2006 cracked swingarm


36 replies to this topic
  • alien

Posted February 13, 2008 - 12:17 PM

#21

William 1, you need to read closer and you will see this is a 2006 bike.
I don't know what line of work you are in but you don't have the total picture on the bike Mfg. process. I would find it unlikley that yamaha makes their own swingarms. I had a 1995 CR 250 that had a cracked swingarm and honda shiped one from canada where it was made. That was the same year they had a recall on the forks, crankshaft and engine cases. Defects happen to the best.

  • grayracer513

Posted February 13, 2008 - 01:01 PM

#22

I would find it unlikley that yamaha makes their own swingarms.

Yamaha may order their swing arms from a vendor, but I would be surprised to find that they did not do their own frames, or at least have direct control over the process, particularly with respect to the custom castings and extrusions used. Yamaha has been a technological leader in that area of the process for the last several years, and it has become an area of corporate focus with them. Besides, Honda is not Yamaha, and vice-versa. What is true of one from a procedural standpoint cannot be presumed true of the other without documentation.

Interesting read:

http://www.aluminum....&ContentID=7648

Also, because of the way that Japan in general operates their inventory processes for manufacturing, there is essentially no room for and very little tolerance of, defective components, and if you are an outside vendor working for a major Japanese manufacturer of any kind, you find this out very early in the relationship. That doesn't eliminate defects, of course, but it makes them much more scarce.

  • William1

Posted February 13, 2008 - 01:20 PM

#23

William 1, you need to read closer and you will see this is a 2006 bike.
I don't know what line of work you are in but you don't have the total picture on the bike Mfg. process. I would find it unlikley that yamaha makes their own swingarms. I had a 1995 CR 250 that had a cracked swingarm and honda shiped one from canada where it was made. That was the same year they had a recall on the forks, crankshaft and engine cases. Defects happen to the best.


Ah.... I used to work for Yamaha, albeit many years ago. I was a field technical rep for a few years. So I am a little familiar with the whole process.

Defects happen all the time. Race bikes like the YZ and WR have a 30 day warranty. After that, the manufacturer has no legal requirement to resolve a defect unless a recall is done. Now, if you create a good relationship with the manufacturer, they do at times, offer assistance.

You are dead to right on the bike, I was looking at the first part of his statement. The bike is two years old, my bad, 23 months (or so, no idea when it was purchased new) out of warranty

Not really sure what the point is you are trying to make. We have a case here of what on the surface appears to be a part that may be substandard.

One other point is, Yamaha is on the forefront of hydroforming aluminum. If they do not make the part in house, I can assure you if it is made using this process, Yamaha techs and engineers are on site at the manufacturing facility, which in essence, is the same as being made in house.

  • alien

Posted February 15, 2008 - 01:07 PM

#24

My point is that defects happen to every manufacturer. You kind of jumped on this guy for suggesting that yamaha had a defect.
I work for one of the major airlines, in the heat treat-welding deptartment. Even with jet engines we can't get it right every time. We have programs in place to reduce defects. Sadly our lack of perfection has resulted in the death of passangers. In my thirty plus years in MX I have seen many of Mfg. errors.

  • grayracer513

Posted February 15, 2008 - 03:42 PM

#25

I believe that the reason Wm "jumped" on the guy was the tone the OP took of being entitled to some sort of compensation for the cracked swing arm, when, by any reasonable stretch, he is not. The warranty, which the buyer accepts at purchase, states that the bike will be free of defects in workmanship and materials for a period of 30 days, and it was. Everything breaks eventually, and as you yourself have pointed out, defects happen sooner or later in large lots of any manufactured product, no matter how much care is taken in its production. Having spent most of my professional career at motorcycle and automotive dealerships, I have seen several examples of failures that were clearly, absolutely, and unquestionably caused by defects in the process, but because the failure occurred outside of the warranty period, it was not covered.

The broken swing arm here is unfortunate, and is an interesting thing to know about, but it really is just one of those things.

  • rbn14

Posted February 15, 2008 - 04:11 PM

#26

What I think is interesting is that the crack is in the top weld. I would expect it to occur on the bottom weld due to tension developed along that face during an impact.

  • 2grimjim

Posted February 15, 2008 - 06:50 PM

#27

I worked as a machinist for a large aerospace manufacturer a few years ago.........manufacturing errors, to some small degree (that escape the quality process), are simply accepted as a cost of doing business. Unless the end user (customer) is willing to pay an exorbitant price for 100% quality inspection (the reason some military/government projects cost so much........a billion dollar spy satellite only has one chance to work perfectly) infrequent failures are a fact of life.

It is also important to know that welding is still a difficult to controll process. I'm an AWS member and receive a monthly publication dedicated to the welding trades and you would be surprized at how often the subject of weld failures is discussed.

As far as Yamaha is concerned, they have no clue to how the machine was handled after it left the factory and unless there was a pattern of failures that would warrant an investigation and subsequent recall they are most likely going to treat this as they should...........an isolated incident.

  • William1

Posted February 16, 2008 - 09:28 AM

#28

My point is that defects happen to every manufacturer. You kind of jumped on this guy for suggesting that Yamaha had a defect.
I work for one of the major airlines, in the heat treat-welding deptartment. Even with jet engines we can't get it right every time. We have programs in place to reduce defects. Sadly our lack of perfection has resulted in the death of passangers. In my thirty plus years in MX I have seen many of Mfg. errors.


