1970 Ford Fairlane - Bulletproof C4

Ask trans guys what type of sealing rings they prefer and you're bound to get different answers. Some feel steel rings seal tighter, while others feel scarf-cut Teflon rings do a better job. Nonetheless, most agree that Teflon units are a better choice on a high-horsepower application, since they won't damage other parts under high pressure. Here, Teflon rings are on the bottom (Hughes adds them to the build if the application calls for it).

The torque converter is arguably the most import part of the transmission, and choosing the right one is an art. Hughes has its customers fill out this tech card with as much information as possible. Cam specs, vehicle weight, rear gearing, and intended altitude play a role in how a converter will work. As the stall speed increases, so does the importance of this information.

There's a huge difference between a stock converter and a true performance unit. One important process Hughes performs on a converter is silicon-flux spot brazing all of the fins in place. In a higher-pressure performance application, the fins will otherwise distort. Stall speed is determined by the way Hughes bends the outer fins' angles (red arrow). You can also see that the Hughes converter incorporates a stronger, splined center hub.

Another upgrade is the sprag assembly. The factory-style sprag (A) is used, but the stock, plastic sprag cover (B) is ditched in favor of a billet-aluminum bearing unit (C). Only in the highest-horsepower applications would a spragless system be used (D); the spragless setup isn't required for the street.

Stators are also upgraded. In most cases, the factory style (A) is more than sufficient to handle the abuse. (It's the one we have.) In hardcore race applications, though, it is replaced with a billet aluminum unit (B) to handle the increased fluid pressure. Another choice is a billet steel unit (C), but Hughes feels it isn't worth the weight penalty over the aluminum one.

The next step up from silicon-flux spot brazing is furnace brazing. This bonds the entire edge of the fin to the body, and makes for a stronger and more efficient converter. After the unit is furnace brazed, it's spot brazed. Only some applications require this, and Hughes can tell you which.

Here's the assembled transmission, minus the valvebody. The red arrow points to the shifter linkage. If you plan to keep your column shifter or other OEM shifter, you'll need to add your own linkage or send it to Hughes. We are switching to a floor shifter, so Hughes installed the parts to make it work.

The fluid pressures within a torque converter can be extreme, especially in an application where the car is under boost or getting hit with a large shot of nitrous. This pressure can cause a normal converter to "balloon." In such a situation, the converter becomes far less efficient, and puts excessive mechanical force on the crankshaft's thrust bearing. This is where an anti-ballooning plate comes into play, as it reinforces the torque converter and can save your converter and engine from catastrophic failure.

Now it's time to assemble our street/strip C4 transmission. All the various parts are assembled as a "drum," then slid into the housing at once. The Ford C4 transmission is elegant in its simplicity.

It's time to run our C4 on the trans dyno. This is a quality-control step, where all the shift points are checked and fluid pressure is observed. All transmissions from Hughes take a turn on the dyno before heading out the door.