We are all aware of the strength and durability of Chrysler's 727 TorqueFlite transmission. The TorqueFlite was well designed for severe duty, and its design has changed very little since its inception, attesting to Chrysler's superior engineering. Anyone who has been around Mopars very long has heard or told a story of a transmission run low on fluid, overheated, neutral dropped, or subjected to some other torture, then survived and went on to provide many more miles of service. There are, however, a few improvements to the 727 that can be accomplished during a rebuild and will make your TorqueFlite virtually indestructible.
Our transmission is a '68 model destined to serve duty behind a fairly stout (450 horse) 440 with a 3,800-rpm converter. In our experience, a stock transmission rebuild would probably suffice, but we have a hard time leaving anything stock. What we are after is tire-barking, neck-snapping, U-joint breaking shifts, and since our driving technique requires the right foot on the floor most of the time, we need a transmission that will handle our abuse. TCI automotive had just the kit we needed-their master rebuild kit that contained all the parts that normally wear, in addition to the seals, gaskets, and rings needed to perform the job. TCI also provided their Trans-Scat valvebody shift improver kit, as well as a 5.0 ratio kick-down band actuating lever to firm up our shifts. For durability, the one part we always include in our rebuilds is an overrunning clutch with a bolt-in outer race.
When contemplating a project such as this, you need to be aware of what you're getting into. A transmission rebuild is not an afternoon job you can do in your driveway, but with the proper tools, parts, and manuals, anyone with intermediate mechanical ability should be able to handle the job. We recommend starting the project with a core transmission that will later be swapped into the vehicle. This way you can take your time, fabricate, purchase or borrow the needed tools, and find replacement parts at your leisure. Also, if you get involved and realize you're in over your head, at least your car is not immobile. We've found rebuildable core transmissions locally from $50 to $150. We also recommend dedicating a reasonable amount of time and work area to the project. An automatic transmission is not extremely complicated, but the unit and its subassemblies do contain a lot of parts, so it helps to have enough space to keep them organized.
This article is not intended to teach transmission theory, nor will it give all the information required to perform a transmission rebuild. Entire books have been written on this subject. Even the most experienced transmission builder will have a shop manual, as well as other references available during the process, and we suggest you do the same. Our intention is to educate the reader about the rebuild process, as well as offer upgrades so that your transmission performs optimally and gives good service life. And if you decide not to tackle the project yourself, we will at least teach you some performance upgrades that you can have your transmission shop perform during the rebuild process
Tools required: normal hand tools, C-clamps, slide hammer, snap-ring pliers, 11/48-inch pipe thread tap if cooler lines are damaged, and a shop manual or other reference for the 727 TorqueFlite.
Note: Always look for defects during the disassembly and cleaning process. Carefully inspect all parts for nicks, burrs, cracks, or other damage so the parts can be repaired or replaced as necessary. Small nicks or burrs can usually be dressed with a file or sandpaper, while larger defects or cracks usually require part replacement, especially in the drums and rotating assemblies. Failure to inspect parts thoroughly can result in premature wear or transmission failure.
For more detailed information about the valvebody modifications, be sure to visit our web site: www.moparmusclemagazine.com.