad
for an "entry level" kit!
Not long after the MR-4's debut, Yokomo decided to pull out all the stops and put
together an MR4-TC Pro kit, aimed at the racing market. New features included a
graphite chassis, a new one-piece upper deck, ball-bearing steering, titanium
turnbuckles, aluminum threaded shocks and more. With this new car, Team Yokomo
became a force to be reckoned with, and racers all over took notice of the car.
After the release of the Pro kit, Yokomo continued to release upgrades and updates
for the car, giving racers plenty of options. Former Yokomo driver Atsushi Hara
piloted a heavily-upgraded MR4-TC Pro to the 2000 IFMAR World Championship at
the Yatabe Arena in Japan. Within months, Yokomo released a "replica" edition
of Hara's worlds-winning car, the MR4-TC Worlds. In addition to everything the
Pro kit had, the Worlds kit came with front and center one-way units, tons of
graphite, optional sway bars, extra blue aluminum parts and more.
Despite how far the car had already come, Yokomo did not stop work on the MR-4
platform at all. In early March of 2001, Yokomo announced that it had been
working on a new version of the car, dubbed the MR4-TC Special. The car was to
have a newly designed chassis and pulley system, among other things. Not only
that, the car would be offered not just in kit form but as a Conversion Kit
for earlier versions of the MR4-TC as well. Demand for the MR4-TC Special,
both in kit and conversion form, was fairly high. When the car finally arrived
in May of 2001, Yokomo once again delivered a fully competitive touring sedan
boasting increased cornering speed, a lower center of gravity, and a lower weight.
Chassis and Drivetrain
Similar to previous incarnations of the MR4-TC, Yokomo chose to stick with a
molded composite graphite chassis for the new Special. Of all the changes between
the Special and previous cars, the chassis is the most radical. Yokomo chose to
make it much narrower than before, moving the weight distribution more towards the
center of the car. Also included are new cutouts that should accommodate all of
the newer battery types, and a finned cooling area for the motor. In addition to
the new chassis, a new graphite upper deck can be found on the Special, milled to
be lighter and to allow for a bit more flex. More flex gives the car more traction
and a more forgiving feel, but this may not be a welcome change for experienced racers.
The new Special chassis is comparatively very light, weighing in at nearly 2 ounces
lighter than the Pro/Worlds chassis. Once again, the narrower and lighter chassis
gives slightly more flex than the older version. The motor sits in the rear of the
chassis, on the opposite side from the six cut-out battery slots. Unfortunately, the
only real room for electronics is in front of the motor on the left side of the car,
which presents a problem for anybody who does not have a small-size ESC and receiver.
I had to mount my Cyclone horizontally and stand my XXL up on end in order to fit
everything into the car. Anybody with a larger ESC than the Cyclone will most definitely
have trouble getting it into the car. Still, with the electronics installed, the
chassis has a very smart look about it with very little unused space.
Another one of the new features to come to the Special is a blue aluminum battery
strap in the shape of the Yokomo logo. With larger batteries like 2400 cells, I
had to file parts of the chassis down to allow the batteries to fit. Although this
was frustrating, the batteries did end up having a very tight fit. With smaller
cells like the newer SMH3000's, no modification should be necessary. Another problem
with the aluminum battery bar is that it can interfere with the solder-tabs on a
side-by-side 6-cell pack. Extreme caution is necessary to avoid shorting out a
charged pack!
One final change to the layout of the Special is a new motor mount, allowing the
motor to ride much lower in the chassis. This lowers the car's CG, and that coupled
with the fact that both the motor and the batteries ride closer to the center of
the chassis means that the car can corner faster, and with less chassis roll. Also,
the newly designed motor mount and center one-way pulley leave the belt running
directly down the center of the chassis, completing the effort that Yokomo put
forth to really centralize everything on the car. The belt itself has been redesigned,
being much thinner (and stronger) than old versions to help reduce friction.
Steering and Suspension
The MR4-TC Special uses a dual bell-crank sterring system with a heavy-duty servo
saver built in the bell-crank closest to the servo. The servo itself is facing
outward, connected by a tie-rod to the crank system. The front hubs sit inside
5-degree castor blocks and are held in place by kingpins. Yokomo makes option
parts that allow the castor to be adjusted.
