Got a tired left leg? Blame the Mustang's ancestry. Your late-model Mustang inherited its clutch cable from the Pinto-based Mustang II.
Sure, the cable was perfectly adequate for working the clutch behind the anemic V-8 of the time, but the Ford engineers probably didn't anticipate that their clutch-release system would still be used 30 years later on a 390hp Mustang Cobra. In fact, it wasn't until the '05 S197 platform that the Mustang got its first hydraulic clutch.
Don't get us wrong--a clutch cable system is simple to design, inexpensive to build, and easy to maintain. When neglected, cable-actuated clutches can become hard to push, especially in high-torque applications. Take the '03-'04 Mustang Cobra, for instance. The Terminator's 11-inch single-plate clutch is designed to hold the supercharged engine's generous grunt, but consequently it takes generous grunt to disengage. In terms of pedal effort, the Terminator probably tops the list. But this also makes it an ideal car to use when investigating how to get the most out of a cable-actuated clutch-release system.
The Maximum Motorsports clutch-release...
The Maximum Motorsports clutch-release package includes a billet-aluminum clutch quadrant, firewall adjuster, and modified OEM Ford clutch cable.
The subject of this project is an '03 Cobra that already has an aftermarket quadrant and adjustable cable. Even with these parts installed, the owner complained of a "heavy and mushy" clutch pedal that, although adjusted correctly, didn't disengage until pushed completely to the floor.
After extensive research, the owner settled upon a new clutch cable, quadrant, and firewall adjuster package from Maximum Motorsports. As with most of its products, Maximum Motorsports evaluated each component in the clutch-release system to minimize its shortcomings and improve upon the OEM and aftermarket offerings. The Maximum Motorsports package includes a billet-aluminum clutch quadrant, a firewall adjuster, and a modified OEM Ford clutch cable.
Since the two biggest factors that contribute to excessive pedal effort and mushiness are friction and flex, they are the design focus of the Maximum Motorsports clutch-release system. Friction is minimized by utilizing an OEM Ford cable; its stiff cable housing also reduces flex. The Maximum Motorsports firewall adjuster eliminates the need for the rubber bushing on the firewall end of the cable, and the one-piece quadrant further reduces flex.
By an unscientific seat-of-the-pants measurement, the Maximum Motorsports clutch cable/quadrant/firewall adjuster package reduces pedal effort by quite a bit. In addition, the clutch disengages roughly midway through the travel of the pedal, making this '03 Cobra easier and more pleasurable to drive.
Follow along as we highlight the details and installation of the Maximum Motorsports clutch cable, quadrant, and firewall adjuster package.
First we got the front end...
First we got the front end of the car in the air. A set of ramps would be sufficient, but we used jackstands to get more working room for photos and used the ramps as backup.
If this Cobra had a stock...
If this Cobra had a stock clutch quadrant, the next step would be to remove it. But since the Cobra has an aftermarket quadrant and adjustable cable, we began at the clutch-fork end of the cable by removing the 8mm screw and the clutch cover.
To remove the adjustment and...
To remove the adjustment and jam nuts from our adjustable aftermarket clutch cable, we used a -inch-deep socket and -inch wrench.
To disengage the other end...
To disengage the other end of the cable from the quadrant, we removed the cable from the fork and pushed it into the housing a few inches.
Next we used a large screwdriver...
Next we used a large screwdriver to remove the clip that retains the clutch cable to the bellhousing.
We then pulled the clutch...
We then pulled the clutch cable free of the housing.
The cable was attached to...
The cable was attached to the car in two more spots: at the firewall and on the inner framerail. We used 5mm and 8mm sockets to remove the two screws.
With the cable free, we snaked...
With the cable free, we snaked it out of the car, noting how the old cable was routed so we could route the new one the same.
Then we removed the existing...
Then we removed the existing aftermarket clutch quadrant. It's in an awkward spot: under the dashboard. While the author is small and limber enough to slither into position by just moving the seat back, people of larger proportions are advised to remove the front seat. It's just four nuts and an electrical connector. Your back will thank you!
This is what we saw behind...
This is what we saw behind the dashboard. Note the aftermarket clutch quadrant that was already installed. The Maximum Motorsports instructions highlight removal of an OEM quadrant, so we'll skip the details of those steps. To remove this aftermarket quadrant, all we had to do was remove two pins (arrows).
The Maximum Motorsports quadrant's...
The Maximum Motorsports quadrant's cable hook angle is aligned with the radius of the quadrant so that the cable ferrule rests squarely on the quadrant. This minimizes the stress on the cable and makes it less prone to failure.
Two major contributors to...
Two major contributors to flex are the rubber firewall bushing and the cable housing itself. Both must compress when the clutch pedal is pushed. This compression wastes pedal travel and makes the pedal feel mushy. The OEM Ford cable's housing is stiffer than that of the adjustable cable, and the Maximum Motorsports firewall adjuster eliminates the need for a firewall bushing. Maximum Motorsports preps the OEM Ford cable that it supplies (bottom) so that it's ready for installation into the firewall adjuster.
With both quadrants out of...
With both quadrants out of the car, we could compare them. Since the position of the pawl shaft relative to the clutch-lever pivot shaft varies from production tolerances, the Maximum Motorsports quadrant (silver) utilizes an elongated circle (or slot) that fits over the pawl shaft. Unlike an oversized round hole utilized in most quadrants, the slotted hole positions the quadrant more accurately and keeps the clutch pedal from rattling.
We transferred the framerail...
We transferred the framerail support bracket from the old cable to the new one.
Maximum Motorsports supplies...
Maximum Motorsports supplies a small rubber bushing to center the cable inside the firewall adjuster and to keep the adjustment knob from rotating inadvertently. We applied a dab of lube to make cable adjustments smoother.
After trial fitting the adjuster...
After trial fitting the adjuster and cable together, we were ready to resume installation. We screwed the firewall adjuster's knob all the way into the housing, inserted the firewall adjuster into the firewall, and retained it with the OEM 5mm screw.
Next we routed the cable though...
Next we routed the cable though the engine compartment the same as the original cable. The cable housing was inserted into the bellhousing and retained by the clip. We then pushed the cable through the keyhole in the clutch fork and seated it in the fork's pivot socket.
With everything installed,...
With everything installed, we turned the knob on the firewall adjuster counterclockwise to remove the slack in the cable. Thanks to the reduced flex offered by the Maximum Motorsports package, the clutch disengaged midway through the travel of the clutch pedal. Pedal effort was also noticeably reduced--the owner's left leg was very grateful!
After we installed the clutch...
After we installed the clutch cover, we were finished underneath the car.
Returning under the dashboard,...
Returning under the dashboard, we installed the Maximum Motorsports clutch quadrant over the pivot and pawl shafts using a series of supplied spacers and the two original pins. Since the adjuster was screwed all the way into the adjuster housing, there was enough slack to easily hook up the clutch cable.