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Thread: Race chassis

  1. #646
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    Thanks for that Dave and Michael. From someone who aspires to build their own bikes in the future using much the same techniques, I appreciate all the commentary available!

    I know very little about metal properties and what is most appropriate for use in bikes. I did an internet search for T45 to try educate myself and found this:

    BS T45 is a carbon-manganese steel tube supplied in the hardened and tempered condition. It finds many different applications in both the motorsport and aerospace industries due to its high strength to weight ration. T45 is also weldable, but unlike other chome-moly tube grades does not require heat treating after welding.
    http://www.aircraftmaterials.com/data/alstst/T45.html

    Being a british standard steel, is there an equivalent that manufacturers use in NZ?

  2. #647
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    Quote Originally Posted by chrisc View Post
    Thanks for that Dave and Michael. From someone who aspires to build their own bikes in the future using much the same techniques, I appreciate all the commentary available!

    I know very little about metal properties and what is most appropriate for use in bikes. I did an internet search for T45 to try educate myself and found this:


    http://www.aircraftmaterials.com/data/alstst/T45.html

    Being a british standard steel, is there an equivalent that manufacturers use in NZ?
    No, bluntly. There is some usable CrMoly brought in from the states for speedway chassis but not a lot in the sizes we need. Unless someone in Auckland knows better ?
    In those sizes and for our uses, given this style of frame is 90% straight pieces, you won't lose much if anything using ERW mild steel.
    If Dave is using 17G T45, I'd use 16G - or as it's sold here, 1.6mm - ERW mild steel.
    I know Dave has used ERW for frames as well - see Vol 2 of The Racing Motorcycle....

  3. #648
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    Chris, I've used CREW (cold rolled electric welded) mild steel tube on all the frames I've built. Remember that all the steels have basically the same stiffness. Stronger tubing makes it more crashworthy and might let you go up on size/down on wall thickness without worrying about denting. 4130 might be a bit better on vibration resistance.

    Kevin Cameron once remarked in reference to having his Kawasaki Bighorn frame built from 1018 instead of 4130 "only if you pick your crashes carefully will you fully benefit from a 4130 frame; you have to be sure to crash hard enough to bend 1018, but not hard enough to deform 4130."

    I think a dirt bike using thinner-wall tube would be an excellent place to use a stronger steel alloy, so it doesn't pick up dents when you drop it.

    I think Dave is in a different situation than me (and possibly you) as he's building a premium product for real money, so the high-spec tube is another positive feature for the customer. If you are building your own frame for your own use you can probably deal better with scrapping/repairing it after a crash than if you've got an expensive commercial frame. Dave's customers might also be crashing at much higher speeds than we do, and need the extra strength to survive the bigger forces.

    If I could get T51 or Reynolds 531 I might well use them. But my choice here in the USA is pretty much mild steel or 4130, and I'm a bit leery of 4130 because of it being touchier to braze without suffering intergranular penetration (that's the steel that suffers it, not me ).

    So if you are just starting, buy the easy to get and affordable tube as it will probably be plenty good enough if you do a good design, and it doesn't hurt so much when you see how heavy your scrap bucket has gotten while you are learning to get good fits on your tube ends.

    cheers,
    Michael

  4. #649
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    Quote Originally Posted by chrisc View Post
    It hardly bothers me that much, it's not me who has to make things in it! I'd happily come check out your dumping yard workshop.



    Just to be clear: It's not the length I'm talking, it's the weight distribution. See the Moto3 'tanks' are actually 2 parts. Only the rear half is the fuel tank which is more vertically designed rather than horizontal. I'm sure the overall dimensions of the fuel tank, cover and air box would feel much the same as a conventional tank between the legs but the weight of the fuel being more rearward in the bike would have a handling effect. I'm wondering if even an amateur like myself would be able to notice it, or if it was one of those slight differences that only world championship level riders can pick up.
    swarf collection area would describe it best...

    I asked about the dropped tanks before i realised the Tigcraft has one. They were standard in FZR400's and Andy Bolwell used a fabricated one on his multi F3 championship winning ZX400. Andy is our equivalent of Pedrosa of course so mass centralisation - and lowering - probably had a noticeable effect.
    The engine i'm building atm has steep downdraft and room for that sort of thing so this is useful for when i think about a frame....

  5. #650
    Quote Originally Posted by Grumph View Post
    No, bluntly. There is some usable CrMoly brought in from the states for speedway chassis but not a lot in the sizes we need. Unless someone in Auckland knows better ?
    I have bought gone down to 1/2" x 0.035 from AFWE for some wishbones. (http://www.afwe.co.nz/index.html)
    They don't list their sizes online but from memory they had a fairly complete range. Might be worth a ring if you haven't tried already.

    But like Michael says, chromo won't make anything stiffer, it will just bend/deflect further before it stays bent. Good for crashes and vibration though.

