Please Help - Rear Wheel Issues

C

cgraham

Active Member
So here is the deal - I bought a 78' CB550K a few months ago that had Comstars installed. The previous owner made some modifications to the bike in order to make the Comstars fit (welded tabs in swingarm, different axles, drum, disc, speedometer sensor,...) and now I am trying to go back to OE spoke wheels and I have to undo his changes. The front went on no problem with the right axle, speedometer sensor, and brake disc, but the rear wheel does not seem to be behaving as nicely. When the rear is all assembled, the castle nut does not thread onto the axle far enough (there is a spacer/bearing on the sprocket side that sits partly inside the hub that seems to be taking up the required space that's needed to sufficiently thread the castle nut on. It came with the wheel I bought, not the axle).

Here are the OE parts for the rear that I ordered - 77' 550F wheel, 78' 550K drum, and 78' 550K axle with both chain adjusters, 1 spacer, and a castle nut.

Is there anything wrong with the setup I am trying to fit? Is the issue that my bike is a 78' 550K and the wheel I bought is off of a 77' 550F? Like I said, I had no issue with the front and I used the same setup - 77' F wheel and 78' K axle.

Any input you provide will help.
Thanks
 
The 550F and the 550K had different swing arms. pics of your setup would help. The swing arm is the only part between the two models that's different in that area. Here's a couple pics to illustrate.
 
Here's the 550K
 

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That being said, the axle is the same length on both models. The hub and brake panels are the same part numbers as well, so regardless of which swing arm you have, the parts should work. Pics of the setup would help to figure out the problem.
 
Sorry for the poor quality pictures. If you need a pic of the wheel on bike, I will try to get some for you later on but I cannot atm. Thanks again.
 

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The spacer/bearing in the second and third to last pictures is what seems to be taking up most of the required space in order to thread the castle on all the way (maybe about 1/4"). And based on the pics you sent, I definitely have the K swingarm.
 
The castle nut looks like it's on far enough - nothing between the swingarm dropouts can change that - what exactly is the problem you're trying to solve?

The swingarm doesn't compress together - the wheel and all the spacers/adjusters needs to fit between the dropouts with almost no play. You're not supposed to squeeze the swingarm tight using the axle nut - it just tightens up, and is kept from rotating off with the cotter pin.
 
That castle nut is on about as far as it's supposed to be for hand tight. Keep in mind that the torque setting for that nut is 57 - 72 foot pounds, which will get you at least one more turn. Then you line up the hole in the axle with the notches in the castle nut and put a cotter pin through. The only error I see in the pictures is that you've got the axle going right to left. It should go left to right. The spacer that's on the spindle in the pictures is in the right place - brake side (right side). You're fine - just put the wheel on and torque it up!


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It looks far enough on because the wheel isn't mounted. If I put the wheel on and then try and thread the castle, I can't get the cotter pin through. I need like 2-3 more threads at minimum. So something is too big for my setup (maybe the spacer on the drum side or that spacer/bearing on the sprocket side) and is taking up that extra 1/4" of the axle I need to thread it properly.
 
The bearing on the sprocket side is correct. The right side spacer may be wrong. I'll measure the one on my 550F.


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It's exactly 38mm or 1 1/2 inches. That works with the 550F swing arm. When you put the wheel, brake panel and spacer into the swing arm, it should slide in with out being loose but also without you needing to force the swing arm open wider to receive them.


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Might be best to throw the wheel in and take pictures with it installed.


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I just measured mine and it is 1 1/4" exactly and I have the 550K swingarm but 550F wheel. But if it were 1/4" longer, wouldn't I have less room to thread the castle?
 
Also, why would the spacer be the wrong size if it came off of the same model bike as mine and is made for my swingarm?
 
Yep, that sounds right because the tabs on your swing arm are thicker so the spacer should be shorter. Well, we've eliminated almost every variable! Mount the wheel the best you can and take pictures of it from the same angles as before, also where the brake panel meets the hub. I gotta go out for a couple hours but I'll check back in when I get back.


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