Measures pump, bushing and valve body bores from 1.4 to 6 inches to .0005 in, with a 9.5 in reach so you can read wear at the bottom of a deep bore.
When a rebuilt 4L80E, TH400 or 4L60E comes back with low line pressure or a burnt clutch, the question is always whether a worn bore was put back into service. This Fowler XTender dial bore gage set, model 52-646-400-0, measures inside diameters from 1.4 to 6 inches in .0005 inch graduations, and its 9.5 inch measuring depth reaches the bottom of deep pump, drum and case bores that a short gage cannot touch. Carbide anvils, a chrome plated handle with an insulated grip and a fitted case come with it.
A dial bore gage does not read size on its own. You set it to a reference, usually an outside micrometer locked at the nominal bore size, and zero the dial there. In the bore, the self-centering head squares itself and the movable anvil reports how far the bore is above or below that zero. Rock the handle slowly and the needle stops and reverses at the true diameter. Take that reading at the top, middle and bottom of the bore to see taper, and turn the gage 90 degrees to see out-of-round. The 9.5 inch reach matters on big rear-drive units because the wear is rarely at the deck. It is down at the far end of a pump gear pocket, drum hub or case bore where the load sits.
The 1.4 to 6 inch range covers the large bores on a rebuild: the gear pocket in a 4L80E or TH400 pump body, the rotor and slide pocket in a 4L60E or 200-4R pump, drum and housing bores, servo and accumulator bores, and the larger case bores. It is not a valve body tool. Valve bores are well under 1.4 inches, so check those by vacuum testing or with a small-bore gage such as our 0.7-1.5 in dial bore gage set.
Measure after the pressure test, not instead of it. Sonnax notes that a worn pressure regulator bore in the cast-iron TH400 pump causes poor line pressure control and that the wear can be verified by testing line pressure and testing the pump. On a 4L60E or 200-4R, Sonnax points to even a worn slide pivot pin as a cause of low or high line pressure. Our 4L80E low line pressure diagnosis and the 4L60E pump rotor and bushing wear guide walk through the gauge test, then use the bore gage to put a number on what the test found.
This is a universal measuring tool, not a vehicle-specific part, so there is no year or model fitment. What matters is your bore range: 1.4 to 6 inches. Fowler lists .0005 inch or .01 mm graduation, a 9.5 inch depth, carbide anvils, an insulated grip, a chrome plated handle, and a 2 inch contact extension with a fitted case. You will also need an outside micrometer or setting ring to zero it. Browse more measuring tools in our diagnostics collection.
If the numbers say the pump body is done, our 1997-2003 4L80E pump is a direct replacement, and the 4L80E bushing driver kit handles the bushings you replace in the same teardown.
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No. Its smallest reading is 1.4 inches, and valve bores are much smaller. Use vacuum testing or a small-bore gage for valve bores and use this one for pump pockets, drums, servo bores and case bores.
A way to set zero, normally an outside micrometer or a setting ring at the nominal bore size. The gage reads deviation from that zero, so it is only as accurate as the reference you set it to.
Wear in pump bodies, drum hubs and case bores is often at the far end of the bore. A short gage reads only the top, where wear is lightest. The XTender reaches the bottom so you can measure taper.
Take readings at the top, middle and bottom of the bore for taper, then repeat each one with the gage turned 90 degrees. The difference between the two directions at the same depth is out-of-round.
No. That set covers small bushing bores from 0.700 to 1.500 inch. This XTender set covers 1.4 to 6 inches. Many rebuilders keep both so every bushing and pocket on the bench can be measured.
