The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: 57BSA on 28.06. 2009 02:22
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I have searched for tech tips on how to check or test the swing arm bushing on my 1957 BSA A10, I have seen a lot of articles about how to remove them, (which seems pretty scary) but I need to know how to inspect the swing arm bsuings to see if they need to be changed before I send my frame to the paint shop. The frame is stripped down to the bare bones except for removing the swing arm, the shocks are removed, how much up and down movement should there be?
wayne
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Wayne,
Welcome to the forum. I suppose you have been watching it for awhile before joining. Some call that "lurking," but I don't like the negative connotation of the word. Anyway, I trust you will find useful help and amusing conversation here, I certainly have.
Now, for your question, you have opened up your participation with one of the more intensly discussed topics that just recently slowed down. If you want to learn a lot about swingarm bushes, you might review the topic at http://www.a7a10.net/forum/index.php?topic=1185.0
To encapsulate a bit of the discussion, the bushes are pinched together between the frame plates and, due to pressure on their outside ends, the inside sleeve holds basically steady with the frame while the outer sleeve moves with the swingarm, the liner of rubber between them being stretched with the movement of the swingarm and, therfore, reducing noise and small-motion vibration that would be transmitted from the road to the frame. If you read all the posts in the topic I've pointed at, you will see that it took quite a bit of convincing for me to come around to believing this functional description. I have thought that it might just be intentional that the contact surface area between frame plates and bush is small so that the bush would turn if the swingarm sees unusually long motion. I think that is still an open question. With regard to motion distance, I think you will see under the other topic that the maximum rotation is 8 degrees (I think this was on either side of center, but I'm not seeing the other topic while typing this under your topic, so I'm not 100% sure).
Hope this helps.
Richard L
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Take the nut off and take a look at the hole in the frame where the spindle comes through. On my Shooting Star the nut was loose and the spindle had been going up and down, making the hole oval. The spindle was well rusted in so I could not remove it to repair the hole with weld. I ended up welding the nut to the frame. *eek*
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Hi Fido,
You seem aptly named *smile* *smile* *smile*
dog of a job welding the nut to the frame *ex* *ex* *ex*
I know well its a pig of a job to remove the swinga arm,
I have put the whole frame in a big pillar drill and drilled away the ends of the pin to remove the swing arm, then used a small 4 or 5mm drill to drill away the rubber bushings in the swing arm, the right size holesaw would do the same thing
I repaired the frame by boring out the worn hole round and welding in a tophat shaped insert.
I made a template from the unworn side so as to centre the worn hole
Regards
John O R