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Thread: Cracked front fender on my /5

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    Cracked front fender on my /5

    I was parked at a local restaurant as the wife and I enjoyed dinner and when I came outside, my bike was laying on its side. After some cussing I righted the bike and assessed the damage. The only thing I could find was my front fender has a crack about halfway through. I was wondering what some of my fellow riders used to fix a crack. I want to retain as much of the original color as possible, so I was wondering if I ground out the crack with a Dremel tool, could I use JB Weld or something similar to fill it in? My 73 R75/5 has the original paint and has a certain "patina" that I want to retain. Thanks in advance!

  2. #2
    Sir Darby Darryl Cainey's Avatar
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    Fixing Cracked Fender

    I had to fix a cracked fairing and I used 2 stage epoxy that you mix in equal amounts.

    caution: do not get on painted side or it will ruin the paint unless it's Glasurite, then you can blend the paint back in.
    Ambassador BMW MOA Ontario Canada
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    Registered User relic's Avatar
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    I have made small repairs, similar to your fender, with the small fiberglass repair kits sold in marine shops or in automotive stores. I've seen various kit sizes. I worked totally on the underside, out-of-sight places. After a generous resin layer, press in a few layers of glass mat for structural support, and baste it with more resin.
    Bob in Indy
    '08 K12LT "Elvira"
    Knights of the Roundel #333

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    Registered User lmo1131's Avatar
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    Definitely use an epoxy vs. a polyester resin. Polyester is the traditional, stinky "fiberglass" resin. Epoxy resins are much more aggressive when it comes to adhesion and are great for repairing all composites.

    On the underside;

    Clean an area an inch or so on either side of the crack (to get rid of grease, tar, dirt, etc.)

    You may need to dremel out the crack so the parts can line up right.



    Now scratch it up well using 36 grit sandpaper; you want deep scratches so the resin has something to bite onto.

    On the painted side:


    Apply some blue painter's tape on either side of the crack to protect the paint.

    EDIT - Then apply some tape OVER the crack to help keep the sides in alignment.


    On the underside:


    Apply some resin to the fender to make sure it is well "wetted" and then apply a strip of fiberglass cloth (NOT mat) and work out the air bubbles with a squeegee or a piece of card stock (the thickness of a match book cover). - apply another strip of cloth and repeat the process several times.

    You want to make sure the fiberglass is well saturated. If it's dripping and drooling you've used too much. Excess resin doesn't make the joint any stronger.

    The top side and that original patina .... yer gonna hafta repair and re-paint. No way around it... .. .

    Fiberglass cloth

    Fiberglass mat
    Last edited by Lmo1131; 12-22-2012 at 01:29 AM.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  5. #5
    God? What god? roborider's Avatar
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    I've always used the traditional fiberglass resin, but I'm interested in the epoxy resin. What am I looking for? What is it called? Would it still be in the same section as the regular resin I get at Home Depot?
    Rob C. , Raleigh, NC
    '10 R12RT, R90/6
    2007 CBR600RR & 09 V-Star
    Suzuki DR 350

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    Registered User lmo1131's Avatar
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    "Everfix Epoxy Resin" by Evercoat Company. Most ACE Hardware stores carry it. It's usually right beside the polyester product. Home Depot... don't know if they carry it. Most any marine/boat shop will have it too.

    Looks like



    Rob... note my EDIT on my original post. If you put tape over the crack ON THE UNDERSIDE.... obviously you would be glassing over tape... my bad. The idea is to protect the painted side with tape on either side of the crack, and then, apply a strip of tape over the crack. That does two things; it helps align the two sides, and it keeps the resin from dripping out of the crack. Thatalso helps minimize sanding.
    Last edited by Lmo1131; 12-22-2012 at 01:33 AM.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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    #4869 DennisDarrow's Avatar
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    Lew is right on with his advice and technique with the only difference for me, being that I just use plain old epoxy, the faster curing the better, to use as my resin. If I was repairing a hole in a boat or filling in a torn fiberglass car fender I would get the huge quantity. When repairing, say 1" or so cracks I just get my epoxy tubes off the shelf and mix up a tablespoon or so glob............God bless........Dennis

