Improved Swing Arm Oil Caps?

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ML

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Jul 30, 2007
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After a weekend of reconditioning the Mk2 swing arm with a new Mk3 type pin, double locknuts and O rings and spruce up with paint and plating on the back end bits I took off for run around the block to see how it felt, returned to the workshop and damn it...there was a pool of gear oil and the right hand swing arm end cap! The little head of the piss weak rod that pulls the end caps in had sheared off despite my very careful attention to not over tightening it. Well its been there for a long time and maybe its just fatigued.

Question is - does anyone know of a better fix for the end caps? I'm inclined to machine up something with a thicker section and a bigger gauge rod?

Mick
 
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Mk IIIs have pressed in caps which must be drilled and pried out when removing the arm. There is a standard-sized convex freeze plug that can be used as a replacement or could be used on older models. It requires flattening with a large, flat-ended drift that expands the perimeter of the plug snug into the hole in the swingarm pivot tube. The plug measures 1 3/16" in diameter with approx. 3/16" convex (pre-flattened)
 
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Years ago I replaced the rod with a larger diameter rod on my 72 Combat. I believe I drilled and tapped the left cover and drilled out the right cover to size. I've not had a problem since.
 
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Ditto on that. I did the same more recently. I used 4 mm steel rod, and the left-hand cap was drilled out and tapped 4 mm. I think this is probably the largest ID you could increase it to without weakening it. I made a new alloy right-hand end cap, drilled to just clear 4 mm, and drilled and tapped a hole for a new grease nipple. I only did this because the original end cap was rusty and didn't look good, so you could modify the old end cap. The new 4 mm rod protrudes though the end cap and is secured with a 4 mm stainless Nyloc nut. There is still some leakage past the seals between the swing arm and the cradle on my bike but I'll live with that. The cross tube is now oil tight at both ends. Mick, if you have the appropriate drills, taps and a 4 mm die (or the equivalent Imperial bits), you could do this.

Dave
 
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