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I've got a project motorcycle which is a bit of a frankenstein. It came to me with a Honda 400T engine but the compliance plate says it's a 1982 CB-250T, looking over the frame though the swing arm at least is definitely off a 78-82 CB400T/CM400T.

I've disassembled the bike completely to get the frame / swing arm powdercoated and now that I've gone to put the swing arm back on I've noticed I've got 2 parts missing, the Swing Arm Pivot Collars. In the attached image they are shown by the red boxes / arrows. I have the bushings (4) shown on either side but not the actual pivot collar. I don't think I've ever seen this part so I'm pretty certain it wasn't in the bike when I disassembled.

How important are these collars? I can't find them anywhere on the net and I'm not sure how important they are structurally?

enter image description here

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up vote 4 down vote accepted

Going by the diagram, they look pretty important - without them, the pivot bolt will be loose in the swing arm. This will lead to the arm being loose in it's position, which in turn could lead to the bike being unstable and dangerous - and at the very least will make the bushes wear out much quicker than they should.

I'm guessing from the diagram that they are simply a short length of appropriate diameter aluminium tube, so it ought to be fairly easy to get a pair turned up at a machine shop if you can find the specs for them.

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+1 I second the vote for "very important." Looking at the diagram, it appears that without the collars, you're hoping the bolt will stay in place relative to the swing arm based on the stiffness of the bushings. I'd expect those bushings to wear or tear out much more quickly than normal (followed by even more play in the pivot bolt - scary). – Bob Cross Jul 24 '13 at 15:49
    
As I expected. I'm always a safety first kinda guy, especially when dealing with a moto so I'll try a little harder to track some down and if not will get some machined. Thanks for the opinions guys, I just wonder how long the bike was going without them :S ... – James Jul 25 '13 at 0:44

Those collars are extraordinarily important. They actually push against the rear wheel main bearing and the seal wraps around it when you insert the collar.

Riding without these is not recommended. It's dangerous. The rear brake can lock up as the wheel moves laterally along the horizontal axis. As the wheel moves all the way to the left, if that's the case, the drum brake actuator rod (Which is set to a particular length for rear drum brake adjustment by the mechanic) will pull the brake lever arm and create a condition where the rear brake can lock up. So, don't ride the bike.

These collars are no longer in production but ebay is loaded with them. I found 10.

Here is an image of one, it looks used but that's fine. It's just a piece of aluminum that is a particular length and has an inside diameter and an outside diameter.

enter image description here

You can also use the collars from the following bikes. I'm sure the list is longer but I'm pulling this out of the memory bank so it's not complete.

  • Pre 1990 Honda Rebel 250 and 450

  • 1982 Honda Hawk

  • 1981 CM400, CM200 and the extraordinarily rare CM250T

  • 1980 CM400, any model

  • 1982 Kawasaki KZ450LTD

Good luck, you can find this on ebay even though it's out of production. I actually lost the same part about 2 years ago helping a friend and ordered a new in package one from ebay.

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