Big Thanks to BigTwin

Discussion in 'Land of the Rising Sun: ADV Bikes from Japan' started by Doug Matson, Nov 28, 2003.

  1. Doug Matson

    Doug Matson Long timer Supporter

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    Just got my kevlar/carbon fiber tank protectors today and installed them. First let me say to Roger (BigTwin) thanks, they are very nice, fit and look great. They go on with a snap as they rap around the front of the tank and lock over the rear area that sloaps down. They also lock under the plastic (two bolts) that is above the tank and on the bottom where the plastic tank protector is connected (two bolts). I got the black ones and they look great on my silver 950. Thanks again Roger for your help and for the excellent product!!
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  2. Doug Matson

    Doug Matson Long timer Supporter

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    Here is a pic.

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  3. Loadedagain

    Loadedagain making chips

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    post big pics. we need detail.... specially those of us that are up to our own carbon shenanigans :evil lets see :clap


    btw.... carbon/kevlar inner fender 640 lc4. loads more to come. lc8 cant have all the fun. :nono
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  4. Doug Matson

    Doug Matson Long timer Supporter

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    This should be bigger.

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  5. Loadedagain

    Loadedagain making chips

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    we're gettin there....... :evil
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  6. fish

    fish Banned

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    Is CF a good material to make bashplates out of? Seems like it would be expensive and brittle. Wouldn't kevlar be a better choice for this application?
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  7. Loadedagain

    Loadedagain making chips

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    i'm doing a bash plate right now.

    the matrix (resin) is what gives you impact resistance. generally an epoxy matrix vs. a polyester based one is stronger. more layers of fibre, or added reinforcement (ie: an aluminium honeycomb) are what give the impact strength.

    the fibre itself has no (none, zero, zip, nada, etc...) impact strength. it does however offer abrasion resistance and awesome tensile properties (which we wont talk about in these cases).

    carbon vs aramid (kevlar tm) vs e-glass, etc.... all the same for impact resistance.
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  8. Jinx

    Jinx Call me Renzo

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    Beg to differ:

    The Epoxy matrix may prevent the finished product from shattering, but it is not the mechanism that absorbs the energy of impact. That is done by the fibers. True, modern epoxy resins have very nice mechanical properties, but the are not in a league with the fibers themselves. Which is why we measure the Tensile Strength of resins in MPa, and that of fibers in GPa. It's primary function is still to transfer the load from fiber-to-fiber.

    Making something shatterproof is not the same as making it tough, resilient, and impact resistant. Safety glass does not shatter: But it is not tough. Toughness is how much energy a material can absorb in both the elastic and plastic phases prior to failure, resilience being how much energy a material can absorb in just the elastic stage, impact resistance is......a bitch. Because it has a velocity component, it also is dependant on time (does it matter how fast you sit down on a chair?), and the shape of the objects involved (it may if your butt is cone shaped). But all three terms have to do with energy. And that energy is absorbed by stretching, and sometimes breaking, Fibers, not the resin matrix.

    Aramids (Kevlar) in a matrix have excellent impact resistance (they can absorb large amounts of energy in a localized area), even though on the face of it Carbon Fiber would appear to have better mechanical properties. It is Aramid's ability to take point loads locally that set it apart, which is why it is so popular for body armor and rotor-burst incursion barriers. And it should work very well when attached to motorcycles and dropped, strictly in the name of science, on rocks. It is not as light as Carbon Fiber, but it is not as expensive, either. So Kevlar is the Dog's Balls? Not quite. Kevlar has excellent properties in tension, they are only average (no better than e-glass) in compression. And these little protectors all have corners, which if (OK, when) we hit, will act as an arch, and dump the loads in compression. Which with Kevlar will be a weak spot.

    Carbon Fibers have much better mechanical properties in compression than Kevlar (so they work well in rounded corners) but not the impact resistance. Why not use both? Why indeed.

