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[oletrucks] Gear grinding

To: oletrucks list <oletrucks@autox.team.net>
Subject: [oletrucks] Gear grinding
From: J Forbes <jforbes@primenet.com>
Date: Sun, 12 Dec 1999 21:41:03 -0700
Brad--

Sounds like you need to check all the stuff that John mentioned, for
when the clutch is not releasing fully.

Often the linkage will be the culprit, sometimes there is a way to
connect it up and have some part in the wrong way, so the leverage is
wrong...and the release arm does not move far enough.  You might check
this by adjusting it so that there is only a smidgen of free play at the
pedal, and see if it lets you put it in gear.  Do not run it long
without freeplay!  as it will burn up the clutch quickly.

Also, check to see that the clutch disk is not bent.  If the tranny hung
by the input shaft during installation, the disk will get bent (warped),
and it will drag, even when it is fully released.  You can check this by
spinning the disk on the input shaft of the tranny to see if it wobbles
(yes, you have to disassemble it all to check this, sorry).

Could also be a defective pressure plate, if one side is not pulling
away from the disk.  Defective clutch parts are more common than you
might think...I used to work at a tranny parts supplier, and they
finally gave up on rebuilt clutches, they only sell new ones now.

Make sure the throwout bearing is the right one for the pressure
plate...Chevy used short bearings and thick pressure plates, as well as
thin bearings and thick pressure plates.  If you have a thin plate and
thin bearing, the linkage angles will make it so that the clutch does
not release fully.  If the pressure plate is flat where the fingers are
(thin pressure plate), then there ought to be about a half inch between
the groove on the throwout bearing, and the bearing part that moves
(thick bearing).  

Also, the pilot bushing can hang up, this is not too easy to check for
unless you have another tranny input shaft to try to put in and see if
it's a free fit.

This is not an easy diagnosis for an experienced mechanic...and it can
drive an amateur nuts!  Patience, and persistence, will get it solved. 
And, yes, this list is amazing  :)

Jim
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959

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