Widening scooter front forks

  1. vino Member

    Houston, Texas
    Hi, I hope it's ok to introduce yourself and dig right in with a project

    We have a Yamaha Vino scooter that I would like to mount a wider
    front tire to. It seems like the only way to do this is to cut the
    fork support, and add about 1/2 inch to each side. I have attached
    some pics of the forks, with a couple of sketches of how I'm
    thinking of going about it.

    1. Make 2 cuts on either side of the steering shaft.
    2. Butweld 1/4 inch filling strip
    3 Grind the welds flush
    2 Lapweld patches over the filler strips.

    The fork support is made of approx 1/8" steel, with stamped braces
    about 0.1" thick, going down to the wheel axle.

    I have a small Millermatic at work, which I have been using to
    lapweld extensions onto motor brackets, to fit larger motors. The
    bracket material is only about 1/16" thick though, and that's the
    sum of my welding experience.

    Does the plan look reasonable?
    • AllPics.JPG
  2. malcolm

    malcolm & Clementine the Cat

    Bedford UK
    Front forks can be under a lot of stress, and the failure mode could be a little final, so it pays to be careful with them.

    I'd say your plan to do a butt weld then fit a reinforcing plate sounds sensible. I'd be inclined to make the reinforcing plate extend to the uprights on the outer edges and the stem on the inner. Should look prettier and spread the load a little better. You could always do a bit of plug welding between the reinforcement and the original metal.

    Not sure if you have the clearance, but a second reinforcement to cover the open section at the rear would make doubly sure. I might be inclined to butt weld the front face and add an additional rear face without reinforcing the front face. Your welding would need to be good and penetration checked on scrap metal first. A box section would really reduce the load on the front face.

    1/8 will need a much higher setting on the welder than 1/16, but should be easier to weld. You should be able to check the penetration from the open side. Probably it would pay to do some test welds on some scrap before starting to get the penetration right.
  3. vino Member

    Houston, Texas
    Hi Malcolm,
    many thanks for your input.

    A reinforcement plate on the back sounds like a good idea. The
    only thing that concerns me is that it might become more of a
    dirt trap than it already is, and start rusting. I could seal it
    copletely though.

    The box section would be my favourite way to go, but there's
    a lot of curves. I can take a look at it again and see how I might
    wrap it around.

    Here's a pic of the revised plan. Might have gone a little overboard
    on the plug welds. Does this look better?

    There is one other thing. I was told that the stamped forks that
    go down to the axle might become hard and brittle if heated up too
    much. That's why I kept the patches away from them in the design.
    Is that really a concern, or would it be ok if I just don't weld
    directly to them? I can just run the bead for the reinforcement
    patch parallel to the weld that's holding the fork.
    • TFRontViewReinforcePlate.JPG
  4. vino Member

    Houston, Texas
    Hi again, just wanted to show off the fork jig!

    One question.. Do I need to remove the paint on the opposite side
    of the joint where I'm butt welding?


    • AdjustedCutFork.jpg
  5. ray

    ray Member

    i would say a definete no! cannot see any reason whatsoever good luck and let's see the results!
  6. vino Member

    Houston, Texas
    Hi Ray, hopefully will be done by next weekend. Need to go to the
    local metal shop and get some steel sheet. I'll take the fork in
    case they can tell what kind would be most compatible for welding.

    All kind of exciting, have to keep telling myself that cutting up
    is the easy part.

    cheers, Walter
  7. malcolm

    malcolm & Clementine the Cat

    Bedford UK
    I'd clean off any paint you can. Weld is molten at the back too so you could get impurities from the paint in there. Also it'll catch fire.

    The revised plan looks better. The jig looks a little weedy though. Worth plenty of tack welds to hold everything together then welding just one section at a time, checking alignment before the next weld.
  8. vino Member

    Houston, Texas
    Hi Malcolm, I'll scrape the inside with a dremmel. I could also stiffen the jig
    up with a couple more sections of rod. Could weld them either between the
    outside ends on each side, or in the middle. Although you probably mean
    that the whole setup is not quite up to snuff. It can definitely be flexed
    by hand.

