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914 Transmission Selector Rod Seal Replacement

Pelican Technical Article:

914 Transmission Selector Rod Seal Replacement


2 hours2 hrs






17mm hex key, small pick or flathead screwdriver, vise and old screw and nut to press out roll pin, hammer, metric wrench set and metric socket set

Applicable Models:

Porsche 914 (1973-76)

Parts Required:

1 large O-ring for the selector mechanism and 1 rod selector seal, gear oil

Performance Gain:

No more gear oil leaking from the selector knob

Complementary Modification:

Make the side-shifter improvements documented in another Pelican Parts DIY article

One of the most common sources of transmission fluid leakage on the 901 transmission is the shifter rod selector. This is the small ball cup joint to which the end piece of the shift linkage is connected. This tech article covers the replacement of the two seals that are supposed to limit the amount of transmission fluid that leaks past the seals. Since the tail shifter and side shifter are dramatically different in this category, we will focus on only the side shifter (1973-76) for this article.

The first step in replacing the seal on the shifter selector is to empty the transmission of all the gear oil inside. For more information and details on how to do this, please see our Pelican Technical Article, "Repairing First Gear on the 901 Transmission." Once the transmission is empty, then you need to disconnect the shift linkage from the selector rod. For detailed instructions on how to disconnect the shift linkage, please see our Pelican Technical Article, "914 Shifting Improvements.

After you remove the shift linkage, then your transmission should resemble Figure 1, with the black plastic shift selector removed. If you are missing your shifter boot, then Pelican Parts can provide you with a new one, or a good condition used one.

Now that you have the transmission drained, and the shift linkage disconnected from the transmission, you need to remove the selector mechanism. This is easily done by loosening and removing the two nuts that hold it to the transmission case, as shown in Figure 2.  Make sure that the transmission is in neutral before you disconnect the selector mechanism. The transmission is in neutral if the selector knob is perpendicular to the direction of travel of the car. After the two nuts have been removed, then the selector mechanism can be twisted out of the case.  Figure 3 shows the selector mechanism removed from the transmission.

There are two seals that have a tendency to leak. It is difficult to tell which one is leaking, so it is advised that you replace both of them. The first and easier one to replace is the large o-ring that surrounds the entire selector mechanism. Remove this o-ring using a small pick or screwdriver, being careful not to damage the metal surface around the outside of the o-ring. Replace the new o-ring after first placing a little bit of gear/transmission oil on the o-ring to lubricate it prior to installation.

The second seal that needs to be replaced is the selector shaft seal. To replace this seal, you need to remove the selector knob off of the bottom of the shaft. The only way to get the selector knob off is to press out the roll pin inside of the selector. You can attempt to press it out yourself, or you can take it to a machine shop that can do it for you.  This roll pin can be seen in Figure 4

The best method of pressing out the roll pin involves using a vise and an old screw and nut. Place the screw against the roll pin, and place the nut on the opposite side. Place the entire assembly in a vise, and crank down, as shown in Figure 5.   Complete the entire process by gradually increasing the length of the screw, and also the depth of the nut. You can use a large socket in place of the nut, if it's too short for the roll pin. You only need to press out the roll pin far enough to remove the selector knob off of the end of the shaft. Removing the entire roll pin will make it very difficult to press it back in later on.

After the roll pin is pressed out far enough, make sure that the selector knob can be rotated slightly on the shaft, and is free of the roll pin. Then, holding the selector knob in a vise, lightly tap the shaft with a hammer, and separate the knob from the shaft. The shaft should tap out pretty easily if the roll pin is no longer engaged.  The assembly disassembled is shown in Figure 6.

After the selector knob has been tapped off, remove the shaft from the main assembly. Make sure that you grab the plastic washer that goes on the shaft. The black seal is located on the bottom of the main assembly. Use a pick or a screwdriver to remove the old seal, as shown in Figure 7 and Figure 8. Be careful not to damage the metal surfaces that the seal mounts into. Figure 9 shows the seal removed.  A new seal is shown in Figure 10.   Install the new seal into the main assembly by lightly tapping it in with a hammer, as shown in Figure 11.   Make sure that it goes in evenly.  Use the back end of a screwdriver, as shown in to make sure that the seal seats flush with the housing, as shown in Figure 12 and Figure 13.  The finished, installed seal is shown in Figure 14.

After you have the new seal installed, then lightly coat the shaft with some transmission oil, and reinsert it into the main assembly. Now, place the selector knob onto the shaft, and line it up with the hole for the roll pin. Make sure that you don't forget the small plastic washer that goes on the shaft. Make sure that the selector knob is facing the correct way in relation to the selector forks on the other end of the shaft. If you press in the roll pin incorrectly, then you will have to remove it again. Use the vise to press the roll pin back into position. Don't force it if you can't clamp down on it, as the selector knob may have rotated slightly on the shaft and the roll pin may not be correctly aligned.

After you get the roll pin pressed back in, you are no ready to reinstall the entire assembly back into your transmission. Installation is easy, you just need to wiggle the assembly to get it back into the transmission. Don't press too much against the shift forks inside the transmission, or you might accidentally put the transmission in gear, which will make it more difficult to reinstall the assembly. Tighten down the two nuts, and make sure that the assembly is engaging the shift forks correctly by twisting the selector knob, and seeing if you can engage some of the gears.

Now would be a good time to replace some of your shift bushings if they are worn. Please see the Pelican Technical Article, "914 Shifting Improvements" for more details. Now, reconnect the shift linkage, and replace the black plastic cover. This cover is normally held on with a bandoleer type clamp that often falls off. Pelican Parts stocks this clamp, or you can use nylon zip ties as an adequate replacement.

Well, that about does it. It's really not a very difficult job. Your transmission shouldn't be leaking any more from the selector knob. Remember that this technical article, and the others like it are possible only with your continued support of Pelican Parts. For the best in parts for your car, please give us a call at 1-888-280-7799, or simply email us. If you have any questions or comments regarding this technical article, please email us. Thanks for your support.

Figure 1

Selector Assembly Attached to Transmission

Figure 2

Selector Handle

Figure 3

Transmission Selector Assembly

Figure 4

Roll Pin that Holds Selector Handle

Figure 5

Pressing Out Roll Pin

Figure 6

Gear Selector Disassembled

Figure 7

Removing Seal

Figure 8

Removing Seal

Figure 9

Seal Removed

Figure 10

New Shift Rod Selector Seal

Figure 11

Installing Seal

Figure 12

Use Screwdriver to Install Seal Flush

Figure 13

Seal Flush

Figure 14

Seal Installed

Comments and Suggestions:
Robert Comments: Would be good to have this procedure for a tail shifter, which I have.
How do I remove the selector shaft which has the seal around it as it passes into the transmission case so I can remove and replace seal? Via the 4 bolt access plate on bottom of case? Or?
Thank You, Robert
February 4, 2017
  Followup from the Pelican Staff: You have to remove the shift shaft roll pin, then extract the shaft. Replace O-rings and seals, then reassemble. It's quite a bit of work compared to the version shown.
We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

- Nick at Pelican Parts
emachine Comments: Is there two seals?? I just see one...what size is the other?? can I purchase it from you in a o ring seal set?
October 10, 2012
  Followup from the Pelican Staff: There is one seal. Give our parts specialists a call at 1-888-280-7799. They can help you find the right part. - Nick at Pelican Parts  

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Page last updated: Wed 2/21/2018 02:22:16 AM