I just re-read the entire post. Not sure where you interpreted I 'Jumped' on the poster. I tried to be as factual as an old fart can be. Many times, I told him what he could do to recoup at least some of his expense. I also tried to point out one bad apple does not spoil, well you know. To want and expect perfection (what ever that really is) has a cost. Someone has to bear that cost. Businesses are structured to make a profit. Therefore, to have "perfection", the consumer is the one who ultimately bears the expense. Personally, I'd rather roll the dice on something from a reputable company like Yamaha that I will get a item with most likely no defects for a reasonable price rather than pay a gazillion for perceived perfection every single time. LOL, with my luck, I'd nail a tree first ride out and trash it!

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  • rexbond007

Posted February 17, 2008 - 09:31 AM

#29

i'm a welder by trade, i own do a lot of aluminum welding. the broken weld is a mystery. it appears to be a clean weld. most welds crack along side of the weld. Where the weld material bonds (the weakest part of a weld). this one is right down the middle and to one side. that is hard to diagnose. it cold be lack of argon, or incorrect filler rod, wire that was used? it could be trapped inclusions. as for magna fluxing, i believe that process is only for steel. As aluminum is non-magnetic. i would have re-welded that. where it cracked between the two vertical welds it would be intresting to dig that out to see if there are any trapped inclusions present. after seeing this, it makes me wanting to check my swing arm welds every 5 minutes

i sent the pictures to some people in the welding industry,

an engineer
specialty welding supplier
welder fabricator for 20 years +
a welding store owner
a kawasaki ex mechanic
a machinist

  • William1

Posted February 17, 2008 - 01:13 PM

#30

Good observations. I am no welder (obvious if you ever saw my welds). I also have never 'broken down a swingarm and therefore have no concrete knowledge of the exact construction. To venture a guess, I would say the axle support casting is pressed into the aluminum box section and that the thin weld where it cracked is directly over the tail end of the box section. But this is just a wild, hopefully relatively informed, guess.

Will be interesting to hear the opinions of some experts. Would be cool if we could get these guys the actual piece to look at too.

  • rexbond007

Posted February 18, 2008 - 09:20 PM

#31

so far, from 2 people that e-mail me back say it's a weld process defect in the heat effected zone.


meaning in the heated area that the weld puddle travels a defect was caused

it could be technique, or not pre-heating, or using the wrong filler wire, or could be from not using the correct flow of argon ,

but to some it up. the defect was caused from incorrect welding

it was not abuse, and it would have broke regardless.

  • William1

Posted February 18, 2008 - 10:03 PM

#32

What does that mean to a layman such as me? As others mentioned, the weld looks, I suppose, a bit 'thin'.

  • grayracer513

Posted February 19, 2008 - 12:02 AM

#33

The weld "looks" fine. A good weld does not need a bead built up higher than the surrounding material, really. The fault could be any of the causes Rex laid out (except, I would think in this case, not incorrect filler). Plain and simple, the weld was weak because the metal was ruined in the process.

  • 2grimjim

Posted February 19, 2008 - 01:11 PM

#34

so far, from 2 people that e-mail me back say it's a weld process defect in the heat effected zone.


meaning in the heated area that the weld puddle travels a defect was caused

it could be technique, or not pre-heating, or using the wrong filler wire, or could be from not using the correct flow of argon ,

but to some it up. the defect was caused from incorrect welding

it was not abuse, and it would have broke regardless.


The crack is NOT in the Heat Affected Zone. The HAZ is the area along the edge of the weld that extends into the base material to the degree and distance that the chemical structure of the base material is altered by the heat input of the welding process but is not part of the weld itself.

The photos indicated that the welding current/voltage was not grossly out of tolerance: if too high the weld appearance would be poor and evidence of undercut; too low would show evidence of lack of fusion/seperation at weld toe.

Because the weld failed through the center of the filler material I would think that the most likely culprits would be;
1) Poor weld penetration due to weld geometry, i.e. weld not along edge of joint but offset to one side; poor fitment.
2) Insufficient weld material deposited caused by excessive travel speed (operator or equipment error)
3) Improper heat treating.
4) Defecient filler material, not meeting specification for minimum strength.

  • rexbond007

Posted February 19, 2008 - 06:29 PM

#35

Bottom line: Yamaha should have gone good on this one!

  • grayracer513

Posted February 19, 2008 - 08:01 PM

#36

Bottom line: Yamaha should have gone good on this one!

Back to that? Sorry, it lasted through the warranty period. We can agree that it should not have broken, and that they rarely do, but Yamaha is not bound to replace it.

  • RJB

Posted February 20, 2008 - 07:09 AM

#37

I'd be bummed, especially at having to replace it and fork out $450 odd, but as Gray and others have mentioned, its warranty had passed. Even the manual tells you to inspect, lube and retighten the swingarm every race.

I had an issue with my Volvo shocks (1 month out of warranty even though it hardly had any miles) a while back. Volvo's take on the matter - tough. I was not happy, given the replacement cost; but then again if every time a consumer had an issue and manufacturers had to negotiate an out of warranty claim, they would simply pass the cost back to the consumer.





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