Since I've had it on the road, the Square Four has felt a bit wayward around the rear end. Since I had rebuilt the rear suspension and knew that it had no wear, I suspected the tyre and wheel though they were both new and rebuilt - until I realised the problem was closer to home. Literally much closer, to my backside.
The saddle nose bracket on an Ariel frame is quite small, giving little bearing area. Coupled with a bolt with an over-long thread, used as a bearing surface produces this effect after a few years:
This picture shows the saddle removed, but with the bolt in position. The red circle shows a portion of the thread used as a bearing - a very poor idea:
So, the first job is to make those worn holes round again. The bolt is 5/16" (0.312", or around 8mm), and they are both worn to over 0.350". I used an adjustable reamer on them to remove the ovality.
Next job was to make two shouldered bushes to fit in the holes:
The bushes pass right through the fixed frame lugs, to provide maximum bearing area; there is a minimal shoulder to allow the bush to be retained in place (or removed).
This repair has removed virtually all the play from the saddle nose bearing.
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