Miata Mailing List: September 1995, Message #41
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   From: phredd@infi.net
Subject: Bad Vibes, Man.
   Date: Fri, 1 Sep 1995 15:46:41 -0400

        Yo, Dudes:

        Here's one for the Serious-Backyard-With-Gusts-To-Professional
mechanic - er - technician (I keep forgetting that).

        I don't know whether this symptom of doom is gradually becoming
more demonstrative or if I'm gradually becoming more used to the car and
better able to pick out individual anomolies. Either way, I don't like
what's happening.

        In preface, I should also mention that I've noticed this in other
cars of my dim past. I don't know if that's bad or good because I can't
remember which cars, ergo, I also can't remember if it was in ones in which
I replaced clutches.

        One last prolegomenous remark; my car is the dreaded '93 1.6L model
and has 12.5M on the odo - - the immediately past 3M being applied by Y.T.

        Here's what's happening. I've noticed lately that when I change
gears in the higher revs range (above 4M) and don't change smartly but
rather let the engine spin down some while I leisurely upshift, I'm feeling
some vibration in the clutch pedal on its way to full disengagement (as
evidenced by pedal travel). I don't claim that it doesn't happen during a
quick gear change (and attendant quick clutch operation) as it's may be
that the transaction takes so little time that the vibration isn't noticed.
Probably moot, anyway.

        This phenomenon surprizes me (lay person that I am) in a car with a
hydraulic clutch which I would expect to insulate its driver's tender foot
from any Flywheel Nasties. Does this, at least, mean that the hydraulic
line has little or no air nor water in it - allowing these messages to be
sent? Small consolation, if so.

        I'm fairly sure I've isolated the vibrations to the clutch. I can
replicate the symptom by revving the engine with the transmission in
neutral with the clutch partially depressed and the car either stopped or
in motion. The vibration is not apparent with the clutch pedal pressed
against the floorboard nor is it noticeable by just pressing my foot on the
floorboard. I also have not detected it through the the steering column.
This all says "clutch" to me.

        I don't know if I'm hearing it or not. There's a lot of ambient
noise flying around with the motor revving between 5 and 6M.

        So, the big question is:  Is this a "normal" operational feature of
the Miata or do I have a release bearing heading south? Other deficiencies
occurring to me are an unevenly tensioned diaphram spring, an improperly
torqued clutch housing, or maybe even a defective driven plate (given that
the clutch may be partially engaged when the vibrations are being fed
back).

        I'd really hope I get some learned opinions on this one as I have
an appointment at the dealership next week for an oil change (that's right,
kids, it takes a *week* to get your oil changed around here** - damn, I
wish my business was that successful) and I'd like to be prepared to
discuss this with them at that time if it's a symptom of the badness I
think it probably is.

        Keep the revs up.

        Phredd



        ** I intend on taking the predominent list advice and go synthetic
but I haven't had time to secure the oil, filter, and filter wrench. Plus,
my jack's in the hydraulic shop for repair and they're really dragging
their feet getting it back to me. I screwed up and the oil's overdue to be
changed.




----------------------------------------------------------------------------

        Fred Donour, Jr. ~ Norfolk, Virginia ~ XCIII RED A
        MCA ~ License Plate (rear only, of course) "MX-5"

        God's Miata is Red!