2006 YZ450: Rear Hub Failed

Number three ..checked mine last night, the sprocket side bearing spins pretty easily in the hub.

damn DPW...now I have to go look at mine too....sounds like time to log calls to Yamaha for a tech bulliten notice :thumbsup:

damn DPW...now I have to go look at mine too....sounds like time to log calls to Yamaha for a tech bulliten notice :thumbsup:

Went to mount a new tire last night and double checked the bearing after reading this thread...spins pretty freely in the hub. The local Yamaha dealer is overnighting a hub and bearings for me...more $$$$

...more $$$$

I know that deal at least it is not a race car!

By the way, a "too tight chain" is not one of the potential causes of the problem I had. I am extremely careful about that (2.5 fingers at end of top chain rub guide... me off the bike and under its own weight). I have ironman's best on this bike (with Regina Z ring) so it never goes out of adjustment. And I check before every ride the chain, sprocket bolts, rear spokes. Too much experience in motocross. Don't want to die out of pure stupidity.

Separated hub and bearing to get a look inside. Bearing is like new. Absolutely as tight and smooth as one that just came out of the box. Hub, however, is another story. It shows wear where the outer race sat. Looks much like the wear that a piston and rings puts on a cylinder wall. There is even a slight "lip" now (from wear). Not unlike that which develops at the top of cylinder wall. And that pretty much confirms that initial specs (outer race diameter and inner bore of hub) were spot on as the bearing press fits normally until it reaches "home" and then its loose. So its after the factory wear.

My guess right now is that for some reason there was lateral stresses. Another left/right movement that over time it moved the bearing enough to overcome the outer races press fit into the hub. And thus the wear cycle began. I need to check the opposite side bearing for clues tonight.

So, yesterday, I went to open motocross practice on an old clunker laying in the garage: a 2000 YZ250. Completely stock except for a heaver rear spring (mostly my son's bike for the past 5 years). So after a full season on the YZ450 (racing 3 classes every Sunday) I now got back on a 2-stroke for the first time. Put about 4 gallons through her on one of the best tracks in the NY area. Boy, do I have a story to tell "ya all!! lol

Sic

My guess right now is that for some reason there was lateral stresses. Another left/right movement that over time it moved the bearing enough to overcome the outer races press fit into the hub. And thus the wear cycle began. I need to check the opposite side bearing for clues tonight.
If you drive out the brake side bearing, then stack the two together with the bearing spacer between them, the gap between the bearings should be very near the same as the distance between the bottoms of the two bearing pockets in the hub. If the bearings were spaced too far apart, your theory could have some merit. If you can check this out, maybe you can let us know what you find.

This isn't nothing new guys..I've had this problem on my 01' YZ426. The reason the bearing wears on the I.D. of the hub is simple...the cast is too soft. I fixed mine by machining the I.D. deeper and putting 2 bearings in the sprocket side of the hub, ...That fixed it and I rode the #$%% of that bike for 3 years without any more problems.

Went to change a rear tube this wkend and my drive side bearing fell out. So add me to the list. I have my local Yam. dealer calling to see if Yamaha will replace the hub. :thumbsup:

Well, its me again, the originator of this thread:

My new hub and spoke set came in. But, you know, just as I looked at the repair in front of me I realized I had a spare rim (from an older YZ) and thought just how close I am right now to have a complete spare wheel for the back of my '06 (soon to be an '07). So after checking the situation closely again I concluded that its not going to fail catastrophically during a test. So I tried RED LOCTITE. Let it sit 24 hours and put a full day of moto in on it. It worked so far. Bearing is locked in their tight. I will continue to monitor it each time I go out for a session for the rest of this season. And after that I will only check it once per riding day "forever". Just add it to my spoke, sprocket bolts & chain checklist.

Stay tuned...

Sic

2nd day of riding on my repaired (red loctite) hub. It was an aggressive day, lots of big air on 90-105 foot jumps. Lots of speed shifting and rockers too. Did about 3 gallons through it. Repair is still holding. I'm getting fairly confident now this may be a long term fix.

Will definitely use the parts I had initially purchased to repair this wheel to build a second wheel now. Always wanted race and practice rubber,,, or an instant rubber change when a dry hardpack track turns to a greasy mudder after an afternoon rain shower.

I won't post anymore updates unless the problem redevelops.

Sic

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