Blue aluminum threaded shocks are standard on the Special, and are really top-notch.
The shocks are top-fill, complete with a bleed screw in the cap to assist in building
fully "pressurized" shocks. The only problem one could find with the Yokomo shocks
is in the assembly process, where it is necessary to insert a small rubber O-ring in
the shock collar. It's a tedious and time-consuming process that people have been
complaining about since the original MR4-TC Pro, and one that I really had hoped
would be fixed by the time this kit came to be.
Graphite shock towers come standard on both ends of the car, with plenty of mounting-hole
options for adjusting shock position (3 left-to-right holes in the front, 5 total holes in
the rear for up-down as well as left-to-right positioning). Camber-link locations are
also quite plentiful in both the front and rear of the car, making roll-center adjustments
very easy. Both the front and rear suspension arms have inner and outer mounting holes
for the shocks, allowing for further adjustment. The hinge pins on the arms are captured
by small phillips-head screws, eliminating the need for E-clips. Still, the screws are
a bit difficult to work with, and without the use of caution it is quite easy to strip
them.
Another upgrade included with the Special kit are new sway bars for the front of the car,
adding yet another tuning option. One has the option of running either the new or old
style sway bars in the front of the car, with one being mounted to the front and the other
to the rear of the bulkhead. The new rear suspension arms are much thicker than those
in the previous incarnation of the MR4-TC, and allow for wheelbase adjustment. The
Special arms do tend to take away a bit of rear traction, so it comes down to a driver's
personal preference as to whether to run the Worlds-edition or Special-edition rear arms.
It is yet another of the many minute tuning options to be found on the car.
Other Stuff
The Special kit includes lightweight blue aluminum drive shafts, thought I opted for the
more durable Shiny CVDs from MIP (I wasn't able to notice a performance difference in
running the heavier MIP shafts). Also included are both the front and center one-way
units, which increase the car's corner speed but make it much less beginner-friendly.
Novice racers should convert the car to full-time 4WD until they feel comfortable enough
with it to use the one-ways (the front one-way is fairly fragile and a hard hit may very
well break the bearing inside of it). The Special also comes with a full set of Lunsford
titanium turnbuckles, and as mentioned before, full ball bearings.
On the whole, the kit is reasonably easy to work on, and almost all of the screws are 2mm
hex screws, which is nice. Still, getting at the diffs is a pain; the car has to be
torn down quite a bit before either diff can be removed for maintenance. Pulling the motor
in and out of the car can also be challenging, since there is a very small amount of space
to get a hex driver in to the pinnion area.
The Verdict
Overall, the MR4-TC Special is a formidable car that has the benefit of years of design
work and track testing behind it. No one can argue with the success that the MR4-TC has
enjoyed in the capable hands of some of the world's best R/C drivers, and the Special
represents the latest in racing innovation.
Still, the car may not be the best choice for novice racers. The level of complexity is
reasonably high, and the sheer amount of tuning options can be quite overwhelming to a
newcomer. On top of that, some of the "quirks" in the car's building process can become
quite frustrating, even to an experienced builder.
Despite these caveats, the MR4-TC Special is a serious contender at any track. Experienced
racers will love the tuning options the car has, and it gets more and more durable with
each new version. The lower CG and enhanced drivetrain give the car a much more responsive
feel on the track, and the double one-way set up gets the car out of the corners as fast
as possible.
The bottom line: If you are in the market for a serious racer that comes fully hopped-up
right out of the box, this is the car for you, and you will find few other kits that match
Yokomo's in terms of quality and craftsmanship. Get one today!
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Likes
- Proven racing platform
- Excellent parts quality
- Plenty of room for tuning right out of the box
- All conceivable hop-ups included
- Excellent factory parts support
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Dislikes
- Added chassis flex may not be good for everybody
- Some quirks in building process
- Very little room for electronics
- Sheer amount of "tunability" may be overwhelming for less experienced drivers
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Speedo's Rating
Craftsmanship:
Innovation:
Performance:
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Overall:
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10
8
9
9
9
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