i want to measure how much the wheel travels with respect to the roll cage or chassis as it moves up and down.
it isnt exactly suspension travel.
i want to place 2 sensors one on the wheels support member and one on the chassis so i can meassure their relative motion
I use a string-pot for this, and it works well. I use 100mm linear pots, but a rotary pot and a pulley would work just as well. Tie the string to the piece of the suspension that you want to measure, mount the pot assembly on the chassis so that it is inline with the string. Use a spring or elastic band to keep tension on the string. If using a linear potentiometer then for reliability and to reduce wear, when you attach the string and spring/elastic band to the potentiometer arrange the attachments so that they do not apply any torque to the potentiometer. (In a normal linear pot, any torque you apply is reacted against the resistive track.)