Might be pertinent to Isetta. Trienkels suffer from play on the rear axle. You would think that tightening it up, with the drum washer the correct way round, would solve this. It does not as the distance tube fitted over the axle to keep the two rear axle bearings in place either end of the casing but in tension is of poor quality steel. It therefore shears within itself allowing more play. Tighten it and a few months later it is loose again. Both Trienkel and Isetta rely on the splines of the hub to be a good tight fit to avoid rear steer. Clearly a sloppy rear bearing allows play and the spline is the weak bit. Once worn it is not easy to repair. So if you have a Treinkel sling the old tube and get one made out of proper steel to replace it. The club should sell these but historically refused to do so. Isetta owners take advice from someone who knows as they might have the same problem.
I like the mercury auto weather brake system. Fair weather, brakes work, can go out and play. Wet and windy, brakes seized, cannot go out and get the car wet.
Messerschmitts are renowned for the invention of the perfectly free functioning frictionless brake system possibly backed with ali brake shoes which only touch at either end of the friction surface when hot. Any Schmitter worth his salt has had to find himself parked on the pavement next to a line of traffic at a red light calmly looking over at them and going 'hi, guys. It's only me'. Further fun is peeing on the front wheels half way down a steep hill to get them working again, like going into Koblenz from the Autobahn Koln - Karlsruhr. So good are Schmitt brakes that they are at their most exciting when the car runs at its best, just after a rainstorm on a hot day. That bit of water vapour cools the charge and magnifies the power. Sadly the tyres do not grip well, or at all if cheapo boys, and the brakes rather crude on/off, well having thought about, off actually, nature can make for some very interesting experiences. Otherwise you drive slowly and the brakes are about adequate but that is really rather boring and you will be left behind by the pack on a run. Perhaps why Schmitts are not everyone's idea of transport as they do tend to suit the nutter element who have little time for dawdling.