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Thread: Permobil C350 question, need more speed

  1. #11
    Senior Member pfcs49's Avatar
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    I don't know what sensible oversizes might be available, but the wheels for my ZX-1 are very simple, are two piece (inner and outer halves, pretty bi-symetrical) mild steel, with flat, drilled centers, no tapered seats like a car.
    A wheel like these would be real easy to mod. It could be easily re-drilled for a different bolt pattern. A cylindric aluminum spacer could be made and drilled/tapped for attachment to the new wheels; the aluminum could be plunge cut and drilled to mount it to the wheelchair's drive hubs. Something could easily be welded onto the wheels if needed.
    I hunch that the drive flanges may all have the same bolt pattern? Maybe not! Being the same would imply intelligent design
    69yo male T12 complete since 1995
    NW NJ

  2. #12
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    Quote Originally Posted by pfcs49 View Post
    I don't know what sensible oversizes might be available, but the wheels for my ZX-1 are very simple, are two piece (inner and outer halves, pretty bi-symetrical) mild steel, with flat, drilled centers, no tapered seats like a car.
    The "rims" are split -- outer and inner -- held together with three sets of two screws (hidden beneath the "hubcap"/wheelcover). Otherwise, the foam core tires would be a real PITA to remove! A large aluminum "hub" (?) sets between the rim and the mounting flange on the motor shaft through which the wheel fastens to the motor.

    Increasing the diameter of the wheel -- while leaving it in the same seating plane -- would interfere with the anti-tip rollers, as well as the support arms for the front casters. I'd have to drag out a ruler to see just how much clearance is available -- but, not likely to be the several inches required to increase the circumference ~two-fold (assuming the high speed upgrade motors aren't installed).

    So, you'd have to move the wheels outboard of their current locations, a bit (might also be needed o clear the chair's frame!)

    A wheel like these would be real easy to mod. It could be easily re-drilled for a different bolt pattern.
    You'd have to preserve the existing mounting holes to align with the "four lobed" mounting flange on the motor. But, if the bolt circle is enough larger than the existing one, you could drill the rim just a bit outside of the existing bolt-hole circle (the whell is three-spoked so this limits where you could butcher it -- unless you replace it entirely)

    A cylindric aluminum spacer could be made and drilled/tapped for attachment to the new wheels; the aluminum could be plunge cut and drilled to mount it to the wheelchair's drive hubs. Something could easily be welded onto the wheels if needed.
    It might be easier to find a "bell shaped" wheel (where the mounting surface is offset to one side or the other -- the Permobil wheels mount on their centerlines) and arrange for the deeper portion of the hub to be outboard (thus shifting the centerline of the tire out).

    I hunch that the drive flanges may all have the same bolt pattern? Maybe not! Being the same would imply intelligent design
    Ha! I've never thought of even checking that -- despite the number of wheels I've removed over the years!! I will have to take a look on Monday...
    Last edited by automation; 05-18-2019 at 08:47 PM.

  3. #13
    Senior Member pfcs49's Avatar
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    "You'd have to preserve the existing mounting holes to align with the "four lobed" mounting flange on the motor. But, if the bolt circle is enough larger than the existing one, you could drill the rim just a bit outside of the existing bolt-hole circle (the whell is three-spoked so this limits where you could butcher it -- unless you replace it entirely)"

    I have no idea how power chair wheels are mated, but the ZX1 wheels are 4 lugs. If the new/different flange has 4 lugs, you simply redrill the lug holes 22.5* from the old ones.
    Minilite used to supply alloy wheels for dual applications with 8 lug holes so they fit the Triumph Spitfire/Herald Lotus 7 as well as the Ford Cortina etc pattern. This was handy; now you could upgrade your Super 7 with the beefy wider ford rear and discard the twisted Herald unit, and all your wheels still fit!)

    If your hubs have only 3 lugs it still is likely you could find room to redrill it for 4 lugs, but two would be close to one another. I wouldn't let it bother me; the speeds and loads are so low that fatigue wouldn't be an issue. Also, given the implementation of the simple ZX-1 wheels, One could resort to rotating the two halves so the original holes are shuttered, and redrlling for the new hub geometry. It wouldn't matter if the new lug went through an old hole, the other hole would locate/index the wheel to the hub and the flat/un-champhered lug nuts would be supported well enough. The way the ZX wheels work, they come apart whenever you remove the lug nuts, the tire pushes the wheel halves apart, so rotating them back to original indexing is simple.
    69yo male T12 complete since 1995
    NW NJ

  4. #14
    Senior Member pfcs49's Avatar
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    REVISIONS: After blowing all this smoke, I went out to measure the OD of the 3.00x4 knobbies on the ZX1.
    The OD id 10.25"
    I mis-remembered! And I had assumed the wheels were the same diameter.
    The outer halves of the wheels are alloy with no place to drill a second set of lug holes, however another pair of inner steel rims may be able to be paired making a drab but malleable part.
    There's a hole @22.5* from adjacent lug holes for the tire tube but solid inserts would resolve the issue if you wanted to re-drill the holes

    Then I Googled the Permobil info: they show that the nominal 3.00x8 supplied tires have an OD of 14" (and they look much taller than mine in the photos of the 350)

    So if you want to do tractor pulls, put my tires on your chair!
    So I wonder what larger wheel/tire sizes might be available?
    Intersting conundrum. As an old racer fabrication/machinist type, if a tire of the proper OD is available, it's not a big problem to solve.
    As a normal consumer, it might be pretty difficult to find a fabricator that was economical.

    EDIT: Googled 3.00x9 tires and found these exist:https://www.walmart.com/ip/Greenball...waArI3EALw_wcB
    Comes with nice, malleable steel rims so modification would be easy. I'm assuming the 19 refers to OD which would be 1.36 times the original, so 6mph becomes 8.16mph.
    You'd need to space these out, but the chair would look like a nasty SOB with these!

    and now, a list of tire specs from Campus Scooters:
    https://www.campusskooters.com/tire-...nversion-chart. 10" might be a hit?

    and from Electric Scooter Parts:
    https://support.electricscooterparts...ead-tire-sizes
    and what's available:
    http://www.electricscooterparts.com/tires.html

    I'm done1 Time for bed.
    Last edited by pfcs49; 05-19-2019 at 12:02 AM.
    69yo male T12 complete since 1995
    NW NJ

  5. #15
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    I have no idea how power chair wheels are mated, but the ZX1 wheels are 4 lugs. If the new/different flange has 4 lugs, you simply redrill the lug holes 22.5* from the old ones.
    The flange on the output of the gearbox looks like a four-leaf clover -- one threaded hole in each of the "leaves". The bolt circle is about 2" in diameter... maybe 3?

    But, as it's a four-leaf clover, there's no "meat" between the "leafs" where you could locate another (tapped) hole. You're essentially stuck with this four bolt-hole arrangement.

    So, the solution is to mount "something" to those four bolt holes and then drill new holes in that "something" to accept whatever wheel you want to mount in place of the stock wheels. One obvious choice is to mount the rim from the original wheels to the motor flange and, somehow, adapt the body of that "wheel" to whatever your new wheel needs.

    This can be a win as it gives you an offset from the normal line of the wheel -- further outboard to help clear the anti-tip and front caster arm.

    I'll take some photos, Monday, as I've got the wheels off a Permobil chair, currently (though it's a mid-wheel drive chair -- I recall because I was amused that removing the batteries left the drive wheels FLOATING above the floor when the chair was unoccupied)

  6. #16
    Easy enough with an adaptor, my motor flanges were 5 bolt, alloy wheels 4 bolt. Adaptor also spaced wheels out as they were wider than original. 120/70 x 8 tubeless tyres were slightly bigger diameter. More comfortable over rough ground than original.
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  7. #17
    Senior Member pfcs49's Avatar
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    Very nice execution!
    I wasn't expecting to see any wheel mounting circle to be small enough to fit inside of the other.
    How much bigger is the tire OD from the original?
    69yo male T12 complete since 1995
    NW NJ

  8. #18
    I hit lucky with the alloys from China having that big pcd. 120/70 is about 10mm bigger diameter I think, 110/80 bigger again and 3.5 by 8 bigger still(15 inch v's 3 x 8 14 inch) . You have to consider that it raises the rear so you need a little more seat tilt.

  9. #19
    Senior Member landrover's Avatar
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    Quote Originally Posted by mrb View Post
    Easy enough with an adaptor, my motor flanges were 5 bolt, alloy wheels 4 bolt. Adaptor also spaced wheels out as they were wider than original. 120/70 x 8 tubeless tyres were slightly bigger diameter. More comfortable over rough ground than original.
    Would they be usable on sand?

  10. #20
    Senior Member Tim C.'s Avatar
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    Quote Originally Posted by Gearhead View Post
    Recently acquired C350 that I will be converting for street use (cane holders, lights, flag, etc.). 5 MPH speed not fast enough for me. Want 8 or more MPH.
    Question: Will reprogramming speed it up or will I need different motors and controller then programed?
    Before I talk to a tech, I need as much info as possible because I usually have to "hold their hand".

    My C500 will do 10 MPH so I can handle the speed, although it can cause a "pucker" moment at times. I just want the stability of a rear drive C350 at speed.
    10mph really?
    Video of this?

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