Yup. That's what I
need, I told myself. A
locker for my Toyota.
Yup. But wait a minute.
Is that what I really
needed? Maybe it was
and maybe it wasn't.
What would Gaffer
say? To find out, I
contacted the old coot
and asked him.
So that you understand, Gaffer has
owned an FJ40 Land Cruiser since the
1970s. He kept the truck through thick
and thin including several marriages
and divorces. "Yer gotter have yer
priorities," said Gaffer. Over the years
he had exhibited an almost frightening
lack of good sense and dumped tubs of
money into all kinds of modifications.
TOYOTA, he said, stood for Toss Out
Your Total Assets and that is almost
what he did. Knowing that he must
have tried a variety of differentials, I
humbly approached him, hat in hand
with downcast eyes and begged for
wisdom. Fortunately for me, Gaffer was
in a loquacious mood.
"Well," wheezed the old geezer. "You
are one lucky lad. I just happened ter
be cleanin' out my garage and stumbled
into a couple of old differentials. Come
on in here and quit standin' around
with yer teeth in yer mouth."
With awe painted over my face, I
entered Gaffer's garage. It was almost
more than I could bear. The Cruiser
parts, the aftermarket goodies, the
drivetrain and suspension parts were
overwhelming. Then, there were the
tools ranging from simple hand tools to
welding and fabricating machines. The
old coot led me through his decade's
worth of accumulated treasures without
sparing them a glance while I trailed
behind in a state of awe and lust. It was
too much and I was relieved to arrive at
his workbench.
The first thing that he showed me
was one of his old open differentials.
Don't ask me why, but the coot
keeps everything. "This here,"
said Gaffer laying his hand on the
open differential, "is a marvel of
engineering. Yer have two of `em and
yer don't even appreciate what they
do fer ya. They let yer Toyota's wheels
travel at different speeds. You young
pups don't realize it but yer wheels
travel at different speeds all the time.
The only time they comes close to
goin' at the same speed is when yer
driv'n down a smooth highway in a
straight line."
"But even then," snapped the Gaffer
as he glared at me to drive home his
point, "yer tires have to be exactly,
mark me exactly, the same size with
the same air pressure or they go
different speeds. And on corners,
every one of them there tires goes at a
different speed. Yer didn't know that,
now did yer?"
I didn't have the courage to tell him
that I knew that open differentials
allowed each tire to turn at a different
speed. Gaffer was on a roll and who
was I to interrupt him?
"These open diffs are perfect for you
whippersnappers," growled the old
coot, "who just use yer four wheel
drive Toyotas to fetch groceries."
Then, peering through his bushy
eyebrows at me one of which seemed
to be singed from his latest work in
the garage he lowered his voice and
said, "Now I'll tell yer, there is one
place where open differentials can
save yer butt. And that is on snowy
highways. On snowy slippery roads
yer really do want each tire to travel at
its own speed. Otherwise, some of `em
are gon' to be slidin' on the snow. Why
I have rolled my Land Cruiser more'n
once by driven' on snowy roads with
lockers. If yer goin' to use yer Toyota
to drive to ski resorts, keep these open
puppies in place. Yer sure as shootin'
don't want to be locked up on snowy
highways. That's a quick way ter git
yerself upside down in a hurry."
Turning from the open differential, the
grizzled old veteran dragged a box out of
a cupboard and set it on the work bench.
After grinning a sly grin at me, he opened
it up and hauled out another differential.
"Now I'll bet", he said with some pride,
"yer've never seen one of these for an FJ40
Land Cruiser."
I examined the differential, noted the
associated metal adapter ring and the
oddly drilled-out bolt holes and admitted
that I had never seen anything quite like
it before.
"This here is a specially modified Truetrac,
made to fit an FJ40." After rummaging
around in the box he pulled out a couple
of old receipts and continued. "This
Truetrac was for a GM 12 bolt `C' clip
rear axle that I sent to my ol' pal Jim, you
know..." Seeing that I obviously had no
idea who Jim was, Gaffer growled and
said, "Well, Jim was one of the great, early
off-roaders who machined this adapter
plate and re-drilled the differential's bolt
holes so as that they would match my
FJ40's ring gear."
"In my day", continued the grizzled old
goat, "yer couldn't get a Truetrac for an
FJ40 and yer know what? Yer still can't!
To put a Truetrac in an FJ40, yer will need
to do what I did and get a Truetrack for
a GM corporate 12 bolt (modern part
number 913A315) and modify it like
mine. However, for them new Toyotas,
Truetracs are as common as dirt." For
those who care, Gaffer and I miked the
adapter plate at 0.167 inches.
I then asked the old man how well the
Truetrac had performed.
"Truetracs are a type of limited slip
differential," said Gaffer. "Now most of
them positracs use cones or clutches to
transfer torque to the wheel what needs
it. And they work. However, them cones
and clutches wear out and they often need
special lubricants. The Truetrac, however,
uses gears. And gears, I figured, would last
a whole lot longer than clutches."
"As to how well they worked, I installed
them Truetracs in my FJ40 and used
`em for years. On slippery roads with
OPEN DIFFERENTIALS
LIMITED SLIPS/TRUETRAC
TOYOTA TRAILS
39