A good subtitle for this article could be “pain in the bottom line.” You may have heard the phrase, “No pain, no gain,” which is often true in physical conditioning or education, but which we prefer not to relate to transmission rebuilding. In this field, the pain – and education – comes in the form of a comeback. It hurts the bottom line to rework or repetitively give up expensive parts. We are referring to both the cooler line and profit line.

In this lesson we will hear of a 4R100 in a 2000, 7.3 diesel with repeated (four times) converter failures.

This is an experience that once learned is never forgotten. During final test drive you notice the TCC apply seems longer and softer than normal in a 4R100. If you deliver the vehicle it may return due to overheated fluid or converter codes 1728 or 1744. Avoiding further diagnosis and swapping converters or coolers can increase the anxiety, as the vehicle returns to the shop after another week. This starts to get your attention. HD converters, new fluid and labor have dissolved the initial profit, so now it’s time to figure out what’s causing this.

What is the Problem?

There is not enough pressure at the TCC piston to reduce the slip as the engine input torque increases. Any circuit restriction is more critical on a modulated TCC in the 4R100 vs. the on-off E4OD, due to the size and position of the TCC control valve orifices.

To explain the problem we could compare the converter to a hydraulic jack. The cylinder will only move as fast as the fluid fills or is allowed to exhaust. With a jack, the handle or bleed screw is the control.

In the 4R100 converter example, the piston travel is controlled by the exhaust of fluid past the turbine hub. If too close/restrictive, the release oil will slowly exhaust as the TCC piston forces the oil out (see Figure 1).

There can be other issues affecting the apply and release of the TCC piston. In descending probability, they would include: the bypass checkball leaking or stuck open (which is external to the transmission), poor pump volume or modified pump orifices.

Why Does this Occur in the 4R100?

On the modulated converter circuit of the 4R100, the fluid coming from the TCC regulator valve goes unrestricted to the converter apply piston (see Figure 2). As the TCC solenoid modulates the control valve, the release oil between the piston and the cover exhausts without an orifice. The apply oil now gets priority toward the piston and is restricted toward the cooler direction. To illustrate the theory, we could use a river’s spillway gate, controlling the water to take an easier path toward a generating turbine. Another example could be the garden water hose. You can see a head pressure spike from a leakage point as you step on the hose.

In the 4R100 converter the piston gets priority pressure due to the orifice and the cooler receives less pressure and flow. If the orifice hole is increased, the TCC piston gets less pressure, but the cooler receives more flow. In this case, less pressure to an overtaxed TCC piston is not a good practice. Likewise, making the orifice smaller increases pressure at the TCC piston, but reduces flow to the transmission lube circuit. The E4OD by comparison, has an exhaust orifice and apply orifice with its on-off control of the torque converter clutch.

Now we add the external pressure bypass circuit. This ball, seat and spring are designed to open at about 60 psi of cooler head pressure, to ensure lube flow around a restricted cooler. Charts, text and graphs aside, think of the radiator and bypass as another person standing further down the garden hose.

How to Isolate the Problem:

Checking cooler flow and head pressure at the same time is the best method to isolate if there is a problem. If you cannot monitor flow, at minimum check head pressure (see Figure 3). On the 4R100 cooler test graph (see Figure 4), note the two units Alt1 and Alt2. Both had restricted converters. There is minimal difference in flow (see GPM flow rate at far left) during lockup and head pressure (see psi flow at far right) does not rise to normal. Normal specifications are the last example shown. The Lot test OE example is from pre-repair, with an unrelated problem. The Alt4 test is using the converter from Alt1 and improving the oil flow, then installed into the same truck. Alt3 is a used OE converter installed into same Alt1 truck. The other bar graphs are testing various stages with bypass closed or open to isolate it.

Can We Apply this Information to the E4OD?

Even though the converters may be similar or the same, the hydraulic control is different. The orifices that control the flow to cooler vs. the converter apply differ between the two units. You can verify this by comparing cooler flow on both types of units.

