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Thread: Race chassis

  1. #1231
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    28th November 2013 - 21:58
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    Just to add that there have been twin shocks with linkages - Maxton and others.

  2. #1232
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    8th July 2013 - 11:01
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    Suspension Smith

    Quote Originally Posted by Frits Overmars View Post
    Until you fit pressurized twin shocks in the old-fashioned position near the rear axle; the gas pressure alone already gives too much preload.

    Yep, you can achieve up to 15% progressiveness that way, which is enough for road racing.
    Omitting the linkage saves weight and components, and avoids wear and extreme forces acting on the frame.

    Try searching for "Suspension Smith". I haven't got a link handy but I will post it when I find it.
    http://pbmagforum.co.uk/index.php?/t...93366612351673

    This is Laurie's build thread (you will have to sign up to the PB forum to view) It started as a hossack conversion to a modern Fireblade (he has done several evolutions of girder/hossack style front ends) then progressed into looking at lateral damping. He is a clever cookie.

  3. #1233
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    13th June 2010 - 17:47
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    Quote Originally Posted by Ocean1 View Post
    Wonder if carefully though out rubber swingarm bushes might not be a better idea. Far lower maintenance and real easy to change for tuning.
    Ever ridden a featherbed with slogged out swingarm rubber bushes ? I have and most surprisingly it wasn't bad at all...

    At the time I raced a good manx and a friend turned up with a 650SS. Try this he said....There was about an inch of sideways movement at the rim.
    Nice bumpy uphill curve past home - and it stayed on line. Weird.
    Reason is a tool - remember where you left it..... The late, great, John Clarke

  4. #1234
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    24th July 2006 - 11:53
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    Quote Originally Posted by Grumph View Post
    Ever ridden a featherbed with slogged out swingarm rubber bushes ? I have and most surprisingly it wasn't bad at all...

    At the time I raced a good manx and a friend turned up with a 650SS. Try this he said....There was about an inch of sideways movement at the rim.
    Nice bumpy uphill curve past home - and it stayed on line. Weird.
    Don't think so. But now that I think about it I did rebuild a minibike with rubber swingarm bushes, originally built by the old man with bronze.

    Had all of 4" travel, wheels made out of Caterpillar pistons and wheelbarrow tyres, so I can't say whether the rear suspension improved at all or not.

    I do recall that the telescopic forks were held together by the springs, you just screwed them onto bosses at either end, a feature that eventually caused me to lose the front wheel on a jump, (and several hours consciousness).
    Go soothingly on the grease mud, as there lurks the skid demon

  5. #1235
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    20th January 2010 - 14:41
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    Quote Originally Posted by Frits Overmars View Post
    Huh? You google, dressed in miniskirt and high heels? Does it help?
    Come again , What sort of website did I just log into......



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

  6. #1236
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    6th February 2012 - 08:54
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    Hand-formed sheet on wooden die

    Click image for larger version. 

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  7. #1237
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    10th February 2005 - 20:25
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    That is a good looking chassis - and made without dies (ie expensive steel press dies).
    Freedom of speech is important but if what we say is considered incorrect by our peers, they will quickly put us right.
    P.C. will eventually destroy our right to tell the truth.

  8. #1238
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    20th January 2010 - 14:41
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    Quote Originally Posted by philou View Post
    Hand-formed sheet on wooden die

    Click image for larger version. 

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    Quote Originally Posted by WilDun View Post
    That is a good looking chassis - and made without dies (ie expensive steel press dies).
    It is a thing of beauty
    This one has 28 diferent hand formed pieces in the head stock alone
    Which formed a forced air system along with one of the frame rails
    https://www.kiwibiker.co.nz/forums/s...post1130228408

    These ones were also hand formed, plus judious use of a press too i think
    https://www.kiwibiker.co.nz/forums/s...post1130228780



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

  9. #1239
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    12th March 2010 - 16:56
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    Hum, I have the 'book'

  10. #1240
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    13th June 2010 - 17:47
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    Quote Originally Posted by Flettner View Post
    Hum, I have the 'book'
    Well there's your tea breaks and lunchtimes spoken for, for some time.....
    Reason is a tool - remember where you left it..... The late, great, John Clarke

  11. #1241
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    6th February 2012 - 08:54
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    Quote Originally Posted by Flettner View Post
    Hum, I have the 'book'
    Hello,

    Is it really good?

    Can you describe the method of forming the frame spar ?

  12. #1242
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    28th November 2013 - 21:58
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    Dawes Jaguar
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    Oxy-propane for frame building/mods

    We moved back to the UK after 28 years abroad a while ago. For various reasons, incompatibility with british stuff, helping my son etc. I left a lot of gear behind, so almost starting from scratch. Currently (not really started) using a 3m square workshop attached to the house. Apparently, it's dashed bad form, what, to store acetylene in a residential area. Has anyone advice, experience, caveats to offer on using propane for bike frames (say; 3/4" or 19mm to 4"(!) 100mm x 16swg or 1,6mm steel), please?

    (Also posted this on the Ask an engineer thread)

  13. #1243
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    16th November 2016 - 20:47
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    I think the problem is more "workshop attached to the house" than anything else. A separate building made of brick or concrete should be ok but it's a gray area.

  14. #1244
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    13th June 2010 - 17:47
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    My local (rural..) engineering co uses oxy/lpg - but only for cutting and pre heating/bending. They glue everything electrically.

    I've seen them use it and asked at the time about any advantages. Price is the big one, much cheaper than acetylene.
    Disadvantage seems to be somewhat higher gas usage than acetylene for the same heat.
    I'd assume that once tip sizes and pressures were sorted, it would be usable for bronze welding.
    No idea how compatible an in-line fluxer would be.
    Reason is a tool - remember where you left it..... The late, great, John Clarke

  15. #1245
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    10th February 2005 - 20:25
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    Quote Originally Posted by Grumph View Post
    My local (rural..) engineering co uses oxy/lpg - but only for cutting and pre heating/bending. They glue everything electrically.

    I've seen them use it and asked at the time about any advantages. ........... No idea how compatible an in-line fluxer would be.
    I bet the Vapoflux would cost an arm and a leg even if it was compatible with LPG and cancel out any savings! - then I could be wrong, I only used the stuff (way back), I didn't have to buy it.
    Freedom of speech is important but if what we say is considered incorrect by our peers, they will quickly put us right.
    P.C. will eventually destroy our right to tell the truth.

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