Repair cracked motorcycle windshield

Discussion in 'The Garage' started by flossandfly, Jan 29, 2013.

  1. flossandfly

    flossandfly Been here awhile

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    I had 2 cracked spitfire windshields and couldn't bring myself to order a 3rd one without attempting to repair them since one was just cracked. (the other had one piece break right off and cracked the rest)

    After googling I found out about Acrylic Cement. Guys use it to make fish tanks out of acrylic and it works well.

    I bought IPS Weldon 5 Oz 16 Acrylic Cement

    It worked pretty well. It doesn't really act like glue, it acts more like a weld. I used it on the 2 broken windshields and I can now flex them without re-cracking them. I haven't taken a ride with them yet, but they seem to be good.
    #1
  2. bwalsh

    bwalsh UUU, UUU!!!

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    Can you post some pics?
    Prices fluctuate quite a bit on that stuff! :huh A quick online search reveals Wal-Mart wanting $21 for the 5 oz tube. but can get it online for under $8 plus shipping.
    #2
  3. flossandfly

    flossandfly Been here awhile

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    I don't have a picture storing account so can't post pics. That price sounds right.
    #3
  4. b1pig

    b1pig Been here awhile

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    correct me if i'm wrong... but shouldnt stop-drilling also prevent the cracks from spreading? i've done that with plastics and sheet metal.

    got pics of the repairs? does sound interesting.
    #4
  5. heirhead

    heirhead Been here awhile

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    Hello,

    Just finished shield repair 5 mins ago and saw this post, what timing.
    Cannot post pics but if someone wants to PM me with there email I will send over for them to post.
    You will see the work of a true craftsman.

    Heirhead
    #5
  6. Contevita

    Contevita Cigar Adventurer

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    You can get a free account here http://www.imageshack.us/

    And that's just one of many free hosting sites you can choose from.

    Now where are those pics? :D
    #6
  7. Strong Bad

    Strong Bad n00balicious

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    [​IMG]

    This thread is worthless without pics!
    #7
  8. Contevita

    Contevita Cigar Adventurer

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    I see you went to the wrong end of the French Quarter before the Super Bowl. :puke1
    #8
  9. foxtrapper

    foxtrapper Been here awhile

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    Well shoot, that would be a heck of an improvement over my normal practice of using zip ties to stitch it back together.
    #9
  10. Skippii

    Skippii Milkshakes, my lad.

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    Here's my method which has worked well, but I warn you it's not the prettiest. On a dark/smoked windscreen it's alright, but I probably wouldn't do it on a clear one.

    With everything nicely held in place, melt/cut a trough in the back of the windshield with a soldering gun (I got my 230W one years ago from radioshack for about $30, but 100W or probably a lot less would work just as well) so everything is attached correctly. Scrape up the burrs or lightly sand with rough grit, and then fill in the trough you melted with plastic epoxy.
    Super cheap to do, and works just fine.
    #10
  11. Ricardo Kuhn

    Ricardo Kuhn a.k.a. Mr Rico Suave

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    #11
  12. Contevita

    Contevita Cigar Adventurer

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    Here are your pics...

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    I'll let you expain what we're seeing here.
    #12
  13. heirhead

    heirhead Been here awhile

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    Hello,

    Thanks to Contevita for posting pics of my Beautiful repair of my Parabellum shield off dr650, also pictured.
    Clean crack do to pilot error. Wanted it to be strong. like a weld, stronger than the material. Edges of 16 ga, 6" steel are very sharp as you can see. Won't break in this spot again. Bending the steel both ways to the contour of the shield is tricky. Neighbors on Harleys won't ride unless I ride something else.
    Kind of gives off that macho Bobber look, you think?

    Heirhead
    Worlds worst mechanic
    #13
  14. flossandfly

    flossandfly Been here awhile

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    That picture is exactly what the acrylic cement repair looks like. It is not pretty but is simple to do and appears to be quite strong.

    That pic of the large lady made me laugh.

    #14
  15. H96669

    H96669 A proud pragmatist.

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    Chain links???? That's pretty crafty.:clap Just my answer I was looking for some off the shelves "thingies" for a rivetted seat cover job.:clapUsually blued when new, that's also easy to redo if working out of the scrap pile. Gun blue does have uses on motorcycle sometimes if just for looks.:wink:

    Looks like you rivetted on the bags also. BMW bags can be a real pita for that, twin walls in some parts with a space in between and if you poprivet may squeeze and they'll crack. Had to do that and ended up filling the void space with expansion foam just so I could rivet without more crackings.

