YZ450F 2010 Shift Shaft replacement

5 replies to this topic
  • greg_

Posted November 29, 2010 - 02:04 AM


I replaced my sprockets and chain the other day but I stripped one of the alloy bolts for the rear sprocket. I replaced it from a bolt kit I bought for my bike. It was a stainless steel bolt with a nyloc locknut. The nut loosened and the bolt came out. The bolt then ate into my rear swing arm before grabbing and ripping my rear sprocket off the hub. The chain then bent my shift shaft down. All this from one bolt.... My question is, how do I replace my shift shaft? Do I need to remove the engine and split it to get to the shaft or can I remove it some other way. Is it possible to bend it straight again too. Any advice on this situation would be awesome...

  • brentn

Posted November 29, 2010 - 02:22 AM


It's a bit of work, but nothing crazy.

Looking at the manual you'll have to remove the whole clutch side case, so you'll be disconnecting the water pump hose and removing all the outer bolts along with the rear brake lever.
Whole cover should slide off as long as you got all the bolts on the outer edge, you should be able to leave the inner water pump housing bolts and inner clutch cover bolts on the clutch case.
You'll have to remove the clutch, this includes the pressure plate, discs and then remove the hub nut (need clutch holding tool for this) and slide the hub and basket off with the bearings and spacers.
Now you can see the shift shaft, the manual says that you have to remove the shift pawl assembly which is connected to the shift star on the shift drum. When that's off the shift shaft should slide out from this side of the engine.

Make sure that before you slide the shaft out, wrap the splines where the shifter connected on the other side with a thin layer of electrical tape. Make sure all the splines are covered so that the sharp edges do not destroy the shift shaft seal. Before you pull it out make sure you also lube up the shaft and the tape so that it slides out nicely.

Have fun!

Can you post some pics of what happened, real curious to see the damage!

  • brentn

Posted November 29, 2010 - 02:24 AM


Looking at the manual again, it looks like the shift pawl assembly is underneath the shift shaft cam, so you should be able to pull the shift shaft out as soon as you remove the clutch.

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  • grayracer513

Posted November 29, 2010 - 07:38 AM


The tape is a bad idea because of the possibility that it can be pulled off the shaft internally, which means a 4 hour fishing trip with a piece of wire (if you're lucky) or splitting the case. Just replace the seal.

You may find it necessary to straighten or cut off the shaft in order to draw it through. When possible, it's best to cut off the outer end, because cutting off the inner end raises the possibility of getting metal chips into the works, but it can be done either way. If you use a torch for cutting or straightening, remove the neutral switch.

  • greg_

Posted December 01, 2010 - 11:49 PM


Cheers for the advice. I've been talking to a few other people and they reckon it can be done in about 2-3 hours so I'm stoked about that!! I'll definately post some pictures of the damage. Damn stainless bolts.... Never to be used again!!! I'm thinking about getting the grove worn in my swing arm welded/filled instead of getting a new one but am a bit concerned about stress fractures happening when I'm racing... Any thoughts..??? Also any reccommendations on good places to buy a new swing arm....

  • grayracer513

Posted December 02, 2010 - 07:23 AM


If it's done by a competent welder, the swing arm should be fine.

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