    I have available a piece of small angle iron. To hold correct alignment I
    could tack weld two strips diagonally across the gap, on adjacent sides. Then
    do the tack weld-check allignment-tack weld for the filler strip.

    Won't bore you with any more details... will post a pick when ready
    to weld.

    thanks for your valued input,

  9. vino Member

    Houston, Texas
    apologies, one more thing

    I put a bracket between the fork cross piece and the chair
    frame for extra support. This wasn't clearly visisble on the last pic.
    • FinalAssembly.jpg
  10. vino Member

    Houston, Texas

    Hi, just picked a 12 gauge steel sheet, but wanted to check
    with you before I use it.

    It looks like it's galvanized. Has a shiny surface, without
    a spot of rust. It was just stored in a non air conditioned
    warehouse in Texas heat and humidity. I wasn't too inclined
    to argue if this was the right material, since they didn't charge
    anything, but I had shown them the cut fork and asked for
    the same material.

    Would it be ok to use if it's galvanized?
    • SteelSheet1&2.JPG
  11. malcolm

    malcolm & Clementine the Cat

    Bedford UK
    Been busy making hellacool computer code for a client over the last couple of days (it's just like being in the matrix). Popped in here for a breath of fresh air.

    Yep, that looks like a galvanized coating, or at least some kind of horrid coating. Best to grind the coating off for at least an inch away from where you want to weld. When you vaporise the coatings they tend give off heavy metal vapour which cause the dreaded shivers (the flu-like symptoms of heavy metal poisoning).

    Your jig is fine - it'll hold the forks apart in roughly the right place, but to hold anything like that perfectly in place you'd need a jig weighing 10 tons. Problem with welding is the new metal goes on hot, then contracts as it cools. In a massively heavy jig the cooling would draw (plasticly deform) the metal to take up the slack. In a little jig you will probably get some deformation of the whole structure. Probably won't be anything you can't bend and hammer back to shape, but it makes sense to check all your dimensions out after each stage of welding then bend things to the correct shape again before the next bit of welding.
  12. vino Member

    Houston, Texas
    Hellacool... found something about gaming on multiple screens is that it?

    Well, I'm not experiencing any ill effects so far, fortunately I
    just did a couple of test welds. Although I am very near sited and
    my nose was about 6 inches away, sucking in fumes.

    Here's a pic of the test welds. They seem to have a white powdery
    residue around the edges. I remembered that when I picked up the
    threaded rod, the lady asked if I wanted plain steel or zinc coated.
    Maybe this sheet has a zink coating? I might make another trip to
    where I got this one, and hope I haven't overextended my welcome.
    If they don't have what I need, I'll grind of the coating on this one.

    I can also use this sheet for practicing. Can't seem to get the
    penetration even at high levels of voltage. I tried a couple of butt
    welds, and never got the seem to close on the other side. Tomorrow
    I'll try the V buttweld.

    About the butt welds on the forks, when I finally get to them, you
    suggest checking all measurements in between very short weld runs.
    Will do.

    cheers, Walter
    • TestWeld1.jpg
  13. vino Member

    Houston, Texas
    Quick way to remove coating

    Hi, I was being lazy, and trying to avoid grinding down
    the coating on the sheet of steel I'm using for the fork

    Here's some pics of how the coating vanished in just
    a couple of minutes. I poured some circuit board
    etchant on a test patch, let it sit a couple of minutes,
    then rubbed the area with my finger (use gloves...).
    After rinsing, the coating was gone!
    • CoatingEtching.JPG
  14. vino Member

    Houston, Texas
    Back to welding, not a good start

    Made my first butt weld this afternoon. Was in high spirits after
    having figured out how to etch off the coating on the steel.:D
    Did a few practice V butt welds and penetration seemed to
    be fine.

    When it came to welding in the patch, the spot welds came out
    ok. Then things started getting hard. I was trying to fill the V,
    but couldn't see it while welding, though I saw it fine while doing
    the practice joints. I don't know what changed. When I was done
    the whole job was very messy, and I was too embarassed to take
    a picture of it! I just ground everything down. Penetration of the
    butt joints wasn't enough, could still see the joint line on the other
    side. I'm thinking of using the hand cutting wheel to recut along the
    butt welds, a small section at a time, and re-welding.
    • MessyFirstWeld.JPG
  15. malcolm

    malcolm & Clementine the Cat

    Bedford UK
    The forks take a lot of fatigue loading so the welds need to be very good. Probably makes sense spending a lot more time practicing on scrap to get the technique spot on before starting on the forks.

