Mastercool 72485-PRC Hydraulic GM Trans Line Flaring Kit

This is the Mastercool hydraulic flaring set with the GM transmission cooling line dies and adapters included. The hydraulic ram does the work instead of a wing nut and a yoke, so the flare comes out square and repeatable even when you are working under a truck with the line still on the vehicle. That matters on GM transmission cooler lines, where a lopsided flare will weep at the fitting and leave you chasing a slow ATF drip after the job is done.

The kit forms seven flare types across 3/16 in, 1/4 in, 5/16 in, 3/8 in and 1/2 in tubing: 45-degree single and double flares, GM transmission cooling line flares, GM fuel line flares, push connect flares, ISO/DIN bubble flares, and straight hydraulic line flares. That covers transmission cooler and return lines, brake line, fuel line and most hard-line repairs a transmission shop runs into when a cooler line is rotted at the crimp and the replacement has to be made up on the bench.

Working procedure is the same as any Mastercool hydraulic head: cut the tube square, deburr, slide the fitting on first, clamp the line in the matching die block, thread in the correct forming adapter and pump the ram until it bottoms. The dies index the tube depth for you, which is the step most people get wrong by hand. Everything stores in a blow-molded case with the die blocks, adapters, tube cutter and deburring tool in marked pockets.

Mastercool built the original patented hydraulic flaring tool, and the -PRC version of 72485 is the one carrying the GM transmission cooling line tooling. If you already own an older Mastercool hydraulic flaring set, check your die list before ordering: the GM transmission line dies are the difference.