05-28-2006, 08:32 PM
When my 968 Cab suddenly developed “no-tip” mode but worked fine in regular auto (left side) PRND321 mode, I suspected either electrical or mechanical gremlins.
A quick search for posts generated no helpful posts and neither did a relay swap.
Out came the tools. The solution is well within the scope of DIY and permanent fix.
1. car level and P Brake ON & ignition OFF
2. move the tip shifter back to “1” so you can remove the Clock cubby (just get your hand into the cubby and get a grip on the sides / bottom and pull straight back to remove it. There are 2 connectors in the back – remove them by grasping the connectors. Set the cubby aside (good time to clean it up, repaint the faded hands – Testors makes a fluorescent paint that is almost a perfect match. Change the burned out bulb, etc.
3. Remove the ashtray (pull straight up)
4. remove the shift knob (I changed mine to a 986 shifter)
5. Remove all 4 phillips screws with washers holding the black centre trim for the shifter– 2 front, 2 in back – in the 4 corners
6. GENTLY pull the centre trim frame up to expose the wiring harness attached to the various switches. Work the connectors off the switches carefully – some of the connectors can be really tight and the frame is pretty fragile so take your time. Once you have all the connectors off, set the frame aside.
7. You should now be able to see the Tiptronic “guts” – a tribute to Rube Goldberg if there ever was one! So many switches, pins, and little moving parts. It’s a wonder it all worked for 100,000 miles on my car!
8. As I had lost the UPSHIFT function in the Tip mode, I focused on the mechanical functions on the PS of the console.
9. Basically, the shift lever actuates a microswitch to engage the Tip function when the lever is moved over to the PS of the console. Then pulling back or moving it forward trips another microswitch. The Rube Goldberg part is that the shifter does not directly engage the switches, but instead works on nice shiny chrome pins running in plastic guides. These in turn engage the switches when the “domed head” of the pin moves in the quides!
10. The problem is that the guides are plastic, and there is a pretty hefty return spring in the hollowed metal pin that puts a lot of pressure on the plastic guide.
11. Strangely, the Rear Downshift guide on my car has a screw/locknut that acts to locate the spring when under tension. The Front Upshift guide however did not have that centering screw – just a molded plastic 1mm pin! That plastic pin finally failed after 15 years / 100,000 miles and how many Tip upshifts. I was pretty sure that even IF you could buy that plastic guide and pin assembly, it would take a Porsche Tech a few hours to replace as it looked to be a “remove A to get to B, then C…… to Z+ before you could actually swap out the broken guide.
12. There’s actually a decent amount of clearance to the front, rear and top of those guides, and since their function is pretty easily defined – back and forth to trip a fixed micro-switch, I decided that a metal “L” bracket and a carefully located screw would do the trick.
13. Fortunately, the 5mm Allen head cap screw holding the right front of the TIP assembly was the perfect way to hold down my homemade “L” bracket.
14. I fabricated the bracket from a piece of scrap 3/32” steel “L” and roughly made various measurements for mounting. I ended up making the mounting hole large enough to allow for adjustment on installation.
15. As for the pin, I used a 8-32 x 1” machine screw – I tapped the “L” bracket for it to save space (no backing nut required). Then to make sure the return spring would slide smoothly on this locating screw, I just put the screw into my HS drill and applied enough effort against a flat file to smooth out the bottom 3 / 4” of the screw. That left enough thread on the top below the screw head to fix it to the L bracket!
16. A quick test assembly to check for proper action, then removing the L bracket for a shot of silver lacquer (stop the rust) before final assembly
17. Putting it all back together is pretty straightforward.
18. Tip action works perfectly again. I am worried about those plastic guides though – they are pretty vulnerable as they take all the loads from the moving parts whenever you use the Tip function.
If your Tip doesn’t shift – up or down – and especially if you cannot feel any resistance from the return springs in the Tip mode, the plastic guides are probably broken.
