built my own swingarm

[80GS1000]

Thanks for saying this Dan, I was thinking the same thing. Another thing, aluminum is usually heat treated after welding; different alloys require different HT’ing techniques. Taking an existing Al part and tacking on extra pieces like these extensions anneals the metal in the heat affected zone and makes it weak. Most likely this reduction in strength is not a deal breaker though. Just trying to make a point to those advocating this method vs. building your own steel swingarm.

The GSXR swingarm extensions are bolt-on, no welding required.

[salty_monk]

I assumed they would be. Much more commercial that way. I didn't really read up on them I just used them as an example in my post.

Who knows who first designed & tested them?
Probably someone much like one of us who wanted that look or to go to the drag strip or something originally.

A lot of stuff on production bikes gets first designed & then tested out on the racetrack, that's how they find the limits. The difference being that you hope these are very talented engineers able to get things right out of the box.... I'm sure things often start out way "overbuilt" to where they end up though (at least that's the safe way to do it..)

Dan

[Nessism]

The GSXR swingarm extensions are bolt-on, no welding required.

Okay I misunderstood. The shock mounts need to be welded though right? Guess that's not enough to matter.

[Hammered]

Okay I misunderstood. The shock mounts need to be welded though right? Guess that's not enough to matter.

Oh no the welding alone is enough to alter the properties of the swingarm, steel or aluminum, enough to cripple the area where they were installed. Thats where having a welder who understands this comes into play. Too much heat and you loss the tempering, too little and you dont ensure a joint between the pieces that will hold up. Not knowing how these extensions install and ride on the swingarm, I couldnt begin to venture a guess as to how they would effect the swinger they are attached to.

[Nessism]

The stress in the swingarm is lower out near the axle where the welding is needed, so even if the metal looses some strength it may still be okay...maybe...not sure.

[Hammered]

The stress in the swingarm is lower out near the axle where the welding is needed, so even if the metal looses some strength it may still be okay...maybe...not sure.

Not really. The first thing that will be noticed (least we hope it would get seen) would be stress cracks. And just as in glass, a stress crack can and will run with the grain of the metal. Vibrations will increase the amount of stress making the area even worse in a short period of time.

[posplayr]

Overkill??




Probably the tire more than the swing arm. You can see here at least the emphasis on underbracing v.s. a larger primary arm dimension.

[salty_monk]

Overkill for me... but then I don't like the extended swingarm look. Puts the wheel all out of kilter with the bodywork & ruins the lines...

[Nessism]

It’s hard to say what’s overkill unless you know what’s gone into the thing. Tubing comes in various wall thicknesses, and of course, steel has significantly different properties than aluminum. A swingarm like that built out of steel would be pretty stout. If it were aluminum on the other hand, it would be significantly more flexible.

[posplayr]

More

http://cgi.ebay.com/ebaymotors/Yamaha-XS650-XS-650-stock-length-swingarm-under-braced_W0QQitemZ390021572240QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item390021572240&_trksid=p4506.m20.l1116

ITEM DESCRIPTION:

Yamaha XS 650 Stock length and Braced Swing Arm for Drum and Disc Brake applications: Up for auction is the Swing arm shown in this auction. We have added an under-brace with 6 attachment points to this swingarm. The U-bend tubing as well as the attachment arms are made of DOM steel with a wall thickness of .090. The U-bend tube is 1-inch OD. This entire process is done in our welding jig as well as the addition of the under brace assy. This model is available for a drum or disc rear brake application.

[Hammered]

http://cgi.ebay.com/ebaymotors/Yamah...4506.m20.l1116

ITEM DESCRIPTION:
Yamaha XS 650 Stock length and Braced Swing Arm for Drum and Disc Brake applications: Up for auction is the Swing arm shown in this auction. We have added an under-brace with 6 attachment points to this swingarm. The U-bend tubing as well as the attachment arms are made of DOM steel with a wall thickness of .090. The U-bend tube is 1-inch OD. This entire process is done in our welding jig as well as the addition of the under brace assy. This model is available for a drum or disc rear brake application.

Thats a good looking swinger. Its along the lines I have in mind for my 1982 GS750. I plan to relocate shock mounts as well as use a standard eye to eye style shock. Ill be running an over brace that will also act as a debris guard. This way I can widen it to run a 4" rim/tire combo which has been loads easier to find than a 2.75 rim. And thats not a bad price.


Seems i know the seller from another forum as well. Joes a good guy. Ill have to ask him if hes doing any GS stuff.

[midnightcafe]

wheel misalignment will upset ride geometry. more importantly, a misaligned sprocket will pull the wheel out of alignment and wear your drive train out.

[zathros]

I would have that swing arm magnafluxed after I used it. I have built many recumbent bike with rear suspensions. The cross bracing adds a helluva lot of strength and wide diameter thing wall is better than small diameter thick wall. My bike was tested at Canondale Bicycle Corporation and they were astonished at what I achieved out of thin tube steal. My bike only weighted 1 half pound more than their aluminum recumbent. They gave me 10 sets of disc brakes and boxes of parts to help me with my home made projects.

That being said, that swing arm looks frail. I would try again with larger tube diameters and cross bracing. It is fun fabricating and the fact that you are doing this is a plus in my book. That Kawasaki had a lot of cross bracing and it looks great. If the welds are right and he used the right materials I would bet that swing arm functions fine. Endeavor to persevere. Why not?

[mikesgs1100e]

suzuki gs1100e swing arms are aluminum,,you can not magnaflux aluminum

[mikesgs1100e]

when correctly done,a sleeve is inserted in the swing arm where it is cut,so that when it is welded the swing arm is actually stronger then before