air ratchet and an impact gun speed up the rebuilding process considerably. However, neither should be used to tighten fasteners because most go into the aluminum case, which is soft enough that the threads may strip out if excessive torque is used.
A torque wrench is necessary, as each fastener size has a torque value based on its diameter and hardness. The long handle on a torque wrench makes it very easy to over-tighten a bolt and strip the threads out of the case. This is easiest to do with the smaller fasteners that hold the valve body in place. Be careful and follow torque specs precisely.
A complete socket set with both metric and SAE is required. Most fasteners are SAE, but a few metric bolts can be found on later units.
In addition to a complete socket set, some hand wrenches are required. I especially like the new styles that have the ratcheting feature on the boxed end. They speed up the time typically required to tighten or remove a fastener that’s not accessible with a socket. Flare nut or tubing wrenches are made specifically for accessing the nuts that hold steel lines in place.
These wrenches have additional material and increased integrity to loosen stubborn flare nuts that hold the steel cooling lines to the case. They allow the wrench to slip over the tube, and still get a good purchase on the flare nut to remove it easily.
All fasteners have a torque setting based on the diameter and “grade” of the bolt. Just keep in mind that transmission cases are aluminum and you must use extreme care and sound judgment when tightening fasteners.
Both standard and metric wrenches are required. Most fasteners are SAE, but you will find that later units incorporated some metric fasteners.
Modern technology has left us with some very nice tools; these wrenches are an example. They can save a lot of time loosening and tightening fasteners that are inaccessible with a socket.
Flare nut wrenches are a must for removing and installing cooling lines. They provide access to the nuts but are designed to have increased contact area, which helps remove and install the nuts without rounding them off.
A spin-handle wrench is preferred to speed up the process of installing bolts and snugging them prior to tightening to final torque specifications. They do not require compressed air, and are much less likely to overtighten fasteners and/or strip out threads in the case.
Using a spin-handle wrench speeds up the rebuilding process dramatically. It also eliminates the possibility of stripping out any threaded holes in the case when using air impacts or air ratchets.
Several varieties of snap ring pliers will be needed, including some that will be modified for a particular purpose. On the TH350 and 4L60 transmissions specifically, the output shaft uses a small snap ring for retention, which is difficult to access. Pry it out carefully with a very small screwdriver, or use modified ring expanding pliers, which are easier.
A variety of snap ring pliers are required for transmission work. Some are available with removable ends to work with a wide variety of snap rings with the same tool.
Large ring expanders can be modified as shown. They are needed in the TH350 transmission to remove the snap ring on the front of the output shaft. They also work well when removing the spring cage retainers on the drums in both the TH350 and TH400 transmissions.
This is why you need a set of modified snap ring pliers. The output shaft front snap ring can be difficult to access and remove because it’s pretty far down in the case; it’s generally difficult to get both hands in there at the same time and see what you are doing.
An alternative to buying an entire assortment of snap ring pliers is to buy one set that has removable tips.
Pliers with removable tips are also available; one pair can cover a broad range of applications. Some snap ring pliers are also designed to be convertible, and can be modified in seconds to remove either inner or outer snap rings.
A variety of screwdrivers come in handy during the rebuild. Large flat-blade screwdrivers can be used to remove the snap rings in the transmission cases and also to reposition them. And, Phillips screwdrivers also double as alignment tools when putting the pump back on the case. A few minutes with a torch can quickly take a couple of small flat-blade screwdrivers and turn them into friction and steel removal tools.
By bending over the ends, they can be used to reach inside clutch drums or into the transmission case to pull steels and frictions out.
Large flat-blade screwdrivers are needed to remove the large snap rings from the cases on the TH350 and TH400 transmissions. You can also use them to remove the manual shaft seals from the case.
Phillips screwdrivers make great alignment tools for installing the oil pump and valve bodies on the case.
You can modify screwdrivers by