Hope this helps someone out! If anyone knows if you can buy the plastic guide and pin on that tip shifter assembly, please advise!
A quick search for posts generated no helpful posts and neither did a relay swap.
Out came the tools. The solution is well within the scope of DIY and permanent fix.
1. car level and P Brake ON & ignition OFF
2. move the tip shifter back to “1” so you can remove the Clock cubby (just get your hand into the cubby and get a grip on the sides / bottom and pull straight back to remove it. There are 2 connectors in the back – remove them by grasping the connectors. Set the cubby aside (good time to clean it up, repaint the faded hands – Testors makes a fluorescent paint that is almost a perfect match. Change the burned out bulb, etc.
3. Remove the ashtray (pull straight up)
4. remove the shift knob (I changed mine to a 986 shifter)
5. Remove all 4 phillips screws with washers holding the black centre trim for the shifter– 2 front, 2 in back – in the 4 corners
6. GENTLY pull the centre trim frame up to expose the wiring harness attached to the various switches. Work the connectors off the switches carefully – some of the connectors can be really tight and the frame is pretty fragile so take your time. Once you have all the connectors off, set the frame aside.
7. You should now be able to see the Tiptronic “guts” – a tribute to Rube Goldberg if there ever was one! So many switches, pins, and little moving parts. It’s a wonder it all worked for 100,000 miles on my car!
8. As I had lost the UPSHIFT function in the Tip mode, I focused on the mechanical functions on the PS of the console.
9. Basically, the shift lever actuates a microswitch to engage the Tip function when the lever is moved over to the PS of the console. Then pulling back or moving it forward trips another microswitch. The Rube Goldberg part is that the shifter does not directly engage the switches, but instead works on nice shiny chrome pins running in plastic guides. These in turn engage the switches when the “domed head” of the pin moves in the quides!
10. The problem is that the guides are plastic, and there is a pretty hefty return spring in the hollowed metal pin that puts a lot of pressure on the plastic guide.
11. Strangely, the Rear Downshift guide on my car has a screw/locknut that acts to locate the spring when under tension. The Front Upshift guide however did not have that centering screw – just a molded plastic 1mm pin! That plastic pin finally failed after 15 years / 100,000 miles and how many Tip upshifts. I was pretty sure that even IF you could buy that plastic guide and pin assembly, it would take a Porsche Tech a few hours to replace as it looked to be a “remove A to get to B, then C…… to Z+ before you could actually swap out the broken guide.
12. There’s actually a decent amount of clearance to the front, rear and top of those guides, and since their function is pretty easily defined – back and forth to trip a fixed micro-switch, I decided that a metal “L” bracket and a carefully located screw would do the trick.
13. Fortunately, the 5mm Allen head cap screw holding the right front of the TIP assembly was the perfect way to hold down my homemade “L” bracket.
14. I fabricated the bracket from a piece of scrap 3/32” steel “L” and roughly made various measurements for mounting. I ended up making the mounting hole large enough to allow for adjustment on installation.
15. As for the pin, I used a 8-32 x 1” machine screw – I tapped the “L” bracket for it to save space (no backing nut required). Then to make sure the return spring would slide smoothly on this locating screw, I just put the screw into my HS drill and applied enough effort against a flat file to smooth out the bottom 3 / 4” of the screw. That left enough thread on the top below the screw head to fix it to the L bracket!
16. A quick test assembly to check for proper action, then removing the L bracket for a shot of silver lacquer (stop the rust) before final assembly
17. Putting it all back together is pretty straightforward.
18. Tip action works perfectly again. I am worried about those plastic guides though – they are pretty vulnerable as they take all the loads from the moving parts whenever you use the Tip function.
If your Tip doesn’t shift – up or down – and especially if you cannot feel any resistance from the return springs in the Tip mode, the plastic guides are probably broken.
Hope this helps someone out! If anyone knows if you can buy the plastic guide and pin on that tip shifter assembly, please advise!
