Why does the steering not return to center after turns on a Mazda RX-7 FB?

Difficulty: Moderate

First, let's set a baseline for the FB chassis: these cars use an older recirculating ball steering gear, so the steering is naturally not going to aggressively self-center like a modern rack-and-pinion setup ³. However, if you are having to manually pull the wheel back to straight after every turn, you definitely have a mechanical or alignment issue.

Here is how you should diagnose a lack of return-to-center on the FB:

1. Directional Tires Mounted Backward (Start Here) Before you touch a wrench, check your tires. If you are running directional tires, verify they are mounted to rotate in the correct direction. Owners have chased this exact self-centering issue on the FB only to find that improperly rotated directional tires were the sole cause ³. Low tire pressure or excessive toe wear can also contribute ¹.

2. Caster Angle (Alignment) Caster is the alignment angle primarily responsible for self-centering the steering wheel. If your caster is set too low, the wheels won't want to snap back straight. When you get the car aligned, be aware that Mazda's factory caster specifications for the FB are intentionally staggered (different from left to right) to compensate for crowned roads ¹. Ensure your alignment shop knows this and doesn't try to force them to match perfectly.

3. Over-Tightened Wheel Bearings Proper front wheel bearing preload is critical for steering control on this chassis. If the bearings are packed and tightened down too hard, the drag will fight the steering geometry and prevent centering. The Factory Service Manual specifies using a pull scale to verify it takes exactly 5 lbs of force to turn the rotor ¹.

4. Steering Box or Linkage Binding Because the FB uses a recirculating ball steering box ⁴, it is notoriously prone to developing slop. As a general automotive rule, when people try to adjust the worm shaft or sector shaft preload to dial out that "wonder steering," they often over-tighten the adjustment screws. An over-tightened steering box will bind internally and refuse to return to center. You should also disconnect the tie rods and check for binding in the idler arm, pitman arm, and lower ball joints ¹.

5. Rear Axle Binding (If Lowered) Because the FB's rear track is narrower than the front, lowering the rear suspension can cause the rear axle to shift off-center if not done correctly. If the car has been lowered, the proper procedure is to loosen all the rear suspension links and the Watts link bolts, let the car settle under its full weight, and then re-torque them ¹. If the suspension was torqued while in the air, the rear axle is likely bound up and pushing the car off its tracking line.