Swinging arm play

[jhg1958]

Just taken my rear wheel off to rebuild it as I have a crack in the hub. It has only taken me 3 years to get around to this job but fortunately it has been fine and the crack has not propagated. Still soon I will have it sorted.

The swinging arm is not so good news. I have had to tighten it up a few times in fact stripping the thread on the nut. Now I have removed the swinging arm I can see that the inner bush has been turning. As it wore through the powder coating it became slack and now has significant play.

I am aware there is a needle bearing conversion but I am no engineer more of a bodger really. Could I insert a thin washer at one end then tighten the frame up on the washer and swinging arm?  I know a single wash at one end will throw the alignment out a little but that sounds better than a dancing swinging arm.

See picture of one side of the frame.

John

[Swarfcut]

 Sadly this is another aspect of this flawed design, where the inner sleeve of the silentbloc bearing is retained in place by the small area of the tube pressing on the frame cheek. Internal corrosion works better to anchor it to the through spindle, which is bolted to the frame. But then controlled destruction is required to dismantle the assembly.....
  For now use a homespun screw jack to spread the frame slightly to slip in a washer, the extra force from the frame cheeks when removed may be just enough to add extra grip to the bearing inner sleeves before the nut is tightened. Divergent
views on the position of the S/A for tightening, so have a read of previous posts and make a choice.

Swarfy.

[RichardL]

Some thoughts on the washer idea. First, regarding my own bodgery, when I used a jack screw in an attempt to spread my A7 frame to accept the dynamo shroud, the frame fractured at the bottom crossmember. Then,  if you manage to install two washers, it seems they would be too thin to hold up to the pressure from the tube ends and you’re back where you started from, or the washers become the friction surfaces against the swingarm’s outer cross-tube. If you install just one thicker washer to withstand the force from the inner tube, the existing wear on the opposite side negates the solution or leads to outer-tube friction on that end.

Swarfy left out “ridiculously” in front of “flawed design.” So, here’s the solution, short of the needle bearings or reconditioning the frame ears and installing new silentblocs……………..(uuuuh, I dunno).

Richard L.

[RichardL]

In some fairness to the design, I don’t believe BSA was negligent in not recognizing that some old farts would be trying to keep their A7s and A10s on the road and in good condition some 70 years later.

Richard L.

[CheeserBeezer]

It is possible to convert to a traditional bush design but, obviously, you'd need to get your hands on a lathe and/or somebody who knows how to work one. I have converted at least 6 A10 swinging arms to bush design. One such A10 has just completed 10,000 miles with the bush conversion and shows no sign of wear.
When you examine the original silentbloc bush, particularly on the cross-over shaft models, there just doesn't seem to be enough rubber to accommodate the amount of movement the swinging arm requires to move its full travel.