my 915 tranny has taught me...
08-22-2006, 11:22 PM
#16
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Location: simi valley
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WOW!!,
Good to see that we have all come up with similar shift behavior with our 915's
I do the same as most above and everything works great. I have a short throw shifter and I still need all the tricks.
But I don't have too much trouble going 1st to 2nd.
I have just learned to shift a bit slower and pay attention.
The first week I owned the car, I was really nervous with the shifting and the initial 1st gear shift.
My friends even laughed a little at me, because I drove my Corvette with a lot more confidence.
After a few weeks, the same friends commented "you seem to be driving this car a lot better" even though I explained to them eariler that the shifting is different on this car then the Corvette.
Because they still don't get it, they haven't drove the Porsche.
Good to see that we have all come up with similar shift behavior with our 915's
I do the same as most above and everything works great. I have a short throw shifter and I still need all the tricks.
But I don't have too much trouble going 1st to 2nd.
I have just learned to shift a bit slower and pay attention.
The first week I owned the car, I was really nervous with the shifting and the initial 1st gear shift.
My friends even laughed a little at me, because I drove my Corvette with a lot more confidence.
After a few weeks, the same friends commented "you seem to be driving this car a lot better" even though I explained to them eariler that the shifting is different on this car then the Corvette.
Because they still don't get it, they haven't drove the Porsche.
08-23-2006, 10:05 AM
#17
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Originally Posted by Peter Zimmermann
Oh, coldstart, your 1/R symptom is a classic clutch adjustment symptom (or trans oil contamination). Tell us more: (1) how much free play is at the top of the pedal?, (2) when was the clutch replaced last - did the job include transmission tear down for a new mainshaft seal?, etc.
Pete
Pete
There is very little free play at the top of the pedal. the clutch engages very smoothly and midway of the pedal travel (I recently drove a friend's 72 911T and the clutch engages at the very very top).
I have no idea when the clutch was last replaced as I have only owned the car 2 years. I replaced the tranny fluid with Swepco when I first bought the car. The previous fluid was like dirty WATER but it did not contain any metal bits (I used a magnet and sifted through it). To my knowledge, the tranny doesn't leak.
It is great to hear that a clutch adjustment may solve my tranny woes. How hard is the adjustment to do? I already have the clutch adjustment tool and the 101 Projects book.
Thanks Peter.
08-23-2006, 11:57 AM
#18
Rennlist Member
No tool required on your car! Just loosen the jamb nut, turn the adjustment nut clockwise about one turn and test. DO NOT lose all of your free play at the top, if you do the clutch will be close to a slip point. Another problem that you might have is your pedal stop might be adjusted to low. It fastens to the pedal board, so pull the pedal carpet away, loosen the two allen head bolts on the stop, move the stop up about 8 mm, snug it down and test. Let us know how it goes!
Pete
Pete
08-24-2006, 05:29 AM
#19
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Originally Posted by Peter Zimmermann
Real: Tell whomever told you that, well, to get real! No, a 915 will never shift like any 944 derivative, nor will it ever shift like a G 50, nor will it... Your car will only shift like a 915, and that little, as you call it, hang-up point is perfectly normal. That's why you use a two part shift with a 915; (1) pull the trans out of gear and into neutral, and (2) pause and then apply pressure to engage the next gear. The pause helps the synchro. For the 1/2 shift it's helpful to find the rpm that your car likes the best, whether it be 3300 rpm, or 4500 rpm, and use that point to shift the car.
Regarding the 915 T.O. bearing - relax, it's bulletproof. I've replaced 80K mile clutches on town driven cars and the TOB was still good. I used to quiz customers and found that, in L.A. traffic, most owners found that it was much easier to leave the pedal depressed at a traffic light rather than getting the horn directly behind blaring the instant the light changed. I've always driven like that (not using the horn!), and this is why I say that it really helps to have a good clutch cable that's properly adjusted. Makes pedal pressure much lighter!
Pete
Regarding the 915 T.O. bearing - relax, it's bulletproof. I've replaced 80K mile clutches on town driven cars and the TOB was still good. I used to quiz customers and found that, in L.A. traffic, most owners found that it was much easier to leave the pedal depressed at a traffic light rather than getting the horn directly behind blaring the instant the light changed. I've always driven like that (not using the horn!), and this is why I say that it really helps to have a good clutch cable that's properly adjusted. Makes pedal pressure much lighter!
Pete
08-24-2006, 09:34 AM
#20
Having driven manual transmissions my entire life, my 915 mystified me after I purchased it. Somebody on this board once said that the whole secret was "fast feet and slow hands". I use this phiosophy daily and I no longer think of the thing as quirky. In fact I often find myself driving my F150 the same way now.
08-24-2006, 12:10 PM
#21
Rennlist Member
mflink...: I've talked with many people about their driving habits regarding the 915 trans. The beauty of that unit is that if it's working correctly, and it's driven correctly, the "hang-up point" discussed here isn't even noticed. It lends itself to a perfectly natural way of driving/shifting. Kudos to you for driving properly! Also, you're right about many of them feeling "clunky" or worse. If the ball cup bushing on the base of the lever is worn out or gone, if the synchros have wear but are on that edge between barely functional and bad, or if the clutch linkage isn't set correctly, the trans can/will feel clunky. The newest car that uses the 915 shift linkage is now about 20 years old. The basic lever, bushing, shift tube, coupler design dates back to the 356 days, the newest of which is now about 40 years old. Add to that a synchro design not used since 1986, and you have a car with old technology that requires a bit of patience to drive.
Pete
Pete
08-24-2006, 12:42 PM
#22
What's interesting is that the 915 eventually forces you to shift smoothly, and with enough practice this will result in seamless, jerk free gear changes.
This is a big plus when on the track and at the cars' limits when you don't want to upset anything.
All good drivers try to do this no matter what tranny they have but the 915 seems to train you in advance for this.
Not designed with this in mind but a plus anyway.
Of course there are the times when ( probably due to worn/misadjusted linkage) it leaves you in neutral "at speed" and offers a different type of training.
This is a big plus when on the track and at the cars' limits when you don't want to upset anything.
All good drivers try to do this no matter what tranny they have but the 915 seems to train you in advance for this.
Not designed with this in mind but a plus anyway.
Of course there are the times when ( probably due to worn/misadjusted linkage) it leaves you in neutral "at speed" and offers a different type of training.
