How hard would it be to design a smooth shifting, lightning quick gearbox .....

[DanL911sc]

+1 for worn bushings. After replacement, 1st and 2nd are still resistant, but shifting is much more precise.

[dd74]

Originally posted by Maxx1
The main problem I'm having with mine is getting it to go into first after stopping at a light. I'll double clutch, I'll shift from second and then try to go into first, sometimes in my hast I'll hit reverse ..... all the time feeling like a dope if there are cars waiting behind me.

I had a 106K mile 87 Carrera and more recently a Boxster S, both were better shifting than this 4 speed is.

Sounds like I need to look into checking the bushings and getting a rebuild kit.

Not that this will resolve your current problem, but I rode in a 930 with an SC 8.31 r/p 915 gearbox, and the car felt extremely fast. You could consider picking up a used later 915 box that's been recently rebuilt. By that point, all the shifting problems you now experience should be eradicated.

[mjshira]

Originally posted by Jack Olsen
For what it's worth, the reviews of earlier 911's often singled out the 901/915 for particular praise. Then the Japanese came along and built a smoother mousetrap. But in some ways, we're comparing apples to oranges; a Corolla or a bike isn't (usually) running a whole lot of torque through its drivetrain.

The 915 is especially susceptible to bad maintenance and age. A lot of the complaints about it come from boxes that are long overdue for a rebuild, with shifters out of adjustment and bushings that are rotted and stretched.

and speaking of gearboxes probably in need of a rebuild..

is yours holding together Jack?

[RoninLB]

I had a full rebuild ++ built around a 3.4L future install.

glad i went that way instead of a G-50

[Mahler9th]

I have never driven with one but... my guess is that if you could get a WEVO dog box, it would be the cat's pajamas. I have raced against them, and they are advantageous compared to a normal 915. But it will cost you. Not sure whether they are available any more as new though.

Another approach was taken by one of our local racers... he rigged up an EMCO (used in DP cars). Not cheap.

Anothe route is to just buy a modern Porsche factory race car and put the parts in your street car. Maybe not practical.

[Maxx1]

Originally posted by srandallf
Maxx1..interesting. my Bday is 3/3 as well and my main interests are guitars, motorcycles and cars ! anyway, ive thought about this also but, have come to enjoy my 915 transmission. I like the involvement and having to learn how to shift it properly. It makes it more fun, to me. I certainly would not want to have to worry about shifting on my bike. too dangerous as it is. The 911 is different. Ive driven newer sports cars with super smooth shifting transmissions and a soft clutch and found them terribly boring

perhaps your transmission is not set up properly or needs repair.

Yep, guitars and cars and wheelin down that long lonesome highway !


Sounds like from everyone's advice that a bushing kit is money well spent. I forgot to mention, 3rd gear is kind of funky to find at times as well.

[KFC911]

Originally posted by Maxx1
The main problem I'm having with mine is getting it to go into first after stopping at a light. I'll double clutch, I'll shift from second and then try to go into first, sometimes in my hast I'll hit reverse ..... all the time feeling like a dope if there are cars waiting behind me.....

Why are you "hasty" shifting into first? Even with my G50, I'll gingerly slip my car into first while coming to a stop (or stopped), and then back into neutral while waiting for the light to change. I also tend to watch the opposing traffic & lights, and usually anticipate my green light, and shift back into first a second before the light changes. Even if I don't anticipate, she shifts easily back into first with this technique (1st > neutral > 1st), maybe it'll work for you for now.

[914efi]

Another comment about non-sycnchro transmissions whether sequential or not: most of them are racing oriented and therefore close ratio, so less difference in gear speeds during shifts and less 'need' for synchros.

I remember the first drive I had in a '79 SC in about '80 or '81, so a pretty new car. I could not believe how nicely it shifted, I came out of british stuff which shifts pretty nicely, but even if the 911 had longer throws than my MGB, it just had a beautiful feel. I remember shifting it just to feel it. I also remember mid '80s BMWs having very slick feel.

[GaryR]

Originally posted by Maxx1
Sounds like from everyone's advice that a bushing kit is money well spent. I forgot to mention, 3rd gear is kind of funky to find at times as well.

Or just go directly to this and be done with it!


http://hargettprecision.com/index.php?cPath=35

[Elombard]

Also, replace your tranny and engine mounts, perhaps with sprotier versions. Keeping everything lined up with the linkage made a big difference for me!

[Grady Clay]

Good discussion.

A feature of a sequential transmission (like a bike) is you CAN’T skip gears. This means every gear change has minimum rpm difference. With only slight power interruption (many use an ignition/fuel interruption system), there doesn’t even have to be de-clutching or lifting on the throttle.

I agree about straight cut gears, they are too noisy for normal street use. The choice of straight cut gears (noisy but strong) compared to the various angle cut gear forms doesn’t have anything to do with the choice of engagement (dog, syncro, etc.)

Some later G50 types (G64 …Japanese G97/01) have changed the syncro angle (to 15°) to reduce the effectiveness and allowing faster (sequential) shifting. I understand some electric systems have 2 mS shifting.

I think the auto industry is going away from automatic transmissions with clutches, planetary gears and torque converters. It seems the choice is regular mechanical transmissions (10+ speeds), dog engagement (no syncros), electric shifting (sub-millisecond) and all computer controlled. I think the reason is fuel efficiency and emissions - AND it gets everything under the control of the computer.

I think the RS Spyder may lead here.

Best,
Grady

[bpoteat]

I agree Grady. The systems with 2 clutches, such as the VW DSG tranny, with one always engaged is appears to be the future of transmissions.

http://en.wikipedia.org/wiki/Dual-clutch_gearbox

[RallyJon]

Helical dogboxes are popular with the Subaru crowd. Quiet for cruising at the cost of some gear strength, but fast shifting.