54 OCTOBER 20194-WHEEL & OFF-ROAD 4WHEELOFFROAD.COM
COVER SECTION: JUNKYARD SPOTTERS’ GUIDES
UNICORN BLOOD
& ANT FARMS
JUNKYARD
AUTOMATIC
TRANSMISSION
SPOTTER’S
GUI DE
A
IRPLANES FLY, COMPUTERS DO
more and more stuff every day, and
automatic transmissions shift when
they are supposed to. We have faith in
all these things, even though all of us
may not understand them fully. At the
end of the day it’s still hard to believe
that thousands of pounds of metal , fuel , and
human bodies could soar through the sky, but they do, and with great regu-
larity. Similarly, small metal or plastic boxes filled with diodes, electrodes,
magnets, solder, wires, and a little electricity create and store most of what is
“important” to a computer-reliant world. How? We, personally, have no idea.
Automatic transmissions are perceived by many to be lubricated with uni-
corn blood and filled with mystery. Near as we can tell, said blood is pumped
through a thing like an ant farm lying on its side past check valves, solenoids,
bands, clutches, and maybe even the occasional gear, and somehow rota-
tional forces arise in the middle. It’s mystifying, but we know even automatics
somehow do what is expected of them unless they get too hot or run low on
that pink viscous fluid.
But one thing that’s not as mystifying is selecting an automatic transmis-
sion that won’t leave your 4x4 dead on the side of the trail. Here are some of
our favorites and how to spot them next time you’re looking for a magical
mystery box for your next build.BY Verne Simons
[email protected]
PHOTOGRAPHY 4WOR ARCHIVES
AND THE MANUFACTURERSGM
TH350
Overview: A compact and strong three-
speed automatic transmission that can
be adapted to many transfer cases and
bolted behind lots of engines.
Found In: 1969-1984 rear-wheel-drive
GM cars, including those with BOP bolt
pattern.
Identification: Aluminum alloy with
integrated bellhousing, 21^3 ⁄ 4 inches long.
Square oil pan with one corner cut off.
Ratios: 2.52:1 First, 1.52:1 Second, 1:1
Third, 1.93 Reverse.TH350