There's a reason Vortech spinners mount the way they do. Long spinner screws flex under load and snap at exactly the point they enter the nut — so Dave Brown's system inverts the problem: a long adapter nut and a short cap screw, putting solid machined metal where the flex used to be. This is the long adapter in M6 x 1.0mm thread, the nut that screws onto your engine's crankshaft and gives the spinner's cap screw a deep, secure anchor.

How to Choose Your Nut

Two specs decide it. Thread: the nut must match your engine's crankshaft — check the manual or measure; if the shaft is M6 x 1.0mm (6mm diameter, 1.0mm pitch), this is your thread. Length: Dave Brown's own rule is to use the longest adapter nut that fits under your spinner cone — longer nut, shorter screw, less flex — with the long version generally required on spinners above 2½ inches. If your spinner is small enough that the long nut fouls the cone, the short version in the same thread is the answer.

The Vortech System

These adapters are the mounting heart of Dave Brown's Vortech spinner range — the spun-aluminium cones, polished to a mirror finish, that have been dressing up sport and scale aircraft noses for decades. The knurled backplate grips between drive washer and propeller, the cone locks into the backplate, and the adapter nut ties the whole assembly to the crankshaft. One nut, correctly sized, and the spinner runs true.