Reinforcing Commando swingarm spindle with extra bolts

I've mentioned before that I don't reinforce the Commando swingarm spindle on pre-Mk 3 bikes by welding nuts to the cradle (as the Norton Tech Digest says), but by tapping two extra holes in the spindle for bolts. Some people have had trouble understanding conceptually what this means, so here's a photo of a spindle I just did (on a '69 S-type Roadster), plus instructions. http://www.flickr.com/photos/miket_nyc/ ... hotostream

I like it miket. Can back up the thin spindle tube under bolt heads to clamp good and stable. I can just picture me trying to get those bolt started as tedium test of will power not to cry in between me tries. Just the top one has about done me in. One thing I can appreciate with your clean design is the collar type get a lot of grit blast that a braid finish then rusts.

One possible issue is that the spindle tube is relatively thin. But using welded nuts or better yet, clamps reinforces the area. Just a thought.

I did this exact mod to an 850 I built up in the early 80's. I was in Northern California at the time and was hooked up with the Northern California Norton Owners Club. I read about it in issue of the "Norton News", their club newsletter in their tech section.
Worked fantastic. One thing to watch out for is that the spindle was surface hardened. I burnt a drill bit or two trying it. Screwd it up and bought another spindle that I had a machine shop do it. I don't know if the spindles available today have the surface hardening, but something to watch out for. Also I had the spindle thined down a thou and hard chromed and centerless ground down to spec, along with new fitted bearings.

JD

Something like this...

Before a shop drills a spindle they can mill off a small flat that takes off the hard layer and provide a square surface for the bit to bite. The bolts are to keep spindle from turning with bushes and from tipping side to side so mainly its the pure clamp force the spindle tube walls must tolerate so a contoured washer should work no need to weld but seal from water of course.

Here's my effort from 1983. I had never worked on a Norton before. I thought the spindle location was rather inadequate.
I had a new spindle turned up in silver steel.
The oil feed is a recent addition.

the 2 piece split collars are a much simpler and easier way and helps to reinforce the thin wall tube along with spreading the load over a MUCH larger area.