Best solution for gouged swingarm at pivot

HardWorkingDog · 02-12-2013, 11:14 AM

During a long, multi-week Baja trip I got complacent with checking my chain and managed to grind the lower leading edge of the swingarm pivot head with the chain on my WR250R.

It took about 3mm of the existing weld bead, and then about 2mm into the swingarm head itself. It's not all the way through into the bearing area, but I have no idea how much material is remaining.

I'd appreciate hearing from knowledgeable welders/metallurgists/swingarm hackers on how best to recover from this. Options I see are:

1. Replace the swingarm--I see used swingarms on eBay for $125-175. Could just be getting another set of problems from a most likely wrecked bike.
2. Get it welded. Don't know if this will do more harm than good, considering the to-me unknowns of the swingarm composition, heat treatment, potential for deformation around the bearing surfaces, etc.
3. Fill with quicksteel-type epoxy.
4. Leave as is.

All of the options include replacing the chain slider ("seal guard") and chain/sprockets.

Thanks!

dmn0507 · 02-12-2013, 11:58 AM

The pic was taken a bit too close go get the idea of the entity of the damage but here are my 2cents anyways:

I'd go either for #1 or #2 (pick the cheapest solution) if u don't feel comfortable to leave it as it is
3 and 4 are pretty much the same, except for the cosmetic difference

Epoxy might be worth applying to the new (or welded) swingarm, in case the chain will try to grind it again it should take some more time before digging into the metal.

Saltydog86 · 02-12-2013, 05:31 PM

4. Leave it as is.

Then replace the slider and but a 14t front sprocket on.

That's what I did when I had the same issue as this.

Beezer · 02-12-2013, 06:44 PM

plenty of metal there still... I'd leave it alone other than file off the ridges. then maybe build a slider or add on to one so that it extends a bit farther to cover the tube. another option would be to get a piece of steel & stick it with RTV so if the chain gets loose again it won't keep cutting into the swingarm. either that or ignore it & keep the chain tensioned

KustomizingKid · 02-12-2013, 06:55 PM

Leave it... If it starts cracking, weld it. The worst thing to do is to fill it in with some epoxy crap that does nothing structurally and keeps you from seeing cracks propagating.

concours · 02-17-2013, 05:03 AM

Leave it as is. 35 years fabricating experience.

It's just fine.

HardWorkingDog · 02-17-2013, 07:22 AM

Thank you concours, KustomizingKid, Beezer, Saltydog86 and dmn0507. My compulsive side would like nothing more than to replace the swingarm

but I think I'm just going to leave it as is. And keep a close eye on it.

Really appreciate the replies

02-12-2013, 05:31 PM	#3
Saltydog86 village idiot Joined: Aug 2006 Location: Hinckley/Wheaton Illinois Oddometer: 828	4. Leave it as is. Then replace the slider and but a 14t front sprocket on. That's what I did when I had the same issue as this. __________________ 12 KTM 350 EXC-F 09 KLR 650 12 Genuine Stella 05 Yamaha XT225 03 Honda Goldwing GL1800

02-12-2013, 06:55 PM	#5
KustomizingKid Gnarly Adventurer Joined: Nov 2012 Location: Minneapolis Oddometer: 192	Leave it... If it starts cracking, weld it. The worst thing to do is to fill it in with some epoxy crap that does nothing structurally and keeps you from seeing cracks propagating. __________________ 1989 KLR 650

02-17-2013, 05:03 AM	#6
concours WFO for 41 years Joined: Dec 2008 Location: Kensington, NH USA Oddometer: 3,994	Leave it as is. 35 years fabricating experience. It's just fine. __________________ Too much is just barely enough..... 2007 Tiger 1050 2005 Royal Star Tour DeLuxe 1973 Yamaha TX750 1974 Norton 850 Commando Roadster

02-17-2013, 07:22 AM	#7
HardWorkingDog ^OP Harvey Mushman Joined: Aug 2009 Location: Walnut Crick, Cal. Oddometer: 1,324	Thank you concours, KustomizingKid, Beezer, Saltydog86 and dmn0507. My compulsive side would like nothing more than to replace the swingarm but I think I'm just going to leave it as is. And keep a close eye on it. Really appreciate the replies __________________ "Coffee first..." Next Trip: didn't get enough...Death Valley "it's a dog's life.............and I love it"

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02-12-2013, 11:14 AM	#1
HardWorkingDog ^OP Harvey Mushman Joined: Aug 2009 Location: Walnut Crick, Cal. Oddometer: 1,324	Best solution for gouged swingarm at pivot During a long, multi-week Baja trip I got complacent with checking my chain and managed to grind the lower leading edge of the swingarm pivot head with the chain on my WR250R. It took about 3mm of the existing weld bead, and then about 2mm into the swingarm head itself. It's not all the way through into the bearing area, but I have no idea how much material is remaining. I'd appreciate hearing from knowledgeable welders/metallurgists/swingarm hackers on how best to recover from this. Options I see are: 1. Replace the swingarm--I see used swingarms on eBay for $125-175. Could just be getting another set of problems from a most likely wrecked bike. 2. Get it welded. Don't know if this will do more harm than good, considering the to-me unknowns of the swingarm composition, heat treatment, potential for deformation around the bearing surfaces, etc. 3. Fill with quicksteel-type epoxy. 4. Leave as is. All of the options include replacing the chain slider ("seal guard") and chain/sprockets. Thanks! __________________ "Coffee first..." Next Trip: didn't get enough...Death Valley "it's a dog's life.............and I love it"

02-12-2013, 11:58 AM	#2
dmn0507 Gnarly Adventurer Joined: Jul 2010 Location: Italy, NE, N45°37'18" E12°33'45" Oddometer: 254	The pic was taken a bit too close go get the idea of the entity of the damage but here are my 2cents anyways: I'd go either for #1 or #2 (pick the cheapest solution) if u don't feel comfortable to leave it as it is 3 and 4 are pretty much the same, except for the cosmetic difference Epoxy might be worth applying to the new (or welded) swingarm, in case the chain will try to grind it again it should take some more time before digging into the metal.

02-12-2013, 06:44 PM	#4
Beezer Beastly Adventurer Joined: Oct 2004 Location: Anchorage, formerly Spenard (hub of the universe) Oddometer: 4,413	plenty of metal there still... I'd leave it alone other than file off the ridges. then maybe build a slider or add on to one so that it extends a bit farther to cover the tube. another option would be to get a piece of steel & stick it with RTV so if the chain gets loose again it won't keep cutting into the swingarm. either that or ignore it & keep the chain tensioned