>ok here we go....
> steve:
> 1. that is not correct...the designers did allow for wear on the trow out
> bearing and here is what they thought.... their assumption and subsequent
> calculations were that the bearing wear would be compensated by a
proportional
> amount of disc and pressure plate wear. as the disc becomes thinner , the
> contact surface of the pressure plate with the bearing would be forced
out
> towards the bearing by virtue of the prings in the pressure plate. think
about
> that for a minute ... as the disc wears the pressure plate moves closer
to the
> flywheel and so moves the throw bearing surface further away from the
> flywheel.
Alex, we are in complete agreement on this point. I commented earlier that
the clutch was designed to compensate for wear in the clutch disc and
bearing, and you have just provided a very clear explanation of how the
clutch does this.
>whether or not that makes sense to you and me is irrelevent.. that
> was the logic of the BMC engineer staff at the time.
It makes perfect sense to me. What doesn't make sense is why rebuilding my
clutch with a new disc and bearing won't let me use a new, standard length
push rod. The answer may be that my fork is, in fact, bent, as Mostyn
says his is (I can't examine mine until I remove the engine next time, but
I did check it for looseness in the pivot, and there is none). My question
then is, how did it get bent? Mostyn thought it was years of pushing
against the clutch springs, but as a structural engineer myself, I know
that metal doesn't take a permanent set this way -- it takes an overload.
How, then, do you overload the clutch fork? Extended push rods are not
uncommon, so if the answer is a bent fork, why are all these forks being
overloaded?
Some think the explanation for the extended rod might be variations in the
clutch dimensions from one manufacturer to another preventing the standard
rod from working. Maybe. I don't have any personal data on this one way
or the other, but I wouldn't expect so much variation that somebody would
have to weld on a half inch or so to the pushrod to make the new clutch
parts work.
[How would you know how long to make the rod extension?]
> if you asked me that question in 1962 when i was working as a mechanic
for
> a BMC dealer i would have been able to tell exactly how long to make the
rod,
> but i have since forgotten.
Then it was a common practice at BMC dealers to weld extensions on the
rods? Was that to compensate for bent forks or worn pivots or what?
Steve Byers
Havelock, NC USA
'73 Midget GAN5UD126009G "OO NINE"
"It is better to remain silent, and be thought a fool
than to speak, and remove all doubt" -- Mark Twain
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