    Someone just gave me one of them kits to fill gaps & cracks. That's industrial strenght CA and 2 little jars of black and grey powders to use as a filler then set with the CA.

    This stuff, Q-Bond:

    http://www.amazon.com/Bond-Repair-Small-Bonding-Adhesive/dp/B003YI421I
    #15
  16. F6BANGER

    F6BANGER Adventurer

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    On cracked abs plastic, I just use ABS cement. Works great.

    [​IMG]
    #16
  17. flossandfly

    flossandfly Been here awhile

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    I wondered about abs cement. Good to know.


    Finally got to ride with the repaired windscreen using acrylic cement. Rode into a wind strong enough that my XR650L was wide open and doing around 95 km/hr. So far it has held up fine although the screen i tried out was only cracked and no pieces broke off. I will try the one that had a piece break off some other time to test the strenght of the repair.
    #17
  18. Twilight Error

    Twilight Error Going nowhere slowly

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    Link plates from a bicycle chain? Nice.
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  19. bwalsh

    bwalsh UUU, UUU!!!

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    About a month ago another inmate gave me a half windscreen to fix off his 4x4 Rhino(I think that's the make). It was broken on both ends...

    [​IMG]

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    I ordered some, SCIGRIP weld on 4 Acrylic and Polycarbonate adhesive...

    [​IMG]

    www.multicraftplastics.com/manufacturers/scigrip/images/scigrip_weldon_4.jpg

    applicator...

    [​IMG]

    http://www.eplastics.com/core/media/media.nl?id=657&c=621686&h=1337ac7e767e2d030d9c

    and some 1/4" Polycarbonate rod(s). The smallest diameter I could find.

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    http://www.eplastics.com/Plastic/Le...-250-Diameter-Machine-Grade-Polycarbonate-Rod

    I studied the damage for awhile to determine the best approach. I decided to weld the cracks since the adhesive wouldn't get into the cracks. I started on the small crack in the broken off piece in the first pic. As you can see in the first pic above, I had already welded one side when I took the pic. I welded both sides then took a dremel and sanded it flush with the windscreen.

    Now the best way to weld plastic or polycarbonate is to create a "V" groove along the crack/break on both sides(not at the same time though) so new material can be introduced into the depth of the crack(so there is no crack left to flex). I used a cheap 30w soldering iron to make the groove as I didn't want to risk cracking the windscreen worse than it was using a dremel. It was SSLLOOWW going. It made about a 1/8"w x 1/8'd groove.

    [​IMG]

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    I made sure to melt the second "V" down into the new material to eliminate all traces of the crack.
    Welding a 1/4" rod in to a 1/8" groove proved to be, uh...interesting! :huh The trick, especially with a 1/4" rod, is to twist/spin the rod so the entire rod gets heated enough. All the while heating(and not meting thru) the windscreen to the point of melting so some of the windscreen material mixes with the rod material. All while moving down the crack and trying to spread out the material so most of it isn't wasted(solidify above the crack). Yes it was a PITA!

    Here's a photo of the first weld before grinding/sanding. Notice the excess material that's going to get ground off...

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    and after grinding/sanding...

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    Then flip sides and repeat. I had to go back and fill in low spots then re-sand all the welds.

    [​IMG]

    Then I moved on to the broken off piece in the pic above. Since the break was clean I decided to use the adhesive. Worked like a charm!
    I tried the adhesive on one of the longer breaks(twice) and no go. Most of the crack was clean but where it turned was a little rough. I figured it wouldn't work but nothing ventured nothing gained!

    OK, I'll have to weld the rest of the cracks.

    The finished product...

    [​IMG]

    the "white" area to the right of the crack, under my hand is distortion from having heat in one place too long. Much longer and the plastic will start to bubble and melt(not good). :eek1
    Other than that, its kind of ugly but back in one piece! I told him to put the stress test to it. I hope it holds up well!

    I have an older Aeroflow windscreen that has a few cracks in it. I have an idea for keeping the rod/repair semi transparent, if I can cut these rods in half's? Thirds? Quarters?

    I will post that repair when I get around to doing the work.
    #19
  20. strongbad

    strongbad Been here awhile

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    Very nice. Thanks for the pics. I suppose one could cut some unneeded plastic from some other part of the windscreen to use as weld rod. That would ensure that the right kind of plastic is used.
    #20