    Carbon-Kevlar weave
    [​IMG]

    And, if using Kevlar or kevlar/Carbon, I would try to make these guards as flat as possible, using facets (two 45 degree changes as opposed to one 90 degree corner) to make changes in surface profiles. (If I had to use curves I would use generous ones, and maybe add an extra ply or two there). I know this is counter-intuitive: Our minds naturally think a round object will deflect impact better than a flat one. But sometimes if the mechanical properties are to be optimized, then flat is better.

    [​IMG]

    And this is not to get anyone's panties in a twist. Just another gearhead discussion. All of these guards are well made, light, and look more than able to do the job. My hat is off to those that made them. Onya.
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  9. Gerg

    Gerg The Destroyer Supporter

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    So, are these available to all AdvRides:dunno

    Gerg
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  10. Grover

    Grover Blinkenlights Adventurer

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    Looking good! :thumb :clap

    Erm... I don't think using the M-1 was really the best example. What I've read on the subject is that Burlington/Chobham armor appears on tanks in a faceted form, not because it is stronger (after all, in the tanker's world faceted armor has long been known to provide inferior protection against shells finding a good biting angle compared to smoothly rounded designs) but the very complex layered construction of this particular armor is difficult to fabricate in any form but flat plates.
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  11. BigTwin

    BigTwin Adventure Hound

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    First of all, Thanks Doug I'm glad you're happy with the protectors. Jean-Luc and Turkish are giving them a workout this weekend.
    Second, I'm not sure that Fish or Jinx realizes that my guards are made of a fabric that has both carbon fiber and kevlar.
    And third, Ugh well it looks like we have at least one mechanical engineer in the group. I agree with Jinx for the most part.
    This all started because I scratched my gas tank and didn't feel like spending $1000 to replace it. I had seen the picture of the guards that a friend of Barbasma had made for him and figured I could do the same. I talked to an engineer friend of mine who works on sail planes and he got me started. His thinking was that the kevlar would give me the toughness and abrasion resistance that I was looking for while the carbon fiber would supply stiffness. He felt that a good quality epoxy resin would be the best matrix for the carb/kev fabric. Polyester resin is cheaper but it is more brittle than epoxy resin. It would be a waste to spend the money on expensive fabric then lay it up with brittle resin. Tough fabric+ Tough resin= Tough tank guards.
    Impact resistance? These were really made more for abrasion resistance, but it is mostly the kevlar that will prevent any type of punture from rocks or whatever, the epoxy holds the fibers in place and provides just a little bit of flexabilty.
    As far as being flat or curved, the gas tanks have multiple and compound curves, and my guards fit pretty much like a glove so they are curved. I'm not an engineer but I still think that the curves make these stronger.
    Hey, I'm just happy that they cover the scratches in my gas tank.
    Here is a picture of the three fabrics I'm using. The natural and dark green colored kevlar have the carbon and kevlar running in both directions. The orange kevlar runs one direction only as does the carbon. The dark green and the orange turn to black and brown respectively when the epoxy is added. They would not do that if I were using a clear surfboard polyester resin.
    Can Jinx or anyone coment on the effects of UV in regards to these materials?

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  12. Jinx

    Jinx Call me Renzo

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    Hey, Onya mate, that stuff looks great! And the shape is fine. Sometimes I think out loud and it winds up on my keyboard! :rofl

    UV is a real issue: Carbon Fiber is relatively immune, Kevlar doesn't like it, and neither do some Epoxy Resins. Actually, no Epoxy Resin likes UV, but a bunch of them come with UV inhibitors and a small percentage of Carbon Black mixed in. Check to see what you have.

    Without the inhibitors, the Epoxy eventually forms a chalky white layer on the surface, which actually protects it from degrading further. And if we left it alone at that it would be fine structurally. But no one does. They say "hey, that chalky stuff looks like crap" and proceed to wipe it all off. Which promptly starts the process all over again.

    But this is a well known event, and like I said, the industry has addressed in with inhibitors and additives. Of course, being in Seattle, UV just ain't much of a problem! Your sailplane buddy probably has more good insights into the whole UV protection problem, as all my experiance has been with internal parts.