  6. #651
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    http://www.tsl-timing.com/event/162004/session/rc1mot

    Tigcraft Moto3 for the win and fast lap at Brands Hatch.

    Not too shabby for the product of a small shed.

    cheers,
    Michael

  7. #652
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    Quote Originally Posted by Michael Moore View Post
    http://www.tsl-timing.com/event/162004/session/rc1mot

    Tigcraft Moto3 for the win and fast lap at Brands Hatch.

    Not too shabby for the product of a small shed.

    cheers,
    Michael
    Gear result.

    Scott, I'm guessing GPR needs to find a Moto3 engine and full the gap between buckets and F3 bikes in the GPR range.

    I wander how many Tigcrafts (monos) have been built?

  8. #653
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    Quote Originally Posted by Bert View Post
    Gear result.

    Scott, I'm guessing GPR needs to find a Moto3 engine and full the gap between buckets and F3 bikes in the GPR range.

    I wander how many Tigcrafts (monos) have been built?
    I'm assuming Scott won't want to try another KTM ?

    Wonder if the local Mahindra importers would come to the party...

  9. #654
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    So i think its fairly obvious what Dave is using to make the TIGcraft frames. And this will likely be an obvious question for most reading this thread but I have no clue so going to ask anyway.
    Is there any tangible benefit building something like this with a tig as opposed to a mig?
    Or
    Is it simply that the outcome is the same but the build process is easier on the builder if they used a tig?

  10. #655
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    Quote Originally Posted by ac3_snow View Post
    So i think its fairly obvious what Dave is using to make the TIGcraft frames. And this will likely be an obvious question for most reading this thread but I have no clue so going to ask anyway.
    Is there any tangible benefit building something like this with a tig as opposed to a mig?
    Or
    Is it simply that the outcome is the same but the build process is easier on the builder if they used a tig?
    Van Diemen race cars are still Bronze welded. (note, this is different to Brazing)
    So are a heck of a lot of Race bike tubular frames
    The answer above question though, is the heat concentration.



    Kinky is using a feather. Perverted is using the whole chicken

  11. #656
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    tig is slow ,mig is fast , tig has more control , weld thinner , bit thicker tube mig is ok . kind of in a nut shell ..
    i'm over buckets

  12. #657
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    MIG often seems to leave a convex bead where with TIG (like bronze) you can get a concave bead for smoother stress transition across the joint. TIG may offer more precision/control than MIG.

    Tony Foale MIG'd his production streetbike frames and bronze welded the race frames.

    Some of it comes down to "which one can you get the best results from?"


    Price also can come into it. A TIG welder is much more affordable now than it was in the 1960s/70s. Bronze welding didn't require you to have any power in the shop.

    No flux to clean off with TIG!

    I suspect there may also be a certain element of marketing in how you decide to stick things together. Some customers may be keen on TIG but not bronze, or vice versa, kind of like with the "aircraft billet aluminum" stuff. Personally, I'd be fine with either as long as they were both done to an equally acceptable standard of quality.

    cheers,
    Michael

  13. #658
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    Quote Originally Posted by mr bucketracer View Post
    tig is slow ,mig is fast , tig has more control , weld thinner , bit thicker tube mig is ok . kind of in a nut shell ..
    And correct. You use both don't you Scott ? If you're being paid for a frame - and the price is sufficient - then TIG all the way as the customer wants to see value for money. Production run is probably more economic with MIG.
    I'm stuck with bronze welding myself due to eyesight problems so have become a reasonably good bronze welder from necessity. But luckily I have a good mate who is probably the best TIG welder in ChCh.
    One offs you lose nothing by using bronze.

  14. #659
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    Quote Originally Posted by Grumph View Post
    And correct. You use both don't you Scott ? If you're being paid for a frame - and the price is sufficient - then TIG all the way as the customer wants to see value for money. Production run is probably more economic with MIG.
    I'm stuck with bronze welding myself due to eyesight problems so have become a reasonably good bronze welder from necessity. But luckily I have a good mate who is probably the best TIG welder in ChCh.
    One offs you lose nothing by using bronze.
    i just TIG them, all my frames are 1.2mm to hard to mig , even i stuggle now days to tig nice unless its 1.5mm )-:
    i'm over buckets

  15. #660
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    Quote Originally Posted by mr bucketracer View Post
    i just TIG them, all my frames are 1.2mm to hard to mig , even i stuggle now days to tig nice unless its 1.5mm )-:
    No hope for me then, lol. My welder mate uses 20G stainless wire as the rod for anything under about 1.2mm.
    Not ideal as a match for mild steel but it's a low quality stainless so it's reasonably ductile. Welds well too.

    edit - For Michael's edification - and amusement - the Colin Lyster frame I have here is MIG welded.
    One of a small batch (3 or 4, i don't know) for CB450 engines built under his supervision shortly before he died.
    I hope to finish it this winter, health permitting.

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