Ford Mustang 1989-1993 Repair Guide

Flywheel/Flexplate and Ring Gear


Flexplate is the term for a flywheel mated with an automatic transmission.


See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: Exploded view of a typical flywheel and flexplate mounting-2.3L shown

The ring gear is replaceable only on engines mated with a manual transmission. Engines with automatic transmissions have ring gears which are welded to the flexplate.

  1. Remove the transmission.
  3. On manual transmission vehicles, remove the clutch.
  5. On automatic transmission vehicles, remove the torque converter from the flywheel.

The flywheel bolts should be loosened a little at a time in a cross pattern to avoid warping the flywheel. Also, some vehicles will have an Orange bolt hole on the torque converter which should be matched with the Orange line on the flexplate for proper balance.

  1. Loosen the flywheel bolts (gradually using several passes of a cross pattern) and remove the flywheel from the engine.

On vehicles with manual transmissions, replace the pilot bearing in the end of the crankshaft if removing the flywheel.

  1. The flywheel should be checked for cracks and glazing. It can be resurfaced by a machine shop.
  3. If the ring gear is to be replaced, drill a hole in the gear between two teeth, being careful not to contact the flywheel surface. Using a cold chisel at this point, crack the ring gear and remove it.
  5. Polish the inner surface of the new ring gear and heat it in an oven to about 600°F (316°C). Quickly place the ring gear on the flywheel and tap it into place, making sure that it is fully seated.

Never heat the ring gear past 800°F (426°C), or the tempering will be destroyed.

To install:
  1. Coat the threads of the flywheel bolts using a Teflon® based pipe sealant.
  3. Install the flywheel on the end of the crankshaft. Tighten the bolts a little at a time, in a cross pattern, to the torque value shown in the Torque Specifications Chart.
  5. Install the clutch or torque converter.
  7. Install the transmission.