YZ450F Rounded out rear Axle Block..axle nut is stuck..help

2006 YZ450F

I'm trying to remove the rear axle to replace the stock axle blocks (Chain Tensioner blocks); however, the rear axle nut cannot come out because the left side of the axle is spinning in the axle block. The axle block is rounded out from the left side of the rear axle spinning in it. I have a pic of this, but I dont know how to upload the pic..I can email it upon request.. Can anyone help me?

grad left side with vise grips through axle hole to outside block and use impact driver to take nut off .could also weld a piece of metal to the left side of axle to hold it while u loosen nut.

Thanks!.. I will give it a shot and follow up.


Edited by blanchdj

hmmm that looks like it was installed wrong. I'd suggest wedging something into the gap to hold the axle while you spin the nut off.

Thanks for that suggestion. When I tried that, the axle would move back, and the left side of the axle would start to slip again. THAT is what is so strange!!.. I can wiggle the back tire side to side about a 1/4 inch, but that NUT is really stuck! I will try to put a 27mm open end wrench on that flat side of the axle and hit the nut with an impact to see what happens.. It that doesn't work, I will try to weld a piece of metal to the flat side of the axle as suggested by motoman. All of this started when I attempted to replace the axle blocks, and I think because the axle moved back when I tried to spin the axle nut, it rounded out the axle block on the left side.

You're going to have to either heat that nut or cut it off. If you have access to a welding torch with a #3 to #5 tip, heat one flat of the nut to bright red as quickly as you can. That will relieve the tension on it, and it should crank right off.

Otherwise, grind down into the nut with a cutoff wheel until you start to see the axle threads on two opposite sides. You should then be able to crack it free with a crescent wrench.

Just put a wrench that fits on the flats of the axle. this happened to me once with my yz 125 and I only needed to get a new chain adjuster

Just put a wrench that fits on the flats of the axle. this happened to me once with my yz 125 and I only needed to get a new chain adjuster

+1 ^^^^ what are the guys above thinking??? weld? :thumbsup: blow torch? :bonk:lmao..

get a wrench on the thing, always put a little dab of grease on the nut and dont tighten it so much next time...

Thank you Gentlemen. Problem solved!

After failed attempts at applying box wrenches and Impact Wrenches etc... I ultimately had to cut a slit in the Nut with a Dremel tool, then spread the nut a little with a chisel, THEN.. come back an hit it with the Impact wrench.. Finally it slowly came off..

My guess is that the Locking Nut threads somehow got pulled when I torqued it down to the "required" 90 ft lbs... I WILL NOT be torquing to 90 again...


I noticed mine and my buddy's bikes had a little notch on the left side where the flat part of the oval rested on the axle block. I guess due to the pressure of torquing down to specs.

I replaced mine with some ride engineering blocks and the oval now sits in a recessed area. Problem solved.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now