I will modify the front wheel fork. The assembly of the front wheel is somewhat akward. The picture shows one of the mushrooms that will hold the wheel in position. Both mushrooms are held in position by torqueing the axle bolt.
The mushrooms are supposed to stay put as the wheel turns, but sometimes they begin to turn. This can induce some oscillations and shimmy.



I found all the informations on VansAirforce. One of the builders even asked Vans about the mod and they didn't object to it. The idea is to install a bolt on the fork that will hold the mushroom.
The only deviation from the informations on the website is that, as suggested by Vans, I'm using a smaller bolt (AN509-8R12).



Here the assembly is done. I only tapped the mushroom, to avoid any cracks in the fork.



Then it's priming time for the fork.



Then the fork is installed on the gear leg, for another special task. It's not possible to verify the torque of the big bolt with a torque wrench. So there is a small trick, it's done by using a small scale. The measure has to be taken a few times after the fork has been rotated a few times to each stop.



Once the correct value set, the gear leg is drilled for the cotter pin.



And now the wheel can be installed.