80's 911 Transmission Question

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

Talisman - 19 Oct 2004 04:45 GMT

Hello all, and thank you very much for having such an active news group,
providing a virtual cornucopia of great technical information for those of
us still learning about our beloved 911's!

I currently own a 1984 911 Targa with a "Turbo Look" package. Just prior to
purchasing the car, I checked the maintenance records as far back as I
could, and confirmed what the seller had told me, in that the transmission
(a Type 915) had been totally rebuilt within the last year. I also asked a
trusted mechanic friend of mine to give the car a thorough going over before
I made the purchase as well. Finally, after all this I was satisfied that
the car had a clean bill of health, and bought the car of my dreams. The car
runs, and looks great, and I'm only the third owner. The previous two owners
left it parked in the garage most of the time, with the individual I bought
it from preferring to drive her "other" 911 convertible most of the time
instead. I think this had something to do with the Targa being a gift from
her "ex."

Anyway, my question is this; from what I've read so far, the 3.2 911's
didn't change much from 84' to 87' other than adding "power everything" to
the interior goodies. So it seems to me that it wouldn't be all that
difficult to replace the Type 915 transmission with a G50. The only hang-up
that I can see so far would be how to deal with the additional oil cooling
system of the Type 915. I'm not sure just how this would affect the car as a
whole by removing it (handling, cooling, etc.)? This may just be allot of
work for little to no real noticeable gain. Right now I'm just tossing
around "what ifs." I've read that the G50 solved most of the shifting
shortfalls of the Type 915. But by the same token, I've also read that the
Type 915 transmission takes a little getting used too in order to develop
what I see referred to as a certain "finesse" in shifting, and will compete
with the best once this is mastered by the driver. Within this news group I
read an earlier post that mentioned replacing the bushings in the shifting
linkage, which I'm also looking into. Yes, I'm going with the "KISS"
principle, in that I'm replacing the bushings first in order to measure the
results. If it's better just to leave it "as is" I'm okay with that, since
the car drives great right now. Like I said, I'm pretty much just tossing
around "what if's" right now, and I have no intention of driving the car
very hard, so this may further justify just leaving well enough alone.

Any thoughts on this would be greatly appreciated.

Thanks,

Lynn

84' 911 Targa

Reply to this Message

Vern - 19 Oct 2004 11:29 GMT

My perspective,
If you look at what aftermarket upgrade / racing parts are available, that
tells you what the pitfalls to the stock parts on a given model. The one
thing on 911's, is shift linkage upgrades. Also if you look at conversion
kits and the power a 915 trans could take, it seems to me the transmission
itself isn't the biggest issue, it is the connection of the driver to it.
Some good, to outstanding upgrades are out their to address the shift
problems in a Porsche. Check the link below to get some idea of the scope of
upgrades for this "connection" If it wasn't an area for improvement, we just
wouldn't have a market for these things, let alone multiple manufacturers
still making them.
Myself I would spend my money on shift linkage first and see how it works
for you, the trans swap is substantially more costly, which for me would
rule it out, and won't do much for you if the shift linkage is poor. Also if
possible, the gain at best would be reliability, nothing you could tangibly
feel unless ratio's are substantially different, which I don't think they
would be.
What kills transmissions, and it doesn't help in the fun of driving, is the
missed shift, and "nicking" reverse as you go by. This usually in a Porsche
is the linkage shortcomings causing it to happen.

http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_pedals_pg1.htm#item2

> Hello all, and thank you very much for having such an active news group,
> providing a virtual cornucopia of great technical information for those of
[quoted text clipped - 42 lines]
>
> 84' 911 Targa

Reply to this Message

Mark - 19 Oct 2004 11:57 GMT

Hello, Lynn -

915 to G50 conversion is, unfortunately, not a simple bolt-in weekend
project. It can be done, and here's an article which describes the overall
process pretty well.
http://www.bodymotion.com/Core/911_transmission_upgrades.htm

In my opinion, it's probably not worth the effort and cost unless you're
REALLY unhappy with your 915's, performance.
Sure, 915s can be quirky, but once you get to know 'em, they're fine.

You mention checking the shift bushings. That's an excellent starting point.
The rear coupler has bushings, which elongate with time and use, introducing
slop in the linkage. Directly below the shift lever there's a nylon cup and
a bushing which also wear, introducing more slop. Extreme cases of wear at
these points have caused all sorts of shifting problems. It's an easy and
inexpensive fix which makes an old transmission feel [almost] like new.
However, even with fresh bushings, and a recently rebuilt transmission, it's
been my experience that shifting a 915 is like no other transmission when it
comes to feeling somewhat, shall we say ... 'imprecise'. ;^)

If you haven't already found it, the Pelican Parts website provides a wealth
of information [and is a good source of parts], as does the RennList site.
There are searchable archives of technical threads and a worldwide
membership which responds well to our many questions about these wonderful
cars. Some of the participants are professional P-people. Some are DIYers,
like myself. All are enthusiasts with experience and stories to share. Check
'em out & enjoy!

http://www.pelicanparts.com/index.htm [click on 911 BBS - take the time to
register - it's free]

http://www.rennlist.com/ [Lots of great info here, as well. Worth the
small membership fee]

best of luck!

Signature

Mark Hald
'77 Carrera 3.0
http://members.rennlist.com/hald

> Hello all, and thank you very much for having such an active news group,
> providing a virtual cornucopia of great technical information for those of
[quoted text clipped - 41 lines]
>
> 84' 911 Targa

Reply to this Message

Weekend Guru - 19 Oct 2004 21:19 GMT

Remember...if you go for the G-50, you're going to have to also replace the
manual/direct clutch cable with the hydraulically operated one used with the
G-50. This means installing the slave cylinder, etc.

Reply to this Message

Don. - 20 Oct 2004 05:33 GMT

I had an '88 Carerra that I believe had the G50. I really hated it, maybe
mine was a special case, I know the car was. After buying it I found out
it had been in a 'slight' accident and the transaxle was jambed in gear.??

The thing I hated about it was the hesitation going from low to second. I'd
bitch to mechanics who would tell me it was OK. But it never shifted like
my 356 or 912. (Stupid comparison.) FINALLY I found reading "Porsche 911
Story" by Paul Frere that the hesitation was deliberately designed into
the G50 because of the higher engine torque. I understand now that the
1989 didn't have the same problem. BTW that's an excellent technical
book. Almost as good as some of the guys here. ;-)

Don

> Remember...if you go for the G-50, you're going to have to also replace the
> manual/direct clutch cable with the hydraulically operated one used with the
[quoted text clipped - 46 lines]
> >
> > 84' 911 Targa

Reply to this Message

Talisman - 20 Oct 2004 05:30 GMT

I knew I would get some great feed-back! You've all pretty much confirmed my
suspicions in that that there are indeed hidden quirks in swapping of a 915
for a G50. Also from the sounds of it, when comparing the gains verses the
expense and work involved, the tables are severely off-balance. From what
all of you have told me, it looks like a mixture of replacing the rear
coupler bushings, and possibly looking into something along the lines of
that Wevo shifter might just do the trick. Yes, the "nicking" of reverse was
a big concern of mine. Back in the 70's I used to play with the street rods
allot. More than once I heard the nail biting sound of a missed shift
resulting in a transmission grinding it's way to an eventual demise from a
brush with reverse while grabbing gears.

Thank you all for some great feed back to my question, and a host of links
to purse ta-boot!

Lynn

84' 911 Targa

Reply to this Message