These are my tips mostly
for asphalt running but you will hopefully find them useful when running
on carpet as well. I will not cover all parameters that you can adjust,
only those I feel are most important.
First, check my standard
setup that work well for me almost everywhere.
Here are a few critical points when
setting up the MR4TC:
- tires and foams are always the
most important
- shock lengths are extremely important.
- use stiffer rear springs and more
toe in on the Special
- make sure the diffs are really
smooth
Shock Length
As I said, this is very important
on the Yokomo. I always try to run the front shocks as short as possible.
Longer shocks (more droop) will give a bit more steering but will make
the car very unprecise. The front end will wander and it will be very hard
to get any feeling for the front end. With my standard setup I try to run
59.8-59.9mm with a ride height of 5mm. This will give the car very little
droop.
Now the rear shock length is not
as crucial but still very important. Longer shocks (more droop) will give
more grip. I have found 60.2-60.3mm to be good with a 5.5mm ride height.
60.0mm is the shortest I have gone. If you run a lower ride height you
obviously have to run shorter shocks if you want to keep the same amount
of droop. As a final note...droop screws would be really nice!
Springs
Now I know that most people running
the Special will tell you that you can run the car softer than the previous
cars from Yokomo (Pro, Worlds). This is what I did in the beginning as
well. Somehow I thought the car was always a bit close to the limit and
difficult to drive. The Special was designed to be a very responsive car
(with the battery so close to the middle of the car) but it was almost
too responsive. I tried to fix this with running soft (blue) rear springs.
This did not work very well so I then asked Masami if he had any cure for
it. As it turned out they had experienced the same thing and also had a
cure for it. He told me to run green rear springs, which are actually quite
a bit stiffer than the yellows that were then the standard setup. He also
told me to remover the rear roll bar and run 2 deg toe in. At the next
test I tried this and was surprised at how well it worked. The rear end
of the car was planted and it was so easy to drive. With more testing I
found that in some cases running the green springs would overheat the rear
tires. So on my standard setup I run the silver springs (YS-14525) which
are in between the yellow and green. I still use the green springs in some
cases, depending on tires and temperature.
Silver springs is what I mostly
run on the front as well as the make the car very neutral and logical.
In really high grip conditions I would use the green springs to calm down
the front of the car. I have also used the yellow springs but they make
the front a bit slow.
Go to the Yokomo Spring List
showing the stiffness rates
Rear Toe In
There are three different hubs for
the MR4, 0, 1 and 2 degree. On the previous cars I almost always used 1
deg hubs. After Masami told me about running 2 deg I have always used them.
The only time I run 1 deg was when I was having problems with corner-exit-understeer.
Roll Bars
For the front end there are 3 different
roll bars available. The ZS-412F uses very short bars and I would say that
this is the type that works least well. The ZS-412FW is the type that was
included with the Worlds car and is also included with the Special kit.
Finally the latest type is the ZS-412FSP which is also included in the
Special kit. I almost always run the silver (1.2mm) SP type roll bar as
it gives the smoothest turn in steering. In really high grip conditions
you might want to run a stiffer roll bar to calm down the front of the
car.
I have basically stopped using the
rear roll bar since I started using stiffer rear springs. When I used softer
rear springs I used the rear roll bar to keep the rear of the car more
stable.
Suspension Arm Position
On the front I always run the front
arm in the most extreme angle (lower inner pin hole and upper outer). This
will give the car really good steering around the apex of a corner compared
to running the arm more horizontal. The car will be also be really stable
and controllable during corner-turn-in. Running the arm more horizontal
will give the car a bit more turn-in-steering but less around the apex.
I always run the rear arm in the
lower inner and outer holes. Using the upper inner hole will make the rear
of the car really stable but the car will roll through the corner (more
corner speed) a lot better when running the standard position (lower inner
& outer).
Upper Deck and Arm Material
On the Special the upper deck is
made of graphite composite. I would probably run this on high grip carpet
but on asphalt I run standard plastic upper deck from the MR4TC Worlds.
I have additionally removed the 2 center sections of the upper deck to
increase flex. This simply give the car a bit more steering and really
make the car more consistent and predictable.
The same goes for the rear arms.
The new rear arms are included in the Special kit. I really liked these
on carpet but on asphalt I have been running the old standard rear arms
(ZS-008R). Again, they give a bit more steering while making the car more
consistent. The only negative side of using the old arms is that they don't
allow you to set the wheelbase.
One Ways: I always run double one-ways.
Damping: I mostly run 40wt/#3.
Shock Position: Always in the most
stand up position.
Camber Link: #2 front and #1 rear.
On high grip carpet I might run the rear link on the bulkhead.
Ride height: Front, 4-5mm. Rear,
4.5-5.5mm.
Wheelbase: Longer will make the
car more stable
Caster: Use standard 5 deg blocks
as I feel the 3 deg ones make the car difficult to drive.
Camber: Between 0.5 and 2 deg depending
on tires and track.
Carpet with Foams
I have never tried this myself but
this is what you probably would want to change compared to my setup:
- Front diff and direct center pulley
for direct drive
- Stiffer springs (use Yokomo GT4
springs)
- Stiffer damping
- Graphite composite upper deck
and new type rear arms
- Rear camber link on bulkhead
Troubleshooting:
