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Forks bent, how bad is it?

Discussion in 'The Garage' started by apox, Apr 21, 2016.

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  1. apox

    apox XS650 Addict

    just order a bunch of stuff from xs650direct.com, got my forks apart and noticed they dont roll on the table very nicely. There is a photo attached of the bottoms together, that is the extreme of the bend on both forks, the gap you see at the top side of the forks. My triple is perfect though, I sat it down on a flat surface and it are true. Are 30 year old accident free forks really straight?... or does everyone have some bend in theirs?

    thanks,
    Rob
     

    Attached Files:

  2. weaselbeak

    weaselbeak XS650 Junkie

    That is not normal, they should be straight.
     
  3. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi apox,
    how straight should they be?
    I'd say, straighter than what's shown in that photo.
    If it's a smooth curve they can be straightened, at least it sez so in Clymers.
     
  4. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    I've straightened fork tubes much worse than that. But, it's best to use a stout press, with proper size aluminum 'C' pads, a fixture to measure runout, and a micrometer to measure post-bend roundness...
     
  5. apox

    apox XS650 Addict

    Ok, thanks for the info guys, I am getting a quote from a local bike shop, if it's more than xs650direct replacement tubes ($180 Canadian set) then I'll be buying those! Hopefully the quality is good....
     
  6. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    I used to get $5 a tube for straightening.

    But, that was billions and billions of years ago...
     
  7. apox

    apox XS650 Addict

    haha nice... well this is Canada so I will keep you guys updated, I bet no less than $200 to have them straightened. The shops I've talked to so far in Toronto (when I lived there) and I can only assume Calgary will be the same, they want ALL your business, they want to build the bike for you, so when you want just a little work done, they hose you. I tried to have the rack taken out of my neck at a place in Toronto, I did the prep work, they wanted $600. Needless to say, I have have the rake... which I would like removed if anyone knows anyone in the Calgary area haha.
     
  8. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi apox,
    what happened to Canadian engenuity, eh?
    All you need to straighten a bent fork tube is two short 2 x 8s, some rope, a plywood patch and a scissor jack.
    Nail the 2 x 8s together to make a 4 x 8.
    Put the scissor jack on it's middle.
    Balance the tube on top with the plywood to protect it's surface.
    Rope the fork tube's ends down onto the 4 x 8.
    Open the jack.
     
  9. apox

    apox XS650 Addict

    Ive been looking at some DIY options, so after that I am just eye balling it? I don't have any measuring tools, or access to.
     
  10. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi apox,
    got an eyeball, dontcha?
    Check for straightness by rolling the tube on any flat surface, like a tabletop or a kitchen countertop.
    A bright light on the tube's other side will show a line of light between the tube and the surface as you bend down to squint at it from your side.
    Look for light line thickness variations.
    You can check for straight within 0.01" that way.
     
  11. apox

    apox XS650 Addict

    I may try this tonight, i'll just have to pick up a jack. Can you elaborate a bit on this set up? trying to understand how this would look... I just imagine the tube, 4x8, plywood and rope all attached, sitting on top of a jack lol, where does the force come from? do I need to put all this between two solid walls or something and then open the jack?
     
  12. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi apox,
    most cars have a scissor jack for wheel changes.
    OK
    Place the jack in the middle of whatever strongback you can contrive.
    Assuming your fork tube bend is a simple arc because if it's kinked or pretzelled it's FUBAR.
    Balance the tube on a protective pad on the jack, positioned so that the jack's upward movement will tend to straighten it.
    You need to hold the tube's ends down onto the strongback with a gap between the tube and the strongback that the jack will fit in.
    Rope will work for that but bridges of bolted 2 x 4s will work better.
    I now see the strongback as a single 2 x 10 with a pair of 2 x 4s bolted to each end as far apart as the length of the fork tube.
    Gonna look like a skinny saw-horse laying on it's back with it's legs in the air.
    The fork tube fits between the 2 x 4s. A 1/4" bolt through a blocking pad each end should be strong enough to hold the tube down against the jack's straightening force.
     
    Last edited: Apr 22, 2016
  13. Oddjob

    Oddjob adsgads

    along the lines of what fredintoon is suggesting you could use the weight of the vehicle in combination with the jack...

    Works best if you have a heavy SUV, essentially you would place the jack in the middle of the front bumper and in between the fork tube which would be stood off from the floor using a 2x4 or 4x4 on either end...

    You could then jack up your vehicle which would then bend the fork tube....

    I've used this method for similar sized tubing but admittedly not fork tubing...

    as with everything on the net, YRMV.
     
  14. cycleranger

    cycleranger Generally Ok.

    Hey Red, you forgot duct tape! :D
     
  15. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    But the thing is, where is the bend..............If its 1/3 rd of the way down the tube then the supports have to be an equal portion in distance away from the center where the bend is, not at each end of the tube
     
  16. apox

    apox XS650 Addict

    It is about a 1/3 the way, I considered that. currently trying to rig something like this picture below, I have cut holes in 2 thick pieces of hardwood that the tubes fit in nicely, and I've got a thick piece of angle. I like the other idea posted but I don't have a scissor jack, and the wife would shoot me if I lifted the 2015 4Runner "IT'S OK HUNNY! I AM JUST USING THE SUV AS A SHOP PRESS!" and I couldn't think of or find any two objects/walls whatever to brace that scissor jack and give me enough leverage. So I need a clamp that offers both the resistance, and pressure.
     

    Attached Files:

  17. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    If you tire of DIY many ag shops are pretty good at tube straightening (hydraulic rams)
     
  18. apox

    apox XS650 Addict

    attached a photo of my prototype! I was able to tighten it just by hand to slightly past true in the opposite direction, it will most likely just spring back to bent... but i'll leave it in over night and see it its any straighter...
     

    Attached Files:

  19. Oddjob

    Oddjob adsgads

    Time will not make any difference... You will have to plastically deform the material past its "elastic" yield point to correct its deformation... Permanent deformation will not occur until you take the materiial past its yield point, with that being time independant...
     
  20. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    Who doesn't have a scissor jack? I'm gonna try this soon, I like Fred's idea. I was thinking about if I could use my workbench, too flexible, table saw, maybe crack the casting. Ahhh!!!! My workbenchs are made from solid doors.......use the edge, not the top!!!!

    Scott
     
    Last edited: Apr 23, 2016

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