Trouble after installing new front wheel bearings

[Yamifj1200]

"Whatdaya think?"


I think you should cut the spacer between the bearings to the correct length for the wheel. That way the bearings are in their correct position and the speedometer drive and the spacer that is on opposite bearing would space the wheel out perfectly to fit the forks. Are you sure you have the correct spacer for the FZR rim? The reason I ask is that the spacer is not suppose to extend through the bore past the where the bearing race is. It is designed to make contact where the inner (axle) bearing race is making the spacers and bearings and inner spacer a solid unit when the axle is installed. HTH


Eric M

[markmartin]

Yes I'm quite sure that the spacer is the correct one.  It came with the wheel and the bearings that were on the wheel at that time turned freely, so I have no reason to believe it to be the wrong one.  I'm going to pull the spacer from my FJ wheel tomorrow (same part number) to see if that is a variable.  I agree and would think that the spacer should sit flush with the bottom of the hub and therefore the inner race when the bearing is installed, but it doesn't seem to be that way.

[markmartin]

I removed the bearings form the FZR wheel and from the FJ wheel and compared measurements.  Both wheels call for the same part numbers on the bearings and spacers, which of course checked out when I took them apart.

I measured the length of each spacer and the bottom of hub to bottom of hub measurement of each wheel.    
(what would be the bearing to bearing distance)

'87 FZR:    Hub to Hub          3.612"
                Spacer length      3.622"

'89 FJ        Hub to Hub          3.612"
               Spacer length       3.624"

The spacer is longer than the distance between the hubs by design.

Being paranoid about the possibility of having damaged the bearings earlier by forcing the outer part of the bearing down too far, I bought new bearings and installed the speedo side all the way down and then the opposite side until the bearing was touching the spacer and turning the bearing on one side would turn both sides.  I found that sticking the axle down through the assembly as I approached the final depth of the 2nd bearing helped ensure that the spacer was straight and in the proper position.

Installed the wheel and it is working well.

Thanks to all for all the input and advice!

[fj1289]

For the folks that are concerned about not having the second bearing installed with the outer race at the bottom of the bore - many of the newer rims I've looked at are that way by design.  The first bearing gets installed until it bottoms sometimes against a circlip!), and the opposite bearing only goes in until it meets the inner bearing race. 

There are a lot of production tolerances to keep up with - as well as different expansion rates for the materials and design of the different parts involved here.  I'd be very surprised if Yamaha actually attempted to get all the measurements perfect in order to have the outer bearing races bottomed in the bore and the inner bearing spacer the exact length to not apply any side loads on the bearing (by either being slightly long or short).  Then they'd also have to make sure each bearing shoulder (machined by an outside company) had a large enough radius to ensure it bottomed properly in the bore machined by Yamaha.