06 Yz 450 Hub Broke

[jamiehughes]

Personaly I am inclined to blame the Ironman sprocket. The same thing happened to me and my buddy. We both had Ironman sprockets. Both broke after landing from a jump while on the gas. My theory is that under extreme pressure the skeleton frame of the ironman folds to one side creating the chain of events which leads to the broken hub. I will never buy another one.

it would be interesting to see if there is something to this as this is the first ironman sprocket i have had. i have never heard of this happening though. and i definitely wasn't on the gas hard when mine broke.

[SC_Spode]

Personaly I am inclined to blame the Ironman sprocket. The same thing happened to me and my buddy. We both had Ironman sprockets. Both broke after landing from a jump while on the gas. My theory is that under extreme pressure the skeleton frame of the ironman folds to one side creating the chain of events which leads to the broken hub. I will never buy another one.

That's why I asked if it was one of those sprockets without the inner ring.

I remember reading about this issue a couple of years ago and someone claimed to have done analysis with some FE software and that it was obvious that the lack of the inner ring was causing a loss of structural strength in the assembly.

I've never seen the results or the data, just remember reading that. It does make sense, but without hard numbers or test data to validate the suspicion, I can't say I'd put money on it.

?

[Ga426owner]

Personaly I am inclined to blame the Ironman sprocket. The same thing happened to me and my buddy. We both had Ironman sprockets. Both broke after landing from a jump while on the gas. My theory is that under extreme pressure the skeleton frame of the ironman folds to one side creating the chain of events which leads to the broken hub. I will never buy another one.

the most ridiculous alligation I have ever heard.....please

I have been and many others have been using ironman for years on many different bikes....pressure on skeleton frame.....from landing with the gas on.....please explain...what a skeleton frame is?

I will only use Ironman Sprockets...?

[Ga426owner]

well after my dealer sent pics to yamaha, they said they are going to warranty my hub and spokes, my dealer said he has warrantied like 5 or 6 of these already. i hope others don't start seeing problems like mine, especially when going over a jump like i was when it broke.

Now this is great news.....you have my curiousity on getting my 06 hubs swapped out now.....?

[jamiehughes]

the idea behind the ironman sprockets does seem to make a little sense to me because all the mounting points are all seperate, whereas most sprockets are a full circle mounting, makes sense about the stability thing, the full circle design may make the hub seem stronger since it makes the hub all one piece with the sprocket, if that makes sense. i might just have to try a different sprocket.

[SC_Spode]

the most ridiculous alligation I have ever heard.....please

Just curious... why?

Have you done or seen any FE analysis that would lead you to believe that a rear hub assembly using a sprocket without an inner ring is as structurally strong as one with?

?

[grayracer513]

the idea behind the ironman sprockets does seem to make a little sense to me because all the mounting points are all seperate, whereas most sprockets are a full circle mounting, makes sense about the stability thing, the full circle design may make the hub seem stronger since it makes the hub all one piece with the sprocket, if that makes sense. i might just have to try a different sprocket.

To some extent, I agree that this theory has merit. There would be a more focused and isolated pressure applied to the sprocket mounting point IF the sprocket bent over.

However, I seriously doubt that any amount of driving force applied by the engine could accomplish this feat. OTOH, I've seen chains snap in half, crankcases broken at the output shaft, axles and adjuster bolts bent, all from having the chain too tight.

So, while you may have something, I still think I know where the central cause is.

[jamiehughes]

i'm just not sure how a chain that hasn't been touched for 10 months, as far as adjustment goes, wouldn't have caused a problem months ago if it was too tight.even though i adjusted it to book specs, of course i guess why would the hub just decide to break at that time also, as i know as of 2 weeks ago there were no cracks developing as when i changed tires i looked at it pretty closely, just for that reason as i remember reading about it last summer on here. whatever, i guess i could make up just about any reason for it to have happened, all would i'm sure have been my fault. at least yamaha doesn't think it was my fault.

[Ga426owner]

Just curious... why?

Have you done or seen any FE analysis that would lead you to believe that a rear hub assembly using a sprocket without an inner ring is as structurally strong as one with?

?

nope and I do not need to do or read any either.......just real world hard racing use and riding/tuning experiences with Ironman Sprockets on 4 different bikes that were mine and many many other riders/racers amature and pro that do and don't ride yamis and don't have sprocket/hub issues......?

[kstutzman]

I was running a Renthal sprocket on mine. Wondering if my chain is jacked too? Any thoughts?

[andy250]

If the hub that breaks the sprocket flange off has no problem with loosening or deformation of the bearing pockets, as they often do not, then it had nothing to do with the failure.

As far as I know, the bearing problem is the fault of a casting defect in the hubs involved.

