Broken Frame 2010 YZ450F

Yamaha YZ450F 2010 Body Frame

84 replies to this topic
  • asnyder2

Posted November 08, 2012 - 09:43 AM

#21

I agree with Gray, looks to still be attached in rear so I find hard for dent to be from chain unless is was broken off and somehow wedged in sprocket.

  • ah665

Posted November 08, 2012 - 09:52 AM

#22

Just by the nature of that crack, if it were me I would be hesitant to have it welded. I'd be looking for a new frame. That looks way worse than that i expected it to. I don't know that this is relivant but I've had steel frames rewelded, years ago and always either had it crack again in same spot or in a stress spot very close to the repair.

  • KJ790

Posted November 11, 2012 - 05:20 PM

#23

Just pulled the tank on a 2010 YZ450F I just bought, this is what I found in the inside of one of the frame spars near the steering head:

Posted Image

  • grayracer513

Posted November 11, 2012 - 06:19 PM

#24

Where do you think the crack originated?

  • KJ790

Posted November 11, 2012 - 06:25 PM

#25

Hard to tell, but it sure looks like the weld. You can see the crack tapers off to nothing at the bottom of the weld, and the other end of the crack goes past the end of the weld and then tapers off to nothing just on the other side of the spar. I'm thinking I might drill a small hole at each end of the crack, grind down into the weld to V it out and then try rewelding it. All of the other welds on the frame look fine as far as I can tell, this is the only crack I found.

  • grayracer513

Posted November 11, 2012 - 07:06 PM

#26

It's hard to say because I don't know exactly where that is, or if the image is rotated, but looking at it makes me think it started at or near left of the point where it changes direction from crossing the weld to running on center, as if there's a lot of tension on that corner at times and the lug is functioning as a fulcrum, localizing that load.

You might run a triangular overlay gusset , maybe wrapping around the other side (is it a tube, or a C spar?), that mirrors the existing lug. Have it bridge across the cracked corner once it's been welded.

  • KJ790

Posted November 11, 2012 - 07:15 PM

#27

It's hard to say because I don't know exactly where that is, or if the image is rotated, but looking at it makes me think it started at or near left of the point where it changes direction from crossing the weld to running on center, as if there's a lot of tension on that corner at times and the lug is functioning as a fulcrum, localizing that load.

You might run a triangular overlay gusset , maybe wrapping around the other side (is it a tube, or a C spar?), that mirrors the existing lug. Have it bridge across the cracked corner once it's been welded.


I would have to agree with what you are saying. This picture is rotated, this is the inside of the left spar just behind the steering head. This is actually the exact same spot that is cracked in the second pic that the OP posted of his bike. That is the top of the left fork leg you can see on the other side of the spar, the top left corner of the picture is the steering tube. This part of the frame is an oval shaped tube, and this area of the frame is typically covered by the airbox. I don't think you would see this crack with the airbox in place until it had propagated all the way around to the other side of the frame rail.

Edited by KJ790, November 11, 2012 - 07:17 PM.


  • MX763

Posted November 12, 2012 - 07:18 AM

#28

This shit makes me worry about my bike. I've heard a few people talking about cracked Yamaha frames now. I know it is hard to pinpoint but I don't understand how Yamaha can say this isn't a defect in the manufacturing.

What would the handling characteristics feel like if the frame is cracked and one doens't know?

  • grayracer513

Posted November 12, 2012 - 08:55 AM

#29

Hard to say. If it broke, then obviously that spar would only be able to resist compressive loads. You'd have to analyze how the rest of the stresses are applied to figure which way it would move, but the steering head would likely roll away from the side with the damaged spar under a vertical loading of the front end, and you might start to see a little bit of "bump steer". Not sure that most people would even detect it.

  • MX763

Posted November 12, 2012 - 11:18 AM

#30

Hard to say. If it broke, then obviously that spar would only be able to resist compressive loads. You'd have to analyze how the rest of the stresses are applied to figure which way it would move, but the steering head would likely roll away from the side with the damaged spar under a vertical loading of the front end, and you might start to see a little bit of "bump steer". Not sure that most people would even detect it.


Good to know! Also, could there be any impact on frame geometry if the frame is welded?

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  • Jeekinz

Posted November 12, 2012 - 11:34 AM

#31

For all I knew, frame breaks were a thing of the past, gone with the steel frames..


Yeah, KTM's, Husky's, etc crack on a daily basis.

  • grayracer513

Posted November 13, 2012 - 11:56 AM

#32

...could there be any impact on frame geometry if the frame is welded?


Only it it's badly mishandled. The first mass produced aluminum bicycle frames were tubes glued into lugs, like many modern airframes. This was a way to avoid the distortion that took place during the welding process, and more so, the even worse distortion the happened when they tried to heat treat/stress relieve the very light gauge frames. Cannondale eventually figured out the process and started producing light, exceptionally strong welded frames in the late '80's.

