Swingarm cracked: weld vs. brace
 

I'm riding a Kawasaki KLR 650 from 2005 from Vancouver to Tierra del Fuego.

About 10.000 km ago, I had a very hard crash which slightly damaged my swingarm. I didn't think too much of it, cause the damage appeared to be minor. A few days back, when inspecting my bike, the damage has gotten worse and cracks have started to form.

http://i.imgur.com/HUSpo1l.jpg
http://i.imgur.com/gyFpB2m.jpg
http://i.imgur.com/nh5hj1c.jpg

So needless to say, this needs to be fixed. The question is how. So far I have 2 different opinions:

1. I met a German engineer who had an internship of a year working with metals, fixing exactly these types of problems, and he even has a degree in mechanical engineering. He thought that welding aluminium is very hard to do well, and if done incorrectly it could cause the swingarm to expand slightly on the one side, causing the backwheel to be misaligned. Therefore, he suggested that I would drill 4 holes, with thread (so I don't have to drill through the entire swingarm), in the aluminium, that would allow a 1cm thick steel brace to be appended to the swingarm. http://i.imgur.com/rrqdizw.jpg
2. So I went to a mechanical worker here in Flores, Guatemala, to propose this solution. He disagrees because of 2 reasons: 1) drilling holes in the aluminium weakens it further (that was my initial thought and I discussed it with the German, but he didn't think it was a big problem). 2) Aluminium is quite brittle, and the drilled thread in it in combination with the constant vibration of the bike will cause the bolts to loosen en eventually fall out. He said he could totally weld another aluminium plate on top of it, cause he's done it before and it went well.

Both of the guys that I talked to seem to make sense and I'm not sure if I can trust this Guatemalan welder's capabilities to not cause the aluminium to expand. He seems quite confident and seems to have a lot of experience. But, you never know, especially this being Central America.

So I'm after some more opinions here, I'd love to hear what you guys would do in my place or if you maybe even have another solution that you think is better.

You might have noticed another problem from the pictures: the rear foot peg keeps bumping into the swingarm due to the suspension, so that needs to be bent outwards a bit. I don't think that requires any discussion, seems quite straightforward, but please let me know if you think otherwise.

Coming from a aviation background where aluminum is common,drilling unless it is filled with a rivet or interference fit bolt is not a fix but a chance of creating multiple cracks along the circumference.
a doubler plate of similar aluminum properly welded would be the second chose,first being a replacement arm . also the dissimiliar metals corrosion with the steel n aluminum is not a permanant(which I assume you want) fix).

If you can get one put a hole new swing arm on - ally welding can be done but you need an real good ally welder and a jig to hold everything in place - which would be fine but it would be as cheap - and safer to put a new one on.

While you are on i would check your frame for cracks - some distance away from the swing arm - a a clout that big could well have transfered energy to a weak point elsewhere on the frame.

Good luck, Jake.

I agree that drilling holes may weaken the thin swing arm.
I would go to Guat. City and find the very best Alu welder you can lay hands on. They are there ... just got to dig them out. You want a super star.

Let the expert welder decide exactly how to proceed ... but my vote would be to do a very delicate bead build up on the crack ... then weld an Alu plate over everything.

Do the job with the Wheel FIRMLY bolted ON the bike. This will hold swingarm in perfect alignment.

Remove tire from wheel, remove brake lines, remove ALL elec., especially your ECU brain. Cover other vulnerable bits with Wet rags. Should be fine if the welder knows his stuff. The swing arm walls are thin ... so must be done carefully and artistically.

Good luck!

This guy had his KLR welded back together in Baja, rode bike back to USA, replaced frame! Headed South again! It was a crude job ... but got him
1500 miles home.

https://lh6.googleusercontent.com/-B...00/040-L-2.jpg

https://lh6.googleusercontent.com/-F...s800/047-L.jpg

From what I am seeing, the pillion peg bracket is wearing through the swingarm doh
That tells me that the swingarm alignment is wrong & the bushes are stuffed.
I see a new swingarm & bushes as the only repair here, otherwise, a serious failure is looming after a patch repair.
Sure, get the thing welded, but do the bushes & bolts at the same time :thumbup1:
Good luck with it :(

I see something different ... and something fairly common with the KLR650.
Take a look at that passenger peg mount plate ... it's been crushed in from a fall(s) (very common) and is subsequently scrapping the swingarm. Should have been caught much earlier. It's the peg bolt coming through the other side of the mount hitting the swingarm when suspension bottoms out. A 30 second tug and it would all be right again ... except now it's torn the Alu swingarm. doh

So doesn't seem like the swingarm is out of align, maybe just the passenger peg mount plate rubbing.

