915 Gearbox Operation...Your Experiences!

[keynsham1]

I have a 1978 911 SC Targa which has covered 76k miles. It has the original 915 gerbox. The operation is best described as follows:

When cold, gear changes are not to be rushed but are generally smooth.

Sometimes it is not keen on going in to first gear whether hot or cold and a flick into second and then forwards into first is often required.

Going up gears is always OK with no crunching or notchiness with the exception of first to second, which can be a bit notchy when cold.

When either hot or cold, down from fifth to fourth is a bit of an art. smooth movement and light hand presasure will always work but if you try to rush or use any sort of force, it crunches.

I have read that 915 gearboxes are all different and need to be 'learnt' and I have learnt how to use mine. I am interested in others views of the 915 box and its operation.

My clutch is correctly adjusted so there is no drag causing any issues.

[ghamilton]

My box has 100k on it with a refresh by PO 30k ago. If set up right, I.e. bushes, adjustment, correct fluids they are great.

Once you get the hang of it, it is a joy to "row" through the gears.

And I usually match revs on shifts, certainly can't hurt and it sounds cool.

I sometimes shift 2 to 1st on stops.

[Jcslocum]

You don't say what fluid you are using in the box, as that can have a significant impact on it's operation. SWEPCO and a few others are recommended for best performance. How is the shifter coupling?? A rebuild there might help some too.

[GMR911]

After driving mine for 208k miles and 35 years(never been apart) I tell people you just have to know how to shift it. I generally have few problems. Sometimes can"t get it in first when stopped, need to select another gear and let clutch out abit then it will go into first. Then shift from 2nd to 3rd for those who have never driven it can be vague. I use swepco in it and made a big differance in the smoothness of shifts. Then shift from 1st to 2nd can be bulky probably due to worn syncros after 208k.

[keynsham1]

I now use Swepco oil and surprisingly it did make an immediate improvement! All bushes/linkages are new and correctly adjusted.

Does a short shift kit help?

[Oh Haha]

I've learned the hard($$) way that the 915 cannot be shifted like a modern manual.

I blew out 2nd gear about 12years ago due to powershifting it like a muscle car. You have to pause between 1 and 2 to prevent damage I have found as most others. This is necessary even when all is well in the gearbox.

Over the last 14 years of owning my SC I have been able to form good habits and can shift it pretty quickly without much loss in momentum. I don't drag race it but it is fun to leave a stop and run it up through 1, 2 and 3.

I read somewhere(probably Pelican) that 1st gear was designed only for leaving the pits.

I switched to Kendall gear oil several years ago from Swepco and saw a little increase in shifting smoothness. My bushings have been replaced but I do have a frankenstein built shifter that suits me.

[puddy]

I'll have to find out what fluid the previous owner used in my 915 but it works pretty good! My only complaint is going into second gear. It doesn't seem to want to go smoothly straight down into 2nd, I have to apply a little pressure to the right and then it fully engages. I've tried double clutch upshifting with a throttle blip or also tried just pausing before pulling it into 2nd and both seems to help but are hard to accomplish quickly but i'm working on that.

Also going into 1st when rolling to a stop doesn't always go smoothly but I blip the throttle a little and it seems to help with that.

[Oh Haha]

Chris(puddy)-you might try adjusting the shift coupler if you haven't already. It may be off by a smidgen.

I've spent many hours working on my shifter setup to mimic the feeling of a modern box without spending much money. Yeah, a WEVO or Hargett would be best but I could never justify spending that much for one.

Mine works well for me and the way I drive and my seating position. Others probably would have difficulty with it.

The fore/aft travel can be altered by moving the shift rod where it connects to the coupler "snout".

[GMR911]

It really resists going into first unless stopped or going verrrrry slow

[ghamilton]

I have heard some do not recommend the short shifter kit as it allows you to shift too fast for the box.

The guys at Porsche were pretty good engineers & usually had appropriate designs.

[OsoMoore]

I've been shifting my 915 for three years and got a good feel for it. I had to replace 1st gear dogteeth and some synchros after a jammed synchro ring last year, and it shifts better since then.

1st to 2nd I always give it about a 1/2 second pause. A wise man once said baby the transmission and spank the engine.

[911SauCy]

In my 5 years experience, mine has only gotten better.

