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TR6 gearbox bench checkout

To: triumphs@Autox.Team.Net
Subject: TR6 gearbox bench checkout
From: Pete & Aprille Chadwell <dynamic@transport.com>
Date: Mon, 17 Nov 1997 17:22:31 -0800
Peter:

You wrote:

>1.     The Moss catalog says to check '2nd gear play' - if more than
>0.020" then the thrust washer in there is probably broken. Well, the
>2nd/3rd gears do go back and forth on the mainshaft a fair amount,
>definitely more than 0.02. Can anybody tell me more precisely how to
>check this out? - (it is the endfloat of the gears w.r.t. the shaft?)

It makes sense that if you can move that gear that much, then you probably
DO have a busted thrust washer... If I remember correctly, the 2nd gear
mainshaft bushing has the thrust washer "built-in."  I rebuilt a later
gearbox than yours, so some minor parts are different.

>2.     Although most of the gears look generally OK, the front of the
>teeth on the main layshaft gear have small chunks out of them. The Moss
>catalog mentions that 'silver pieces and sludge mean the layshaft and gear
>>are destroyed'. Any input/more info anyone?

By "main layshaft gear," are you referring to the 4th gear on the layshaft,
otherwise called the "constant" gear?  This is the gear on the layshaft
that has the largest diameter (number of teeth) and is at the forward end
of the layshaft.  I had to replace this gear in my gearbox, as it had teeth
missing.  I'd recommend that you change it.  As I remember, it didn't seem
to add all that much to the dollar amount of the project.  Or, you could be
referring to the 1st gear, which is at the other end of the layshaft.  This
MAY mean replacement of the entire laygear or "cluster" gear, as the first
gear portion is not removable as the 4th gear is.  Whether to replace or
not I suppose depends on the severity, as I suspect the cluster gear is
pretty spendy.  You might be seeing debris from what's left of the needle
bearings that support the laygear around the layshaft, also.  Replace the
layshaft regardless (I think it's a cheap part!) and use the needle
bearings that come in their own race, or "cage" as I understand that they
are much more durable.

When I rebuilt my gearbox, which was the first such project for me at the
ripe old age of 20, I made a mistake which would later mean that I would
have to do it all over again... While installing the needle bearings inside
either end of the laygear, I overlooked one critical item.  The bearing
that goes in the 4th gear end of the laygear was definitely a PRESS FIT.
But, it didn't bother me (and it should've) that the bearing on the first
gear end just DROPPED RIGHT IN!  Well, after a couple thousand miles, it
started whining.  So, I ended up pulling it all apart again.  That needle
bearing (in the first gear end) had destroyed itself, and was taking the
layshaft with it.  It should've been a press fit like the other end.   I
replaced the layshaft, both the needle bearings, (got the caged needle
bearings) and managed to save the laygear.  I took the laygear to Bearings
Inc and they mic'd it for me against the caged needle bearings I provided
and told me that the dimensions would allow me to, in effect, GLUE the new
bearing into place.  They sold me some Loctite "Bearing Locker" and gave me
specific instructions on the installation.  Well, there's now 30,000 miles
on that gearbox, and it works perfectly.

>I don't think I'm going to try to rebuild it myself by the way.

Well, Peter, it really isn't all that difficult.  Granted, I did have some
troubles, but I didn't have this list as a resource, either.  I took that
gearbox apart three times in the process of rebuilding it, but I'd bet that
with help from this list, you'd get it in the first try!  Plus, you'd learn
a helluva lot.  I realize, however, that for some this would be impossible
because of time constraints.  I understand that.  But, if you've got the
time, find a way to do it yourself!!

Pete Chadwell
1973 TR6 CF10732



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