Swinging arm ouch

A recent post about interference between the stud for mounting the left silencer and the swing arm got my attention. I decided to take a look and found this:




I fixed the offending stud, but I am worried that this is a symptom of bad bushings. I had the rear tire off 3 months ago and I pushed around on the swing arm. It seemed tight.

So:

1. Can you tell bad bushings by just pushing and pulling on the arm when the tire is off?

2. How difficult is it to replace them? I don't mind hard work and time but is it something that should be left to a shop.

3. If it's not the bushings, any ideas on why the interference. I would guess that it is about 3/16".

Could happen to brand new parts if ridden like your BSA flinging. The major hassle is how screwed up and rust fused the s-a spindle is. Don't have to remove the primary if spindle can come out the R side via a puller, ie: don't need maniac sledge/drift from the L hand side. Its standard practice to grab s-a and tug laterally to watch for slack at the spindle/cradle but a bit fuzzy to not watching for the isolastic give too. Ideally just break chain, wipe grime, steal front axle or iso bolt or what ever threads into spindle configured as puller, slip off s-a then heat and boop out the bushes and boop new in, then reverse the video. Sloppy iso clearance at front can allow s-a to move enough to foul Lords studs. Hope you don't find the reason the collars are such a good idea, Consider them while down there. The notch itself don't look like a stress riser weakness, just a crumple zone so if there no radiation fractures and never over loading by side flings and cargo, likely a none issue. Only takes one spot weld in wrong place to tweak s=a alignment I've read here, that was up by the spindle area, don't know if mid tube an issue to tack over and grind back. Also twist s-a legs. Check lower shock mounts.

The Norton Service Notes mention the factory fitting washers behind the rear mounting holes on the Z-plates to splay them out - maybe this was the reason?

Then all you need to worry about is the kickstart knocking chunks out of the silencer... :roll:

Herman,
When you are checking all of the above,the bike should be suspended off the centerstand and supported by a jack or
some other means if yours is mounted to the cradle.I kept getting a false reading on the rear iso shimming until I did
this.Try checking this first.The collars make a big improvement also.
Mike

Diablouph said:

3. If it's not the bushings, any ideas on why the interference. I would guess that it is about 3/16".

Click to expand...

Don't forget to allow for the fact that the pivot end of the swinging arm is offset 3/16" to the left (because the cradle is offset by 3/16").
A certain amount of sideways deflection is also to be expected due to the Isolastics so any side to side movement isn't necessarily down to worn bushes or (more likely) the spindle becoming loose in the cradle.

I had exactly the same problem on my 850. The wear on the swing arm was a little deeper so I had it welded. I installed new bushings and spindle so there was no play there, that wasn't the problem. I cut back the iso bolt, put a thinner nut on and shimmed out the z-plate. There is clearance now, but its still close. The same swing arm in my 750 has no clearance problems what so ever. Both frames are pretty close to spec.

The threaded middle of the rocker puller has the same thread and works well.