Hi I needed a tool to properly measure a brake booster rod to master cylinder for proper adjustment.
Here is what I made:
The tool is made from 3/4 by 3/16 inch by 7 inch long steel pieces.
The brace is welded in approx 2/3 of the way of the legs leaving 2 1/2 inches and 3 1/2 inches to either side. The width of the legs apart is 2 3/4 inches on the outised and 2 3/8 inches on the inside. The screw is simply 5/16 inch threaded rod exactly 7 inches long (precisely the length of the legs of the tool) The one end is chamfered to fit inside the the brake booster plunger and the other end has a nut welded on and is ground flat.
I use it to quicly check adjustment and booster or pedal return on a system I end up replacing a master cylinder on.