2006 cracked swingarm

After riding a WR426 for 4 1/2 years without any problems (15000 miles), I purchased a 2006 YZ450 hoping it would be half as reliable as my 426. It hasn't been, a fork seal went at 40 hours, water pump seals went at 115 hours, and now I have a cracked swing arm. Make no mistake this bike is maintained perfectly, (much better than my 426) all bearing disassembled and greased, oil changed every 3 hours, cam chain changed at 100 hours, valves checked/adjusted, fork oil changed twice, coolant flushed and replaced etc. The cracked swing arm is a big deal not only because the cost of a replacement but more importantly had I not looked really closely at the inside weld and noticed the crack it quite possibly could have resulted in a failure on landing a big jump. I'm 44 years old, 193 pounds I ride fast but I'm not crazy. This bike has only been down 4 times all low speed (wet track slide falls) no damage at all. I had my local dealer look at the swing arm and they have no idea what I could have possibly done to cause this. They sent pictures to Yamaha and their response was tough it's passed the 30 day warranty. I can't be the only one with this problem, check your swing arm.

It looks like Yamaha's quality has suffered since 2002 this will probably be my last Yamaha and that's to bad because Yamaha is the only brand I have owned.

Sh*t happens.

Fork seals do not need a lot to cause a failure. some abrasive sand gets in there, wears the lip and you have a leak. Could bo 1,000 hours till it happens, could happen in the first hour.

I assume when you say to have a cracked swingarm, you mean a weld has failed. This too is just one of those things. To prevent it, Yamaha could of maganfluxed and X-rayed it and all welds on the bike, confirming they are all areospace quality. Would you want to pay an extra grand to have had this done? 10,000 bikes go out, one has a bad weld. Sad but a fact of life. Like engine tolerences and HP output. One bike makes 48 Hp, another only 46, why? Yamaha could sell all 48 Hp bikes, by making the tolereences better, but you'd have to pay for it, like an additional $500.00. would you pay for it or are you willing to accept these kinds of variables? To get one bike that has had a seal go and have a bad weld and condem the entire brand is like meeting one other person how is a jerk and deciding all people are jerks. Now, after owning 10 Yamahas, and all of them have manufacturing problems, I would think it fair of you to feel like you do.

Sh*t happens.

Fork seals do not need a lot to cause a failure. some abrasive sand gets in there, wears the lip and you have a leak. Could bo 1,000 hours till it happens, could happen in the first hour.

I assume when you say to have a cracked swingarm, you mean a weld has failed. This too is just one of those things. To prevent it, Yamaha could of maganfluxed and X-rayed it and all welds on the bike, confirming they are all areospace quality. Would you want to pay an extra grand to have had this done? 10,000 bikes go out, one has a bad weld. Sad but a fact of life. Like engine tolerences and HP output. One bike makes 48 Hp, another only 46, why? Yamaha could sell all 48 Hp bikes, by making the tolereences better, but you'd have to pay for it, like an additional $500.00. would you pay for it or are you willing to accept these kinds of variables? To get one bike that has had a seal go and have a bad weld and condem the entire brand is like meeting one other person how is a jerk and deciding all people are jerks. Now, after owning 10 Yamahas, and all of them have manufacturing problems, I would think it fair of you to feel like you do.

I agree with you on the seal problems, bad luck with water pump seal and one muddy day could cause a fork seal to go but the swing arm is a different story. The crack is on the inside of the arm behind the chain ring, if I had the stock chain ring on and not the iron man chain ring I never would have noticed it possibly until failure. What Yamaha should have done is took my swing arm and X-rayed the cracked weld to find out were the problem is. It appears to be a machine weld and looks good I suspect that maybe the heat treating process was skipped but thats just my guess. This sport is dangerous and everyone accepts that but to have a major component like a swing arm crack and for Yamaha not to be interested why is unacceptable. Do you think Yamaha's response would be any different if the crack had resulted in a failure which caused injury and they were dealing with my lawyer and not me. Like I said I'm 44 and I ride fast but nothing like a 22 year old kid trying to make a name for himself on the amateur circuit. If it happend to me it could happen again.

lets see some pics:prof:of that cracked swingarm

Sadly, in today's litigious society, especially if a an attorney was involved, Yamaha (and any company) would distance themselves.

If you wanted to be assured of a 100% perfect weld, you have to have it magnafluxed and Xrayed. Not Yamaha's job to do they, it is the consumers either by paying more at time of purchase or by a consumer doing a tear down and having it done.

In your job, is the work you do always perfect, is it checked and inspected everytime to ensure it is as good as it can possibly be?

The warranty on the bike expired 4 years, five months ago. Their support responsibility ended long ago. However, you may find they have a open ear if you approach them right. Put yourself in their shoes.

At least Yamaha gives a 30 day warranty, Honda gives none and I am not sure about Suzuki and Kawasaki.