I agree that part of the problem *may* be overly tight chain adjustment, but why have we not seen aftermarket hubs blowing up at the same rate? I have yet to see a talon/excel/rad/pro-wheel hub fail on these bikes.

[grayracer513]

Percentages, most likely, even if you take into account the fact that the Talons should be stronger. In truth, only a small number of these hubs have failed, relative to the number of bike in production. An even smaller number of '06's have Talons on them. Assuming the same percentage of Talon equipped bikes would be subject to chain tension errors, that number would be so small as to be statistically insignificant.

If the chain is a little too tight, the swing arm can still pass over center even though the chain causes it to bind as it does so. The total assembly flexes enough to allow it. If it's a little tighter, things have to flex more, and the stress applied to the associated components are magnified. It's unlikely that the first compression of the rear suspension would break anything, but certainly conceivable that the cumulative effect of 20 hours of such a thing could. And, maybe (fairly obviously) the hub is the weak link in this "chain", and maybe the ringless centers of Ironman sprockets contribute.

I'm not trying to point fingers, blame anyone, or absolve Yamaha of the responsibility that may be rightly theirs. I'm just pointing out that chain tension is a very likely suspect as an underlying cause, and it's one that can be easily followed up on to avoid it contributing to such a failure.

[jamiehughes]

definitely gonna recheck tension when i get it back together. i don't know if my body and assorted appendages could take another get off like that anytime soon.

[SC_Spode]

nope and I do not need to do or read any either.......just real world hard racing use and riding/tuning experiences with Ironman Sprockets on 4 different bikes that were mine and many many other riders/racers amature and pro that do and don't ride yamis and don't have sprocket/hub issues......?

Okay, but I'm still curious to see some numbers that tell whether or not there is a reduction in the strength of the assembly and if the lack of an inner ring could weaken it to the point that it significantly decreases the original design FOS for the hub/sprocket.

Since the suspicion was raised I'd like to know if it's worth investigating.

I'm a "show me" guy... so sue me! ?

[Ga426owner]

Okay, but I'm still curious to see some numbers that tell whether or not there is a reduction in the strength of the assembly and if the lack of an inner ring could weaken it to the point that it significantly decreases the original design FOS for the hub/sprocket.

Since the suspicion was raised I'd like to know if it's worth investigating.

I'm a "show me" guy... so sue me! ?

? I am a trial by fire guy....experience/factual evidence from many years of use is my best ammo....that is why I don't need no stinkin numbers....and no law suits:prof:

[SC_Spode]

? I am a trial by fire guy....experience/factual evidence from many years of use is my best ammo....that is why I don't need no stinkin numbers....and no law suits:prof:

That would still be anecdotal evidence!

But you see, I used to design "stuff" and had to know why we did what we did, and what it was supposed to be able to do - in case the litigation-happy bunch decided they were bored.

Nothing guns down speculation and unfounded rumors like good ol' facts. ?

Hey, it's a disorder! I'm protected by the ADA!

[grayracer513]

Regarding ringless sprocket centers, SC's instincts are correct. In a more typical chain ring, any force applied to one sprocket bolt is distributed in part to the adjacent bolts by the center circle of material into which the bolts are drilled. This is true whether the force is directly perpendicular to the axle, as is the design ideal, or a bending load placed on the outer edge of the cog by an excessive level of chain tension (from whatever source). An attempt to bend the sprocket laterally would ordinarily be resisted by the entire mass of the sprocket as well as the hub flange it's bolted to, and in particular, the resistance to twisting between adjacent bolts provided by the continuous ring of metal at the sprocket center. Cutting that center into separate segments connected only at the outermost of the sprocket obviously eliminates much of the sprockets internal resistance to such twisting, and places a greater percentage of the load on the mounting ears of the hub flange.

The Ironman is probably not to blame for the problem, but it could reasonably be a contributing factor, and definitely won't add strength to the hub.

[jamiehughes]

guess i'll try a renthal dual ring this time.

[Dr.Crankenstien]

So no reported '07 failures just '06

[never59]

So is the chain in good shape still? I forget to order a chain for this weekend..can i borrow that? Maybe a few gatorades and a pair of goggles too?

i'm just not sure how a chain that hasn't been touched for 10 months, as far as adjustment goes, wouldn't have caused a problem months ago if it was too tight.even though i adjusted it to book specs, of course i guess why would the hub just decide to break at that time also, as i know as of 2 weeks ago there were no cracks developing as when i changed tires i looked at it pretty closely, just for that reason as i remember reading about it last summer on here. whatever, i guess i could make up just about any reason for it to have happened, all would i'm sure have been my fault. at least yamaha doesn't think it was my fault.