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Discussion Starter · #1 ·
I have a 1970 CB450 and i think i have a bad rear wheel bearing but i need some help with my diagnosis. If i spin the rear wheel w/ the motor off and the bike in neutral i hear some creaking metal sounds. I am not sure if the noises are normal i hear most of the noise from the rear wheel and then some noise from the gears and such rotating in the transmission. If i have the bike up on the center stand and have it running in first gear the rear wheel slows down for part of its rotation and then spins freely for the rest of the rotation. This repeats for every rotation of the wheel not the engine.

I also feel a vibration when the bike is deccelerating and the frequency is directly related to the rotation of the wheel.

The wheel does not have play side to side but i do occasionally get some "chatter" in the rear wheel when making a tight left turn from a stop.

If this sounds like a wheel bearing problem what is a good replacement bearing and what else should be replaced while i'm working back there? My rubber cover on the chain side of the rear hub has a tear in it so i will be replacing that.

Thanks for the help,
Brad
 

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Sounds like it could just be a bad chain maybe.

Put the bike on the centerstand, grab the chain at the 3 o'clock position on the sprocket and pull it away from the sprocket.
If it pulls out more than just a little bit, it's probably bad.

Or just remove the chain and see if you still get noise when rotating the wheel.
While the chain is off, grab one end and extend it out "against the grain", about hip-high.
If it sags like a rope, you need a new chain.

Let us know what you find...........
 

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Sensei
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I would guess the chain and/or sprockets as well.....
 

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rockgineer said:
the chain was just replaced about a month ago. could this be caused by sprockets in any way?
Yes, or possibly misalignment of the rear wheel when the chain was adjusted.
 

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You'll usually get a little lateral play when the bearings are going. Some of your description does fit bearings, but would also fit chain - because it's new, it probably isn't the problem but never depend absolutely on a new part having nothing wrong with it if the symptoms fit that cause. Take a look at your sprockets. The teeth/valleys should be completely symmetrical. If they're "cupped" in the direction of chain pull or if you wrap the chain all the way around the chainwheel and the rollers don't sit evenly into the valleys all the way around, it's time for new sprockets. Worn bearings usually make a sort of rumbling or grumbling sound when the wheel is spun, but the chain would probably make too much noise for you to hear it with the chain on.
 

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Discussion Starter · #7 ·
thanks for the tips guys. i'm going to try to take a look at it tonight as long as it doesnt rain. I am going to start by taking the chain off and seeing if the noise is still in the rear wheel and then going from there. i'll let you know what i find.
 

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Discussion Starter · #8 ·
ok so i took the chain off and spun the rear wheel. it was ok except for a funny clicking noise. i found it it was coming from the sprocket . . . it was loose!

I think the loose sprocket was caused by some mis alignment of the two sprockets. now that i fixed the sprocket i am getting more noise. i need to take off the front sprocket cover this weekend and see what is going on. it seems like the side of the front sprocket is rubbing the chain or something. but i'll know for sure when i take a look.

if the wheel is aligned what could be causing this? is there a way to adjust the front sprocket position? it feels like a pretty severe misalignment if that is whats going on.
 

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Is the chain an "O" ring type?
 

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rockgineer said:
ok so i took the chain off and spun the rear wheel. it was ok except for a funny clicking noise. i found it it was coming from the sprocket . . . it was loose!

I think the loose sprocket was caused by some mis alignment of the two sprockets. now that i fixed the sprocket i am getting more noise. i need to take off the front sprocket cover this weekend and see what is going on. it seems like the side of the front sprocket is rubbing the chain or something. but i'll know for sure when i take a look.

if the wheel is aligned what could be causing this? is there a way to adjust the front sprocket position? it feels like a pretty severe misalignment if that is whats going on.
No way to really re-align the front sprocket, other than maybe putting washers on the counter sprocket bolt holder to move it inboard a bit.
It is not unusual on these bikes to have fairly serious misalignments right out of the crate.
Read my Project Log - this 450 had a rear wheel that was 7mm off center when I got it....as you can imagine the chain didn't like that much at all. The PO was such an idiot he didn't even realize what was going on.
http://home.comcast.net/~tbpmusic/id54.htm

They were made in the very early days of robotic welding (Honda was a pioneer in the technology), and misalignments are common.

You didn't happen to put an o-ring chain on, did you??
That's a no-no with these bikes, it rubs against the clutch lifter apparatus next to the counter sprocket.
 

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HOW was the rear sprocket loose?....Were the nuts loose, or was the snap-ring off?
 

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Discussion Starter · #12 ·
nope no o-ring chain.

the nuts were not loose but the studs seemed to be a little loose if that makes any sense. I was able to correct the problem by tightening the nuts but they hadn't backed off or anything. it seemed that the chain has pulled it loose due to misalignment. I only think this because the noise of the chain go louder when i tightened the sprocket which moved it approximately 2mm toward the hub.
 

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Sensei
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There is a snap ring that retains the sprocket on the hub.... Sounds like yours is missing or "out of its groove"...... Two mm of wobble can cause some chain problems.
 

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Discussion Starter · #14 ·
my snap ring is there (the one on the left side of the sprocket). i'll have to see why its not tight agains the sprocket.
 
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