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Thread: Casters sticking/grinding brand new chair

  1. #1

    Casters sticking/grinding brand new chair

    WTF is it with my luck!? I've posted my Ki Rogue saga, where I'm on the second frame of the chair...well first, as the second the ATP had made just 14" high. How I missed that IDK! But this frame came first with big knobby tires, and the COG way off. So new footplates made, (still too long) and different tires. Taking it for a whirl yesterday, and I noticed the casters fluttered some, and got sticky. Today, they sound like a loud screeching grinding metal sound when rotating! Yet they're loose when I'm not in the chair. Too loose, one has about a quarter inch jiggle to it. Anyone have any ideas what this is? I think maybe they didn't adjust the angle properly, and it's not tightened up enough? How annoying! I also noticed that there's no more adjustment room for COG, and I do need some more. I can't pop a wheelie easily. The dump is 2", and it was made so I can have more, but not less. Which I may want. Ugh.
    Ki has been great, I have faith they will figure it all out and make it right. But for crying out loud, it's been months of this. The caster housing has a gouge on one of them, too, so a tech must've been messing with it.
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    Last edited by heartdog; 09-22-2018 at 11:15 PM.

  2. #2
    Senior Member brian's Avatar
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    That sounds like two separate issues:
    1. Caster flutter is likely the result of the stem not being tight enough
    2. Scraping sound is likely coming from the bearings

    What does 'sticky' mean? Are both casters behaving similarly? Or is one fluttery and one sticky?

    Do you have the tools and wherewithal to open up your casters and stem and make adjustments? If so, do that and see if you can't figure out the issue. Pay close attention to how things are put together, make small adjustments that make sense, then put it back together and see if the issue is better or worse. Rinse and repeat until solved.

    If you do not have the tools or feel comfortable doing that, just call your DME or Ki. But I encourage everyone to completely take apart their chair and understand how it works so you can make repairs and adjustments on your own. Life's too short to wait for your DME.

  3. #3
    The grinding one is obviously loose, it has a lot of jiggle. But sticky meaning when I lean forward, or just sitting in the chair, when it rotates, the grinding is where it's sticking. Like metal on metal. Like when a shopping cart pulls you to one side. No I don't have the tools or knowhow. I can't even figure out how to adjust my Roho Agility back. Though I'm getting a different one. But the casters seemed fine for one outing, then today they went downhill suddenly.

  4. #4
    I have run into a couple of new chairs that exhibited the grinding/sticking phenomenon you are describing. It can be difficult to identify an obvious cause through visual inspection of the individual parts. Solving it can be frustrating because it may not be noticeable unless you are actually sitting in your chair so there is weight over the front casters.

    The sticking occurs when the surface of the fork makes contact with the underside of the dust cap when the fork swivels under load.

    Even if there are no obvious nicks or scratches in the top of the fork or in the ring on the underside of the dust cap, all it takes is a subtle irregularity to cause one to rub against other. The dust cap should only make contact with the inner portion of the bearing and the tolerances here are fairly precise. Any contact between the fork and dust cap will cause it to to catch.

    This problem may not be caught at the factory unless they test the chair under load. An improperly milled bearing housing may not be visible to the naked eye.

    I have tended to see this more on chairs with single sided forks, 5" casters, and conservative COG's. It appears 2 out of 3 of these things apply to your situation.

    The caster flutter is a secondary problem that occurs when it is not possible to tighten the fork so there is enough tension to prevent flutter without the dust cap making contact with the fork causing it to bind.

    Ensuring the fork is perpendicular and distributing more weight over the rear axle could eliminate the problem, but I suspect the fork may need to be replaced. Temporarily swapping left and right forks/caps could help diagnose the problem. if the fork swivels normally on the opposite fork stem, then there is a problem with the alignment.


