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HomeTech Articles > Replacing and Adjusting the 911 Clutch - Page 1

Pelican Technical Article:

911 Clutch Replacement
Page 2

Difficulty Level 7

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

[Click on Photo]

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Figure 24: New Flywheel Bolts

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Figure 25: Torquing Flywheel Bolts (915)

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Figure 26: Special Flywheel Bolt Tool (915)

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Figure 27: 915 Flywheel Installed

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Figure 28: 901 Flywheel Installed (901)

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Figure 29: Placing Disc on Flywheel (915)

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Figure 30: Disc Placed Inside of Flywheel (901)

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Figure 31: Clutch Alignment Tool

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Figure 32: Aligning Disc (901)

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Figure 33: Aligning Clutch Disc (915)

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Figure 34: Proper Order of Rings for Installing Throw-Out Bearing (915)

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Figure 35: 915 Pull-Type Pressure Plate

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Figure 36: Throw Out Bearing and Ring (915)

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Figure 37: Throw Out Bearing Retaining Ring (915)

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Figure 38: TO Bearing Placed in Flywheel (915)

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Figure 39: Rear Ring Behind TO Bearing (915)

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Figure 40: Rear Retaining Ring (915)

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Figure 41: TO Bearing Installed (915)

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Figure 42: Throw Out Bearing Installed (915)

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Figure 43: Original NOS 901 Pressure Plate

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Figure 44: Clutch Alignment Tool (915)

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Figure 45: Clutch Alignment Tool (915)

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Figure 46: Using Clutch Alignment Tool (901)

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Figure 47: New Bushing Installed in Throw-Out Arm

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Figure 48: Original NOS 901 Throw-out Bearing

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Figure 49: Grease Shafts, Install New Throw-out Bearing

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Figure 50: Reassemble Throw-out Fork Assembly

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Figure 51: Transmission Still in Car

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Figure 52: Throw-Out Bearing Arm

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Figure 53: Throw-Out Bearing Arm

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Figure 54: Removing Pin for Throw-Out Bearing Arm

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Figure 55: Bushing for Throw-Out Arm

     When you mount the flywheel, you should also use new flywheel bolts, as shown in Figure 24.  These bolts are under a lot of stress, and should really only be used once.  You would hate to have one stretch or strip next time you need to to a clutch job.  Place the flywheel on the crank and attach all of the flywheel bolts.  Attach the flywheel lock and begin to torque them down.  Start by using a low torque and then work your self up to the working values of 150 N-m for the 911s through 1977, and 90 N-m for the 1978-89 911s.  Figure 25 (915) shows the use of a torque wrench to tighten down the flywheel bolts.  It is imperative that you use a torque wrench for this procedure.  If you don't have one - buy one.  Don't guess on this one, and don't be cheap either.  Having the right tools for the job will mean the difference between a good job and one that will fail later on. Speaking of proper tools, you will need that special flywheel removal tool that you used previously.  Figure 26 shows the process of tightening the bolts using this special tool.  Once you have your flywheel attached properly, it should resemble Figure 27 (915) and Figure 28 (901).  Now would be a good time to install your starter ring onto your 

     Now it's time to install your pressure plate and clutch disc.  The procedure is nearly identical for both the 901 and 915 transmission.  Once the flywheel is attached, remove the flywheel lock and place the new disc on the flywheel with the center knob pointing out towards the rear of the car, as shown in Figure 29 (915) and Figure 30 (901).  Place the clutch alignment tool (Figure 31) in the center of the flywheel and clutch disc.  Make sure that the tool is in tight, as shown in Figure 32 (901) and Figure 33 (915).

