Hi Anthony Rayner!!
On Thu, 20 Mar 1997, Anthony Rayner wrote:
> If I replace the clutch do I have to get the flywheel machined? What
Some people "shave" the flywheel to let the engine rev up easier. It
all depends on your car's state of tune, and the type of driving you do.
The primary task of the flywheel weight is to store energy to be
released when the car is "launched" from a start, to get the car moving
fast enough so that the engine rpm comes up to the torque band of the
cam. If the flywheel isn't heavy enough for any given situation,ie.
starting on a hill, starting while towing a Miata, then the clutch must
be slipped to allow the engine to speed up enough to develop the torque
to accellerate. Racing flywheels, on the other hand, have light-weight
flywheels because they spend almost zero time starting from standstill,
and they must put the available engine power into the car, rather than
the flywheel.
If your clutch has damaged the friction area of the flywheel, it can be
resurfaced without loosing much weight.
> about the release bearing?...should that be replaced as well?
YES!!! When I was just starting to delve into the mysteries of the BMC
Marque, I asked an old factory mechanic why I had to replace the release
bearing as well as the clutch. He asked me if I had EVER adjusted the
clutch, and I had to admit that until the clutch had worn out, the pedal
stayed about the same distance from the firewall. He then told me that
as a rule of thumb, the clutch friction disc wore 0.001" per thousand
miles of travel (adjusted for driver habits, and routes [hwy vs town]).
This causes the pedal go lower, and lower, to actuate the clutch. Also
as a rule of thumb (big coincidence here...) the release bearing wears
down at a rate of app. 0.001" per thousand miles of driving; and as it
wears, it causes the pedal loose the free play neede to actuate the
clutch. If all goes according to plan, both actions cancel out, until
either the clutch glazes (and starts slipping), or you run out of stroke
in the slave cylinder.
> Sounds like a costly exercise to me!!
Well, costly is if you DON'T do it, and it buggers up, and you have to
pay to have the job done again. Note that the engine MUST be separated
from the transmission to do this job. Big expense
TTUL8r, Kirk Cowen
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