Clutch Cable / Helper Spring
Replacement & Adjustment

Difficulty Level 3

Difficulty scale:
Adding air to your tires is level one
Rebuilding a 911 Motor is level ten

Figure 1: Foot Pedal Assembly

Figure 2: Clutch Cable End

Figure 3: Clutch Cable End Removed at Pedal Assy

Figure 4: Clutch Cable Adjustment Nuts

Figure 5: Clutch Cable End

Figure 6: Clutch Cable Tube at Firewall

Figure 7: Threading New Cable into Firewall

Figure 8: Clutch Cable at Firewall

Figure 9: Clutch Helper Spring

Figure 10: Clutch Lever Arm Assembly

Figure 11: Disconnect Return Spring

Figure 12: Remove Circlip

Figure 13: Sliding Off Clutch Arm

Figure 14: Removing Large Clutch Lever Arm

Figure 15: Clutch Arms Removed

Figure 16: Helper Spring with Shaft

Figure 17: Clutch Arm Assembly

Figure 18: Clutch Cable Arm

Figure 19: New Clutch Cable

Figure 20: New Clutch Cable Installed

Figure 21: Setting Clutch Play Clearance

Figure 23: Tightening Clutch Cable

Figure 23: New Clutch Cable Installed

Figure 24: New Clutch Cable Installed

     The symptoms that it was exhibiting were a really stiff pedal, combined with a very long throw to disengage the clutch.  It was so bad that the only way to get the car to release the clutch was to remove the floor boards and push the pedal all the way to the floor.  Needless to say, I removed the engine, replaced the clutch, and then reinstalled everything, only to find that there was little or no improvement in the feel of the clutch!  Frustrated, I replaced the clutch cable and helper spring, and the problems vanished.  It is with a little egg on my face that I confess that I was mistaken about the clutch going bad.  My suggestion, based on this experience is to replace all the easy components first, and then move on to the really tough stuff later on.  Don't replace the clutch without replacing the clutch cable and helper spring first.

     The photos that accompany this article are taken of my 1982 911SC, and may differ slightly from your car depending upon the year and transmission.  The procedure should be the same for all of the later model 915 transmissions (1973-89).  I will add some details on the clutch cable replacement procedure for cars with the 901 transmission in the near future.  In general, the principles of cable replacement are the same, and you should be able to garner enough information from this example to apply to your own 911.  Besides, you can always feel free to ask us questions.

     Replacement of the cable is a really simple job.  I like to start at the end of the cable that is located underneath the pedals on the driver's side.  You can gain access to this end of the cable by removing the wooden floorboard that protects the pedal cluster.  Start by taking out the driver's side floor mat and carpet.  The wooden floorboard is attached to the chassis by a few nuts.  Remove these, and you should be able to negotiate the board out of its position.  Once you have the floorboard removed, the pedal cluster should be visible, as shown in Figure 1.

     The first step is to locate the end of the clutch cable that is attached to the pedal cluster.  The cable has a trunion pin on the end, and a small retaining clip in order to hold it onto the pedal cluster end.  The trunion pin and retaining clip are shown in Figure 2.  Depending upon the age of your car, and the amount of corrosion in your pedal cluster area, the retaining pin may be difficult to remove.  I would spray the entire area with some WD-40, and let it sit for awhile as the lubricant gets into the retaining pin.  A long screwdriver, a pair of vise-grips, and plenty of elbow grease should loosen it up enough for you to get the retaining pin off.  Don't worry about damaging the pin either, as they are pretty inexpensive to replace.

     Once you get the retaining clip removed, you need to remove the trunion pin.  This is because you will pull the cable out of the car from the rear.  When you have the cable disconnected and the trunion pin removed, your car should resemble Figure 3.

     Now it's time to move to the other end of the cable, located under your transmission.  Unless you are really, really thin, you will need to jack up the car.  Refer to our Pelican Technical Article, 911 Engine Removal Made Easy for instructions and pictures on the best methods to jack up and secure your car.  Once the car is elevated, take a closer look at the clutch lever arm assembly.  You need to remove the clutch cable from where it is clamped to the transmission.  Figure 4 shows the clutch cable adjustment nuts, which both adjust the throw of the clutch, and secure the cable in place.  Loosen up these two nuts, and the cable should slide right off.   When there is slack in the cable, the end should slide off of the hook, shown in Figure 5.  Now pull out the cable from underneath the car.  If you have properly removed the trunion pin from the other end of the cable, it should just slide out underneath the car.

