Pelican Technical Article: Shifting Improvements Wayne R. Dempsey
Time: 3 hr
Tab: $35-$85
Talent:
Tools:
Socket Set, Hex Keys
Applicable Models:
911 (1965-86) 930 Turbo (1975-86) 912 (1965-69)
Parts Required:
Shift Coupler or Coupler bushings, Shift Rod Bushing, Shifter Bushing
Hot Tip:
Install all the bushings using a little lithium grease
Performance Gain:
Better, more precise shifting
Complementary Modification:
Install the factory short shift kit
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.
Check out some other sample projects from the book:
Porsches have never really been known for their supreme shifting abilities. Very often on the older 911s, the shifting ability deteriorates as the years go by. While many people blame their transmissions and prepare for a full rebuild, their worries may be needless. In many cases, the shift bushings have simply worn out and need to be replaced. Worn bushings can result in sloppy shifting, misplaced shifts, and grinding when engaging gears. Most people are amazed at the improvement that occurs when they replace their bushings. A mere $45 spent on new bushings is a heck of a lot cheaper than a $1500 transmission rebuild.
The first step in replacing the bushings is to gain access to the shifter. On the later 911s, the center console surrounds the shifter, and needs to be removed. There are three screws that secure the console to the chassis floor. The front access panel of the console hides the two screws located in the front of the car. The rear screw is usually hidden under the carpet, and requires some fishing around in order to locate it.
Once you have the center console removed, you should be able to pull away the carpet and gain access to the shifter. Be careful not to tear your carpet when pulling it back. The original carpet was glued to the floor, and has a tendency to weaken with age.
The shifter is bolted down to the floor with hex socket cap screws. Simply place the car into first gear, unbolt the shifter from the floor, and remove it from the chassis. Placing the transmission in gear prior to removing the shifter helps to keep the transmission selector rod from moving when disconnecting the shift rod coupler later on. The shifter bushing is a ball cup bushing, and is located at the base of the shifter handle. Remove the old one and pop on the new one. Make sure that you put some lithium grease in the new bushing before you install it.
Now, move behind the front seats and remove the small access panel that is located on the center tunnel. Underneath, you will find the shift coupler that connects the shift rod to the transmission selector rod. Using a permanent marker, mark the location of the coupler with respect to the shift rod: you will need to line it up again later. Make sure that you mark the rotational position of the coupler, as well as its location along the length of the shift rod. Remove the coupler by loosening up the hex key cone screw, and the clamp on the shift rod.
The two bushings that are located within the shift coupler often wear with age. The center pin of the coupler needs to be pressed out and removed in order to fit the new bushings. Installation of the new bushings is not an easy job, and is perhaps best left to a machine shop with a heavy-duty press. Its quite easy to damage the aluminum coupler if you dont have the proper tools. An alternative to replacing the bushings is the replacement of the entire coupler. For only a few dollars more, you can replace the coupler with a brand new one, and forget about the hassle of pressing out the center pin.
With the shift coupler disconnected, the shift rod bushing can be removed. This bushing is located behind the shifter in the center tunnel. Its held in place by a bracket that mounts to the top of the center tunnel. To remove this bracket, unbolt it from the top of the tunnel. Then disconnect the ball cup bushing adapter that is mounted to the end of the shift rod. It may require some maneuvering in order to get the adapter off and the bracket out. Install the new bushing into the mounting bracket, and then replace it in the center tunnel.
On the 1973 and earlier cars, the shifter has a concave ring-shaped bushing that tends to wear out over the years. In addition, the lockout springs within the shifter assembly tend to become weak with age. When you have the shifter out of the car, its a wise idea to disassemble it and replace these parts. For all year cars, its a wise idea to clean and grease the shifter while you have access to it. If you want to install a short shift kit (Pelican Technical Article: Installing a Short Shift Kit), now would be an excellent time to do it.
When reinstalling the entire shifting system, make sure that you line up the coupler in the same place that you marked previously. If you werent happy with the alignment of the shifter previous and you often nicked gears when shifting, then you might want to readjust your shifter.
The procedure for adjusting the shifter is simple. Reattach the shift coupler to the transmission, but keep the clamped end of the shifter rod very loose. With the transmission in first gear, place the shifter into the upper left hand corner of the shift pattern. Now, clamp down on the shift coupler. The shift assembly should be properly adjusted in this position, and the shifter should cleanly lock into all gears including reverse. However, depending upon transmissions, chassis, and linkages, this doesnt always work on the first try. It may be necessary to loosen up the coupler clamp again, and play with the final adjustment of the shifter.
You can gain access to the shifter by removing the center console. The console is held in place by three screws that mount it to the floor of the chassis. In order to access the two screws in the front, remove the front-most part of the console. The third screw may be difficult to locate, as the carpeting usually covers it.
Pull the carpeting back to reveal the shifter, which is mounted to the chassis floor. Unbolt the shifter and remove it from the floor. The bottom of the shifter contains the shifter bushing, which wraps around the shifter rod. Remove and replace this bushing, using a little lithium grease spread inside the bushing. Make sure that the bushing is on tight; air tends to get trapped inside the ball cup, and can unexpectedly pop the bushing off of the end of the shifter.
Removing the access panel behind the front seats reveals the shift rod coupler. The two bushings in the coupler often wear with use, as sometimes does the small cone screw that holds the coupler in place.
New bushings installed in the coupler make a world of difference when shifting your 911. These bushings cost about $20 for a pair, and a new coupler itself is only about $50. Be careful when reinstalling the coupler. If the screw hole in the coupler is not perfectly lined up with the hole in the shift rod, you can cross thread the coupler when tightening the cone screw. If this happens, the coupler is destroyed, and needs to be replaced.
The shift rod bushing supports the shift rod in the tunnel. In order to replace this bushing, remove the bracket that holds it in place. It is held on by two screws that fit through the top of the center tunnel.
Comments: Just finished this exercise and have a few suggestions. 1. Replace the coupling bushings first because they are easy to access and mine were extremely worn. The removal/replacement is about 30 minutes TOPS. BE SURE TRANSMISSION IS IN 1ST GEAR because that's what you need for final adjustment and then you don't have to worry about moving the gear shift when removing the coupling. CONCLUSION: What a huge difference, there was abolutely no play or slop ANYWHERE. 2. Everything in the coupling like pin, bushings, shaft, and coupler is an "interference" fit which means "really tight". Beating it apart and back together will most likely mean buying a new one. I took mine to car repair with a hydraulic press. It took about 15-20 minutes and he didn't even want to charge but I gave him $10. Machine shop wanted $100 just to look at it. 3.The article said "remove the console" and left it at that, like no big deal. Another article said remove all the controls in console; DON'T. However, do remove the passenger side carpet and foot board underneath to access the wiring harness connections in center tunnel. Check wiring color before disconnecting but all should match. I couldn't really remove the console completely because it was attached by the decorative leather boot on the gear shift shaft but you have to disconect the wiring.
March 8, 2012
Golfdadbob
Comments: Where can I buy a $50 coupler?
March 7, 2012
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