Fox Body Clutch Overview - Quadrants, Cables & Flywheels
Fox Body Clutches - Additional Facts
Clutch quadrants compensate for clutch cable wear as the clutch ages
Flywheels are the plates on the engine that connects to the clutch and transmits the power to the wheel
Stock flywheels are made of iron and weighs 22 pounds
Aftermarket performance flywheels use either billet steel or aluminum and weigh much less than stock
Adding an aftermarket flywheel will not cause the engine to gain any power, but it will rev faster because of the decreased weight.
How Fox Body Mustang Clutch Cables Work
The clutch cable works exactly like brake cables do on your bike. Pull the brake lever and the brake engages. Release the lever and the brake releases. In the automotive world of mechanical clutches, the same principle applies except opposite motion. Pushing the clutch pedal causes the cable to disengage the clutch, and releasing the pedal engages the clutch. No surprise here. Anyways, after years of use, just like bike cables, automotive clutch cables can stretch, fray and even bind in their housing leading to sloppy clutch movement. To fix this issue, simply replace the cable.
Replacing a Fox Body Clutch Cable: Stock or Aftermarket?
Surprisingly, many Mustang enthusiasts recommend using a stock, OE cable. They seem to be quite durable. An option that you may notice many aftermarket companies offering on their clutch cables is an adjustable option. The idea here is that if used in conjunction with a firewall adjuster (basically a screw you install in the firewall), you can adjust the cable and thus clutch engagement point from inside the car no wrenches necessary. This is an entirely optional choice. Many people prefer this adjustable setup (the firewall adjuster is another separate piece) and many also keep the stock setup. The choice is left to you.
1979-1993 Mustang Clutch Quadrants
The second piece to look at is the clutch quadrant. This is a piece you do not want to replace unless you have to (meaning the one in the car is broken). Later model Foxbodies (1987-1993) came equipped with a self-adjusting mechanism incorporated onto the clutch pedal. This self-adjusting system is basically a ratcheting piece built into the clutch pedal assembly to compensate for clutch cable wear as the cable ages (and stretches). Now, this system works really well. The only issue is, the stock piece is plastic, and after a lot of use they commonly strip, no longer working. You typically notice this problem when you press the pedal and hear a ratcheting noise. The stock quadrant is toast. The solution is to replace it with an aftermarket aluminum piece. The aftermarket aluminum pieces are much more durable, and some are even tailored to work specifically with their own adjustable clutch cable. The issue with this part however, is that it is a pain to replace! The whole pedal assembly and a good portion of the steering system and lower dash must come out to accomplish this.
Now onto the last piece of the puzzle, the flywheel. As previously mentioned, the flywheel (or pressure plate) is the plate on the engine that connects with the clutch and transmits the power to the wheels. It was also said that when replacing the clutch, the flywheel must also be replaced or machined. The main reason people replace the flywheel is if they are building a high-performance car. In most cases, the stock flywheel just needs to be resurfaced and you are good to go. If the stocker needs to be replaced you can go with a stock option, which is recommended for street applications, or aftermarket.
Aftermarket or Stock Fox Body Flywheels?
The difference between a stock and aftermarket flywheel is construction material. A stock flywheel is made of iron and weighs 22 pounds. Aftermarket performance flywheels use either billet steel or aluminum and weigh considerably less (both stock and aftermarket are 157 tooth, 28 or 50oz balanced, depending on year of engine).
Benefits of an Aftermarket Mustang Flywheel
Flywheels are kind of like differential gears in the sense that they can radically change how the car performs. Swapping the stock pressure plate with an aftermarket aluminum or steel piece will entirely change the driving dynamics of the car. The engine will not gain any power, but it will rev faster due to less weight, thus acceleration will increase. With this increase in performance, however, comes a decrease in overall driveability. As a street car, you may find the revving nature of a billet flywheel to be somewhat annoying. For this reason, performance flywheels are recommended mostly for acceleration-built or racing applications.
The cable, quadrant and flywheel are some of the necessary components to check when doing work on the clutch. At the minimum, a new clutch cable is a good idea when replacing the clutch. It is cheap insurance!
One last note, if you are purchasing a new flywheel, double check that you are buying the correct flywheel with the right external balancer. Different years used different weights.