Topic: Strange rear hub issue - CB550

[DrJones]

Hey guys,

Just finished restoring a '74 CB550. I put about 100 miles on it yesterday that ended with me getting a flatbed home! I was almost home when I started noticing a drag in the rear wheel. I ended up totally stuck at a traffic light, my rear wheel wouldn't at all. I got it towed home and had a look at the rear wheel. Here's some pics of the damage done.





Can't figure out exactly what happened.. No damage to rear brake. Wheel bearings are new, and as far as I know, every spacer was where it should have been.

Any idea what could have gone wrong?

[TwoTired]

What does the brake anti rotation stay look like?

[754]

 Check the bearing on that side, it may be narrower than stock..that would do this.

[Johnie]

Just a thought...100% sure this internal spacer got put back when the bearings were changed out?
COLLAR B, RR.
42625-283-000

[SOHC4 Cafe Racer Fan]

100% sure this internal spacer got put back when the bearings were changed out?

This and check to see if the bearing retainer has been pushed out.

[754]

That spacer shown is the sprocket side.  Should not hurt the drum.

[strynboen]

mix up cb 500 and 550 hubs..later cb 550 k3 use the new type hub..looks like you have the new type hub..so is the brake plate a erly one..i think it can make problems..have you mixed parts..Photo is a 78 k3 hub
id the internal distance tube is missing..the bearing can move a short vay..looks like it have moved some distance to crask that plate

[DrJones]

I bought the bike from the original owner, I can't be 100% sure but I would be very surprised if the hub was from the wrong model.

http://imgur.com/ruKEj6r

Brake stay appears straight, and it went together easily enough. I guess next step will be pulling the bearings and making sure everything is ok there.

[754]

Did you ride it before bearings were done?
Them spokes dont look restored..

[Stev-o]

... but I would be very surprised if the hub was from the wrong model.

But arent you surprised you had this issue?!  Something is obviously wrong...

[bryanj]

There are two variations of 500 to 550 wheels and the brake plates with spacers are different so if it wasn't ridden before that could be your problem, if it did ride before and you fitted new bearings then something wasn't fitted right

[seanbarney41]

This happened to me once when I had adjusted the rear brake so it was razor sharp, very small amount of movement engaged it.  Somehow, bumps or heat expansion or something caused the rear brake to engage enough to really heat up, resulting in very similar, but less severe, damage.  I just backed off the adjuster, rode back to my shop, and could find nothing else wrong.  I was amazed that the brake dragging could create enough heat to melt the aluminum of the hub.  This was on a cb750, but the brakes and spacers and everything work exactly the same as a 500/550.

[Gene]

This happened to me once when I had adjusted the rear brake so it was razor sharp, very small amount of movement engaged it.  Somehow, bumps or heat expansion or something caused the rear brake to engage enough to really heat up, resulting in very similar, but less severe, damage.  I just backed off the adjuster, rode back to my shop, and could find nothing else wrong.  I was amazed that the brake dragging could create enough heat to melt the aluminum of the hub.  This was on a cb750, but the brakes and spacers and everything work exactly the same as a 500/550.

*loosening up my rear brake pedal*

[754]

Freeplay is your friend..

[seanbarney41]

Freeplay is your friend..

did learn that lesson that day

[Scott S]

That spacer shown is the sprocket side.  Should not hurt the drum.

 It will if it's left out. Ask me how I know. My bet is that's his problem.

[DrJones]

Nope, just double checked that this spacer is in place.

I did not ride the bike before as it had been off the road 25 years.

The brake still had freeplay and seemed to function while the wheel was stuck.

[754]

Its not the shoes, the backing plate is just plain rubbing..no clearance.
Probably a thinner bearing, or wrong backing plate.

[DrJones]

... but I would be very surprised if the hub was from the wrong model.

But arent you surprised you had this issue?!  Something is obviously wrong...

Yeah, you're absolutely right! I'll check into that, and maybe call the previous owner to see if he remembers replacing any parts like that.

If not, I guess we're looking at a bearing issues or a missing shim. As far as I can see, all the larger spacers are in place!

[scottly]

Is the spacer that fits in between the hub inner bearing races present?

[DrJones]

Is the spacer that fits in between the hub inner bearing races present?

Yep, spacer is present.

The bearings are totally shot. Brake side won't spin at all, sprocket side not so bad.

[Stev-o]

Who put the bearings in?

[DrJones]

Who put the bearings in?

My old man did... he said they all seated nicely and from what I can tell they are both seated where they should be.

The dust seal behind the sprocket cover is worn right down too. Every spaced seems to be present. I looked at the other style brake cover and I don't think that mine has been mixed up. Bit of a mystery!

[754]

Is there a stepped spacer, in between that sprocket bearing shown in top pic, and the bearing in the hub ?
 Its looking maybe like you dont have a manual ?

[bryanj]

Not sure, but it doesn't look like the screwed retainer is all the way in and that would mean the bearings are not sat in there correct places