Q: How do you remove, inspect, and reinstall steering knuckle on BMW Z4?
A: New suspension strut-to-knuckle bolt, tie-rod balljoint, and lower arm balljoint nuts will be required for installation. Firmly apply the parking brake, raise the front of the vehicle, and support it securely on jackstands before removing the relevant front wheel. If replacing the steering knuckle, do not reuse the hub assembly. For reinstallation, loosen and remove the two bolts securing the brake caliper mounting bracket, then slide the caliper assembly off the disc and tie it to the front suspension coil spring to avoid straining the hydraulic brake hose. On models with ABS, also remove the wheel sensor. Loosen and remove the nut securing the tie-rod balljoint to the steering knuckle, then release the balljoint tapered shank using a universal balljoint separator. Unscrew the lower arm balljoint nut and release the balljoint tapered shank from the knuckle with a universal balljoint separator. Loosen and remove the bolt securing the suspension strut to the knuckle, then slide the knuckle down and off from the end of the strut, using a large screwdriver to slightly spread the clamp as needed. Examine the steering knuckle for wear or damage and replace if necessary. Before installation, clean the threads of the strut-to-steering knuckle bolt hole with a tap of the correct size and pitch. Engage the knuckle with the lower arm balljoint stud and install the new retaining nut. Position the knuckle on the suspension strut, ensuring the locating pin on the strut slides into the slot in the knuckle's clamp, then slide the knuckle up until it contacts the stop on the strut. Install the new strut-to-knuckle bolt and tighten it to the specified torque, followed by tightening the lower arm balljoint nut to the specified torque. Engage the tie-rod balljoint in the steering knuckle, install a new retaining nut, and tighten it to the specified torque. If installing a replacement steering knuckle, install a new hub assembly. For models where the hub was not disturbed, slide the caliper into position over the disc, ensuring the pads pass either side of the disc, clean the threads of the caliper bracket mounting bolts before installation, and tighten them to the specified torque. Finally, reinstall the wheel, lower the car to the ground, and tighten the wheel bolts to the specified torque.