A long while ago, I confessed that I had realised the tank that my SQ4 kit arrived with, and which I had painted at vast expense was not a Square Four tank at all, but one which had once belonged to a KH Hunter twin. It did look good though:
It looked even better on the bike:
I started to look for another tank and after a short interlude with a very rusty tank from Denmark I found one in original paint at Yeoman's Motorcycles. When they are on the bench together, you can see how different they are:
So now, with a new tap (actually a refurbished original) and a balance pipe, here is Amelia in her latest incarnation:
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.
Ovality in the frame holes is not the only problem - the holes in the saddle frame are also very large. I have another problem in this area in that the fuel tank has very little clearance around the saddle nose bolt and I have solved both these problems in one go. In this picture, the original bolt has had it's head thickness reduced to produce a shoulder which fits in the saddle frame hole with very little clearance, and the full nut used at the other end has been reduced to the thickness of a half nut, again with a shoulder. This enabled the bolt length to be reduced, to get more clearance for the tank, and removed the whole assembly to the right to move the thread out of the bearing area.
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.
The rear brake rod is a much simpler affair than the front - it has a clevis at the rear end and this just needs a new pin, which is easy to make on the mini-lathe using a tailstock V-block:
The brake rod is just a bit of 1/4 round bar, threaded 1/4 CEI for the adjuster. The clevis is there, though very worn and we can find a spring from stock. The adjusting knob is missing, so we will turn that from a bit of 303 round bar, 1 OD:
It's reduced to 1/2" at the rear end, and the front appears to be domed but other than that is is similar to the front one. Same straight knurl:
Dome is made after parting off, with a combination of turning and a bit of filing:
We can mill a shallow groove in the rear to accommodate the clevis using an end mill.
Job done, though I think that clevis will need replacing.
