Before embarking on your Ford C4 or C6 transmission project, you’re going to need to equip yourself with a proper work setting and tools necessary to do the job. Because automatic transmissions encompass dozens of tiny parts—clips, balls, pins, valves, springs, and other items—your workspace must be well-lit, neat, orderly. “Hospital clean” is an abused term, but it is appropriate in automatic transmission building. Even the smallest particle of dirt can disturb an automatic’s precision tolerances, causing undesirable results and failure.
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As in any other area of an automobile, automatic transmission building poses its share of safety hazards. You’re going to be exposed to all kinds of toxic chemicals, which calls for hand, face, eye, lung, and ear protection. You’re going to need nitrile rubber gloves, which are similar to latex types used in hospitals, to protect your hands from harsh chemicals. Solvents can dry your skin and pose a certain cancer risk. You also want to protect your skin from sharp edges. Iron and aluminum castings have their share of sharp edges, as do stamped sheet-metal components. Iron and aluminum particles can penetrate your skin and cause pain and infection.
High-frequency noise from power equipment can damage hearing, which calls for earplugs or muffs. Even the low-decibel din of shop equipment, electric motors, gear and belt drives, air compressors, and the like, damage hearing with exposure over time. Cleaning and drying parts with compressed air, which isn’t always recommended, is loud enough to damage hearing.
Eye protection is paramount. Use goggles or safety glasses to protect your eyes from flying debris. Use wraparound goggles that keep debris well away from your eyes. Protect your face with a good face shield. Welding, for example, requires specialized eye protection to prevent permanent retina damage and sight loss.
Whenever you use harsh chemicals such as petroleum or alcoholbased cleaning solvents, protect your lungs with a good respirator. I see dust masks used occasionally—dust masks are not enough. A good respirator keeps all chemicals and particulates out of your lungs. The same rule applies to spraying paint. Always use a respirator, no matter how well ventilated your shop or driveway is.
A Place To Work
It is impossible to successfully rebuild an automatic transmission on your filthy garage floor or workbench, nor can you do it with an inadequate tool crib. You must have a clean, well-lit shop with a workbench. Dust and dirt are an automatic transmission’s worst enemies. A tiny grain of dirt or sand damages or locks up an automatic transmission’s precision parts.
Think of an automatic transmission like a Swiss watch—perfectly mated surfaces must have perfect tolerances. Clutch frictions and steels must mate precisely and smoothly. Sliding valves must glide through the valve body smoothly. Servo pistons and seals must be clean. When there’s dirt, these parts bind because tolerances are extremely tight in order to provide proper containment of hydraulic pressure.
Seals can also be damaged by dirt and friction material, which causes internal hydraulic leaks and failure.
When you’re not working on your transmission, keep it wrapped up tight inside a large heavy-duty plastic trash bag.
Your tool collection should include some type of transmission support fixture for both disassembly and build-up if you can afford it; it’s much easier than building a transmission on your bench. Transmission shops typically have cobbled up holding fixtures made from transmission cases and shafts. There are also holding fixtures you can purchase from tool supply houses such as Harbor Freight, which offers cool shop tools for all kinds of operations at affordable prices.
You need an air compressor for air-tool functions, blowing out passages, and checking servo and clutchpiston function. Air leaks, when pressure is applied, tell you there are potential fluid leaks around servo and clutch-piston seals. The absence of a telltale click of a control-valve piston, when air pressure is applied, means something’s amiss. Air tools also speed up the process of transmission disassembly and build-up. Good advice: always use a torque wrench (inch-pounds and foot-pounds) on all fasteners when it’s time for assembly.
Tools of the Trade
There are tools in the automatic transmission trade you need to be familiar with: slide hammers, snapring pliers, mallets, tiny screwdrivers, awls and picks, presses, punches, bushing drivers, slide calipers, seal installation tools, roll-pin removal tools, alignment pins (made from old bolts), seal drivers and installers, Torx drivers, and more. Some of these items can be rented or borrowed, especially if you intend to do a transmission build only once. With others, you have to bite the bullet and buy them if you want to rebuild a transmission yourself.
