Paul Bakker

Hi.
My 1985 3.2 carrera is currently at the shop because I had some problems with my transmission. The guy called me and told me the transmission under my car is one of a SC Some previous owner connected this SC trans. to my 3.2 engine

OK, I have this car now for 12 years and I intent to keep it for a long time so I must take a decision what to do.

My trans. is now opened and ready for rebuild. Cost € 2000,-
For this money I get a good trans. for many years I'm promissed.

But;

I could also dump the SC trans and buy a "new" original 3.2 transmission but if I want to be sure this one is good inside I have to open it to inspect it. There is a risc this trans. is also bad.

I'm no mechanic and this job has to be done by a shop so labour costs must be paid.

What would you do ?

Thanks.
Paul

rockrimmon

Paul:

I thought the SC's and the first few years of the Carerra's had the same 915 transmission. Later Carrera's had the G50. So, an 85 should have the same as the SC, right? Of course I am still very new to the P-world. And I only know the US market so maybe different in Europe.

Tom

Paul Bakker

Hi Tom,
the guy told me somebody had cut out some metal from the trans. to make it fit the engine.
He's a Porsche specialist (a real one!) and I presume if this was original Porsche he'd mentioned it.

Thanks.
Paul

Peter Zimmermann

Paul; In order to install an SC 915 into an '85 Carrera cuts must be made to the bell housing for sensor clearance. This is done regularly when a Carrera trans is not available on an outright sale or exchange basis. The SC trans has a weakness (pinion shaft bearing looseness in diff housing) that an '85 trans won't have. For more info than you ever wanted/needed, check out my repair Tutorial at...

http://porsche.wikidot.com/forum:start

...click on "915" under "Page Tags."

theiceman

Pete
There is a sleeve available that fixes this right ? and if he does this he should be good to go with his original transmision I would assume ?

rockrimmon

Peter:

Does this imply that since the metal was cut from the bell housing (which I think is part of the Trans) that he would have the option to re-fit a Carerra G50 if he was so inclined? No harm, no foul?

T.

Peter Zimmermann

Not a G 50, 3.2 Carreras used 915s through '86 production. That said, any replacement Carrera 915 would be a straight bolt-on with no mods needed.

rockrimmon

Okay, I'm making progress. I think what I am missing is that you're saying the 915 that came in a SC and the 915 that came in the early Carerra's is somehow different? So there's a 915 SC edition and a slightly different 915 Carerra edition? Getting back to the original poster, sometime in the past his original trans was removed and a 915 SC version was installed? And this necessitated the modification to the bell housing?

Are all G50's the same or are there different versions?

Thanks for filling in my knowledge gaps...

Tom

tvanbroekhoven

Hi Paul

Just wondering, who is doing the rebuild ? Because 2000€ isn't that expensive

theiceman

Sounds like you have it rigth Rock slight variation to the 915 case for the Carrera is what I am thiking

race911

The other thing to consider is that Euro SC's didn't have the external oil cooler like Euro 3.2's..........right? Not that you really NEED it. But the one tranny I have like that is safely installed on a friend's car, ready to ****** back if it's needed.

Daniel Dudley

The gearing on fourth and fifth on my 85 Euro car is slightly higher than fourth and fifth on my 78 SC, but it is not really a big difference, cruising in fifth is slightly more relaxed.

I guess I would prefer the later box if one presented itself, but I think if your current box were rebuilt properly, you would have to drive it very hard for a very long time before any real advantage to the later box would emerge.

I would want any 915 box I had rebuilt done properly, and not just a quick replacement of the syncros.

Paul Bakker

I agree.
Sadly my box was "rebuilt" a couple of years ago (4) but this socalled "expert" did a very bad job. It was done together with an engine rebuilt. The engine still runs well but the box never lived up to its expentations.
Now I found a shop which was recommended by other Porsche owners and I visited them before I gave any order to them. It looks good, 4 personell, only Porsche maintanace. The have a couple of Porsches for sale.
I had my '90 928 S4 done (new brakes, oil leakage, distribution) and I'm very happy with the result.
I asked them to take a look at my 911 gearbox. Lately it leaks oil and sometimes I hear a high pitch noise from it. It always was hard to switch gears and often I couldn't switch gears at all! Often the gear wouldn't release and I had to pull hard to get it from a gear. The box didn't make strange noises as if the gears are not fully realeased by the clutch so I think synchros are OK. Also the clutch was very hard to push. I didn't let my wife drive the car because of this (nice excuse not to ruin my toy).
The shop called me to get permission to get the box from underneath the car to get a closer look. The box is now disassembled and it's a mess. I'm not informed what exactly is wrong so I'm not sure it needs a complete rebuilt but I got an estimation of € 2000,- repair costs (labour included, in/out).
Because I'm not "into" the gearboxprices I thought maybe it would be an option to place a complete other box underneath. The shop didn't agree because a replacement would cost also around 2000,- If I want to know if its a good one it still needs to be opened for inspection. The cost could double in worst case scenario....
So I also think to let them repair my own box, at least I know then the quality is tip-top !
Thanks for your input. Learned a lot about numbers and years (handy).

Thanks!
Paul

500

The last generation 915s (Early '85 through to '86) have a smaller pinion bearing (as Peter said) which results in there being more casing material to support the bearing. This is a bearing that has been known to come loose in the earlier 915s on occaision due to deformation in the casing. There are ways to repair this, but I don't know how well they work long term. However, this is likely not going to be the case with every transmission.

The problem with a "new" Carrera transaxle is that it could be in rotten shape inside, as you point out. Also, if the Carrera transaxle is an '84 or early '85, it will not have the smaller pinion bearing upgrade anyway.

I would ask the mechanic what he would do if he found the pinion bearing to be loose and then post that up here, the knowlegeable people (like Peter) would probably be able to say if that makes sense. If it does, then it would be a good sign that the mechanic is knowledgeable and you can go with him comfortably.

Peter Zimmermann

1st pic = Carrera 915 bell housing w/sensor cut-outs...
2nd/3rd pics = SC 915 bell housing - no cut-outs needed