The TR6 Thrust Washer Blues
If you have performed a crankshaft end float check and
found that it
is beyond the allowable limits according to your
workshop manual,
you need to stop driving your car immediately and
determine what is
causing the problem.
If the end float dimension is slightly greater than
the allowable limit,
then it may be related to high mileage, in which case
you may only
need to replace the old washer with a new one. If the
end float is five
or ten thousandths of an inch more than the allowable
limit, then you
may have already wore through the soft copper facing
of the washer,
which means you now have steel on steel and the wear
rate will
increase dramatically. In this case, you will want to
remove your oil
pan and main bearing end cap, and inspect everything
for any
damage. Fortunately in many cases the crank shaft
surface may be
worn, but also may be polished. If this is the case,
you can replace the
old steel type washer with a washer made of a material
that has very
good wear characteristics when used with steel, such
as the one I am
developing made from an alloy.
This thrust washer wear problem may be related to many
things.
Premature failure could be attributed to an improper
clutch pedal
adjustment or the driver of the car "riding the
clutch" with his or her
foot on the clutch pedal when not needed. Holding the
clutch pedal to
the floor while waiting at stop lights, or pressing
the clutch to the floor
whenever the car is first started can also cause
premature wear. This
is a time when there is a lack of oil supplied to this
area until the oil
gets flowing.
Another very common mistake that causes very rapid
wear is
re-installing the thrust washer backwards. If the
wrong side of the
thrust washer is mated with the crankshaft thrust
surface, you will
have the steel thrust washer surface wearing against
the steel
crankshaft surface and the result will be fatal...this
can ruin your day.
Whenever you press on the clutch, you are adding a
force to the face
of the flywheel, and forcing the crankshaft toward the
front of the car.
This little thrust washer (the one on the front side
of the rear main
bearing) has to maintain this load against the
spinning crankshaft,
and it's amazing that it lasts as long as it does!!
Once the thin, soft copper facing on the steel washer
wears through to
the steel, it will wear rapidly until the washer wears
enough that the
crankshaft is now coming in contact with the end cap
face which is
wider than the engine block side of the journal. Once
the end cap face
wears, it then loses its ability to retain the thrust
washer, which then
slips out of place and ends up in the oil pan. The
crankshaft will now
continue to wear into the end cap face until it
finally comes in contact
with the side of the engine block portion of the main
bearing journal.
Once the crankshaft has worn far enough to damage the
block, you
will most likely have to pull the entire engine and
perform some major
$repairs$, and possibly replace the engine block!
If the problem is caught before any engine block
damage has
occurred, the main bearing end cap face can be
repaired and the
crankshaft thrust face can be inspected for anything
other than some
light wear. If the crankshaft thrust surface has been
lightly worn, and
has a polished appearance and feel to it, it can most
likely survive
without any major work being carried out. The alloy
thrust washer
that I am developing will conform to the slightly
irregular polished
surface of the crankshaft thrust face, and should
perform as well if
not better than the original steel washer, and there
is no soft copper
facing to wear through to steel which is a very big
advantage!!
A word of caution: Do not use a stock thrust washer if
the thrust
surface of the crankshaft is less than perfect,
because the new
"stock" washer will most likely have a very short life
and extensive
engine damage will most likely occurr in a very short
period of time.
This is where the washer that I have developed comes
in to play. It is
made of a material that is known to have superior wear
performance
when used in this sort of application. It is a
material that, to my
knowlege, is not currently available in the form of
the thrust washer
we need for our 6 cylinder Triumphs. That is why I
have taken the
time and expense to make my own from scratch. There
are other
materials that may possibly work, but they would most
likely have
inferior results.
I don't quite understand why the engineers at Triumph
decided to use
the thrust washers that are currently being used, but
they probably
had a good reason. Maybe availability. I personally
feel much better
using the bronze alloy washers that are currently in
my TR6. If you
have any questions, or interest in learning more about
the thrust
washer material I am using, feel free to drop me an
e-mail and I will
do what I can to help you out. Remember.....when the
thin copper
facing wears through to the steel on the stock
washers, you're going
to have problems.
Scott Helms
E-mail me: Trmgafun@aol.com
=====
tpdwinch@yahoo.com
Dale Morgan
Chesapeake, Va.
1974 TR-6
CF 17477U
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