Hi Fish. The outer ring in the picture is a spacer which comes with the brake kit. It sits on the wheel studs and is bolted tight to the hub when the wheel is bolted on. They are both currently held in place on the wheel studs by one bolt only to keep them out of the way. The original wheel nuts are in very poor condition and I am waiting for replacements which should have been here yesterday. The spacer ring is not threaded and is a fairly loose fit on the wheel studs. This is still very much a work in progress.
More worrying is the fact that I cannot build pressure in the braking system. The manual I have says to bleed the furthest wheel, ( the left hand one when sitting on the quad), first and while I have got a stream of brake fluid coming out with no bubbles on both callipers, there is no pressure on the brake lever and the brake pads have not moved up to the discs. I had a look at some youtube videos and have followed the suggestion that I put a spring clamp on the brake lever to hold it in the pulled position for some time, 24 to 48 hours, to see if that improves things. If it does not I will disconnect the brake pipe from the master cylinder and see if the lever is generating any fluid pressure using my finger as a gauge. There are no fluid leaks that I can see from the brake lines. The fluid on the floor under the bike spilled when we disconnected the drum brakes.
It appears from talking to Turbo that the front brakes failed pretty well as soon as he unloaded the quad from his van when he purchased it. The master cylinder and lever both appear to be new and are I suspect from China.
Photos attached showing the spacer pushed up against the hub and the master cylinder.