As much as I have enjoyed the two 911s I have owned, neither one shifted like I thought a true sports car should. Even with replacement of all the bushings in the shift linkage, the shift throws were still long, vague and imprecise. In my current 1983 911SC, the shift from second to third was sometimes balky. The factory short shift kit was the answer to all my complaints. My only regret is that I didn't install it sooner.
The best thing about this short shift kit compared to others is that it was designed and engineered by the factory as an option (M241) that could be specified when the car was ordered, or installed later if desired. One of the reasons Porsche encouraged the use of the short shift kit was that it provides additional room for moving the seat further forward for shorter drivers. It was also recommended for the sporting driver.
The factory design takes a different approach than aftermarket short shift kits, as shown by the greater number of parts in this kit, and by the quality of the parts. Just one of the superior design features of the factory kit is that while it reduces the length of the throw to shift gears, it maintains the lateral spacing of the gears in the shift pattern 1/2 the side-to-side motion is reduced by only a small amount. This makes it more unlikely that you will select the wrong gear.
Keep in mind that the laws of physics are still in force, and that when we reduce the movement required to shift gears, the shifting effort goes up a little bit. However, the short shift kit will make shifting seem quicker because the throw is shortened. I didn't find the slight increase in shifting effort significant.
Clockwise from the top left, Figure 1 shows a new shift rod bushing and shift lever ball cup bushing. Both of these are inexpensive and should be replaced. If these bushings are even slightly worn or tired, it will induce sloppiness into the shift linkage. Following the bushings in (Figure 1) are the parts included in the factory kit: the lock pawl plate, shift pivot housing, stop plate, shifter pivot pin, springs, shifter guide plate, and shift lever. In the improved design, the shift lever and the shift pivot housing are modified, with a raised pivot point. Figure 1a shows the new shift lever at the top, and the new shift pivot housing at the left.
To begin the installation, remove the console. Start by removing the cover at the front end of the console, which is retained by four screws (Figure 2 and Figure 3). Next, remove the trim piece inside the console opening, by removing the two screws on the left outside of the console (Figure 4). Remove the knobs from the air conditioner temperature and fan controls, and remove the retaining nuts for these two units. Take out the two screws on each side of the console, and pull down the AC control panel. Push the two AC control units through the hole in the front of the console, and unplug the stereo fader unit wiring at the white multi-pin plug (Figure 5). Take out the screws that hold the bottom of the console to the tunnel. There are two in the front, and one hidden under the carpet in the rear. Remove the console from the car by rotating and pulling it up.
Remove the passenger side footboard, pull the carpet up over the shift lever, and fold it back (Figure 6). The 22mm locknut for the set screw on the front of the shifter housing must be loosened. On my car, it was fairly tight, so this is a good time to break it loose (Figure 7). There are five allen-head screws in the base of the shift tower, three which hold the tower (6mm allen-head), and two which hold the shift rod bushing bracket (5mm allen-head) Take out all five of these screws, pull the shift tower straight up, and remove it from the car (Figure 8).
Remove the shift lever coupling by taking out the set screw on the left side (Figure 9). Slide the shift rod bushing bracket off the shift rod, and remove it from the car. Replace the shift rod bushing, and reinstall the bracket and the coupler (Figure 10).
Before disassembly, take a good look at the shifter mechanism from the top and bottom, and note how the parts fit together and function. Disassemble the shifter mechanism by placing it on its side in a vice, and removing the two 10mm lock pawl plate retaining nuts. Slowly open the vice, releasing the pawl plate springs. Remove the locking clips from the shifter pivot pin and remove the pin. The shift rod can now be removed, along with the other internal parts.
To install the new shift pivot housing, the set screw in the front of the shifter housing (Figure 7) must be removed. Then drive the roll pin at the opposite side out just far enough to remove the shift pivot housing (Figure 11). Reassemble the shifter mechanism using the new parts, as shown in the diagram (Figure 11a). Tighten the set screw in the front of the shifter housing just to the point that end play in the shift pivot housing is eliminated, and tighten the locknut. Lubricate all of the contact points in the shifter mechanism. I used a spray lubricant that dries into light grease-Wurth HHS 2000.
Reinstall the shifter mechanism into the car (Figure 13). First, install the two screws into the shift rod bushing bracket (5mm allen-head), and then the three shifter mechanism mounting screws (6mm allen-head).
If you plan to reuse your stock shifter knob, the shift lever may be too long for it to fit correctly (Figure 14). I had to trim about 13mm from the tip of the shift lever for the shift knob to bottom onto the annular ring (Figure 15). You can remove the knob from the old shift lever by clamping the lever in a vice, and using a 15mm open-end wrench and a mallet to drive it off. You may also be able to reuse the crush ring for the shift knob, but it is an inexpensive part, so it is a good idea to have a new one on hand. Be careful with the shift knob-OEM replacements are very expensive.
After installing the short shift kit, I took the car for a test drive. Now it shifts like a sports car should, with precise, shorter throws. It is easy to select the correct gear, without worrying about damaging the transmission or the engine by missing a shift. This kit is one of the nicest upgrades I've done to my 911, and it really increases driving pleasure.
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Hope this helps,