This article is one in a series that have been released in conjunction with Wayne's book, 101 Projects for Your Porsche 911. The book contains 240 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Porsche 911 owner's collection. See The Official Book Website for more details.
In 1977, Porsche changed the design of their clutch release lever to incorporate what is commonly known as a helper spring. This spring aids in the engagement and release of the clutch by giving the pedal a snap-in feel. As the clutch gets used more and more, the helper spring has a tendency to wear out, leaving the car with a clutch that feels like it is about to give way. It is recommended that you replace both the clutch cable (see Pelican Technical Article: Clutch Cable Replacement) and the helper spring before you do a full-blown clutch job.
The first step in replacing the helper spring is to remove the clutch cable. The cable is mounted to a flange on the underside of the transmission, and hooked into a large throw-out arm that actuates a smaller arm connected to the throw-out bearing. Loosen up the two nuts that hold the cable, and remove the hooked end of the cable from this arm.
Now, remove the circlip that holds the large arm to the transmission. Try not to destroy the circlip, but if you do replacements are easily available. After the circlip is removed, you should be able to use a large screwdriver to remove the arm from the transmission. Be careful of the helper spring as you pull the arm off, as the spring is under tension, and will spring back when it slips off its pin. Make sure that you wear eye protection, and that your hands are not near the spring as you pull it off. You don't have to worry about it flying off though, because it is firmly attached to the long arm.
Once you have the arm assembly removed from the transmission, take it over to a workbench to begin the disassembly. Remove the small circlip that attaches and secures the helper spring. Once this circlip is off, try to remove the helper spring using a screwdriver or a pry bar. Chances are the spring will not come off. If this is the case, then it will be necessary to cut the spring off using a Dremel rotary tool. Start with the outer layers of the spring, and cut inward. When you get to the last layer of the spring, cut about half-way in, and then take a screwdriver and try to break the remainder of the spring off. Using this method reduces the chances that you will damage the small shaft that onto which the helper spring is pressed.
Once the old spring is off, check the shaft and the bearings in the arm to see if they turn freely. If not, then press them out and replace them with new ones. Once you've confirmed that your bearings are in good condition, take the new helper spring and tap it on to the shaft with a small hammer. Make sure that you place the spring on the shaft in the proper orientation: it is possible to place it on backwards. Replace the small circlip, or use a new one if you destroyed the old one getting it off.
Now, move back under the car and replace the arm on its shaft on the underside of the transmission. In order to properly install the helper spring, you will need to set the spring against its pin and then use a big screwdriver or crowbar to pry it into place. Make sure that you keep your hands away from the area when you are doing this, and remember again to wear safety glasses. When the helper spring is snapped back into its position, then the curved side of the spring should be right up next to the heat exchangers.
Reconnect the clutch cable and adjust your clutch (Pelican Technical Article: Clutch Adjustment). Test the clutch to see if there is an improvement, and you may find that all of your worries about having to replace your clutch were needless.
After the new helper spring is installed onto the large throw-out arm, mount it back onto the transmission. Make sure that you orient the helper spring properly, as it is easy to install it backwards. With the arm in the position shown in the photo, pull back using a screwdriver or crowbar on the lever, and the helper spring should snap the arm into place. The final resting location of the spring should be extremely close to the heat exchangers. Wear eye protection, and watch your fingers when snapping the spring into place.
An exploded view of the helper spring and lower clutch arm. Items indicated for replacement should be replaced if the arm bearings are bad, and the small shaft does not turn smoothly. 1-Circlip (replace if necessary), 2-Washer, 3-Plug (replace), 4-Circlip (replace if necessary), 5-Washer, 6-Spring, 7-O-Ring (replace), 8-Washer (replace), 9-Shaft, 10-Needle Sleeve (replace), 11-Release Lever