1981 Mazda RX7 rear axle bearing

Loosen, but do not remove, the rear wheel lug bolts.
Raise the vehicle and safely support it on jackstands. Remove the wheels.
Remove the brake drum and shoes or the disc brake caliper and disc.
Disconnect the four bolts attaching the brake backing plate to the axle housing.
Disconnect the parking brake cable clip and remove the cable. Disconnect any interfering brake lines attached to the backing plate.
Remove the axle shaft/backing plate assembly by attaching a slide hammer to the axle shaft.

Remove the inner oil seal by prying it out.

Remove the inner oil seal only if it is defective, because the seal will probably be damaged when removed.

To replace the bearing:

The wheel bearing can be pressed off the axle shaft using bearing separator (tool number 49 8531 746 or equivalent) and its attachment (tool number 49 0259 747 or equivalent).
If the separator and its attachment are not available, or if the press does not generate enough force to press off both the bearing and its retaining collar, grind the bearing retaining collar down, then cut it with a chisel to loosen its grip. Remove the collar.
Remove the bearing with a puller or a press. Remove the spacer and backing plate.
Install the backing plate and spacer on the axle shaft with the chamfer of the spacer toward the axle shaft flange.
Position the bearing on the axle shaft and press it until the spacer comes in contact with the shoulder on the shaft.
Clean off the new bearing retaining collar and its mounting space on the axles shaft, then press the bearing retaining collar on the shaft until it firmly contacts the bearing inner race.

Never lubricate the retaining collar when installing. Always use a new bearing retaining collar. If the bearing retaining collar can be press fit using less than 2.7 tons (5,900 lbs.) of pressure, replace the collar with a tighter fitting one.

To install:

If removed, lubricate and install the new oil seal in the axle shaft housing. Apply grease to the oil seal lip.
Install the axle shaft in the reverse order of removal, being careful not to damage the oil seal with the splined end of the shaft. Engage the splines on the shaft with the splines in the rear axle.