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RE: TR4A Transmission qustion

To: "Arnold S. Gilmour" <gilmo004@mc.duke.edu>, <triumphs@autox.team.net>
Subject: RE: TR4A Transmission qustion
Date: Thu, 3 Jun 2004 12:47:50 -0700 >
> Has anyone ever drilled an access hole in the transmission bellhousing in
> order to have an easy access for replacing the clutch fork pin? I've had
> them shear off and make quite a difficult time trying to remove
> the pieces.
> Seems like a small one inch hole in the bottom would allow periodic
> replacement before they inconveniently shear. I would like to hear of any
> experience that you all have had with this pin.

Someone else was telling me that this fix didn't work for them, but so far
it has worked very well for me :

With the shaft out of the transmission, install a new taper pin, and make
sure it fits properly.  (Consider a new shaft too, but I reused my old one.)
The pin must bottom into the shaft before it runs out of threads or hits the
bottom of the hole in the yoke.  There should be absolutely no play with the
pin only finger tight.

Be sure it's assembled in the right orientation (guess who got it wrong the
first time).  Install the taper pin (shaft still out of the transmission)
and torque it down to spec.  (The fork actually distorts slightly under the
clamping force, so this step is important to get the holes lined up just
right in the next step.)

Find a 1/4" grade 8 bolt that has a shank just slightly shorter than the
thickness of the fork, and measure the diameter of the shank.  ISTR mine was
.243" but I may be wrong about that.  Get a drill bit the same size (or the
next larger size) ... a letter D drill is .246".  Center punch and drill
(preferably in a drill press) through the fork and center of the shaft.

Assemble the shaft into the transmission, install and torque the taper pin,
then insert the bolt with a nyloc nut and cut off the excess threaded
portion of the bolt.  Check that the nut clears the bolts in the front cover
with some room to spare.

This mod is mentioned in Nelson's excellent article at
http://www.buckeyetriumphs.org/technical/Clutch/ClutchShaft/ClutchShaft.htm

I honestly believe that, with this mod properly done, you'll never have to
replace the taper pin again.  And you won't need any unsightly holes drilled
in your NLA gearbox housing either !  If you decide to undo the mod I
described at a later date, all the parts involved are readily available new.

Randall





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