http://www.miata.net/garage/timingbelt.html
* 1990-'91: Remove the 21mm crankshaft bolt. This will be difficult. Put the car in 5th gear and engage the parking brake. Using a long breaker bar, crack the bolt loose.
* Remove the Woodruff key.
* Remove the timing belt pulley.
You may require a wheel puller to get this off.
* Remove the oil seal.
Be extremely careful not to score the crankshaft during the removal. This can cause leaks. The oil seal is a steel ring covered with plastic and rubber. The best way to remove it is to carefully cut the plastic and rubber and pry out the seal with a screwdriver. Be sure to put a piece of cloth between the screwdriver and the metal areas so you don't score anything. This takes a bit of work.
* Install the new seal
Coat the new seal with a bit of oil and press it firmly into place with your hands.
* Seat the seal
You need to drive the seal flush with the oil pump body. A large socket or pipe is good for this. I use a piece of pipe covered with tape to prevent damage to the seal. Drive the pipe against the seal with a hammer until it is seated flush.
* 1990-91: Replace the timing belt pulley.
* 1990-91: Install the Woodruff key.
* 1990-91: Tighten the crankshaft lockbolt to 80-87 foot-pounds.
* 1992 & later: Install the woodruff key and timing belt pulley.
* 1992 & later: You will need to install and remove the crankshaft bolt and pulley a couple of times, so install it, but do not torque it down.
http://forum.miata.net/vb/showthread.php?t=302020
http://forum.miata.net/vb/showthread.php?t=172497
http://forum.specmiata.com/cgi-bin/u...4;t=002926;p=0