Benjamin Ruset wrote:
> Fourth (heh), on my 78, the car makes an odd noise. At idle with the clutch
> in, it makes a low whining noise. With the clutch out (meaning depressed)
> the noise goes away. The car seems to shift gears fine, and the clutch
> pedal seems to have a good feel to it. Is this normal?
The nice thing about this list is that you can get lots of dissenting opinions.
As I understand your description, when at idle, tranny in neutral, there is a
low grumble in the center of the car. When you engage the clutch, the sound
disappears.
It that's the scenario then it is not your clutch throw-out bearing but the
first transmission main bearing on the input shaft of your transmission. The
bad news is that it is most of a transmission rebuild to fix it. The good news
is that it is a ball-type bearing and will tolerate some abuse and wear -- you
don't have to fix it right away. If you let it go too long then you get some
wobble in the input shaft of the tranny and this can take out some other stuff.
It would be real unusual for the bearing to actually freeze up (and burn).
If it is your throw out bearing, you hear some noise when you depress the
clutch and can feel some grinding on the clutch pedal. Also, you may not be
able to disengage the clutch fully -- the hydraulics can only take up so much
slack in the system (caused by the loss of material on the throwout bearing).
The throw out bearing is generally not a bearing at all but a flat, donut
shaped machined piece of carbon. When you engage the clutch, it presses against
the clutch "throwout" and will eventually wear. This is the reason you should
not sit at a light with the car in gear and the clutch in.
There are throw out bearings that truly have bearings but these, IMHO, are not
all that desirable. The bearing sits in a pretty dirty environment and can fail
quickly if it gets contaminated. Also, there must be a secondary spring
mechanism that will pull the bearing away from the clutch when the clutch is
not in use. If not, the bearing spins all the time and fails faster.
The carbon donut will last a very long time if not abused. If it is only
lightly up against the clutch when the clutch is not engaged (typical), wear is
minimal.
--
Bob Allen, Kansas City, '69CGT, '75TR6, '61Elva(?)
ALLEN'S THEORY: Progress consists in replacing a theory that is wrong with one
more subtly wrong.
|