     Installation of the new cable is relatively easy.  Take the new cable, and guide the threaded end into the tube located on the firewall.  Figure 6 shows where the cable should go.  Once you have the new cable pushed up against the firewall (Figure 7), then make sure the protective sheath surrounds the tube, as shown in Figure 8.  Once the cable is in place, you can move back to the front of the car, and screw on the trunion pin and reattach the cable to the pedal cluster.  I advise using a new retaining clip.  Don't reattach the floorboards just yet, as you might need to adjust the position of the trunion on the clutch cable later on.

     Now it's time to replace your helper spring, shown in Figure 9.  I highly recommend doing this when you replace your clutch cable.  The helper spring does what its name implies - it helps with the motion of engaging and disengaging the clutch.  With many cycles on the clutch, it can lose it's ability to 'help.'  To replace the helper spring, you need to remove the clutch cable lever arm assembly, shown in Figure 10.  Start by removing the small return spring that helps remove the backlash from the linkage, as shown in Figure 11.  Make sure that you disconnect and remove the spring , because it will most likely get lost.  Now, remove the small circlip on the small lever arm, as shown in Figure 12.  Slide this arm off its shaft using a small screwdriver.  This is shown in Figure 13.  Once this arm is off, the main arm assembly should be able to be slid off.  Beware of the force of the 'U-shaped' clutch arm helper spring, as this is loaded pretty tight, and will spring back when you pull off the arm.  The helper spring can only move within a small radius, so you don't have too much chance of getting hurt unless you purposely stick your fingers in there.  Figure 14 shows the entire lever arm assembly being removed.  After the entire assembly is removed, the bottom of your transmission should look like Figure 15.

     Getting the helper spring off of the shaft on the lever arm is probably the hardest part of this job.  The Porsche factory manuals recommend that you press out the entire little shaft that the helper spring is attached to.  I feel that's not necessary and a bit too much work.  Start by removing the small circlip that appears to hold in the helper spring on.  In reality, this circlip basically does nothing because the helper spring is pressed onto the small shaft that it rotates on, as shown in Figure 16.  I removed my helper spring by cutting it off with a Dremmel rotary tool.  The Dremmel tool is one of the most important tools in my collection.  I used it to cut the outer 'layers' of the helper spring, and most of the last layer.  If you are careful in your cutting, you should be able to cut close enough so that you can then snap off the remaining helper spring 'layer' with a screwdriver.  This seemed to be better than replacing a whole bunch of parts in the arm assembly that got ruined when you pressed out the helper spring shaft.

     Installing the new helper spring is a breeze; just tap it on with a hammer.  Just make sure before you tap it on that it's facing the correct way, otherwise you might have a difficult time getting it off.  If you happened to damage the circlip when removing it (I did), then use a new one.  Make sure that you install all of the washers in the proper order.  Refer to Figure 17 for guidance.  Once you have the new helper spring installed on the clutch lever arm assembly, install the assembly back onto the transmission.  Be careful to align the splined small lever arm into the correct position.  There should be an adjustment screw that should be very close to contacting the larger lever arm, as shown in Figure 18.

     Once you have the entire assembly installed, you are ready to adjust your clutch cable.  With the cable completely disconnected, adjust the small adjustment screw, shown previously in Figure 18, until you have a clearance gap of 1.2 mm.  This procedure is shown in Figure 21.  Tighten up the adjusting screw with the lock nut.  Now, attach the new clutch cable end (Figure 19) to the small hook on the lever arm, as previously shown in Figure 9.  Tighten up the clutch cable until the clearance gap between the small arm and the release arm decreases to 1.0 mm.  This procedure is shown in Figure 22.  If you have trouble meeting this distance within the range of travel of the adjusting nuts, then you might need to readjust your trunion pin on the other end of the clutch cable.  Now, check the clutch release travel.  Reinstall the floorboard over the pedal cluster.  Measure the distance that the release lever travels when the pedal is pressed (you will need an assistant for this one).  Figure 23 shows the length that you should measure.  Take a measurement of this distance, and then have your assistant step one the clutch pedal.  Then take another measurement.  This travel, which is the result of the first measurement minus the second measurement, should be 25 mm +- 0.5 mm.  If this travel is not within this range, then adjust the floor stop on the floorboards (Figure 24) to obtain this travel distance.

     Well, that's about it.  The clutch cable and helper spring are two items that seem to wear out consistently on these cars, and it is a very wise idea to replace them when you are doing a clutch job, or before you do any major clutch work.  This Pelican Technical Article was brought to you by the good people at Pelican Parts, who depend upon your business to help support this FREE and growing website.  Please make sure that you tell all your friends about the internet's largest Porsche and BMW site, and also make sure that you consider letting Pelican Parts earn your future business.  If you have any questions, concerns or (heaven forbid) any complaints, as always you can send us email, or give us a call at 1-888-280-7799. 

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