I've seen this before and also seen it from a bent side stand rubbing on the swing arm.

It's easy enough to determine if the swingarm bearings are shot or not. With the bike jacked up, just wiggle it back and forth. If uncertain, pull the thing apart and have a look at the bearings ... and everything.

Also thinking swingarm bearings are OK unless lots of underwater exploring has been done or if bike is 70K kms or more. It's Japanese, not German.

But with the wheel out you can get a good idea of swingarm bearing condition (by feel) and detect undo slop. I doubt there is much. But while at it, check wheel and hubb bearings and check for bent axle.

I'd bet a good weld up on the swingarm will hold it for life of the bike.
bier

I think Mollydogs advice is spot on. A carefully welded plate should make a lifetime repair. The only extra comment I would make is to advise you to keep a good eye on the repair welds for the first month or two after the repair to ensure there is no sign off cracking. The biggest problem with welding aluminum is structurally poor welds can look good on the surface and conversely poor looking welds can be structurally sound - this makes the initial visual judgment of the quality of a welders work very hit or miss so keep an eye on it for awhile. Good luck

Sent from my GT-P3110 using Tapatalk

The swingarm is not cracked its worn from the footpeg hanger rubbing it away.
Weld a plate over it and it should be fine for many more miles.
Bend the hangar back to where it should be and you shouldn't have any more problems.

Hahahaha oh my god what an absolute legend.

That sounds like a really good idea, taking the tire off and then putting the wheel back in so everything remains in place.

So it seems like most people recommend going for welding rather than the brace. I'm going to take my chances with this Guatemalan welder then, I have a good feeling about him.

Thanks for the very helpful replies everyone! I'll let you know how it goes.

Hope it goes well ! :thumbup1: Please do chime in after it's finished and especially after doing some serious off road after the "fix". Pics Please!

!Nos vemos!

Personally I take a minute every morning to stand back and walk round my bike look at it before riding off. ( as well as "my" daily pre-flight checks) You soon notice anything not quite the norm if you do it every day. I like to think I know my bike well and feel sure I would notice the start of something like this, even covered in dirt.

Good luck with the repairs

Pre-Flight checks ... only way to go! :clap:
I do this when cleaning/oiling my chain ... which I do every morning when on tour. I clean the chain, rear wheel ... and while doing that it's easy to have quick look around.

I've found all sorts of problems doing this ... most caught before something bad happened: Loose nuts/bolts, missing nuts/bolts, bent or dented parts & pieces, disconnected hoses, pulled wires, vent tubes, burnt plastic & parts, tire condition, loose spokes, broken or cracked luggage and mounts ...
on and on.

Once you really learn the bike, it's easier to spot something that does not look or "feel" right.

bier

It could be that I may have been incorrect in my assessment mollydog :innocent: but don't all forums have to have a wee bit of 'out there' estimate information. At least he will go & have another look :rofl:

I will stand corrected for the 1st time ( do NOT confer with my wife though:nono:) :thumbup1:

I think this is the best solution.......



Finding a good Aluminium welder will be the problem though.

I wouldn't worry about distortion. Allow it to cool every few inches of weld. The repair isn't that big. You don't need to weld on a huge plate. Maybe just 30-40mm each side of the damage.. The hole can be filled with filler rod.

When I first saw tje pictures I immediately thought of side stand damage. As I've experienced side stand wear on swingarm on a DR650. The passenger peg being the culprit would be right.
Repair the foot peg & bracket.
As for welding thevswing arm, that's what I did.
Use alu welder to fill damage area & then add extra support by welding a plate over damaged area. But be warned that unless the swingarm is properly supported during this process it will bend out of alignment & you may end up unable to insert the axle through swingarm & wheel.

Sent from my GT-I9295 using Tapatalk