Extender Dial Bore Gage Kit 1.4-6 in, .0005 in Graduation

A two-point self-centering bore gage that reads inside diameters from 1.4 to 6 inches in .0005 inch graduations, with a 9.5 inch measuring depth. That reach is the reason this kit lives on a transmission bench instead of only in an engine shop: pump bodies, drum hubs, and case bores put the wear surface several inches down from the deck, and a short-stem gage cannot get to it.

Typical bench use: zero the indicator against a micrometer set to your nominal size, drop the gage into the bore, and rock it through the low point in two planes ninety degrees apart. The difference between those two readings is your ovality; readings taken at the top, middle, and bottom of the bore give you taper. On a 4L60E or 4L80E pump you are checking the stator support and pump gear pocket for out-of-round before you spend money on a rebuild kit. On a 700R4 or TH400 case you are checking the rear bushing bore. Same procedure for a valve body bore before you decide whether an oversized valve kit is needed or the bore is still within spec.

The carbide-tipped contact points hold size against cast iron and aluminum far longer than steel anvils, which matters when you are measuring several dozen bores a week. The set ships with two self-centering measuring heads, an extension holder, spacers, and a fitted case, on a chrome plated handle with an insulated grip so hand heat does not walk the reading while you hold it.