The E4OD will have less cooler flow when TCC is not applied; flow rises sharply with TCC command. Average E4OD cooler flow, in 3rd with TCC not applied is 1.2 to 1.4 GPM and goes to 1.8 to 2.0 GPM at time of TCC command. It is almost the opposite of the 4R100. The 4R100 with modulated converter control drops during TCC apply and is greater before lockup (refer to chart). The E4OD does not have the external pressure bypass either. This makes the E4OD much easier to diagnose. You can identify when the TCC solenoid commands apply by looking for a rise in flow or pressure. You then know the apply valve has stroked.

Knowing how these circuits are interrelated is like having the answers for a geometry exam before you enter the class. For this lesson, the 4R100 TCC test answers have been compiled here, so all you need are gauges and your garden hose as a reminder.

Each model of the 4R100 valve body varies depending upon casting numbers located on the main valve body and the accumulator body. They can also be identified by the type of lower valve body separator plate.

Casting Number Identification

Lower Valve Body Separator Plate Identification

Changing the line pressure modulator ratio to increase shift firmness is a very popular upgrade in Ford E4OD and 4R100 units. All too often however, the result is a transmission that shifts harder than expected. Choosing the right Sonnax kit for your application is key to achieving the shift feel you want.

The accumulator control body is very sensitive to changes, so it’s easy to go too far — or rather, too big — when choosing a line pressure modulator plunger valve kit. Very often when a .500" kit is selected, the results are much firmer shifts than anticipated. We can eliminate this by choosing the appropriate modulator based on vehicle application — see chart for the breakdown of Sonnax options.

For many, the .500" and even .427" options are going to be too aggressive with modestly modified street performance vehicles. For this scenario, we have found that combining the .372" LP modulator ratio with the performance-rated accumulator spring kit [36948-18K] and a line pressure booster kit [4R100-LB1] in the pump will provide a balanced, progressive increase in shift firmness without the side effects associated with a large-ratio LP modulator change.

For all heavy-duty builds, we also recommend adding Sonnax line-to-lube pressure regulator valve [36424-04K] to ensure converter and cooler flow are maintained regardless of the pressure regulator valve position.

Whether you are searching through a core pile or looking for a specific part to complete a rebuild, sorting out the various identifying features of Ford E4OD, 4R100 and 5R110W converters can drive you crazy. A six-stud version of each converter that happens to have the same K factor (impeller blade angle) will look almost identical. If you have not educated yourself on the subtle contour differences where the impellers mate to the impeller hubs, or cannot recognize the .200" difference in the relationship of the pilot to mounting pad difference in the 5R110W compared to the E4OD and 4R100, you can become easily frustrated. The following are part-by-part differences, as well as some hints for identifying each one.

Covers

The early-style E4OD covers (first generation) had round mounting pads at the base of the studs (Figure 1). The round pad converter covers were prone to crack and leak around the base of the mounting stud.

For this reason, most round-pad E4OD converters have already been removed from service. The improved replacement covers feature a mounting pad that looks like a round pad with a flat machined on the inboard and outboard sides (Figure 2).

This improved pad solved the crack/leak problems on the E4ODs and is still used today on the 4R100 and 5R110W converters.

From the outside, the late-style E4OD and 4R100 covers look the same. But looking inside, you will see that the sides of the E4OD are smooth and the 4R100 are grobed to hold a clutch. For this reason, you can use a 4R100 cover to build an E4OD converter, but you can only use an E4OD cover to build a 4R100 converter if a single clutch is used. The 5R110 cover is also grobed on the inside, but cannot be substituted for either because of the shorter-pilot-to-mounting-pad relationship (Figure 3).

Turbines

The turbines for the E4OD, 4R100 and 5R110W converters look very similar and in many respects are identical: they are the same diameter and have the same number of vanes. The differences become noticeable when you look at where the turbines mate to the turbine hubs. The E4OD turbines have the same piloting bore diameter (2.765") as the C4, C5, C6 and AOD turbines. They also have the same rivet circle and use the same diameter rivet (.218"). The late-style E4OD turbines have a slight contour dip at the rivet surface (Figure 4), while the early-style turbines are nearly flat (Figure 5) but this does not seem to affect internal clearance.

