Miata Mailing List: May 1999, Message #40

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In a message dated 4/30/99 1:33:35 PM Eastern Daylight Time, 
ESorrentino.MBA2000@ivey.uwo.ca writes:

> My mechanic at the Mazda dealer tells me I need a new clutch.  I =
>  notice a little slippage in 1st gear but nothing major (yet).
>  Anyhow, I don't know too much about clutches...
>  Should I buy an OEM clutch?
>  Aftermarket?  What one?  Where? How? How much $$$?
>  Thanks!
>  
>  
>  Eric Sorrentino

  It depends on your intended use and the power level of your car.  If you 
pump power up more than about 20%, and show the clutch no mercy, you may need 
one of the many available high-dollar aftermarket clutches.  If you go that 
route, be aware that performance clutches are, by nature, a bit trickier to 
drive smoothly.
  The OEM clutch is really a very good piece for most applications.  I 
replaced the one in Rocinante at around 100,000 miles because I had the trans 
out for synchros anyway.  It looked surprisingly good given that I autocross 
frequently and launch at 6500-7000 rpm with a 125 HP motor and sticky tires, 
and practice no-lift shifts (not to mention driving the same way on the 
street).  Now, 100,000 miles later the replacement OEM clutch is still fine.
  You didn't mention whether you have a 1.6 or 1.8 (94+) car.  A nice upgrade 
to a 1.6 is to pick up a 1.8 flywheel at a wrecking yard, have it shaved to 
bring the mass back down to that of a 1.6 wheel, and install an OEM 1.8 disc 
and pressure plate.  The added cost is little more than that of the junkyard 
wheel, since you'll want to resurface your original flywheel anyway.  Machine 
shops charge by the setup -- not machining time.  If, for some reason, you 
buy a new flywheel it's not really necessary to trim it down.  That's only to 
gain a bit of acceleration due to reduced inertia.  For that matter, the 1.6 
wheel can be lightened to gain a small advantage.  Just remember that a light 
flywheel car is more temperamental on the street, and will wear the clutch 
quicker due to more slippage require to launch smoothly at low revs.
  Don't forget to put in a new release bearing while it's apart, and be 
prepared to replace the pilot bearing in the back of the crank, the 
crankshaft rear seal, and transmission front seal.  If this stuff needs 
replacing later most of the same labor is involved and leaking oil can trash 
a perfectly good clutch.  Good luck!
  Foureagles
PS: 1st gear is not typically where a worn clutch exhibits problems.  First 
make sure that the clutch is engaging fully, and not being held-off by the 
linkage (not usually a problem on a Miata), then do the following test.  Set 
the handbrake hard.  Put the car in second gear.  Rev to maybe 5000 and try 
to take off.  The motor should stall if the clutch is good.  If it doesn't, 
and the car doesn't move, the clutch is toast (at least it is now).