'12+ WR450F Rear Chain Guide and Welding


2 replies to this topic
  • mebgardner

Posted October 27, 2014 - 11:40 AM

#1

I had some unexpected thrills on the trail this weekend that ended abruptly with me making trailside repairs to my chain and sprocket system.

 

At the end of my unexpected flight, my chain was off and double-wrapped around the front sprocket, my rear sprocket was bent (but not permanently broke, I bent it back inline), and my chain guide rubber was stuffed into the guide body.

 

I'm not completely sure of the sequence of events leading to that final state, so I'm pointing the finger at me (*not* the mechanicals of the cycle: loose chain, out-of-align chain etc). What I can say for sure is, during a mid-steep hill climb on a mix of loose scree and embedded football/ basketball sized rocks, I launched up the face of one of those bigger rocks, became airborn (and I was ready for that), and when I came down, I went off the back and watched the cycle doing an endo in front of me.

 

Anyway, today I find myself in need of some parts. While looking for suggestions on a new chain guide, I read about this poor fellow's woe about a failure on his recent model year cycle (he does not say which year) where a chain guide breaks the welds on the bracket welded to the swingarm, that mounts the guide (he calls it a "block"):

 

http://www.thumperta...e#entry11211839

 

...and then there's some further talk about checking *your* welds, because of another cycle's failure in the same area, on a brand new cycle of '12 or '13 vintage:

 

http://www.dirtbikew...ad.php?t=107173

 

 

So, I'm interested in "beefing up" this weld area, and I'm looking for some advice.

 

For those of you who've done this mod, did you just get it re-welded with TIG, or did you also weld in some additional plate metal around it?

 

 

 



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  • mch

Posted October 27, 2014 - 01:10 PM

#2

Honestly, I wouldn't do anything unless you see some cracking.  I haven't looked up the part number, but the swing arm has probably been in use for several years on other models.  If there are cases of this breakage on forums, there are probably several more that aren't reported.  That being said, there are thousands of people who haven't had those issues so it's not an epidemic.  I have wacked my chain guide a bunch and my swing arm looks pretty beat from all the rocks, etc. I encounter.  I have one of the TM designworks chain guides and it seems to work pretty good.

 

If you insist on bracing it, you could reinforce it with more aluminum, or just put a better bead.  The welder of choice would be a Tig, but can be done with a Mig if the welder has the handle/tip meant for aluminum.

 

Edit: 

 

Obviously this doesn't include the 12's+, but these are other models that use the same swingarm:

 

2008 YZ125 - YZ125X1 REAR ARM

2008 YZ250 (Deep Purplish Blue Solid E) - YZ250X REAR ARM

2008 YZ250X1 REAR ARM

2009 WR250F (DEEP PURPLISH BLUE SOLID E) - WR250FY REAR ARM

2009 WR450F - WR450FY REAR ARM

2009 YZ125 (DEEP PURPLISH BLUE SOLID E) - YZ125Y REAR ARM

2009 YZ250 (DEEP PURPLISH BLUE SOLID E) - YZ250Y REAR ARM

2010 YZ125 - YZ125Z REAR ARM

2010 YZ250 - YZ250Z REAR ARM

2011 WR 250F - WR250FA REAR ARM

2011 WR 450F - WR450FA REAR ARM

2011 YZ 125 - YZ125A1 REAR ARM

2011 YZ 250 - YZ250A1 REAR ARM


Edited by mch, October 27, 2014 - 01:15 PM.


  • mebgardner

Posted October 28, 2014 - 10:48 AM

#3

Honestly, I wouldn't do anything unless you see some cracking.  I haven't looked up the part number, but the swing arm has probably been in use for several years on other models.  If there are cases of this breakage on forums, there are probably several more that aren't reported.  That being said, there are thousands of people who haven't had those issues so it's not an epidemic.  I have wacked my chain guide a bunch and my swing arm looks pretty beat from all the rocks, etc. I encounter.  I have one of the TM designworks chain guides and it seems to work pretty good.

 

If you insist on bracing it, you could reinforce it with more aluminum, or just put a better bead.  The welder of choice would be a Tig, but can be done with a Mig if the welder has the handle/tip meant for aluminum.

 

Edit: 

 

Obviously this doesn't include the 12's+, but these are other models that use the same swingarm:

 

2008 YZ125 - YZ125X1 REAR ARM

2008 YZ250 (Deep Purplish Blue Solid E) - YZ250X REAR ARM

2008 YZ250X1 REAR ARM

2009 WR250F (DEEP PURPLISH BLUE SOLID E) - WR250FY REAR ARM

2009 WR450F - WR450FY REAR ARM

2009 YZ125 (DEEP PURPLISH BLUE SOLID E) - YZ125Y REAR ARM

2009 YZ250 (DEEP PURPLISH BLUE SOLID E) - YZ250Y REAR ARM

2010 YZ125 - YZ125Z REAR ARM

2010 YZ250 - YZ250Z REAR ARM

2011 WR 250F - WR250FA REAR ARM

2011 WR 450F - WR450FA REAR ARM

2011 YZ 125 - YZ125A1 REAR ARM

2011 YZ 250 - YZ250A1 REAR ARM

 

Very kind of you to provide me this perspective. I'll heed your advice, and let this go.






 
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