Actually Bob Lang offered a number of reasons why the thrust washers might
fail, not just the backwards installation theory:
<snip>
The cause for thrust washer failure is usually improper installation (the
washers are installed backwards), the motor oil maintenance is poor (long
intervals between changes or the wrong oil) and over-revving the engine.
But some folk seem to think that adding stress to the bearings by pushing in
the clutch will reduce t/w bearing lifespan. My personal feeling is that the
possibility is over-stated.
</snip>
However I cant think of a good reason to depress the clutch before starting,
for me it seems to be habit as my modern cars require it but I will try and
stop doing it in future as the arguments against it make sense to me.
Stan
-----Original Message-----
From: owner-6pack@Autox.Team.Net [mailto:owner-6pack@Autox.Team.Net] On Behalf
Of DLylis@aol.com
Sent: Monday, November 05, 2007 9:39 PM
To: lang@isis.mit.edu; im_sloane@hotmail.com
Cc: 6pack@autox.team.net
Subject: Re: [6pack] Engine Preluber
Do what you will. I drive my TR6 once every week and when it starts the
likelyhood of the thrust washers being properly lubricated at a cold start
is
not very good, regardless of oil. In will leave the car in neutral and
start
it.
The thrust washers are a "bearing" that restricts the movement of the
crankshaft fore and aft as you put in the clutch and let it back out again.
Those
springs in the clutch pressure plate are trying to push the crankshaft
forward and out of alignment. The thrust washers job is to prevent the out
of
alignment. The thrust washers are lubricated by the engine oil. After your
car
has sat, the engine oil drains down from the galleries. If you put in the
clutch you are putting pressure on the thrust washers. When you turn the key
to
start you are creating the single greatest wear point for the thrust washers
as the oil has to pump up to them. If you put the car in neutral with the
clutch out you are not placing any pressure on the thrust washers and
therefore drastically reducing the wear point at that moment as the oil
pressure
comes up.
Replacing the thrust washers is the most common internal engine repair in a
TR6 motor. That they fail only because they are put in backwards is simply
not true.
David Lylis
69 TR6 CC26160L
60 TR3A TS74461LO
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