Hydraulic Flaring Tool Kit for Transmission Cooler Line

This is a hydraulic flaring set for making your own transmission cooler lines and hard lines on the bench instead of hunting a discontinued OE line. The dies cover 3/16 in, 1/4 in, 5/16 in and 3/8 in tubing, which is the range factory automatic transmission cooler lines actually run in: 5/16 in and 3/8 in are the two sizes you meet on almost every domestic truck and car cooler circuit, and 3/16 in and 1/4 in cover brake and fuel line work on the same vehicle.

The head is hydraulic rather than a screw clamp. You cut the tube with the included cutter, deburr the end so the flare does not split, clamp the tube in the die, and run the ram down. The hydraulic ram is what makes a clean 45 degree double flare and an ISO bubble flare repeatable in steel line, which is the part that goes wrong with a cheap bar-and-yoke flaring tool: uneven pressure gives you a lopsided flare that will not seal against the cooler fitting and will weep ATF at the connection every time the line heats up. It also does 37 degree flares for AN fittings, so it covers aftermarket -6AN cooler line conversions as well as OE-style inverted flare.

Where this earns its keep in transmission work: a rusted or kinked cooler line at the radiator, a cooler line pinched during a transmission swap, adding an auxiliary cooler and needing to cut into the existing hard line, or rebuilding a section of line where the original flare has cracked at the nut. Cut the bad section out, flare a new end, and put a union or a new fitting on it rather than buying the whole formed line assembly.

The kit is 24 pieces including 15 dies and adapters, the tube cutter, a deburring tool, an extension bar for tight work under a vehicle, and a blow-molded case that keeps the dies sorted. Each die is stamped with its size.