Can I drop a 930 transmission in a 3.6 SC?

Moses · 05-14-2003, 08:24 AM

I'm not sure yet what damage, if any, I've done to my 915.

If I tore up the tranny, is a 930 a reasonable option? I really do want taller gears for easier street driving. From what I've read, the G50 conversion is very involved ($$$).

Maybe a 930 will give me a durable tranny with less cost. Anybody done this?

Sean Hamilton · Sean Hamilton's Garage

Oh oh!

So it wasn't just the CV's then?

Moses · 05-14-2003, 08:34 AM

Quote:

Originally posted by Sean Hamilton
Oh oh!
So it wasn't just the CV's then?

Haven't heard yet. Lately I just assume the worst.

thethrill · 05-14-2003, 08:58 AM

An early 76-77 turbo trans (short bellhousing) is basically a bolt in to an SC. Short bellhousing models are tough to find! Long bellhousing versions are readily available, however you would need to have a new rear panel/motor mounts installed.

To take advantage of the trans your would want to shorten 3rd and 4th gear (and possibly 2nd).

Turbo trans are bullet proof. I have 100K on mine with a 400+ hp turbo, no problems! Also most turbo trans come with LSD's.

ruf-porsche · ruf-porsche's Garage

Just don't try to shift into 5th gear

Embs · Embs's Garage

Moses,

I asked this exact same question a while back. I believe both John Walker and Jack (OMRBCHWDP) