[6pack] Trying to locate the source of a TR6 vibration

jim hearn jimhearn1 at comcast.net
Wed Jun 24 13:53:39 MDT 2009


Thanks for all the input.  I've been all through the wheel bearings and
they are fine.  I too have had tire balance issues that were pretty
evasive but finally conquered.  This vibration doesn't have a particular
speed range; it just needs to be in fourth gear (at just about any
speed) with some acceleration taking place.  My thought is that it could
be a bearing in the tranny to do with the final output shaft but I don't
know TR6 trannys or any trannys enough to say for sure.  Jim


-----Original Message-----
From: Navarrette, Vance [mailto:vance.navarrette at intel.com] 
Sent: Wednesday, June 24, 2009 8:25 AM
To: jim hearn; '6 Digest'
Subject: RE: [6pack] Trying to locate the source of a TR6 vibration

 
	Jim:

	I am inclined to agree with you. The issue seems to be one of
two things in my mind, tire balance or front wheel bearings. It doesn't
happen in third, because the tires are not rotating fast enough. If it
were u-joints, I would expect third and fourth to be similar, depending
on the RPMS. Also, it doesn't happen in fourth going up hill because it
does not depend on throttle setting, it depends on car speed, which
stays flat or climbs very slowly when going up hill.
	So here is my suggestion:

	1. Check your front wheel bearings for slop. Grab the top of the
wheel with both hands, place your feet against the bottom of the wheel
and lean back while tugging (pretty much your full body weight). If you
feel the wheel rock back and forth, then your wheel bearing is loose or
worn out. Fix this first. I have found that the Bentley manual is
incorrect in the wheel bearing setup. Bentley mentions something about
"back off one flat" when tightening the castle nut. I feel this is just
"flat" wrong (Har-har-har. I crack myself up!). Finger tighten the
castle nut, but do not back off one flat.
	2. Have your tires balanced WITH THE TRIM RINGS ON THE WHEELS.
If you don't have trim rings then this is not as big a deal. My
experience is that tire shops take the trim off to balance the wheel,
then puts the trim back on ASSuming that the trim will not affect the
balance. WRONG! Ask me how I know.

    Vance Navarrette
    Cogito Ergo Zoom
    I think, therefore I go fast

-----Original Message-----
From: 6pack-bounces at autox.team.net [mailto:6pack-bounces at autox.team.net]
On Behalf Of jim hearn
Sent: Wednesday, June 24, 2009 8:00 AM
To: 'Todd Bermudez'; '6 Digest'
Subject: Re: [6pack] Trying to locate the source of a TR6 vibration

My first suspects for the vibration were the tires and/or the drive
shaft, but the conditions under which it vibrates would seem to
eliminate these two sources and I'm not sure but doesn't it also
eliminate the u-joints since why doesn't it vibrate accelerating on the
flat in third gear?  Jim


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