06 YZ 450F Transmission Bearing Questions

I have done a complete tear down of my 06 YZ450F, and have inspected each of the ball bearings. I am questioning two of the bearings in the transmission. The attached photo shows the bearings in question. One bearing rotates smoothly, but has a fair amount of drag when rotating it. Is that typical? Also, how do you remove that bearing if needed (can't get behind it to press it out)? A second bearing seems to be bad (has a notchy feel when rotated). I am curious if that is a bearing prone to failure?

There is a lot of great information on this site. I appreciate the willingness to share knowledge.





here is my expirence'

i rebuilt my 06 after the lower rod bearing went. the tranny bearings felt the same way as to what your describing. what i did was throughly cleaned up the cases and bearing with brake cleaner and compressed air. after i did that they all felt normal and all smooth.

if you already cleaned them up and there still crappy feeling. deffanitly replace them. but you will need a blind bearing puller. i dont have one but i bought a few specialty tools from these guys and i was impressed with the quality. http://pitposse.com/poblbebrpuse.html

Yea, I already used brake cleaner and compressed air. I guess I'll have to replace both bearings. I was hoping to not have to buy another tool. This project is bleeding me dry. I just bought the bike a couple of months ago, and am now into it another $1000 and counting. Thanks for the tip on the blind bearing puller.


maybe a local auto machine shop can swap them out for you for a couple of bucks?

The blind puller will work, and it will work much easier if the case is heated. Use a controlled heat source like an oven or a gas grill with a thermometer on it. Preheat to 275 ℉ and then place the case in the heat for 15-20 minutes. Pull it out with a glove and slap it squarely face down on a wood surface. The bearing will probably drop straight out, but if not, it will pull free easily with the puller.

Quite often, tools like that can be rented from rental yards or chain auto parts stores.

The small main shaft bearing that is stiff is more failure prone than the other trans bearings because it's the small one on the faster turning shaft. I always replace them when I'm in an engine with any time on it. The notchy feeling bearing on the other side is the end of the output shaft where low gear is, so it gets beat a little harder because of that.

Some good tips guys.


Autozone has a blind bearing puller on their loaner toold program.. you give them $15 and you get it back when you return it.. I think they call it a pilot bearing puller..

it attaches to a slide hammer, if you dont have one of those, they can supply it as well

Heating the case up to 275F did drop out the blind bearing. Thanks Gray for the tip!

The pilot bearing tool rented from AdvanceAuto also made removing the crank main bearings easy, though I had to have the cases heated before it worked. It would just slip on the bearing race and couldn't pull the bearing with enough force. With heat to loosen the fit, it came right out. I could have also just pressed it out from the other side. FYI, the pilot bearing puller did not work for the blind bearing (wouldn't fit right, and couldn't grab the bearing strong enough).

Also, regarding the blind bearing, I replaced it because it had a drag to it when I rotated it, even though it rotated smoothly. As it turns out, that bearing has a lip seal on the back side to keep oil pressure since that cavity is used to send pressurized oil to both transmission shafts. The drag I was feeling is just the lip seal drag, which is normal. The front side of the bearing is unshielded, and just the back side has a shield with a lip seal. You can't see it because it is installed in the 'blind' hole. So as it turns out, the bearing may have been fine after all. No regrets in replacing it, but good to know that some rotation drag is normal for this bearing. It turns out that the counter shaft bearing is the same way (back side has a lip seal) since that bearing also has to hold oil pressure to keep the countershaft center pressurized with oil.

Thanks all for the help.


Edited by wweagleflyer

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