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> From: ajs@hpfcla.UUCP (Alan Silverstein)

> ...  What can cause clutch chatter in a front wheel drive Datsun?
> It's a quiet chain-rattling sound ...
> ... whether the clutch is engaged or not.  ...

Huh?  What make you think that it's the clutch?  Clutch "chatter" is usually
only heard while engaging the clutch.  If you hear it while the clutch is
engaged it could be anything from motor mounts to CV joints to loose sheet 
metal.

More info?

-- 

   Pat Vilbrandt
   John Fluke Mfg. Co., Inc.
   Everett, Washington USA
UUCP:
   { decvax!uw-beaver, ucbvax!lbl-csam, allegra, ssc-vax, decwrl!sun }!fluke!pwv
ARPA:
	fluke!pwv@uw-beaver.ARPA

Here's a summary of responses to my question:

> What can cause clutch chatter in a front wheel drive Datsun?

I received mail from six knowledgeable advisors on the subject (thanks
to you all).  Most suggested more than one possible problem.  In total
the suggestions (and number of repeats) were:

4  Throw-out (== clutch release?) bearing worn, "hammered", or needs
   grease.  Should be obvious if so; it's the only bearing in the area.
   Should be replaced when the clutch plate is replaced; it's cheap
   insurance.  [Seems likely to me.]

2  Sounds like transmission trouble.  Transmission input shaft or
   bearing is bad.  [Possible, as the F10 transmission appears to be
   badly designed.  I've already had it replaced once due to gears
   just wearing out.]

2  Clutch assembly is out of balance, which would cause vibration
   throughout the car.  [Doesn't seem to be the case.]  Check all
   spinning parts in clutch assembly.

1  Sounds like CV (constant velocity) joints chuckling.  Check that they
   are lubricated with correct (graphite based) grease; cheaper is not
   good enough.  If the noise exists when the car is not moving [yes it
   does] then it's not the CV joints.

1  Flywheel surface is glazed or has oil on the surface.

1  Were the big clutch disc packing staples removed?

1  Probably not pressure plate or disc; get a free inspection.

1  "Chain rattling" sounds like rear-end trouble (bearings).  [My fault,
   I decided later that "gurgling" is a better description.]

1  Clutch chatter is really violent drive train shaking during
   engagement; it doesn't sound like that's your problem.  [No; sorry
   for my abuse of terminology.]

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

I'll have the car checked soon, probably next week, and post one more
short followup on what the problem really is.  Thanks again for the free
advice.

Alan Silverstein

> Here's a summary of responses to my question:

>> What can cause clutch chatter in a front wheel drive Datsun?

I "showed" the noise to a Datsun######Nissan mechanic.  Surprise!  He
thinks it's just a harmonic vibration in the car frame somewhere, and
suggested I go underneath looking for a loose hunk of metal.  He said if
it were bearings, the noise would appear independently of the RPM.

Well, you can't hear it at all outside the vehicle, and it's tough with
the door open.  Yes, it does act like a harmonic vibration -- it has a
peak at 2500 RPM -- though it falls off much more slowly on the high
side.  It sure sounds like it's coming from the clutch, but since it's
only noticeable inside, I guess I'll have to poke around down there
(maybe with a microphone connected to an amp?) to find the source.
(This I will do as soon as the temperature climbs back to where cold
metal doesn't remove your epidermis...)

Alan Silverstein, Hewlett-Packard Fort Collins Systems Division, Colorado
{ihnp4 | hplabs}!hpfcla!ajs, 303-226-3800 x3053, N 40 31'31" W 105 00'43"