The 4R100 turbines use the same rivet circle and rivet diameter as the E4OD turbines, but have a larger I.D. bore (2.955"). This is the piloting diameter for the turbine hub.

All of the 5R110W turbines have an I.D. that is about .015" smaller than the 4R100 turbine’s 2.940" I.D. The four- and six-stud versions of the 5R110W use the same rivet circle and rivet diameter as the 4R100 turbines. The eight-stud version of the 5R110W turbines move the rivet circle slightly outboard of the 4R100 rivet circle and use a rivet with about a .065" larger diameter. Ford may have been anticipating the larger rivet diameter when they made the I.D. bore .015" smaller.

In a side-by-side comparison, you will notice that the depth of the arch is slightly deeper on the 4R100 and 5R110W turbines than on the earlier turbines (Figures 6 and 7). The arch is created from where the oil enters the turbine to where the oil exits the turbine.

This means that the oil will travel a greater distance through the turbine and will spend more time in the turbine giving more push in the direction of the rotation. This may explain why Ford assigns a 105 K factor to the low-stall E4OD converter and a 110 K factor to the low-stall 5R110W converter, even though both use the same stator and have the same vane angle in the impellers. The 4R100 and 5R110W turbines have vanes that are .005" thicker than the earlier turbines, and all 5R110W turbines are furnace-brazed. Remember this when retrofitting an earlier turbine. You may want to limit their use to low-output applications.

Turbine Hubs

All E4OD, 4R100 and 5R110W turbine hubs are different and need to be matched to their respective clutch assemblies.

Turbine Hubs to Turbine Rivets

All rivets, with the exception of the eight-stud 5R110W, are 2.18” in diameter and vary in length depending on turbine hub flange thickness and whether the application uses a retaining ring.

Stators

The E4OD, 4R100 and 5R110W stators are the most universal parts of these converters. All have the same design and function. If the stator caps and bearing assemblies are properly mated to the turbines and impellers, they will work.

Impellers

The E4OD, 4R100 and 5R110W impellers come in three vane angles. The high-stall impeller has a vane angle that looks like a left-handed salute. It has a 140 K factor and is primarily used on small block gas applications. There is no high-stall impeller used with the 5R110W converters.

The low-stall impellers have a vane angle that is almost straight up and down. In most other converters, this would be called a medium stall. The E4OD converters with the low-stall impellers have a 105 K factor. The 4R100 and the 5R110W converters with the low-stall impellers have a 110 K factor.

The extra-low-stall impeller has a vane angle that looks like a right-handed salute. The converters with the extra-low-stall impellers have a 95 K factor. Most 5R110W converters use an extra-low-stall impeller. Most customer complaints are the results of using an extra-low-stall impeller for a low-stall application. This results in an off idle hesitation in a gas model or a turbo lag in a diesel model.

There are many generations of bearings and wear plates used between the stator and impeller and most are specific to a given impeller hub. Start by making certain that the stator cap and bearing are still available (some have been discontinued). Then match the impeller with the desired K factor to your bearing and stator assembly. Remember that you can always replace the impeller hub to come up with the proper mating part.

All E4OD, 4R100 and 5R110W converters have the same diameter pilot, bolt circle at the flex plate, overall height, 31 input splines (same as a C6) and stator splines. The clutch assembly will determine what cover and turbine hub you use. The desired K factor will determine what impeller to use. Most mismatches in parts will show up as too much or too little internal clearance, or too tall or too short in overall height.

Ed Lee is a Sonnax technical specialist who writes on issues of interest to torque converter rebuilders and member of the Sonnax TASC Force (Technical Automotive Specialties Committee), a group of recognized industry technical specialists, transmission rebuilders and Sonnax Industries Inc. technicians. ​​​​​​​