Wheel Spindle Nuts Getting Loose. Why

Posted in Axles & Driveshaft

I have a vintage 1984 Subaru 4wd wagon that I’m fixing up. It has the oddest problem. The front wheel spindle nuts (NOT the lug nuts – the big nut in the middle if the wheel assembly) keep getting loose. I’ll take out the cotter pin and tighten them down to 150 ‘Lbs like the book says and within 500 miles they are loose again. I can’t understand it. How can they get loose if there is a cotter pin in in there? I took the whole wheel – axle assembly and cleaned everything with brake cleaner and made sure the axle shaft was seating all the way but it still loosens. I’m at as loss. Otherwise I have this car running like a champ. I’d like it to be 100%
Additional details. The wheel bearings have about 15K miles on them and this problem only started within the last 5K miles. They do not make noise. The cotter pin is replaced each time the nut is tightened and there is no room for it to move. I did not grease it after I cleaned it and I’m going to take it apart now and apply grease to the cone shaped washer.

There are 5 Answers for "Wheel Spindle Nuts Getting Loose. Why"

    1. Pedal2themetal45 says:

      The only thing I can think of is the cotter pin holding the nut solid to where it can not move?
      good luck

    2. Larry E says:

      It sounds like the bearing races aren’t pressed all the way in.

    3. Btec88 says:

      It could be possible that there is a sequence to torquing the nut. such as tighten to 150 then loosen and re-tighten to 150 etc.. this is to ensure seating of all components and taking up all the slack. is it possible the wrong axles are installed or wrong hub and bearing? this could cause improper clamping loads on the assembly allowing it to loosen. i personally never torque these nut and just run them down with an air gun and install the cotter pin or peen the nut, depending on vehicle.

    4. Br549 says:

      The hub bearings in the “knuckle” are wearing out.

      They should be starting to make noise. If not by now, they will soon!

    5. Knockyourteethout says:

      All the other answers are wrong. Ignore them. If your bearings were wearing that much you’d hear noise. There is nothing wrong with the cotter pin either. You gave a big clue. You took it apart and cleaned everything. I bet you didn’t grease that cone shaped split washer before you put it back in. It won’t seat properly, it will bind unless it is greased. Take it apart, grease it and put it back together. It’l be fine.