  5. #5
    Thanks. Yep I bet that's it. They may have the second chair that was made, and be able to swap out the casters. But both are sticky when weight on them, just one is grinding. The COG needs to be different, and she said it can't go any further forward. Sigh. I am hoping Ki will actually come and spec me out and make yet another one. Cuz so much misinterpretation happened. I wanted Spox wheels, but the narrower hub, because I can't have these move in closer to the sides. They're both about 2" away from the sideguards! I'm not sure I needed 85 degrees of bend, cuz now that's a lot to be in front, when it could be 90 and have less footprint. Have no idea if/how they can get these footplates up another inch or so. Seems there's excess to cut off below the caster stems, but supposedly that's not possible either.
    Pretty funny that despite all the wrong, it still is much easier to push than my two previous chairs. Probably cuz it has more dump. But since my spine curves in a C away from the back, I think the dump makes that worse...? Like I feel strain on my neck, and when I boost the cushion to be more at 1" dump it relieves it.

  6. #6
    Quote Originally Posted by heartdog View Post
    WTF is it with my luck!? I also noticed that there's no more adjustment room for COG, and I do need some more.
    Ki has been great, I have faith they will figure it all out and make it right. But for crying out loud, it's been months of this. The caster housing has a gouge on one of them, too, so a tech must've been messing with it.
    The dump is 2", and it was made so I can have more, but not less. Which I may want.
    From the image and if this is doable. Reverse the camber tube mounting and clamp brackets, that may allow more COG.
    I am never a fan of single side castors on wheelchairs.
    The only decent examples I have seen are on BMW motorcycles.
    IMO, no matter how beefed are the housings, the load on the bearings (and spindles) appears to be not evenly distributed proportionally, especially when changing direction-huge forces.

    About dump. It would appear that longer camber tube towers are available. See here in the accessory chart. The example shown is longer than that fitted to your chair.
    https://permobil.co.nz/Content/Image...Chart%20v1.pdf
    Last edited by slow_runner; 09-23-2018 at 10:02 PM.

  7. #7
    I would also check into ordering foot plate spacers or you can just get them a home depot. Drill out the bolt holes if you have to put those under your foot plate. You can bring up your footplate an extra 1 to 3 inches no problem. The most inexpensive fix and easy to do. I am sure your feet are getting swollen correct? From lack of blood circulation because the pressure on the underside of your femors? If you need help on how to do the spacers. You can private message me and i can give you my number and explain it. I own a dme store in Scottsdale Az I don't mind helping or talking you threw it. Nick M. Phx az.

  8. #8
    Heartdog: Thanks for the great photo as it helps to see the whole set up. I'm sorry I'm going off-topic, but I think I notice, looking at the axle adjustment, that your frame is set at the highest up position. I know it's been commented on CC that the ideal position for pushing would be that your fingertips touch near the area of the axle when your arm is held straight down. However, from your photo are your fingertips higher up from axle, which can make the chair more difficult to push?
    If you did lower the rear of the chair it would probably give you too much dump and to counteract that you might lower the footrest.
    If you are completely comfortable sitting, then never mind my comments.....but it just looks like you're sitting quite high in the chair. I'm no PT but it appears the angle downward of your thighs may be putting some stress there.
    Hope you let us know how it's going with the chair. Information and feed-back about the fit of a chair are so important here.

  9. #9
    Triumph: My fingers do touch the axle ok. I think a big part of it is that the footrests are still too low, so it makes my legs hang down. It throws my balance off and everything. But, they will not go further, and the only option I have is risers, or a clamp on (yuck). I'm hoping to appeal here maybe for some hacks. Some sort of material that I can make a booster for just my feet, and a middle area stays open for the Freewheel to attach. Not that I've been using it, as the footprint of the chair makes it really stable. Even with 4" casters.
    What I'm not happy about is that I got up early, got in my car- which is hard for me now (trying to get a wheelchair van, a whole other story lol)- and drove an hour to meet the regional rep for Ki, thinking they were going to switch out the entire forks from the chair that was more wrong. I thought they hadn't sent it back yet, so could just give me the good fork from it. He takes it, then comes back and had put in a new bearing. Huh?? The fork was still catching while rotating, and I was dismissed, saying did I realize how much work had been done behind the scenes to make this work for me?? Wow. I didn't argue, and apologized even. But isn't it their jobs?? Their policy is make it right. I'm not at fault for the measurements coming out wrong. Anyway, so it still catches, and now even has play in it. The chair also creaks. A LOT. When I turn in place, there is loud cracking sounds. Don't know what that could be, but it comes from the axle area.

    So, I'm waiting now to see what they're going to do. It's already been all week and no word. Sigh.

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