     It's now time to install the pressure plate.  If you have a 901 transmission, you can skip over the next few paragraphs, as these will describe the tricky installation of the 915 throw-out bearing.  As mentioned previously, the 915 is a pull-type clutch mechanism.  This means that the throw-out bearing is attached to the pressure plate.  In the box with the new throw-out bearing, you will find a whole mess of rings and clips that are used to attach the bearing to the pressure plate.  Figure 34 shows the arrangement of these clips.  Start with your new pressure plate, as shown in Figure 35.  Place the circular ring (#9 from Figure 34) around the throw-out bearing, as shown in Figure 36.  Then place the spring clip (#10 from Figure 34) on top of the circular ring, as shown in Figure 37.  Now, place the throw-out bearing in the center of the pressure plate as indicated in Figure 34.  This should now resemble Figure 38. Place the larger rear ring (#7 from Figure 34) around the throw-out bearing, and attach the whole assembly together with the large circlip (#6 from Figure 34).  This large ring is shown in Figure 39, whereas the circlip is shown being installed in Figure 40.  The throw-out bearing is shown installed in Figure 41 and Figure 42.  I've provided so many pictures here, that you should be able to figure it out.  If you have problems, then it doesn't hurt to take a look at your old throw-out bearing.  This, of course, assumes that the old one was installed correctly, which is not always a valid assumption to make.

     Now, place the pressure plate on the flywheel.  A new 901 pressure plate is shown in Figure 43.  Place all the bolts except one in the flywheel and turn them so that they are finger tight.  Make sure that you install the starter ring (915 transmissions only) so that it is sandwiching the pressure plate between the ring and the flywheel (Figure 45). The pressure plate goes in-between the ring gear and the flywheel. The clutch alignment tool should be sticking out of the pressure plate as shown in Figure 44.  Now, reattach the flywheel lock using the on free bolt hole.  Torque down the pressure plate screws in a criss-cross pattern using the same technique used to attach the flywheel.  After all the bolts are torqued to 14.5 ft-lbs, remove the flywheel lock and tighten the last bolt.  You can use a breaker bar to keep the flywheel from turning while you are torquing down the last bolt.  When you are finished, the installed pressure plate, disc and flywheel should resemble Figure 45 (915) and Figure 46 (901).  Now, pull out the alignment tool.

     Ok, all your work is done on your motor, now it's time to move to the transmission.  The next few paragraphs will talk about what needs to be done to prepare the 901 transmission.  Most of the photos and text is from the 914 clutch replacement article, primarily because the 901 transmission used on the 914 is nearly identical (with respect to the clutch) to the 901 used on the 911.

    The first thing that you need to do on the 901 transmission is remove the throw out arm from the transmission.  Loosen up the screw on the front of the arm and remove it off of the ball that holds it in place.  Make sure you capture the small fork that mounts to the rear of the fork.  Once you have the fork removed, inspect the throw out arm carefully, as these have a tendency to occasionally crack or bend.  Make sure that it is flat and not curved.  Also inspect the small fork that holds the arm to the ball on the transmission.  These often split or crack.   Now pry out the old bushing from inside the fork.  It may take some effort in order to fully remove the bushing.  Make sure that you remove all parts of it, as it has a tendency to break apart when you are trying to pry it out.  Install the new one by tapping it in with a small hammer.  The fork with the new bushing is shown in Figure 47.

     Now remove the throw-out bearing from the shaft of the transmission.  Your new throw-out bearing should resemble the one in Figure 48.  Place the new bearing on the transmission with the new guide clips installed on each end of the bearing.  Grease the shaft a bit before installing the throw-out bearing.  Figure 49 shows a new throw-out bearing (guide clips not yet installed) on the drive shaft.  Make sure that you place some grease on the tip of the shaft for the pilot bearing in the flywheel.   Now attach the throw-out arm and retighten the small fork that holds the arm to the ball on the transmission.  Make sure that the flat edge of the small fork is flat against the back of the throw-out arm when you retighten the arm.  Check the entire assembly (Figure 50) when you are done.   The throw-out bearing should ride smoothly on the shaft.

