you use a feeler guage for solids because there's supposed to be a gap, with hydraulics the "gap" is in the hydraulic pistons movement, they're adjusted to be partly compressed, which is why you need to do them hot [and oil filled]
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
