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Thread: Frog Legs ?UNI-TINE? Wheelchair Forks pivot bearing tightening

  1. #1

    Frog Legs ?UNI-TINE? Wheelchair Forks pivot bearing tightening

    I think this has been discussed but I can't find it. I want to tighten the pivot bearing to provide some damping to reduce wheel flutter at higher rolling speeds. I have done this in the past (with good success) with the same model Uni-tine Forks. I recently replaced my Uni-tines after having mine damaged by the airline and they furnished me a new pair. We did not change the caster angle.They flutter horribly at as little as 8mph.
    Now I can't figure out how to tighten them. We took the wheel off and put a socket wrench on the exposed nut which would not budge at all. I don't recall the fork having to come off the chair to do this but perhaps it does. My mechanic friend is out of the country for a couple weeks and I'd rather not try to do this using my wife for working hands unless we have a pretty good likelihood of success. Does anyone have first hand experience doing this? My chair is a ZRa in case that matters.

  2. #2
    I couldn't find the answer, but it should be in the ZRa manual. See chapter 11 if you haven't gone through it already. Isn't what was discussed before is to tighten the wheel spin and not the steering axle (pivot bearing)?
    http://www.wickedwheelchairs.com.au/..._zra_aeroz.pdf
    I have had periodic paralysis all my life. I lost my ability to walk in 2011 beginning with a spinal block, which was used for a hip fracture caused by periodic paralysis.

  3. #3
    I found some old 2009 threads confirming that the problem and solution are exactly what I recalled--just need more dampening. Now I just need to figure out why on my current Uni-tine the adjustment nut doesn't seem to turn. What I didn't try was loosening it first just to make sure that the nut moved and then try to tighten.

    http://sci.rutgers.edu/forum/showthr...ghlight=caster (thread)

    https://www.rehab.research.va.gov/jo...37/3/kauzl.htm (technical paper)
    Last edited by endo_aftermath; 11-05-2019 at 09:49 PM. Reason: fixed link to old post

  4. #4
    I would try that, if it's bottomed out add a washer

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