frame\swingarm stretch

elhefa

New Member
what are the most common deciding factors when stretching a frame or swingarm? is it looks,comfort,or more on the tech side? what are some common stretch lengths for both? and why...
 
I have no idea what you mean when you mention stretching a frame... Unless youre talking about a hardtail, than for the smaller Japanese bikes you usually see about 4" of stretch.

As far as stretching the swinger, you really dont want more than 4" or so.

There are several reasons for doing this. Added stability, better traction off the line, looks, etc...
 
Stretching is the anti-tech. It dis-improves handling and safety. It's just about looks.
 
teazer said:
Stretching is the anti-tech. It dis-improves handling and safety. It's just about looks.
unless your tring to keep the front of a rd down
 
thanks sorry for being so vague. want to add 2-3" to my swingarm and was curious if it was basic or if i had missed something,thanks again.
 
I'm looking to do a swingarm stretch on my cl350 as well. What's everyone using for their slugs to weld it in? I found a company that makes them but they're like 50 bucks for the steel slugs
 
Just my opinion here, but you want to avoid slugs and stretched swingarms at all costs. They are dangerous unless the modification is planned and executed by someone who really knows what they are doing and understands the forces involved and consequences when it cracks (it will. The only question is when).

Either find a longer arm from another bike or leave it alone.
 
its for a cb 550, what would you recommend as far as a swap for a longer swingarm? maybe 3" or so.crack(s) scare me.
 
cracks should scare you. I stretched mine 4" simply for appearance. I dont do alot of racing around tight corners. I did not cut the arms. I think it could, and would be disastrous. I believe compromising the integrity of the original arm is a bad idea. I gained my length on the bushing end. I measured the original swing materials using my digital caliper, and ordered the new steel to the exact thickness specs. (Welding 2 pieces of different thickness material together is not ideal.) A good and trusted friend at the machine shop cut and fit the steel, perfectly. My best friend, who is an educated welder w a certification did all the welding on my patio while I watched, double checked and measured. I was not about to blindly trust "god knows who"...If he or I had any questions about the entire project it wouldve been scrapped immediately.
The swing arm floats, so it really does not support any weight per se. The weight of bike and rider is transferred from the frame through the resistance of the shock springs to the axel, bearings, hub, up through spokes, down around rim, through the tire and to the ground. HOWEVER, Even though the arms are "connected" to one another through the axel. The arms will twist and flex a bit. Due to the fact that each shock is somewhat independent of each other. This twisting and flexing minor as it may be. eventually will cause breakage at the weakest link...anyone care to take a guess where? At the EXACT point these guys are cutting and welding. Espeacially if the welded parts are of different thickness. The heat needed for good penetration on the thicker steel will harden the thinner. Causing it to become brittle. OR, if its welded at a lower temp setting for the thinner material, it will not penetrate the thicker deep enough. The bead will literally just be sitting on top of the thicker metal.

Also there are more pressures placed on the arm. Pushing and pulling. The arms are constantly being compressed by the force of the rear tire pushing the bike forward. Not to big of an issue with these small lightweight bikes w little horse power. However, The pulling apart force generated every bump and pot hole we hit. could be tremendous. Pulling that arm free of the rest of the bike and you. If one cuts and welds those arms I wonder where its gonna pull apart, after hitting that pot hole at 80 mph while passing that big truck.
I can write alot more...If you like? Its your ass on that thing. I recommend you dont do it.
Heres how I did mine. http://www.dotheton.com/forum/index.php?topic=28306.0
 
Just ordered some extension for my swingarm and ordered from wrench tech racing and they look good. Good people to order from. They have 3, 4, 5, and 6 inch extensions.
 
I stretched mine 3 or 4 i cant remember right now . I braced it all together before cutting then used 2 pieces of thicker pipe as the slugs . They are about 1 to 2 inches longer than the piece I put in . Then I took another swingarm and cut out the pieces I needed for the stretch .
 
I did a 4" stretch on my '75 CL360 swing-arm. No slugs, just heavy tube, one that slips inside the stock about 2-3" on each side and one that is same outside diameter for your stretch. Did build a heavy duty jig out of angle iron to keep swing-arm in place while welding it back together, don't want it to twist and deform under heat! Also punched several rosettes on each end to help firm up the added pipe length.
 
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