CRF450 swing arm failure - got lucky today

MxKing809
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MxKing809
Edited Date/Time 7/15/2019 1:50am
Landed over a table today mid-race and clunk. Motor stopped and I rolled to the side of track.

Anyone ever have this happen?

Anyone one have a swing arm for sale? 🤦🏻‍♂️








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109
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109 7/14/2019 3:55pm
7/14/2019 3:55pm
Must have bent the chain guide at some point. Can weld it back on but needs to be straight.
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FLmxer
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FLmxer 7/14/2019 3:57pm
7/14/2019 3:57pm
You know I'm going to guess some comments about sprocket bolts are about to explain everything.
Glad it didn't lock up and cause a crash.
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CK312
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CK312 7/14/2019 4:00pm
7/14/2019 4:00pm
Had 2 2013 crf 450s, this happened to both of them. Just had it welded back on.
MxKing809
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MxKing809 7/14/2019 4:12pm
7/14/2019 4:12pm
CK312 wrote:
Had 2 2013 crf 450s, this happened to both of them. Just had it welded back on.
I was thinking that too..... but the tabs are wrecked. I could go get some measurements off a complete one, but if she’s off - will it happen again?

The Shop

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inthebadboycorner 7/14/2019 4:24pm
7/14/2019 4:24pm
Did the chain break or derail and rip it off or did it fatigue and break itself and the chain.

If it was the later the breaks would look obvious.
MxKing809
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MxKing809 7/14/2019 4:57pm
7/14/2019 4:57pm
inthebadboycorner wrote:
Did the chain break or derail and rip it off or did it fatigue and break itself and the chain. If it was the later the...
Did the chain break or derail and rip it off or did it fatigue and break itself and the chain.

If it was the later the breaks would look obvious.
The chain is still intact - and fully connected.

My current guess is that a rock derailed the chain on the rear sprocket, and that bound and pulled it off. Don’t know how it would have happened otherwise - as the chain never broke.
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snackfedbear
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snackfedbear 7/14/2019 5:06pm
7/14/2019 5:06pm
Try privateer Mx supply on eBay. They have swingarms. They’re actually the people I bought the stock exhaust from to replace the yosh system you have right there. Lol
Also, I’d look into putting a 19 swingarm on it if you’re going to go oem. The 19 swing arm is supposedly less rigid
GPrider
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GPrider 7/14/2019 5:12pm
7/14/2019 5:12pm Edited Date/Time 7/14/2019 5:14pm
am I missing something or is it the chain guide that broke off, not the swingarm?
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kb228
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kb228 7/14/2019 5:29pm
7/14/2019 5:29pm
FLmxer wrote:
You know I'm going to guess some comments about sprocket bolts are about to explain everything.
Glad it didn't lock up and cause a crash.
I suspect a lose sprocket caused the guide to break off.
slipdog
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slipdog 7/14/2019 6:01pm
7/14/2019 6:01pm
FLmxer wrote:
You know I'm going to guess some comments about sprocket bolts are about to explain everything.
Glad it didn't lock up and cause a crash.
kb228 wrote:
I suspect a lose sprocket caused the guide to break off.
The recent seismic activity in the SoCal high desert has caused a glitch in the calibration capabilities for torque wrenches statewide. Without recalibration sprocket related hub/chain/swingarm failures stand to increase at record levels. It will be an epidemic of mass proportions unseen in this lifetime!
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JM485
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JM485 7/14/2019 6:14pm
7/14/2019 6:14pm
The way every Jap manufacturer attaches their chain guides is an absolute joke. Here we have a part hanging in an incredibly vulnerable spot, and their answer is a couple of short weld beads and some prayers it holdsPinch Ask pretty much any off-road rider, their get ripped off all the time, mine cost me a rear hub when it blew off at an endurocross. It’s just absolutely shit engineering and there’s really no excuse for it. I wish this was the type of stuff magazines would throw a fuss about, not grips that were too stiff. . .
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kiwifan
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kiwifan 7/14/2019 6:23pm
7/14/2019 6:23pm
Never seen that happen myself....nasty
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GIwasB4
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GIwasB4 7/14/2019 9:15pm
7/14/2019 9:15pm
Peely should be along shortly to discuss sprocket bolt torque requirements and post a DD snowboarding vid?
The chain guide broke off, it's not the swingarm's fault.
Shit happens
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rex.e
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rex.e 7/14/2019 9:55pm
7/14/2019 9:55pm
JM485 wrote:
The way every Jap manufacturer attaches their chain guides is an absolute joke. Here we have a part hanging in an incredibly vulnerable spot, and their...
The way every Jap manufacturer attaches their chain guides is an absolute joke. Here we have a part hanging in an incredibly vulnerable spot, and their answer is a couple of short weld beads and some prayers it holdsPinch Ask pretty much any off-road rider, their get ripped off all the time, mine cost me a rear hub when it blew off at an endurocross. It’s just absolutely shit engineering and there’s really no excuse for it. I wish this was the type of stuff magazines would throw a fuss about, not grips that were too stiff. . .
Your bike was designed for mx not Enduro cross. I wouldn't blame it on the short beads if you slam the guard into rocks. Common sense.
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colintrax
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colintrax 7/14/2019 10:06pm
7/14/2019 10:06pm
JM485 wrote:
The way every Jap manufacturer attaches their chain guides is an absolute joke. Here we have a part hanging in an incredibly vulnerable spot, and their...
The way every Jap manufacturer attaches their chain guides is an absolute joke. Here we have a part hanging in an incredibly vulnerable spot, and their answer is a couple of short weld beads and some prayers it holdsPinch Ask pretty much any off-road rider, their get ripped off all the time, mine cost me a rear hub when it blew off at an endurocross. It’s just absolutely shit engineering and there’s really no excuse for it. I wish this was the type of stuff magazines would throw a fuss about, not grips that were too stiff. . .
rex.e wrote:
Your bike was designed for mx not Enduro cross. I wouldn't blame it on the short beads if you slam the guard into rocks. Common sense.
Check KTM swing arms.
Also there are ruts in moto....
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Pit Row

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Last Braaap
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Last Braaap 7/15/2019 1:50am
7/15/2019 1:50am
keeping traditions alive.

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KW62
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KW62 7/15/2019 6:22am
7/15/2019 6:22am
My chain guide was ripped off when I exploded my hub due to sprocket bolts. I got it re-welded on by a shop in Royal Oak and didn't have any issues after. Luckily the way mine came off, it was pretty easy to get it to sit back nice where it's supposed to be before welding.
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dadofagun
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dadofagun 7/15/2019 7:23am
7/15/2019 7:23am
CK312 wrote:
Had 2 2013 crf 450s, this happened to both of them. Just had it welded back on.
MxKing809 wrote:
I was thinking that too..... but the tabs are wrecked. I could go get some measurements off a complete one, but if she’s off - will...
I was thinking that too..... but the tabs are wrecked. I could go get some measurements off a complete one, but if she’s off - will it happen again?
That was my first thought. I would think if it is off by the slightest bit, likely could very well happen again. Glad you're ok....
Jeremy Macbeth 7/15/2019 8:05am
7/15/2019 8:05am Edited Date/Time 7/15/2019 8:06am
Happens all the time to those anemic chain guides. Take it to a good aluminum fabricator/welder and have them re-weld new tabs on there and replace that crap OEM guide with a TM Designworks chain guide. Give the new chain guide to the welder so it can be used to position the new tabs on the swingarm. Easy job. Couple hundred bucks + the cost of a new chain guide and chain.

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