Tuesday, January 18, 2005
Swinging back
At last I've all the bits to replace the swingarm. I've felt unable to do anything else to the frame in case it had to go off for machining. Anyway, the swingarm has new bushes in that have been reamed to fit the pivot, I've a stainless pivot pin that has been machined twice and a set of handmade nuts, washers and shims to fit it together.
A quick check showed that the pin machining is now correct and will allow it to seat into the remade thread and that the new 'shoulder' part would fit into the frame but not interfere with the arm. There was a little bur that needed a spot of emery paper to allow it to fit the bushes (after first machining NP had checked this but this time he didn't have the bushes) but otherwise nicely finished. The thread into the frame had been loosened a little but it was still stiff in the helicoil. I suspect that the insert is not dead square. Anyway, it looked as though it would go in all the way.
I chose a pair of the shims to fit between swingarm and the frame to take up all side-to-side slack.
Then after applying plenty of LM grease it all went together. The pin took a fair bit of effort to screw home as every half turn it binds - the other half turn is fine. That shows that something is not round! The pin was screwed in until flush on the right of the frame. A turn or so later I think I could tell that the shoulder was catching the shim on the left as the shim started to turn with the pin. So I backed it off a few degrees. The locknut went on with a washer on the right and tightened up. That leaves the left...
Here the nut can't be tightened up as it will cause the pivot to bind if there is any flex in the frame. Also the pin has an additional 'drive' section with 10mm WAF flats to screw it in. I'm concerned that this might catch my legs and be dangerous. I guess these aspects are why the original pin had the nut welded on. Anyway, the plan is to remove the nut, clean up the threads and reseat it with red Loctite to hold it in place. As for the sharp end, I'll have to see if it is a problem and decide what to do then. At least I've got a working swingarm.
At last I've all the bits to replace the swingarm. I've felt unable to do anything else to the frame in case it had to go off for machining. Anyway, the swingarm has new bushes in that have been reamed to fit the pivot, I've a stainless pivot pin that has been machined twice and a set of handmade nuts, washers and shims to fit it together.
A quick check showed that the pin machining is now correct and will allow it to seat into the remade thread and that the new 'shoulder' part would fit into the frame but not interfere with the arm. There was a little bur that needed a spot of emery paper to allow it to fit the bushes (after first machining NP had checked this but this time he didn't have the bushes) but otherwise nicely finished. The thread into the frame had been loosened a little but it was still stiff in the helicoil. I suspect that the insert is not dead square. Anyway, it looked as though it would go in all the way.
I chose a pair of the shims to fit between swingarm and the frame to take up all side-to-side slack.
Then after applying plenty of LM grease it all went together. The pin took a fair bit of effort to screw home as every half turn it binds - the other half turn is fine. That shows that something is not round! The pin was screwed in until flush on the right of the frame. A turn or so later I think I could tell that the shoulder was catching the shim on the left as the shim started to turn with the pin. So I backed it off a few degrees. The locknut went on with a washer on the right and tightened up. That leaves the left...
Here the nut can't be tightened up as it will cause the pivot to bind if there is any flex in the frame. Also the pin has an additional 'drive' section with 10mm WAF flats to screw it in. I'm concerned that this might catch my legs and be dangerous. I guess these aspects are why the original pin had the nut welded on. Anyway, the plan is to remove the nut, clean up the threads and reseat it with red Loctite to hold it in place. As for the sharp end, I'll have to see if it is a problem and decide what to do then. At least I've got a working swingarm.
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