Corrales911

I know that the G50 transmission on the later Carreras is "more desirable" than the earlier 915s. What are the differences in terms of driveability? My price range kept me in 915 territory, but of the half dozen or so examples I drove there was great variability in the vagueness and crunchiness of shifting. What I ended up with is very liveable even with an aftermarket SSK and in traffic. Is the G50 more "snicky snacky" in its shifting, more like some of the Japanese trans?

Edward

Yes, the g50 has that definite "snick-into-gear" feel that the 915 lacks. Moreover, it is a shorter throw. I am, of couse, comparing stock, assuming good shape for both examples. I have felt a 915 that "snicks" in with a very short throw, but that was with a wevo kit. A good 915 is not a "bad" thing, just feels antiquated, IMHO.

Edward

JackOlsen

Partly, the problem is that the Japanese built a better mousetrap in the seventies by imroving the manual transmission so much that -- in time -- the whole world learned to speak the one language of the 'snick-snick' manual box. A suspension like the 915 suffers (in part) because it has a different character than what became the norm. Back when early 911's were getting their magazine reviews, the 915 was often singled out as the car's single best feature.

However, the earth continued to turn, and the Japanese perfected the mass-produced manual tranny, and 915's continued to age. Eventually, the G50 bridged the two worlds. It has a more precise feel, even with the distance that has to be gapped on a 911 between shifter and transaxle. The G50 can also handle a lot more torque than the venerable 915.

That said, I love my 915, and swapping in a G50 is a long way down on my list of things to do to imrove my car.

A properly-rebuilt, and in-spec 915 is a very good manual transmission. Many of the ones out there are old and need to be rebuilt.

I've always liked mine. Then again, I've recently added the full chain of Wevo improvements, which makes my 915 shift like a freakin' dream.

Corrales911

Tell me more about the Wevo improvements.

Edward

Corrales,

Here you go:
http://www.wevo.com/wevoshifter.htm

Like Jack said, a good 915 is a good tranny. Mine is stock (no wevo) but is rebuilt and shifts cleanly and easily ...no complaints other than it just feels different. But the Wevo ware is really nice, high-quality stuff (with prices that attest to it), but really transform the feel of the tranny.

Edward

epbrown01

That's mostly it: adjustment. Lots of 915s have gotten sloppy and the owners didn't notice because it was gradual, and newbies don't know the difference. Once set up, they aren't so bad. Still, my 944 shifts a LOT better - you'd think it was a much later-generation Porsche instead of the same year.

Emanuel

billatlanta

In usability the 944 gearbox has a modern gearbox feel and blows away the 915. That said I was told the 915 gearbox can handle a lot of torque. My 915 feels vague and clunky. It demands precise deliberate shifts that are not rushed. Not sure if that is the norm.

Not to hijack this thread but does anyone know what it costs to have a professional rebuild a 915 box?

Thanks,

Peter Zimmermann

Bill: Unfortunately there is no "quote" to rebuild a 915. Each trans has had a different level of driver-induced abuse, which affects rebuild time cost dramatically. I think that you're safe to start at about $1400, and go up from there to about $4-5K (most people will shop for an exchange trans at this cost level). Mileage, and even oil quality, can affect the 915 in major ways. Usually, under 200K miles the ring & pinion is still OK, but to preserve it the diff carrier bearings must be replaced and set up. Usually 915s are taken apart for synchro problems, however if a synchro has failed/broken, all bets are off regarding cost. There are also bearing issues that should be corrected, unless the car is under 75K miles and just needs a second gear synchro. The key is the level of experience your mechanic has, and also if he has the special tools needed to do the job.
Pete

billatlanta

Pete: Thanks for the reply. My SC has 93k miles and I have a notchy first gear, if I am not real smooth and not too fast I get a clunk. Sometimes second is a bit notchy too, but never a clunk. If I rev it out second engages smooth vs an early shift. All the others seem fine.

Peter Zimmermann

Bill: Your symptom is really typical. You might get away with just doing 1st/2nd synchros, including the 1/2 slider (MANDATORY!). Have you found broken "dog teeth" on the drain plug magnet yet? An additional problem you will probably have to address is the pinion shaft bearing closest to the pinion head. That bearing's outer race gets loose in the housing and spins in the case. There is a great fix available but you need a really good machine shop (I have a referral if you need it, here in LA) to do it (you'll need to ship the diff housing).
Pete

billatlanta

Thanks Pete. Sent you a PM.

glenncof

Having my 1985 915 transmission (157K miles) repaired three times; 1st syncho 63K miles, clutch & blown 2nd (my fault) at 82K, and blown 1st & 2nd (?) at 120K I have one word:

SWEPCO 201

http://www.paragon-products.com/Sear...x=9&Search.y=9 ($38)

The first was probably factory fluid since I got the car from Porsche direct with 17K (first owner).

My mechanic was putting in REDLINE 80/90 synthetic. I read the brass synchro's don't like slippery synth. The bad news...shifting was really scary I think it caused or contributed to my problems.

(I also read break-in should be done with petro before using synth unless item was machined for it like Corvette. This applies to engines, differentials, and I assume tranny.)

Racers apperantly like this stuff. At first it made little difference but now in over 1000 miles with the 201 and it's CONFIDENCE INSPIRING. (I don't even need to think about shifting !)

also see http://www.bobistheoilguy.com/ for anything on oils