GT-TUNED 25T POWER
Sorry, Tamiya fans—Tamiya did not bring back
the 1986 Bigwig’s original Technigold motor,
but the kit does include a unique motor with
a similar vibe. ;e 25-turn “GT- Tuned” motor
gets a Bigwig decal for its chrome-plated
can, and the fully rebuildable design includes
stu; from the final years of brushed-power
dominance. Tamiya supplies 13T and 15T
pinions with the kit, so you can choose a
10.043:1 or 8.704:1 ratio. I went ahead and
installed the 15 T gear.
The Bigwig gets a specially decaled version of Tamiya’s
GT-Tuned 25-turn motor. It’s rebuildable and has surface-mount capacitors.
Here’s a weird detail:
Stacked metal shims are
used to set gear mesh. The
manual specifies the order
of the shims required for
each of the four available
Of course it’s old school—this car is
from 1986. But what’s especially old school
are the di;erentials, which are not enclosed
in a case and removable as complete units, like
modern cars and even other Tamiya models of the
era. Instead, each di;erential’s output gears are fixed to
their respective halves of the gearbox. When the gearbox is
assembled, the di; gear is simply sandwiched in place. It works
just fine but is much less convenient for maintenance. Or it was,
anyway—modern Bigwig drivers won’t likely be getting into the
gearboxes after the initial build. A wire propeller shaft connects the
front and rear gearboxes, and dogbone driveshafts are used all around.
The Bigwig’s differentials cannot be removed as self-contained units;
they are, instead, held together by the gearbox.
The dogbone driveshafts are hefty hunks of steel. They’re color-coded
because the front (black) driveshafts are a tick longer than those used
in the rear.
In order to lift the center driveshaft above the battery, the Bigwig puts a
lot more gears to work than modern designs.