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Thread: [Help]Adjusting The Toe On Tilite ZR

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  1. #1
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    [Help]Adjusting The Toe On Tilite ZR

    Hey guys,

    Awhile back I cracked my carbon fiber camber tube in half on my Tilite ZR (I?m assuming from being bumped down too many stairs?). Anyways, I had an older Tilite ZR laying around with a perfectly good camber tube so I replaced the cracked one with the older one (hope you?re following this lol). But now my chair is ridiculously hard to push. Like it used to push super easy than coast for like 10 or fifteen feet now it is significantly harder to push and doesn?t coast and when it slows down starts to roll backwards a few feet.

    I talked to the wheelchair people, they said they were ordering me a new camber tube that won?t be in for weeks and they will fix it then. So in the mean time I still have to push this turd around.

    Is is there an easy way to adjust the toe?( I?m assuming that part of the problem).

    ANY help would be awesome.

  2. #2
    Senior Member Oddity's Avatar
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    If you have a carpenter square it's easy. The flats on the side of the camber plugs need to be perfectly perpendicular to the floor for proper toe on a TiLite ZR. Could the old wheel's bearings be bad?

    The hard way is chucking the front and back wheels, the measuring the distance between a specific spot on the middle of each tire on both front and back. The measurements need to be equal. I usually measure and mark each tire first. Makes it easier.
    "I have great faith in fools; self-confidence my friends call it." - Edgar Allen Poe

    "If you only know your side of an issue, you know nothing." -John Stuart Mill, On Liberty

    "Even what those with the greatest reputation for knowing it all claim to understand and defend are but opinions..." -Heraclitus, Fragments

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    Quote Originally Posted by Oddity View Post
    If you have a carpenter square it's easy. The flats on the side of the camber plugs need to be perfectly perpendicular to the floor for proper toe on a TiLite ZR. Could the old wheel's bearings be bad?

    The hard way is chucking the front and back wheels, the measuring the distance between a specific spot on the middle of each tire on both front and back. The measurements need to be equal. I usually measure and mark each tire first. Makes it easier.
    thanks so much for the advice! I don’t have a carpenters square, will get one tho, should it be the kind with a level in it? Sorry if that was a silly question. I really don’t think it could be the bearings but I guess that’s a possibility!

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    Senior Member Oddity's Avatar
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    Quote Originally Posted by jhm View Post
    thanks so much for the advice! I don?t have a carpenters square, will get one tho, should it be the kind with a level in it? Sorry if that was a silly question. I really don?t think it could be the bearings but I guess that?s a possibility!
    This is what I meant.

    https://en.m.wikipedia.org/wiki/Steel_square

    I'm sure there are other ways to check that angle. I happen to have a square and thought it was easy enough.
    "I have great faith in fools; self-confidence my friends call it." - Edgar Allen Poe

    "If you only know your side of an issue, you know nothing." -John Stuart Mill, On Liberty

    "Even what those with the greatest reputation for knowing it all claim to understand and defend are but opinions..." -Heraclitus, Fragments

  5. #5
    Senior Member pfcs49's Avatar
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    Sounds entirely like toe in/out is seriously off!
    So much so that looking down from above you might see the tires either pointing in or out.
    What you want is a 2" "framing square" They're pretty cheap and have no bubbles.

    I don't know how well it would work, but you could get a piece of hard cardboard backing and lay it on the floor. If there's toe in or out, rolling the empty chair straight across it will make it go in or out depending on how it's misaligned. If toed in, it will move out and out if toed in.
    Loosening the two axle clamps and then rotating the axle will change the toe in; a quick twist one way and the other will make it clear which way you'll need to turn it to change toe appropriately. (rotating the top of the axle tube forwards increases toe-in/rearward increases toe out. You want -0-)

    PS: if using a framing square, it doesn't matter if the floor isn't level, but it must be uniformly flat where you're wheels and square are touching.
    A nice flat table would be ideal for accessibility.
    69yo male T12 complete since 1995
    NW NJ

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    Quote Originally Posted by Oddity View Post
    This is what I meant.

    https://en.m.wikipedia.org/wiki/Steel_square

    I'm sure there are other ways to check that angle. I happen to have a square and thought it was easy enough.
    Quote Originally Posted by pfcs49 View Post
    Sounds entirely like toe in/out is seriously off!
    So much so that looking down from above you might see the tires either pointing in or out.
    What you want is a 2" "framing square" They're pretty cheap and have no bubbles.

    I don't know how well it would work, but you could get a piece of hard cardboard backing and lay it on the floor. If there's toe in or out, rolling the empty chair straight across it will make it go in or out depending on how it's misaligned. If toed in, it will move out and out if toed in.
    Loosening the two axle clamps and then rotating the axle will change the toe in; a quick twist one way and the other will make it clear which way you'll need to turn it to change toe appropriately. (rotating the top of the axle tube forwards increases toe-in/rearward increases toe out. You want -0-)

    PS: if using a framing square, it doesn't matter if the floor isn't level, but it must be uniformly flat where you're wheels and square are touching.
    A nice flat table would be ideal for accessibility.
    mucho appreciate you guys help! When I roll backwards the tops of my wheels angle in and rub hard against my side guards, doesn’t do that when I roll forward. Weird right?