Although automatic transmission building calls for specialized tools, most of the tools you’re going to need are simple hand tools you can buy from Harbor Freight or Sears. Here’s a good basic list of what you need:
- Combination Wrench Set (SAE), 1/4 to 1 inch
- 1/4-inch-drive Deep- and Shallow-Well Socket Set
- 3/8-inch-drive Deep- and Shallow-Well Socket Set
- 1/2-inch-drive Deep- and Shallow-Well Socket Set
- 3/8-inch-drive Speed Handle
- 3/8-inch-drive Breaker Bar
- All kinds of socket extensions of various lengths and sizes
- 3/8-inch-drive Torque Wrench (foot-pounds)
- 1/4-inch drive Torque Wrench (inch-pounds)
- Common and Phillips-Head Screwdrivers (all sizes)
- Awl and Pick Set
- Ball-peen Hammer
- Punch Set
- Tap and Die Set
- Thread Chaser
- Needle-nose Pliers
- Duck-bill Pliers
- Snap-ring Pliers Set
- Channel Locks
- Vise-Grip Pliers
- Putty Knife
- Wire Brush
- 4 Large C-Clamps (work just as well as a clutch pack assembly fixture)
- 55-Gallon Trash Bags (to use as dust covers)
Most professional transmission shops have transmission holding fixtures to support transmission cases during disassembly and assembly. Not many of us can afford such a fixture or even need it more than once. This calls for a hard work surface on which to build your C4 or C6. Although you might feel like you need a holding fixture, it really isn’t necessary for the home garage technician. Where transmission disassembly and assembly gets tricky is when it is in the stack position and it’s time to load components. I’ve seen some transmission shops use tailshaft housings as holding fixtures. Alternatively, you can always bore a hole in your workbench for a stack assembly. Places like Harbor Freight offer inexpensive holding fixtures, designed for most transmission types, that work well for disassembly and assembly.
Rebuilding any automatic transmission calls for compressed air. You need it for removing parts such as clutch pistons and sliding valves. You’re also going to need it to clear passages. During assembly, you need compressed air to check component function. You need a huge industrial compressor; a 10- to 30-gallon compressor that operates off 110/115/120 vac produces the volume you need. And getting 220-vac power for more powerful compressors isn’t always easy in some places.
Air tools make transmission building faster and easier. You’re going to need a 3/8-inch-drive air wrench and ratchet. A 1/2-inch-drive air ratchet is overkill for automatic transmission repair. If you’re going to use an air grinder, take extra care not to damage cast aluminum contact surfaces.
An air blowgun is useful for clearing passages and for disassembling clutch packs and servos. It is also useful for doing operational checks on clutch packs, servos, and control valves. Always use eye, face, and ear protection whenever you use an air blowgun.
Because automatic transmissions have dozens of tiny parts, organization is very important. In my home shop, I use small, disposable kitchen containers and mark them for identification. Cooking sheets are also a good idea for larger parts like fasteners and can be reused. Good old-fashioned coffee cans are good for cleaning parts. Lacquer thinner and brake cleaner are the best solvents because they have a high evaporation rate. Petroleumbased solvents are also good because they minimize the risk of rust and corrosion and make excellent grease cutters. When the heavy crud is gone, lacquer thinner and brake cleaner are good for final prep work.
For cleaning items like the main transmission case, tailshaft housing, and bellhousing, dishwashing detergent and a high-pressure washer work very well. A pressure washer can be rented or purchased for a modest amount of money.
Although hammers occupy most toolboxes, you’re also going to want a hard mallet for things like servo covers and pistons. A mallet provides passive-aggressive force without inflicting injury. However, if you have to force any component, ask yourself why. Although servo covers and pistons must have a snug fit, installation by force means something’s too tight or you forgot to lubricate seals and parts.
Written by George Reid and Republished with Permission of CarTech Inc