     Now, for 915 owners, the procedure is completely different.  Figure 51 shows the 915 transmission in the car.  Figure 52 shows the throw-out bearing arm, or the release bearing arm.  This arm often breaks and is definitely worth replacing, even if it looks fine.  Figure 53 affords us another view of the release arm.  In order to remove this arm, you need to tap out the small roll pin that holds it to the release shaft.  Figure 54 shows the process for tapping out the roll pin.  The new arm can be installed on the same shaft.  Use a little white lithium grease before you install it to make sure that it will keep rotating smoothly for many years.  Tap in the new roll pin, making sure that you have the appropriate bushing/spacers on the top of the arm, as shown in Figure 55.  There is another one of these spacers at the bottom of the shaft that you removed when you removed the engine from the car.  After you have installed this throw-out arm, you have completed the clutch job, and you are now ready to reinstall the engine into the car.

     The reinstallation process of the engine is not covered here, but will be detailed in a Pelican Technical Article that will appear on the site in the very near future.  For adventurous types, you can just reverse the installation process of removal.  This technical article, and all of the other ones like it on the site are made available only by your repeated support of Pelican Parts.  If you use this article to install your own clutch, and save hundreds, if not thousands of dollars by doing it yourself, then please help support us by purchasing the parts through us.  Click here for access to our latest 911 catalog, or feel free to email us with any questions or requests.  Remember that your repeated support is what helps this site grow.


Note: If you replace your throw-out bearing guide tube (the piece that the throw-out bearing rides on), you should also replace your transmission main seal (especially on the 915).  The seal and the guide tube interact, and the seal should be replaced when the guide tube is removed.


Click here to look at comments, suggestions, and feedback from other people who have read this article.  Or, add your own feedback, and help everyone else out by learning from your experience! 
Comments and Suggestions:
brithebold Comments: Not written for novices like me. No mention of the indexed washer that the 6 bolts pass through. My question on my new fly wheel there is timing marks including a Z1 mark. I have not been able to attack the wheel so that this Z1 mark matches the Z1 on the fan belt pulley. Must it? What is happening here? It seems off by about 15 degrees if I go to the next bolt hole I am off even more in the other direction? Help Brian PS attaching a 74 2.7 CIS to a 68 901 transmission.
October 7, 2012
  Followup from the Pelican Staff: Hi there. Yes, the 1974 CIS flywheel is a six-bolt crank and uses six flywheel bolts that fit under a thin washer. The flywheel is indexed, meaning there should be no way that you can attach it incorrectly. I will copy this question to the forums, and perhaps others there can assist as well - I'm a little confused as to what the issues are based upon your description here. - Wayne at Pelican Parts  
techtrg Comments: i have read your article which is excellent but my problem is that i have removed all the bolts which attach the transmission to the engine and the engine and transmission will only seperate about one inch where it refuses to come any further. I appears that the release bearing is holding it there. How do I get the two apart i.e engine to seperate from the transmission?. many thanks for any help on this. the car is a 1981 911 fitted with a 5 speed manual transmission.
September 15, 2010
  Followup from the Pelican Staff: You need to disconnect the clutch release mechanism below the transmission - the fork is indeed holding it on. Release the helper spring and let the little lever float free, and it should then come apart. - Wayne at Pelican Parts  
gsxr 1000 Comments: I have a 1991 c4 I need a new clutch can u recomend someone fair an honest in sacramento.
November 29, 2009
  Followup from the Pelican Staff:
I opened a post in our forums. A Pelican community member may be able to answer your question. - Nick at Pelican Parts
 
Ken Faust Comments: I have a 82 911 SC, I read your article on engine removal which is good. My question is do you have any suggestions for removing the tranmission for replacement.
Thank You
November 5, 2009
  Followup from the Pelican Staff: You need to remove the engine in order to remove the transmission, so the instructions are exactly the same. - Wayne at Pelican Parts  
wolfgangk Comments: Hi,
I removed the Throw-out Arm to replace it but forgot to mark its location. Now I have a problem to identify the location of the arm.
What can I use as a reference to install it at the correct location??

Thanks
Wolfgang
October 5, 2009
  Followup from the Pelican Staff: This photo should be helpful. - Nick at Pelican Parts

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