    Is positioning the reason why you can't see the weld pool clearly? It'll help to orientate the forks in the same way as your practice piece - if you are welding downwards onto a horizontal practice piece then orientate the forks so you weld downwards. Actually the welder settings are different for different orientations too.

    Back to the practice sheet - when you have a neat weld with good penetration, try a short 1 inch butt weld between two 3 inch plates. Bend it backwards and forwards in a vice until it breaks. The break should be around the weld not through it.
  16. vino Member

    Houston, Texas
    Hi Malcolm, yes it was a different orientation. The practice welds were
    horizontal, flat on the bench, the fork weld was vertical.

    Will practice more, and do the bending/breaking test.


  17. vino Member

    Houston, Texas
    Hi, did some more practice welds, and it appears that the
    penetration problem is solved. I turned up the voltage to
    almost double what it was, wire speed is about the same.
    Also kept welding orientation horizontal.

    Took a picture of the test piece, which I had to stop trying
    to break because the vice was coming loose!

    Also grinded out one of the old butt weld joint, a section at
    a time, and rewelded. Does that look like too much penetration?
    • SecondTry.JPG
  18. malcolm

    malcolm & Clementine the Cat

    Bedford UK
    From the photos the penetration looks about right. The most important thing in my mind is not being able to see the original edge of the metal - a sharp edge can act as a stress raiser.

    It's tricky to work out the scale from the photos, but the weld looks slightly wider than necessary. Might be worth practicing with a higher setting and moving slightly faster down the metal and not going so wide, but otherwise I suspect the weld will be quite strong.

    Are you holding the torch in both hands? That can help a lot with keeping the weld straight. If not, bin any hand held masks and buy a full face one (less than £10).

    In general I'd say you are doing well - if all the welds end up like that it should be a decent job.

    :D :D I've edited this post quite a lot, so ignore the email you get when someone replies to your posts :D:D
  19. vino Member

    Houston, Texas
    Thanks Malcolm, I was getting depressed and about to scratch the
    whole job and start over :( . Thought I had delivered it a death nail
    by recutting the joints, and welding the gap. Now I'm happy again :p !

    I am not holding the gun with both hands. My helmet is full face and
    straps to my head. I don't remember what I was using my other hand for,
    I think it's free. The weld did come out a bit crooked, will try going faster
    with both hands.

    I read yesterday that a good place to start, as far as welder settings,
    is as high as possible, short of blasting holes. I did that and it seemed
    to go a lot better.

    many thanks,

  20. vino Member

    Houston, Texas
    Nothing new

    Morning! Nothing much to report just dropped in to say hi. A friend
    is lending me a big wheel cutting saw, which I hope to pick up
    this morning. It should make the fork project go faster. I've been
    cutting my strips with a small hand held Makita, and the forks with
    a wheel attached to the bench grinder. Bodgy I think would describe

    Good time for an R4 story? minus a beer... oh well. Many moons ago,
    was forced to leave Leatherhead in Surrey. Wanted to go back and
    visit for years, till a friend told me that they had demolished the
    town center and replaced it with a mall.... but that's another story.
    Ended up in Venezuela, where I saved up and got an R4, beauty... light
    blue, pretty much mint. One weekend I decided to go on an adventure
    down to the Orinoco.

    On the way back, about 100km from home, had a gas station check
    under the hood, which turned out to be a big mistake. At a light, a
    few blocks from home, it died. No warnings, no idiot lights. Tried to
    restart, and I think every warning light came on and stayed
    on. The gas station attendant had forgot to put the radiator cap
    back on. My beautiful R4 was toast. It would not hold any kind of
    fluid, either oil, or water. What was odd, was that it didn't seem to
    have any leaks either. While driving, the fluids would just vanish.

    Off to the shop...