Most of the problem was due to the light gauge of the metals used, and hasn't been as problematic with the heavier components assembled in a contemporary motorcycle frame. Usually an MC frame is robust enough that it will hold its form well through the repair if it's done right, and the bigger concern becomes one of trying to avoid building a lot of tension into the heat affected area.

  • rider-99

Posted November 13, 2012 - 05:07 PM

#33

Good luck with the crack. I do wish you would call Yamaha Motor Coprporation at (800) 962-7926 and ask to speak to Farris in the product specialist dept. I ask this because she told me that no one before me has had an issue with cracked frames on those year models. I would like to see if she gives you the same answer. Just have your vin number ready. I have taken my bike apart and am just waiting to find a deal on a used frame. Then this puppy will be for sale. It scares the heck outta me that this not far from being broke in half. If I had known that there was a problem with these bikes cracking I may have been inspecting after every ride. After 4 Yamahas I think its time for a change to green. I have some better pics after disassemble. Its very clear that the welds broke right down the middle and then put stress on the other joints/aluminum. You an actually see in the second pic that a rather large part of the weld actually chipped off. Thats tells me that it didnt penetrate at all.
Posted Image
Posted Image

  • sir speedy

Posted November 26, 2012 - 02:07 PM

#34

Rider - 99 -
Here is you solution. New frame for $900.-

http://www.moto-recy...50-YZ450/Detail


Moto on-
Sir Speedy

  • bryce716

Posted November 26, 2012 - 02:46 PM

#35

I found a frame for my 05 crf450 on ebay with 5hrs. on it for 199.00 plus 50.00 shipped.My frame crac ked on the bottom from casing a rock but I've heard of some Hondas cracking on the spars.

  • gbalias

Posted November 26, 2012 - 03:39 PM

#36

you will have to preheat the frame real good (theres some controversy on this depending on heat treated or not base material, etc....), clean the ever living heck out of them (deep 'V') and then be sure youre getting 100% penetration. then bury it (play sand, back yard, etc....lol) to allow it to cool over the course of a whole day or two.


rider-99 is correct. the welds on that particular frame are faulty. looking at the way the material had flaked and where the weld bead ends, it tells me the shielding was insufficient at the starting/ending point of that bead or there was foreign material in that area. Im guessing starting point, but just the way the bead shape is so different in that area also dictates something was amiss. some of my job is to troubleshoot welding issues here at work. we do a lot of welding, mostly automatic and with exotics such as inconels, nimonic, stellite, etc. there are a number of factors that weaken welds, but what im seeing here seems to be poor prep and/or faulty equipment. doesnt appear to be a preheat issue as the welds havent separated from the base metal at the connection point.

heck, theres even a chance they were using cheap filler material. with that being said, no amount of prep or good equipment can help that.

my question is why is it black in those areas? on the 2nd pic rider99 posted.....just left and lower of the crack, another black spot. was something rubbing there perhaps?

i also wonder if theres a way to track down the affected VINs and see if theres any connection.

Edited by gbalias, November 26, 2012 - 03:39 PM.


  • TooFast

Posted November 26, 2012 - 08:03 PM

#37

Our bikes are probabally seeing higher loads with bigger jumps, whoops, etc than ever before

Trail ridden bikes may never see the mx/sx loads and not crack like this

However there is some discussion to be had about nitrogen embrittlement on the weld pics - the weld itself and cracks along the bead tell the tale...it's not the frame material away fom the welds that fractured first...when the welds broke the frame cracked between them

the inert gas shielding is supposed to deal with this embrittlement

Edited by TooFast, November 26, 2012 - 08:04 PM.


  • gbalias

Posted November 26, 2012 - 08:56 PM

#38

i know this may be a long shot, but what are you guys (cracked frame folks) using to clean the bike?

some cleaners are known to have adverse effects on certain alloys.

  • KJ790

Posted November 27, 2012 - 05:14 AM

#39

i know this may be a long shot, but what are you guys (cracked frame folks) using to clean the bike?

some cleaners are known to have adverse effects on certain alloys.


That is actually something I was just going to ask. Unfortunately I cannot answer this question because I bought my bike with the cracked frame, I haven't even ridden it yet.

I do know that in my line of work I see small voids in weld hold liquids inside of them on a daily basis. We actually use chromic anodizing to help with this, as that finish is designed to get up inside voids in welds and protect that area better than other forms or anodize. I wonder if these welds are holding soap when the bike is washed, and if the person is using any sort of a causting cleaner it will slowly eat the weld from the inside out.

  • grayracer513

Posted November 27, 2012 - 07:34 AM

#40

I'd call that a huge long shot.





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