►A feeler gauge is a tool used to measure gap widths. Feeler gauges are mostly used in engineering
to measure the clearance between two parts.
►They consist of a number of small lengths of steel of different thicknesses with measurements
marked on each piece.
► They are flexible enough that, even if they are all on the same hinge, several can be stacked together
to gauge intermediate values.
► It is common to have two sets for imperial units (typically measured in thousandths of an inch) and
metric (typically measured in hundredths of a millimeter) measurements.
►The lengths of steel are sometimes called leaves or blades, although they have no sharp edge.
► Straight leaves may also be referred to as parallel leaves. The sides are parallel all
the way from the locking screw to the tip.
► The leaves have smooth rounded edges for comfort and safety when handling.
STRAIGHT LEAF FEELER GAUGE
TAPERED LEAF FEELER GAUGE
► Tapered leaves gradually narrow towards the tip. They tend to be shorter than
► The leaves have smooth rounded edges for comfort and safety when handling
GO NOGO FEELER GAUGE
► A Go NoGo feeler gauge is different to a regular feeler gauge as it
differentiates between a thick base and a thinner tip.
► The thinner end of the gauge is able to 'go' into the gap and the thicker body will not -
IMPERIAL FEELER GAUGE
► An imperial gauge gives measurements in thousandths of an inch
METRIC FEELER GAUGE
► A metric gauge gives measurements in hundredths of a millimeter.
COMBINED IMPERIAL AND METRIC FEELER GAUGE
► Some feeler gauges combine both imperial and metric measurements.
► The measurements are often found on separate leaves at alternate ends of the tool.
They can sometimes be found on the reverse side of the same leaf.
► Offset blades are bent toward the tip for easier access in most motor vehicle
applications and work in restrictive areas
INSERT FEELER GAUGE
► Firstly rotate the inner or outer ring a few times, making sure that both bearing
rings and the roller are aligned in respect to each other.
► Insert the feeler gauge as shown, between bearings and casing.
MOVE BLADE BACK AND FORTH
► Move the blade back and forth until it can be inserted to the middle of the roller.
► Check the bearing clearance against specification before mounting
TAKE ANOTHER MEASUREMENT
► Take another feeler gauge measurement after mounting the bearing onto the shaft.
There may be variances between the two measurements.
TAKE ADDITIONAL READINGS
► To find the 'true' bearing clearance, take a further 3 feeler gauge readings at locations: a
(9 o'clock), b (3 o'clock) and c (12 o'clock) as shown.
► Feeler gauges should be cleaned with an oily cloth before storage to prevent rust.
►Immediately after use, close fanned out feeler gauge blades.
► This should be done by grouping smaller blades against the consecutively larger sizes for support.
►This will prevent the thinner blades bending when they are closed into the case.
►Immediately after use, close fanned out feeler gauge blades. This should be done by grouping
smaller blades against the consecutively larger sizes for support.
►This will prevent the thinner blades bending when they are closed into the case