Re: '78 Spider Clutch problem, m/c & s/c...

[Scott Fisher <sfisher71@domain.elided>]

--- JeffreyOlson@domain.elided wrote:
> Clutch has been increasingly difficult to disengage 
> completely, i.e. shifting into reverse or first gear
> from a standstill.

So, the biggest (and cheapest) likelihood was that
this was the hydraulics, and you seem to have
disproved that.  

The next two most likely candidates are:

1 - Throwout bearing wear.  When your foot presses the
pedal and squeezes the hydraulic fluid out the hose,
it pushes the slave cylinder far enough, which in turn
presses the clutch lever far enough, but if there's
significant wear on the throwout bearing, it doesn't
push the clutch pressure plate enough to disengage it
fully.  Common on HSOBSCs* (at least those of the
MOWOG persuasion, which use a carbon-faced throwout
bearing that lasts about 30k miles at most), but not
usually a problem on Alfas, which use a proper metal
bearing if memory (augmented by a quick scan of the
nearest Centerline catalog) serves.  Prognosis for
your '78 Spider: unlikely, but possible.

2 - Pressure-plate spline breakage or wear.  Your foot
does the same as above, the throwout bearing pushes
forward, but breakage or wear on the splines of the
pressure plate causes it not to release the proper
amount.  Result: sticky shifting in first and reverse,
slight synchro grinding in second, USUALLY enough
synchro action in third-fifth that you don't notice
any grinding.  Prognosis for your car: sadly at this
point, probable.

If you think there could be ANYTHING you've done that
would introduce air into the hydraulic lines, or that
would otherwise cause it not to be really flushed, try
bleeding again.  However, I once spent a truly
miserable weekend trying to bleed a clutch when what
had really happened was problem 1, on my HSOBSC* at
the time.  If you KNOW you've got all the air out and
no more is getting in (that's the tricky bit with
clutch bleeding), then no use trying to bleed it
further.

Sadly, diagnosing either of the next two probable
causes almost certainly involves dropping the
transmission and/or removing the engine.  While it's
possible to get either the engine or the transmission
out by itself without removing the other component as
well, for the job you have ahead it will actually be
easier to remove the engine and transmission as a
unit, disassemble them on the floor or bench, and then
inspect the throwout bearing and pressure plate.  

Actually, where the job gets easier is with the engine
on the bench when you install the new clutch -- it's
pretty easy to get the pressure plate installed, with
the friction disc on the little alignment tool, while
the engine is standing either on a bench or on the
floor.  Tip: to avoid simply turning the engine while
trying to install the pressure plate, torque the
pressure-plate bolts by crossing the engine's
centerline with the handle of the torque wrench.  That
is, to tighten the bolt at 6 o'clock on the flywheel,
hold the torque wrench at about 11 o'clock and move it
to about 1 o'clock, repeatedly.  (Works for lug nuts
while the car is in the air, too.)

If anyone here knows of a way to inspect
pressure-plate and throwout bearing operation on a '78
Spider without engine removal, I think Jeffrey would
be very grateful for it, and so would I, though I hope
it's years and years before I ever need to know it. 
(On a mechanical-linkage 1300/1600 car, for example,
I'd be tempted to just pull the sheetmetal cover off
the bottom of the bellhousing and look at everything
while someone else operated the clutch pedal, but
that's not an option on 2-liters -- unless there's a
clutch observation window I haven't noticed.  And
anyway, the pressure plates on 1300/1600s are
completely different...)

Best,

--Scott Fisher
  Tualatin, Oregon

*HSOBSC: Hopelessly Shot Old British Sports Car, a
phrase I have shamelessly lifted from Peter Egan of
Road & Track.  MOWOG, on the other hand, stands for
"MOrris WOlseley Group," the division of the British
Motor Corporation responsible for M.G. and
Austin-Healey; many of the parts on Sprites, Midgets,
and MGBs have MOWOG cast into them, suggesting the
name of some ancient and jealous chthonic deity,
voracious in its appetite for sacrifices human flesh
skimmed off countless knuckles and forearms.  (As
Nicole Hollander might say, "Worship your deity by
lying on your back under 3/4 of a ton of precariously
balanced steel, cast iron, and grease, as grit, rust
and toxic powder falls into your eyes, while chanting
'Bugger all, bugger all, bugger all' as you
methodically remove all the dermis from the wrist
joints down to the fingertips.")

While I note that the Centerline catalog uses the term
"release bearing" to describe the piece that
disengages the clutch, HSOBSC owners adopt the phrase
"throwout bearing" at least in part because that's
what we are sorely tempted to do to the damn things
once we get them out of the car.  Like wooden boats,
vintage aircraft, and teenaged children, HSOBSCs
provide a sense of satisfaction that at first glance
would appear to be out of all proportion to the ratio
of pleasure to pain spent on their care and operation,
but which I now believe (having experienced three of
the four members of the set) is actually derived in
part BECAUSE of the pain.  At least during those
all-too-brief periods when the pain abates
momentarily.

--SF
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