    And congrats for tackling a problem with insight, initiative, and a quality product! Katooms rule. The BMW tossers would still be whining about how "those Germans should really......." :rofl :evil :rofl
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  13. nomiles

    nomiles Sledge-o-matic

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    Not sure about the effects of UV on the fiber layers but UV will effect the epoxy. Epoxy used in the marine industry is always over coated with a UV filter, usually LPU (Linear Poly Urathane) paint, sometimes UV filter materail is added to the epoxy. The Sun <i>will</i> screw up epoxy, it starts with micro cracks and brittleness, and it turns to trash in time.

    They look nice. Have you tried Vacuum bagging the parts yet to squeeze the epoxy out?

    If you believe Loadedagain you can just leave out the fabric. :arg
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  14. BigTwin

    BigTwin Adventure Hound

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    Easy guys, don't get the beemer dudes and Loaded started here. Actually I think Loaded knows what he's talking about, it's just that Bart and Homer temporarily distracted him. Hey let's see pictures of the skid plate project.
    Thanks for the comments regarding the UV. The resin I am using is WestSystems. I went looking for a clear linear polyurathane yesterday and ended up comming home with Epifanes clear varnish with Extra UV Filters. This is what the manager of the chandlery said to use. I'm not real sure he understood the application.
    #14
  15. Renazco

    Renazco Formerly AKA Boejangles

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    Hey BigTwin, Jean Luc stoped by the other day and I noticed the protetors, they look great! Are we getting close for another shipment up North :evil ?
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  16. BigTwin

    BigTwin Adventure Hound

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    San Diego, Sweden, Austria, the Bay Area, the East Coast, Texas...
    I'm just working my way down the list.
    #16
  17. nomiles

    nomiles Sledge-o-matic

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    The Epifaines is old school wooden boat stuff, oil based but will work. I've been around yachts and race boats for the last 40 years, an x-grrl friend was a 'Brightworker' she varnished yachts and I've done my share, I had a 48' wooden ketch for 25 years.

    You need to sand the epoxy with 3M 220 grit wet/dry paper then put on a coat of the Epifaines, let it dry and then next day 'frost it out' sand with the 220 paper...just sand it lightly to turn it all white. Apply another coat of varnish, frost it out and varnish again etc. In the SF Bay area starting on new teak you need 6 coats of varnish, then 2 coats every 6 months. :): You shouldn't need that many coats for the epoxy parts.

    Epifaines makes a clear polyurathane varnish that might be better to use.

    * just realized maybe that's what you got?
    #17
  18. Doug Matson

    Doug Matson Long timer Supporter

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    I have a skid plate made by E-Line on my 450EXC and it is a mix of fiberglass carbon fiber and kevlar. I have tested it plenty and it is scratched but no chips or breaks.
    #18
  19. Greg Minor

    Greg Minor The Trespasser

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    Boy I almost got my Tank protectors to late. I was up on Big Bear mountain coming down the North side after climbing up the south side up a neat fireroad (kind of rocky) anyway there was a lot of snow on the ground that soon became ice on the road That stuff gets real slick after thawing in the day a freezing at night. To make a long story short I put a dent in the corner of my Brand New KTM panniers but the good news is no damage to the bike the pannier took the hit The dang real wheel tried to pass the front on a real slippery off camber corner Don't ride on the ice with the stock tires with lots of air in them I'm worried about denting the rim on the rocky mountain roads we have around here. I'm meeting some guys from this site to do Saddleback mountain in the AM so I need one more day with no more crashes and then I will have my REALLY COOL tank protectors Thanks

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  20. BJZ

    BJZ Been here awhile

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    It seems like everyone here has a good no excellent grasp of laminates. Just thought I would add.

    Maybe put some S glass on the outside of the carbon fiber in case of impact with sharp objects. Once the carbon gets exposed it is hard to deal with.

    Also How Much?? Just might buy a KTM 950 ADV soon
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