As we were driving the teener back home from dinner, my wife noticed the shift pattern of the 901 transmission, and asked why is Reverse in the upper left and 5th is lower right. On most American cars, some other Porsches it is in the opposite comfiguration.

I really didn't have an answer, so I said it was so women wouldn't drive them.

She said dont worry about it, I'll figure it out after I get it in the divorce.

Any answers??

The reason for the change from the 901 pattern to the normal "H" pattern was more usability for the "normal" driver.

Like the ignition switch on the left side ( which survived until today) the 901 pattern is a relic from the early Porsche racing configurations.

In the past where the racing start was with a runnig driver ( like early Le Mans race) and the engine was off it was easier to start the engine with the left hand and put the gear in with the right hand. The first gear was very short and not often in use at the most races at this time

My understanding is that first gear was used for so little time that it was considered essentially a granny gear and 2nd through 5th would then be a straight (and quick) H pattern.

When the 901 and 914 transaxles are turned around from the rear engined 911 to the mid engined 914, the geometry changed. Without a really effective reverse lockout that also provides a bit of grinding drama now and then. On the other hand a forth gear to reverse shift at the top end (911 like) would be even worse. The 915 shift tower has a better lockout than the 901/914 tail-shifted cars.

So in the tail-shifter cars, the linkage configuration (at the shifter) is identical to that of the 911 with a ball and socket that swaps the pattern right to left. The side-shifter cars have a simpler, direct attachment to the rod, So there's no change in direction right to left.

More than you've asked for but hopefully will help some folks...

Examples of cars that utilized this pattern for performance reasons include the BMW M535, Early 635CSi (Non-US) and (Non-US) M3 E30, BMW 2002 Tii and Turbo, Mercedes-Benz 190E 2.3-16 and 2.5-16, Ferrari 308 GTB/GTS, Ferrari Testarossa, Porsche 914, early 911, 924 Turbo (all featuring Getrag gearboxes) Porsche 928, Talbot Sunbeam Lotus, Vauxhall Firenza HPF the Lamborghini Miura, the Maserati Biturbo and the De Tomaso Pantera.

Actually Porsche had vision beyond their years. Without the ball pattern, it becomes and excellent theft deterrent for those who pull into a garage...heck, even with the ball..I've even seen mechanics unable to get it into any appropriate gear. Unfortunately, when I added a few too many hp, any forward gear works just fine for a dead stop take off.

I would speculate that it's simply an engineering decision, not a design decision. The transmission has the 'dogleg' pattern simply because that's the way it worked out.

I have no idea how it came about, but sure is great for racing (which probably explains it). With a 1st & reverse lockout and neutral gating shifting is easy and thoughtless. I like it better than the typical 5speed pattern.

When I'm asked that question all I say is "you don't need first gear on a race track."

Enough with the esoteric speculation! The internal design of the transmission dictates the shift pattern! When first and reverse share the same operating sleeve, the shifter is gonna operate in a single plane for those 2 gears. When they don't, it won't.

The Cap'n

Well, yeah. We know that already. The question was why did they design it that way.

It would be cool if someone dug up some actual history that covered the decision making process.

Your wives answer is both funny and kinda scary!

Which came first, the chicken or the egg? I think the argument that the shift pattern dictates the internal design makes just as much sense.

I personally believe the explanation regarding 1st was not to be used very often and that 2-5 fit into an H pattern that you would be expected to use most often. But that ultimately customer feedback resulted in a revision (915) and wait for it....

The desired shift pattern dictated the internal design!

Richard

The quote below is directly from Karl Ludvigsen's "Excellence was Expected". It is the section that talks about 911 development and in particular the introduction of the type 915 transmission which replaced the type 901/911 transmissions (the 914 uses a variation of the type 911 transmission)...



People love to slag Ludvigsen. So believe him or not with respect the shift patterns. Personally it makes total sense to me. I think the initial designs (including the 901) was optimized for racing and that in general "Porsche knows best" was their attitude for a long time. Eventually they acquiesced to customer complaints. The way I look at it is that we have a racing transmission! On a related note, the 901 design was developed for both the 911 road car and the 904 race car. In fact most of the initial development issues were dealt with during the development of the 904 race car.

Richard

I've been around Porsches since 1964, and I've NEVER heard a complaint about the shift pattern in the 901 derivatives. I also doubt there were many such complaints to the factory. To this day, German manufactures are known for their arrogance regarding "how things are supposed to be done". "If you don't like it, go buy something lesser, because that's what you deserve." I also believe that shift pattern considerations had NOTHING to do with the design of the 915 and subsequent gearboxes. They HAD to get that highly torque sensitive first gear off the weakest part of the mainshaft and out of the nose housing. Most of you don't even know about the change in the mainshaft (1970) because the 2.2s were snapping the end off. There was a major change in the lockout assembly a year AFTER the 915 appeared in production cars. I maintain to this day that "lock out" problems lie with the person doing the shifting, not the linkage or the design of the transmission. If you make it your personal practice NOT to move the shifter diagonally from first to second, the grinding (and the subsequent wear on the 1/R slider and dog teeth) never happens. IOW, learn to work with what you have!

The Cap'n