Dear B.B.,

Hope you're well. If you wish to assess the condition of your 940's hubs, jack up the car, just enough that the tire is clear of the ground. Spin the tire with your hand. If it spins easily and noiselessly, the hubs are fine.

If, though, there's a grinding noise, that could mean: (a) a brake pad is binding on the rotor (which can cause poor mileage) or (b) a hub is "on the way out".

If you suspect (a), remove the tire and the steel pin, that holds the rotor to the hub. Then loosen the two 10mm hex head bolts, that secure the caliper frame to the strut housing. Slide the caliper off of the rotor.

See if the caliper pins allow the caliper to move freely. If not - if the caliper moves sluggishly or not at all - separate the caliper from the frame. Remove the caliper pins, remove any corrosion with a rotary wire brush, grease lightly with caliper grease and re-assemble. That should ensure the brake pads don't bind on the rotor. If the caliper pins are corroded into place, see if a penetrating oil (e.g., PB Blaster, Kroil, etc.) will free them. If that can't be done, replace the caliper and/or frame.

While the hub is unburdened by the caliper, try to turn the hub by hand. It should move easily and quietly. If not, the hub is at the end of its service life. There should be no "wobble" when you turn the hub.

Hope this helps.

Yours faithfully,

Spook