5 Attachment(s)
Converting to a gated shifter
We all know that the 915 gearbox is hardly a paragon of smooth shifting. And its easy for people like me who drive enthusiastically, but who are still getting used to the gearbox, to miss a shift amd overrev because of the imprecision in the shifter.
There are a bunch of solutions from Wevo and others out there that purport to improve the experience. They all require you to bin your original parts to one extent or another. One such example is the Seine Sytems upgrade https://www.seinesystems.com/GateShift-1.htm which requires a change of the dowel pin that the gear lever pivots on, some holes to be drilled and you have to cut your boot to allow for the tension spring that keeps the shifter in the 3-4 plane unless you apply a bit of force to move it over into the 1-2 plane. It essentially recapituales what Porsche did on the 5-R side, but one has to make a number of undesirable modifications.
One bonus of the Seine system is that it has tabs on the 1-2 side and a tab on the gear lever that engages those gate tabs which removes the tension on the gearbox selector mechanism when you are in 1 or 2, just like the tabs on the 5 and R gears do on the stock shifter.
Well a few months ago, I noticed on Pelican that a guy in Germany named Karsten was making a spring that piggybacked over the stock dowel pin in the shifter and did much the same as the Seine spring system but with no modifications to the shifter assembly. http://forums.pelicanparts.com/porsc...nt-spring.html
Clever idea, but it does place tension on the selector mechanism in the gearbox. Whether that matters or not, who knows? But its not ideal, especially if you do any city driving.
But what if you combined the gate tab system of the Seine system with Karsten’s spring? Then you have a completely invisible, reversible modification that might improve the shifting experience and will certainly reduce the chance of a missed shift.
So today I did exactly that. I had gotten the spring from Karsten several months ago and today I went into the shop at work and made a gate with tabs and a piece for the gear lever to engage those tabs.
Here’s the spring, installed. It keeps the gear in the 3-4 plane and you have to apply a litte pressure to the left to take the gear lever over to the 1-2 plane. To give you a sense. it is a bit less pressure than you apply to get over to 5-R, but it gives you a secure tactile feel of where you are in the shift pattern. No 5-2 shifts with this thing!
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Here’s the gate with tabs on 1-2.
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And here’s the inverted tab that holds the sprung lever on the gate tabs. Currently held on with a gear clamp but eventually I’ll tack weld it in place.
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Here is the whole thing in the car.
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And for good measure I replaced the almost new bushings in the coupler at the rear of the tunnel with more precise ones from our own JimmyT. https://www.early911sregistry.org/fo...=1#post1066363. These have a round hole on the internal part of the bushing unlike the Porsche ones that have an oval, but they are made of a material that has some compliance unlike some of the metal bushings out there. All my bushings were new anyways, replaced during restoration, including the selector rod bushing and the cup bushing under the shifter tower. But the coupler always had some slop, by design I imagine, so vibration didn’t get tranmitted to the gear lever.
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Net result? Well, it’s still a 915 and so it just doesn’t want to be hurried, no matter what. But shifting is more of a pleasure and I feel much more secure on rapid downshifts than I did before. I don’t feel the need to double clutch anymore.
Ravi