Topic: Rear wheel does not spin freely - '76 CB750F

[Tugboat]

The verdict:

Wheel still doesn't spin freely when rear axle nut is tightened.

Loose:
http://youtu.be/AMSa19cSZpE

Tight:
http://youtu.be/W6Bzu_fiXuI

[Cqyqte]

I am repling to this based on the supposition that you are talking about your '76 CB750.  The two rear bearings are spaced correctly with a central spacer tube.  If either of the two bearings are not seated properly in the hub then the outer races are too far apart and when you torque the axle nut, it drives the center races of the bearing tightly against the center spacer which in turn cause the balls to press against the inner egdes of the outer races.  Remove the rear wheel and reseat the bearing on the brakeside, then loosen the retainer on the sprocket side and reseat the sprocket side bearing.  Re-assemble the wheel and try torquing the axle nut and see if that corrects the problem.

It is imperative that the brakeside bearing's outerrace is driven completely against the ridge in the hub.  Then when the sprocket side bearing is being set you support the brakeside inner bearing race when driving the sprocket side.  The impact of the sprocket side bearing on an unsupported brakeside bearing can cause the outer race to shift away from the ridge.

Sorry for the complex response, I couldn't think of an easier way of describing the issue.

I believe I suggested to check this out sometime back.

[Tugboat]

UPDATE: I needed to have my rear tire replaced and took the rear wheel to my local moto shop to have that done. While there I happened to insert my thumb into the bearing to make sure it spun freely... it didn't. In fact it was almost impossible to turn. Same with the bearing on the other side of the hub. And even when you could get it to turn, it felt "crunchy". So I left the wheel with the shop to see what was up.
 
My mechanic noticed that the bearings were really hard to remove, which caused him to wonder if they were the correct size. The bearings themselves are All Balls, and are the correct size: 6304, which is the same bearing that's used on the K model's rear hub. He then measured the OD of the bearings: ~51.9mm. The inside hub itself measures ~51.5. No wonder they were binding! The bearings are bigger than the hole they're supposed to go into!

So now down this rabbit hole.... is this not an F hub after all? It is laced up to a 16" Harley wheel, which was common back in the 70's. I always assumed that it was the stock hub but maybe not? Can someone measure the ID of their F hub for me to confirm?

[Tugboat]

Well, hopefully this is the end of this saga. I finally broke down and bought a 16" NOS Henry Abe rear off ebay for ~$150 shipped, rather than spend the time and effort trying to figure all of this out. My wheel wasn't in the greatest condition anyway. I had been keeping an eye out for a replacement wheel and/or hub for a 75/76F for months now but none ever surfaced. Super lucky to have this Abe drop into my lap for a decent price!

http://www.ebay.com/itm/Henry-Abe-Seven-Star-Honda-CB750F-CB750K-Rear-Disc-Brake-16-Wheel-Cafe-/321094472380?pt=Motorcycles_Parts_Accessories&hash=item4ac2b8d2bc&vxp=mtr

[HughL]

Having this same issue but have confirmed that I have all of the necessary bearings and spacers along with new bearings. Wheel spins fine until I tighten the axle down.

[Don R]

 When the bearings and spacers are all in place and stacked correctly, there is a stack of solid steel from one side to the other. One bearing is fixed under the retainer and the other one floats to where it is needed. If one bearing or the other isn't properly in place, leaving a gap behind one or the other spacer that can cause a gap in the stack of steel parts where the balls to bind up and not rotate easily.