As a '78 with 176k on it, I'd say it shifts great. Being younger and less intelligent about it, when I first got the car I hammered through a couple power shifts...yea, I don't do that any more and thank my stars the thing is still intact.

With new lube, new bushings, a (what i think is) good adjustment. It effortlessly slips into first at a stop. The 1-2 is dramatically better, where it used to feel like a downward-left click, it's more like a rearward engagement now, and all the other gears are trouble free.

I do enjoy double clutching the 1-2 shift, which makes it smooth as glass. Leads me to believe the synchros are tired.

Only strange thing I experience, is sometimes I go to engage reverse (car idling still) push in the clutch and i'll get a little toothy clunk noise. Not like a grind, but like one of the gears was spinning slowly when i engaged it.

Anyone else on that?

[porwolf]

Originally Posted by GMR911

It really resists going into first unless stopped or going verrrrry slow

My 1979, 53k mile 915 shifts easily from 2nd into 1st when braking to stop, releasing the brakes just before the car stops completely, and then shifting to 1st. Very smooth.

[word]

Originally Posted by 911SauCy

Only strange thing I experience, is sometimes I go to engage reverse (car idling still) push in the clutch and i'll get a little toothy clunk noise. Not like a grind, but like one of the gears was spinning slowly when i engaged it.

Anyone else on that?

Mine is the same. I have the WEVO kit installed with the reverse lockout. Sometimes if I try to go straight from N to R it will block me all together. I have to be patient with reverse, similar to a first gear downshift when coming to a stop. Still gives a hearty clunk once it accepts the shift.

[yelcab1]

My experience: They all break after a while.

[TheSt|G]

My first gear synchros are definitely getting a bit tired, so I just borrow second's before I go into first or reverse.

[puddy]

Originally Posted by Oh Haha

Chris(puddy)-you might try adjusting the shift coupler if you haven't already. It may be off by a smidgen.

All my bushings are new. And I will try to adjust the coupler a little better when I have time. I've already tried doing this several times, but i know that tiny a movement can make a huge difference, so I wouldn't be surprised if I can still find improvements with a little more time & patience.

[CVDH]

According to the receipts that came with my 911, my transmission was rebuilt shortly before I purchased the car. Oddly enough, the shifter bushings & coupler weren't touched, so I took care of that right away, and installed the factory short shifter. I can shift it very well with practice now. I drove the car up to Michigan a few months ago to have some work done on it, and one thing I did notice is that it didn't want to go into fifth until after I was outside of Cleveland (about a half hour of driving). Keep in mind that ambient temps were in the low 40s. When I get it back, I might fiddle with the coupling, but I never have any trouble when it's warm out. Perhaps a drain & fill with new Swepco fluid is in order.

[ClickClickBoom]

95k, Stomski shift coupler, short shift kit w/ lengthened lever, Seine Shift Gate and a dose of Swepco. It is the nicest, smoothest, most precise shifting transmission I have ever driven. The Rebel Racing Sport trans/engine mounts tighten things up as well. It makes the Japanese transmissions seem like a straw in a milkshake.

[universeman]

+1 for baby the transmission and spank the engine

I am running stock 915 in my 82, 305k miles (rebuilt motor/trans at 295k by PO so pretty fresh)

When I bought the car, shifting was sloppy and vague. Rod bushing was totally shot, so I replaced it and the shift cup bushing. Have not replaced coupler bushes yet, due to stripped set screw that I have not wanted to deal with.

Replacing bushings above made massive improvement in shift handle tightness.

Then switched gear oil to Kendall and saw noticeable improvement.

Shifting into first at stop, when cold, sometimes requires a trip to 2nd. Does not seem to matter whether I'm rolling or not.

1-2 shift is dicey sometimes (usually when I'm in an intersection crossing traffic and need it quickly)

Shifting with fingertips rather than palm seems to help it find its way.

All other 1-5 shifts are fine, nearly 100% of the time. The words "notchy" and "positive" come to mind. You definitely "feel" the transmission doing its thing; I like that. My wife and daughter do not. Maybe that makes me like it more.

Reverse can sometimes resist me. This car doesn't like to go backward! I have to mess around with 4-5-N patterns every once in a while to get it into gear. Feels like a lockout problem, but I have the stock shifter.

All in all, the 915 with its quirks is one of the reasons I enjoy driving the car. The little reminders that you're driving a machine made for rolling around in....