I'll post pictures of the swing arm and the bike so you can see its condition when I get home, I'm in Tahoe boarding or trying to the lifts are closed because to much snow. Let me be clear this is not about money I bought a new swing arm before I got a response from Yamaha. It's about the next guy who doesn't see the crack. Sorry to stop in mid thought but Lifts just opened got to go.

Well, if it is not a money matter for you, I suggest having your entire bike maganfluxed and XRayed when you buy your next one. Then you can make a warranty claim with in the warranty period.

Me? I ride the bike. If something fails out of warranty (doesn't it always) and the failure was due to a design or manufacturing defect, I calmly and rationally discuss it with the manufacturer. Every time, they have paid at least half of the repair cost, even when it has been over ten years out of warranty.

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That crack does not look like a bad weld. Looks like a stress fracture.

To see if it defective, you would have to seperate the parts and have the metal looked at under a microscope to determine is in fact it is a stress fracture or a contanminated weld.

You've done at least 115 hours and only fallen off 4 times?

One other question.... Why replace it when all it needs is a re-weld?

Looking at the first two pictures, it looks as if the swing arm forward of the weld is undercut somewhat by the weld, so I wouldn't give the weld itself a very high grade.

Still, this is the only one of these I have heard of cracking up to this point.

i'm curious as to how you have kept the warning sticker on your shock from obtaining any wear whatsoever after 115 hors of riding. dude face it you don't ride that much it's obvious from the condition of the bike.i have the exact same bike and approx. 100 or so hrs on it and i maintain well and it doesn't look as new as yours. i mean the plastic disc gaurd and caliper gaurd are unscathed. mine were shredded after a short time, and thats track time. don't bag on yamaha just cause one bad apple got through. the truth is you probably bought it used and that person did something stupid and passed the problem on to you.

i'm curious as to how you have kept the warning sticker on your shock from obtaining any wear whatsoever after 115 hors of riding. dude face it you don't ride that much it's obvious from the condition of the bike.i have the exact same bike and approx. 100 or so hrs on it and i maintain well and it doesn't look as new as yours. i mean the plastic disc gaurd and caliper gaurd are unscathed. mine were shredded after a short time, and thats track time. don't bag on yamaha just cause one bad apple got through. the truth is you probably bought it used and that person did something stupid and passed the problem on to you.

The shock sticker on my '03 with over 350 hours on it looked like that, and the caliper and disk guards were a long way from "shredded". You're free to speculate, but you have no real knowledge as to whether he's been accurate or not based on such shaky criteria.

Your point that this is an extremely uncommon occurrence

is well taken, though.

i'm curious as to how you have kept the warning sticker on your shock from obtaining any wear whatsoever after 115 hors of riding. dude face it you don't ride that much it's obvious from the condition of the bike.i have the exact same bike and approx. 100 or so hrs on it and i maintain well and it doesn't look as new as yours. i mean the plastic disc gaurd and caliper gaurd are unscathed. mine were shredded after a short time, and thats track time. don't bag on yamaha just cause one bad apple got through. the truth is you probably bought it used and that person did something stupid and passed the problem on to you.

I never said the bike has 115 hours on it because it doesn't it has 140 hrs ( 90% track ) and I bought it new and put the hour meter on it before it was even started. so it has exactly 140 hours. The reason the bike looks the way it does is because I don't fall ( much). Centermass where the hell do you get off calling me a liar? I hope you're from northern California, and if you are, lets set a time to ride. We'll see how quickly I change your mind. You apparently missed the fact that my disk cover, fork guards and skid plate are pitted to hell. The weld on my sub frame is nearly worn smooth from boot rub. I will post more pictures of the bike tomorrow to show what you obviously couldn't see from the previous pictures. If you truly own an '06 450 you would know that because of the recessed location of the warning sticker on the shock, it is impossible for your boot to touch it.

a quality welder can repair this, no problem.....

a quality welder can repair this, no problem.....

If I have the swing arm welded it will have to be heat-treated and that's a process that requires a lot more skill than welding in order to increase strength without becoming too brittle so I decided buy a new one, it will arrive Monday

Definately a good choice in buying a new one. You take a huge risk in having somebody who doesn't know the metallurgy of Aluminum to start welding and hoping that it doesn't crack again.

I didn't see any undercut, if any discontinuty is visually seen than it is overlap on the outside of the arm. I can't tell from the pic but may be a crater crack on the lower side of the arm propagated into a larger crack in the side of the groove joint while under stress from riding.

There are so many reasons why this happened, like improper weld prep, maybe the robot was out of calibration/adjustment, improper heat treatment, etc...

Like I said, you did the right thing by getting a new one.

Thanks for the info and pics. Nobody's perfect, not even yammie, but you keeping an eye on your equipment is right on the money. I'll check my rig tonight, ya never know..

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