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    Registered User dwyandell's Avatar
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    A couple of tips. . .Marine stores will give you better advice on products than auto parts stores. Expensive though . . and hard to find the right materials in small quantities; if you know any boat or hot rod builders, they'll gladly share cloth scraps but buy your own epoxy ($$). Beware though, there are some cloth products for resin-based fabrication and repairs that cannot be sanded. Polypropylene cloth is easy to confuse with fiberglass but cannot be sanded--it just gets fuzzy. If you're using scraps from someone, make sure you have fiberglass.
    The marine stores will have a powder filler additive (ground up fiberglass) that can be added to your epoxy to thicken it and make it less drippy. Extremely useful.
    You can also add dry pigment to two-part epoxies to get a better base color for your repair--I keep some inexpensive powdered artist pigments including powdered charcoal (carbon black) in the shop and you'd be amazed at how well this works. Even cheap powdered kid's finger paints will work, although I wouldn't use these for anything structural (they're less concentrated than pigment so you need alot more). For a painted fender the base color doesnt really matter, but when that crack in your side case starts to leak and you finally decide to take the time to fix it right. . .
    It's hard to bite the bullet and accept the cost of buying and keeping some proper materials around for these occasional glass repairs, but (like most things) if you always use shortcut materials, it will always end up looking like a 3d grader did it. If you follow Lew's advice, get the correct materials and do the repair right, you wont regret it; most shortcut repairs with fiberglass you will end up regretting.
    Dave in Vermont
    '84 R80ST
    '81 R100 hack

  9. #9
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    FWIW, "carbon black" is a petro chemical product. I have intimate contact experience with the stuff having breathed & eaten it for several yrs.
    You can buy the fiberglass cloth & resin @ Meijer's too, if that helps you. I used the epoxy in the twin tube dispenser from an AP's store for fixing the same fenders. A handy tool for this repair is a HF right angle air grinder-get an asst. of twist-lok 2&3" discs & say a 36 grit to do the rough up mentioned above for "material bite" into repair area.
    What I haven't figured out is how to store those twin tube epoxy things and keep the material from oozing out over time??? -seems to leak on purpose!

  10. #10
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    I recently repaired a hole in my fairing using a West 105 epoxy system marine repair kit of this type: http://www.amazon.com/West-System-10...d_sim_sbs_sg_1

    The kit contains fiberglass cloth, eight pre-measured epoxy applications, two pairs of gloves, structural and non-structural micro balloons, a couple of mixers, brushes, and some cups for the epoxy. Epoxy is a liquid and flows like water. So, while fiberglass cloth 'soaks up' epoxy, the epoxy will still take the path of gravity flow. That means you will need to remove the fender.

    The structural (white) micro balloons can be mixed with epoxy to form a gel. The fiberglass cloth - which provides the strength for epoxy - must be applied as a layer after carefully cleaning and preparing the surface. The surface prep (aside from cleaning) is roughening with some 60 grit sandpaper. If there is a gap, an application of epoxy w/micro balloons can fill it, then (after ~ 5 hrs. curing) the fiberglass cloth laid and filled with epoxy for repair.

    But, and this is important, the work must be planned - much like painting - due to the limited life of the epoxy after mixing the resin and hardener. While completely re-doing a repair is an option, it is better to plan and prepare the part (making sure the most critical area is at the low point) to avoid unnecessary time and material for rework. Good luck!
    Stan

    AH# 13238

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    Thanks, and Merry Christmas!

    Thanks to all who replied. I live near the coast, so there are plenty of boat shops around here.

  12. #12
    God? What god? roborider's Avatar
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    [QUOTE=Lmo1131;843962]"Everfix Epoxy Resin" by Evercoat Company. Most ACE Hardware stores carry it. It's usually right beside the polyester product. Home Depot... don't know if they carry it. Most any marine/boat shop will have it too.

    Looks like



    Thanks, Lew. A quart of this will end up in my shop soon. I don't like the fiberglass resins but didn't know of this alternative.
    Rob C. , Raleigh, NC
    '10 R12RT, R90/6
    2007 CBR600RR & 09 V-Star
    Suzuki DR 350

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