[TR] TR3A timing chain lower gear

[Randall]

Art,

When it's assembled, the timing sprocket is clamped against the front crank
journal by the pulley hub.  It has to be clamped tightly enough to resist
any motion whatsoever (relative to the crank) or things will quickly fail.

The crank in turn is located by the thrust washers and should have only a
few .001" play.  You can insert/change shims if needed between the gear &
crank journal, to align the timing sprockets.  Procedure is in the workshop
manual.

It does look like you have more rotational play between the sprocket and
crank than I would expect ... Are you sure the key was installed and in good
shape?  A new key certainly wouldn't hurt.

If it has been allowed to run loose, such that the fit between the gear &
crank is worn, I expect they will both be worn more-or-less evenly.  That
was certainly the case when my pulley hub worked loose, and I doubt the hub
is hardened.  There is a Loctite product for "restoring" circular fits that
I used with good results; but I don't recall the number offhand.  At the
time, it was called "Circular parts mount", but they've changed the name
several times, and there are probably better choices now anyway.

> But the sprocket will also move forward & 
> back, when it does there's less side to side play like it's 
> fallen into a groove when it's in it's normal position.

I think what you are seeing is the chain becoming tighter, as the sprocket
moves out of line.

-- Randall