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Discussion Starter #1
can someone please send me any info on streching/ extending the rear swingarm.. i cant seem to find a good link to a thread with pics and info.. thanks guys
 

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You can buy kits from japan, or simply chop it and insert rectangular tube same diameter as inside diameter of swinging arm and weld it together. Smooth over the gap with filler or weld and grind.

Here is a link to a guy in OZ who did it. i read his build before doing mine. some good step by step pics and info on his build.



http://www.vjmog.com/ftopict-3227.html



good luck

Dave
 

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Discussion Starter #3
thanks dave that looks nice.. alot of inspiration
 

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Discussion Starter #6
is this swingarm in use today? hows it holding up? what kind/size steel did you use? thanks
 

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You have not stated how much you want to extend your swingarm, and why you want to extend your swing arm. Both of those are important questions. There have been some 1 to 3 inch extensions to fit ATV tires that have been documented here as being relatively easy, strong, and durable off road. As you approach 5 to 8 inches of extension these are typically street only bikes and for cosmetic purposes only.



I have a swingarm that I extended 150mm. I chopped it, made inserts, welded them in and then capped them. Cosmetically it did not suit me, but it is very strong.



I wanted a cosmetically smooth swingarm because I am building a pure street bike. Thus, I imported one from Japan that I am very pleased with.



That means I have an extended swingarm that is just sitting in the garage, but I am leery of selling it or letting it otherwise leave my possession due to potential liability issues.



I would recommend one of two options: 1. PM or email member VillageIdiot (be patient he is not often around here) about having him extend your swingarm. He has a jig, which most closely resembles a pure engineered solution and has a track record of success; or 2. Go with a pure engineered solution and buy an extended swingarm from Japan.



I was impatient and didn't wait long enough to hear back from Village Idiot, which meant when mine didn't meet my expectations, I added to our trade imbalance with Japan.



Good luck.
 

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Discussion Starter #8
well i def would consider buying it if u ever would sell it.. i plan on doing this myself as i dont have much $ to pay someone else hundreds of $ as i have a welder, tools and time. thanks
 

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I'm going to use this method to extend my swingarm. People say "cap" or "build up" or some other phrase (in the japanesse guy's thread.)



Is that body filler or what? Why not just use square tube that matches ID of the original, and another square tube to wrap around it? I also want a smooth finish.
 

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Actually, you'll get a stronger swingarm by cutting at an angle instead of perpendicular to the tube.
 

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Has anyone bought a long swing arm from Japan? I'm looking at them at the moment and there seems to be a few makes. One make, Beams is about half the price of the others, does anyone know what the quality is like? I can't weld to save myself hence buying a pre made one.

Cheeers
 

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Has anyone bought a long swing arm from Japan? I'm looking at them at the moment and there seems to be a few makes. One make, Beams is about half the price of the others, does anyone know what the quality is like? I can't weld to save myself hence buying a pre made one.

Cheeers


Yes. I purchased my Swingarm from Megaton. I detailed how I got it stateside HERE. I am very pleased with the Megaton swingarm. Mine is 200mm over stock. The kit comes with an extension to lengthen your brake rod too.
 

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I won't be ordering an arm from japan because of the cost. I do have people there to get parts for me, but I would rather use the money to buy a welder! I'm going to need one anyway because of electric work.



When you said cut at an angle, you mean when looking from the top right? say a 45 degree angle and then cut the metal inserted (probably in the 5-7" range) at the same angle. Seems like you wouldn't want them cut with an angle when looking from the side, but I think good welds are stronger than the metal, so longer welds via an angle cut would be stronger. I plan to at the least put plates on the side welded on to brace it as well.



If worse comes to worse, I have a local custom bike guy that I lease a building to who has mentioned before that he makes arms and can make any arm I needed. I really want to keep cost down on this project and it's really meant to be a learning experience.
 

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Theoretically, a weld is as strong as the media. Theoretically. Theoretically, epoxy and fiberglass are stronger than plywood. In reality, no, a composite butt joint wrapped in fiberglass will eventually break. When scarfing 2 pieces of ply together taper is always at least 12 times the width. I was taught 45* on the long side of a rectangular swingarm was about right.



It is not possible to extend a swingarm with a tube inside the originals, than a tube the same as the original. How are you going to get the second tube in place?



Instead, cut tubes that fit inside 6-10cm long. Cut slots in the original parts parallel to the cut ends of the original parts for welding. Weld the stubs to both ends of the original parts. Form tubes the length of the desired extension the same height and width as original. Cut slots to weld to the stubs. Weld the tubes to the stubs and original front part of the swingarm, weld the stubs and rear parts of the swingarm to the extensions. Grind and paint. What you end up with is three rows of welds at each joint instead of one, and a smooth, attractive appearance. If you want to get fancy, the inner tubes can be cut at an angle to match the angle of the outer tubes. Saves a bit of weight, but doesn't affect appearance.
 

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Theoretically, a weld is as strong as the media. Theoretically. Theoretically, epoxy and fiberglass are stronger than plywood. In reality, no, a composite butt joint wrapped in fiberglass will eventually break. When scarfing 2 pieces of ply together taper is always at least 12 times the width. I was taught 45* on the long side of a rectangular swingarm was about right.



It is not possible to extend a swingarm with a tube inside the originals, than a tube the same as the original. How are you going to get the second tube in place?



Instead, cut tubes that fit inside 6-10cm long. Cut slots in the original parts parallel to the cut ends of the original parts for welding. Weld the stubs to both ends of the original parts. Form tubes the length of the desired extension the same height and width as original. Cut slots to weld to the stubs. Weld the tubes to the stubs and original front part of the swingarm, weld the stubs and rear parts of the swingarm to the extensions. Grind and paint. What you end up with is three rows of welds at each joint instead of one, and a smooth, attractive appearance. If you want to get fancy, the inner tubes can be cut at an angle to match the angle of the outer tubes. Saves a bit of weight, but doesn't affect appearance.


Thanks!



I was going to put the outside one on in 2 pieces.




I'm going to have to read this post a few times.
 

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It might not be a Forth Road Bridge,but the outcome of a swingarm failing from a faulty unknown weld going down a road with traffic is going to horrific.


Very true RisingSun,



My point was if you doubt your own or your welders ability you should not even think about this job.

But on the other hand if you or your welder are properly competent there is no need to over-think the method used.

Companies like HPN or Richie Moore (Moorespeed.com I think) do frame and swingarm mods, extensions, strengthening, you name it for real hardcore off road and desert racing on heavy and powerful bikes (I won't mention what breed of bike,Qwerty doesn't like them
) and their methods are pretty simple and straight forward. No angled cuts or anything like that.
 
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