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Steering Head Bearing Tension

Discussion in 'Technical and Troubleshooting Torque' started by charlie_bird, Apr 12, 2008.

  1. Hi I have researched some other posts on this topic, but I'm still not 100% clear on a couple of points.

    I've just fitted aftermarket tapered roller bearings in my 99 CBR600. They fit well and everything went back together fine. If I set the tension with the adjusting nut (and locking nut) the tension is 'perfect', however tightening the steering stem nut to the specified torque (76 foot pounds), the steering tightens up. Is that normal?

    Next question. Will the steering loosen up over time / kms? Right now I'd say its just a tad too stiff. Wondering if its worth re-adjusting...

    Final question. The shop manual nominates a certain preload on the steering measured by a spring scale. What is best description of 'rule of thumb feel'. I've heard that the bars should fall from side to side on thier own, others say one or two fingers to push the bars from side to side.

    All opinions and any help very much appreciated. Thanks
  2. Tighten it right up a bit further (this helps press the bearing races right in if they're not already perfectly seated), then loosen it right off, and tighten again until it's at the specified torque. There shouldn't be any resistance moving the bars from side to side.

    Err on the side of looser, but be aware you might have to re-tighten again in a month or so.
  3. thank you loz.

    I did crank the adjuster nut down hard initially and turned the forks several times to seat the bearings. I then adjusted the adjuster nut so the forks fell from side to side easily. However when I tightened the steering stem nut, the steering got somewhat tighter. Will the steering stem nut typically add tension to the whole assembly and do you have to compensate for that when adjusting the bottom adjuster nut?

    As I said, they are just a tad tighter than I think they should be. I can turn the bars from the bar end with one finger. They don't fall from side to side though. If they do loosen up over time, do you reckon it may come good over time?
  4. Yeah they might... I'd err on the side of loosening them off until the bars turn freely, and then re-tightening in a month or so if need be.
  5. Unless they have not been fitted correctly (paint in the stem stopping the race from seating correctly; inserted at an angle so only a part of the bearing surface is in proper contact) they should not loosen up at all, really.

    You do not adjust steering head (or any other ball or roller or tapered bearings that I know of*) with a torque wrench. You adjust them so that they spin freely but without play.

    Too tight is just as bad as too loose, as far as wear goes. As far as handling goes it can lead to some awful characteristics, including weaving.

    The forks should fall gently to either side when just off from centre, as long as the cables or wiring are not so stiff as to impede the movement.

    Back them off again and adjust them so that, once the lock nut is tight, the forks will just drop to either side when slightly off centre.

    All the best

    Trevor G

    * In a motorcycle application. Some larger applications possibly have a set torque figure.
  6. Thanks. I'll have another go then and loosen them off a tad.