Technical & Reference Section > Tech and Restoration
She's finally arrived - Changa Build
Picklez:
Coaster arm wise, looking at the article it's obvious Woody mounted his in the less conventional position, on the upper side of the seat stay, rather than lower side of the chain stay. Stating it was to try and reduce induced stresses on the frame. Now I'm not confident of the validity of that logic, if you think about the forces and direction thereof when applying the 'brake', but for the sake of the build I'm planning to bend my coaster arm similarly and mount it the same.
The only thing I'll do differently is the anchor. Woody's used an Addicts seat clamp. But for two reasons I'm choosing not to, 1. I'm not an Addicks (plastic/composite) fan. But 2. I plan to try something a little different regards the seat post clamp fitting. I'll use the more conventional Dia Compe MX. But rather than padding out the over-size gap between the outer of the seat stay tube and inner circumference of the seat post clamp I plan too cut/engineer the inner diameter of the seat clamp to match the outer diameter of the seat stay as best as possible. And I could not bring myself to 'destroy' an og Addicks clamp. Or come to that matter even an OG Dia-Compe one.
Taking this kind of approach will also allow me to engineer the coaster arm pick up area better too.
So, seat post clamp in question, a repo Dia-Compe MX twin bolt:
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And here it is after a first pass, to test the idea. I basically removed the 'new release' text these things have embossed on them, not to fool anyone that it's OG, just to fit the build theme better (most parts are og etc.), and then set about trimming down the inner edges of the mating faces of the two halves so that when mated back together the inner radial clearance between the two halves would be reduced to be approximately equal to the outer VDC seat stay tube diameter. Hopefully you get a better understanding of what I'm doing with a piccie. Here it is when i've shaved 1.5mm off of one end of each inner faces, doing so to give me an extra 3mm of clearance at one end to house the coaster arm pick up, whilst maintaining equal torsional force on the two seat clamp bolts when it's finally tightened up on the frame.
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Now I just need to trim an extra 1.5mm off of all four faces, to get the inner diameter to better match the outer diameter of the seat stay. But, man it takes some patience, a steady hand, and a decent Dremel.
But, again, for the moment I've paused with these final mods on this until I receive the coaster arm back from the chromer.
Cog wise, I'll either run with the og 16t one that came with the coaster, or the Bendix 14t one I have as a spare. Basically chain fitting will dictate that at a later date.
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But, that's probably more than enough waffle form me for one day, so I'll sign off for now. But be back with the front wheel build up soon, and by then maybe even all the bits in hand to do the rear wheel too.
Cheers guys & stay safe :radbmxsmilie:
Picklez:
--- Quote from: deeman on May 29, 2020, 04:53 PM ---Hell Yea Pete, this is turning out awesome,,,,top parts choices as usual! :daumenhoch:
--- End quote ---
Cheers Damo, good to see you around a little more lately bud :daumenhoch:
bobafett:
Great update mate.... Coming along very nicely and great attention to detail :coolsmiley:
Picklez:
--- Quote from: bobafett on May 29, 2020, 05:32 PM ---Great update mate.... Coming along very nicely and great attention to detail :coolsmiley:
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Thanks buddy. Forgot to add, found out the coaster is an April '83. Suntour date stamps are two letters:
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See "Japan Z-D" on the inner arm...
And found this on the web:
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Chilli Rinse:
This can't end ! Please take it slow... I love this build thread. A mention from a pro fistblump :LolLolLolLol: Those little bits add to the bigger picture of the build, this I think will be a masterpiece, full stop ! explosion
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