  7. #7
    Quote Originally Posted by jhm View Post
    mucho appreciate you guys help! When I roll backwards the tops of my wheels angle in and rub hard against my side guards, doesn?t do that when I roll forward. Weird right?
    Something is awry for that wheel behaviour to occur.
    Question::
    How is that possible for your wheel to act in such a way? Unless your camber tube is not clamped firmly or, and this is a stretch, the camber plugs are moving????
    Is the replacement tube the same diameter as the carbon fibre unit? can you measure it with a vernier? Are the tube clamps fully closed? There should be a clearance on the clamp split when they are fully tightened. If they are closed up I would assume the tube is a smaller O.D than the original carbon unit..
    If you do not have a vernier but have a tape, a quick bush measurement can be done by wrapping a tape around the tube and read from a reference point, say at 10cm. Record the reading then measure the other tube using the same reference point; compare.
    Or put the tube back in your old chair and use that chair until repairs can be done.
    Personally, I wouldn't have a carbon camber tube on my chair. IMO the weight advantage, break risk is not worth the cost outlay or the stuff around when they fail.
    A rafter square is useful but not necessary
    Set your camber by locking your wheels - measure and mark your wheel centre height on the tyre face/edge (whatever works best for you) front and rear.
    Measure the front and rear width and record. Depending on how much camber/toe in you want then slacken off your tube clamps (only enough that a firm grip will move the tube as you don't want it freely rotating to its natural rest point) and rotate fore or aft to achieve your result. Start at 0 - i.e when the front measurement is the same as the rear. At this point the wheels will be square/perpendicular to the floor ( bearing wear and any slop excepted).
    Regardless, at this point you decide what toe in/camber you wish to set your wheels at.
    I set mine with 5mm or so of toe in because I am comfortable with that. Measuring the toe in from the rear is easier than buggering around with my rafter square. Just remember, if adjusting from the rear, to add to otherwise you will achieve toe out
    Last edited by slow_runner; 07-13-2018 at 03:52 PM.

  8. #8
    Senior Member pfcs49's Avatar
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    Quote Originally Posted by jhm View Post
    mucho appreciate you guys help! When I roll backwards the tops of my wheels angle in and rub hard against my side guards, doesn’t do that when I roll forward. Weird right?
    Your wheels are toed out; when you roll forward they want to move away from themselves, and when you go backwards, they move in as far as there's play or compliance to do so. That's also why when you come to a stop, it wants to roll back: it's probable that the wheels deflect and that spring-force wants to relax/return to null, which rolling backwards restores.
    So there's a quick way to eyeball the toe: loosen the axle clamps enough to twist it in place, have a buddy move it and you'll see the change in behavior.
    If you have a large, level, hard floor, you could experiment with coasting. The best toe is the one that coasts the farthest. I don't know about skinny, radiused wheelchair treads, but with automobiles (race cars) with much camber, -0- toe is not the lowest rolling resistance.
    Imagine when you roll one of your wheels across a floor. As it inevitably leans over (gains + camber; our wheelchairs have neg camber; so do cars), it begins to turn into the way it is leaning. Hold it as possibility that to achieve minimum loaded rolling resistance, -0-Toe may not be ideal! A little toe-out may be better! It will compensate for the force that is trying to have the tires turn in? Some one needs to test this!

    So, the ball is in your court! Go get some empirical data for us! Do coast-down test with different alignments an let us know if your axle isn't aligned with the framing square when it hits the optimum.

    PS: you should check the camber plugs to ensure nothing is rotated. Both have two parallel flats which technically should be 90* to the plane the chair is parked on. If one is twisted, then of course they can't both be right and you'll need to fix this first. If you have an aluminum axle spare, that would be the best fix! CF axles sound like bullshit to me.
    Last edited by pfcs49; 07-15-2018 at 05:56 PM.
    69yo male T12 complete since 1995
    NW NJ

  9. #9
    Senior Member Oddity's Avatar
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    I think there have been a couple iterations of the camber plug-tube interface on the ZR/TR chairs. Epoxy then pinned then epoxy again (stronger). It's possible it is not tight enough. There were issues, especially with the early CF tubes when they first came out.
    "I have great faith in fools; self-confidence my friends call it." - Edgar Allen Poe

    "If you only know your side of an issue, you know nothing." -John Stuart Mill, On Liberty

    "Even what those with the greatest reputation for knowing it all claim to understand and defend are but opinions..." -Heraclitus, Fragments

  10. #10
    Quote Originally Posted by Oddity View Post
    I think there have been a couple iterations of the camber plug-tube interface on the ZR/TR chairs. Epoxy then pinned then epoxy again (stronger). It's possible it is not tight enough. There were issues, especially with the early CF tubes when they first came out.
    Hi Oddity. We know how well epoxy secures items that have smooth surfaces. More often than not it acts as a gap filler and not much better. If the surfaces are roughened then the application is more successful but still reliant on the 'interference/keying-in' factor.
    Epoxy on wood- yes, IMO it is fine. On steel/ aluminium? I am not convinced.
    When used with axle tubes and CF it is a substitute for an interference fit; and that is all. IMO
    I wouldnt trust it for too many kms

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