> From: Don Malling
> Sent: Tuesday, January 27, 2004 5:38 AM
>
> Sounds like maybe I should use the old original pin
> and cross shaft rather than the TRF replacements?
>
> I think Nelson did not like the idea of the roll pin
> because they flexed and would therefore not add much
> additional strength over the taper pin -- not much
> "sharing". Is a hardened roll pin different? Any
> thoughts would be appreciated.
This clutch pin issue is one of the more "popular" problems which plagues
the TR6. It gets a lot of discussion. It seems there are many fixes to the
"problem", the additional 1/4" bolt being perhaps the most popular. A few
years ago a gentleman named Brian Schlorff of Power British in Pennsylvania
offered this diagnosis of the problem to the big triumphs list. I saved it
because I consider Brian to be one of the most knowledgeable Triumph
mechanics out there, and one who selflessly shares his knowledge with us,
the masses. Not sure if he still posts to the triumphs list as I no longer
read that (too much traffic, low S/N last time I checked).
Anyway, here is Brian's post:
>>>>>>>>>>>> begin Brian's text >>>>>>>>>>>>
The fundamental engineering problem with the clutch fork is simply this:
The pin is tapered.
The cross-shaft has a tapered hole to accept the tapered pin.
The partially threaded bore in the fork IS NOT TAPERED!!!
What this means is that contact is made on only one side of the fork pin.
(the side nearest the threaded portion just below the head) All the force
is concentrated at that spot and the pin will ALWAYS break at this spot -
never anywhere else.
The best, albeit not so easy, solution is to ream the hole in the
cross-shaft to the same diameter as the bore in the deepest part of the
fork. Then fabricate a new pin, one with a straight shank of corresponding
diameter + .001" for an interference fit that will tightly engage both sides
of the fork. No modifications are made to the fork, but now the shear force
is divided equally between the top and bottom of the new pin, which is also
slightly larger in diameter than the original tapered pin.
The real benefit comes from the fact that the topmost portion of the pin
extends directly up into the right-hand finger of the fork, thus there is no
chance of overstressing or cracking the base of the fork around the shaft.
I know it is not exactly a do-it-yourself prospect to make such a set up,
but just about any machine shop can make a pin for you fairly easily.
>>>>>>>>>>>> end Brian's text >>>>>>>>>>>>
Incidentally, Brian is also the source of the tapered top cover shaft tool
idea. He has provided numerous other such innovative gems in the past,
always very well explained.
He also helped me with my own version of the sticky clutch problem long
before Nelson's web site (which is another great source of info BTW).
I've never met Brian but would really like to. Too bad we live a few
thousand miles apart.
Peter Zaborski -- CF58310 UO
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