Pete & Aprille Chadwell wrote:
> Andy wrote:
>
> >Pete,
> >You may be correct and I don't have any information to dispute what you
> >say, however, even with the pin in there is enough rotational movement to
> >wear down
> >the pins in the fork. It seems to me, and I've be wrong before, that if
> >the sleeve can rotate freely it will wear down the pins faster.
> >Andy
>
> Providing that the TO bearing is not seized up, there THEORETICALLY is no
> reason for the sleeve to rotate when the clutch is disengaged. Therefore,
> there should be very little wear on the pins and groove. I think the wear
> we see in the groove and on the pins is more a result of throwout bearings
> that go bad or don't work properly than whether or not there is a pin in
> the sleeve. Like you, though, I'm only speculating... I have no imperical
> evidence myself except to say that my TO bearing WAS seized up, and I
> continued to drive it like that, and then finally when I got to change the
> clutch and bearing, I found SEVERE wear on the fork pins AND the sleeve.
> (Big surprise there! Doctor, doctor... It hurts when I do this!!)
>
> Pete Chadwell
> 1973 TR6
I always insist on installing a heavier pin to prevent sleeve rotation. Pete's
theory
certainly makes sense, but let me present another THEORETICAL viewpoint.
When engaged (foot off the pedal), the throwout bearing is just riding against
the
face of the fingers of a diaphram clutch. Witness this by the fact that if you
try to
push the lever back by hand, it does not move - therefore there is no
clearance. If
you push forward, and then back, you will hear the "clink" of the throwout
contacting
the fingers. This riding pressure occurs due to force applied by a spring that
is
located behind the piston in the slave cylinder. The throwout bearing spins
constantly due to this light contact. Since there is only an insignificant
load on
the bearing, wear in the bearing as a result is not a factor. However,
friction is
present in the bearing, and drag also occurs due to the heavy grease inside the
bearing. This drag has the effect of wanting to spin the sleeve. Going down
the
highway, inertia will bring the speed of the throwout close to the speed of the
engine. If the resultant drag is greater than the friction between the sleeve
and the
pilot on the trans, the sleeve will also spin constantly. Again, under light
loading,
this may or may not be a problem.
Without side-by-side testing, I can't really say one way or the other which
would show
the least wear. The engineers at Triumph certainly thought this important
enough to
specify an extra machining step to drill that hole for the pin, and we all know
how
cheap they were! I suspect the reason that the hole is omitted on the new
sleeves is
that the extra drilling operation added too much to the cost of a low volume
production run.
Regards,
Brian Schlorff '61 TR-4 '64 TR-4 '72 TR-6 '79 Spit
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