How do I replace the rear axle bearings and seals on a Mazda RX-7 FB?

Replacing the rear axle bearings and seals on an FB RX-7 is a Moderate difficulty job, primarily because you will need to outsource the bearing press work if you don't have a shop press.

Depending on your trim, you either have rear drums (GS) or rear discs (GSL/GSL-SE) ⁵. The brake teardown differs, but the axle extraction is the same.

Here is the procedure for getting the axles out and the seals replaced.

1. Prep and Safety

• Drain the differential: Drain your rear diff fluid before pulling the axles, or it will pour out of the axle tubes ².
• Support the vehicle: Break the rear lug nuts loose, chock the front wheels, and get the rear of the car securely on jack stands supported by the frame.
• Shock Warning: Raise the axle slightly with your jack so it isn't hanging freely at full droop. The rear shocks on this platform do not like holding dangling weight for extended periods ¹.

2. Brake Disassembly

If you have rear disc brakes (GSL/GSL-SE): Remove the wheels, unbolt the brake calipers, hang them out of the way with wire (never by the hose), and pull off the brake rotors.

If you have rear drum brakes (GS):

1. Loosen the handbrake cable adjustment under the center console cover.
2. Loosen the starwheel adjuster through the port in the backing plate to remove brake shoe drag from the drum. Remove the two large Phillips screws on the drum face and pull the drum off. If it's rusted or stuck, tap the outer edge of the drum face with a rubber mallet to rock it loose ¹.
3. Disassemble the brake shoes. Community Pro-Tip: Before undoing the heavy retaining springs, wrap a 1" nylon web strap tightly around the shoes. This keeps the assembly from violently flying apart when you release the tension and makes reassembly much easier ¹.
4. Remove the coil springs, unclip the retaining pins by rotating them 90 degrees, detach the handbrake cable lever (held by a C-clip), and unclip the cable from the backing plate.

3. Axle Extraction

1. Remove the four bolts securing the axle to the differential housing.
2. Use a slide hammer (axle puller) to yank the axle straight out of the housing ².

4. Seals and Bearings

• The Seal: The axle seal sits right at the end of the axle tube ². Pry the old one out with a seal puller. Clean the mating surface thoroughly, lubricate the outer edge of the new seal, and tap it in squarely using a seal driver or a large socket that matches the outer diameter.
• The Bearing: The wheel bearing is pressed onto the axle shaft itself. Removing the old bearing and pressing on the new one requires a hydraulic shop press. Take your pulled axles and new bearings to a local machine shop; they can normally press the old ones off and the new ones on for a modest fee ².

5. Reassembly

Once your axles are back from the machine shop, coat the splines and the inner lip of the new seal with a little gear oil. Carefully slide the axle back into the housing, taking care not to nick the new seal on the way in.

I do not have the verified torque specifications for the four axle retainer bolts or the wheel lugs on this specific chassis. Do not guess on these—check the Factory Service Manual (FSM). You can find digital copies of the Mazda FSM hosted at Foxed.ca ³.

Torque the axle bolts to spec, reassemble your brakes, adjust your handbrake cable, and don't forget to refill the rear differential with the correct weight gear oil before dropping the car back on the ground.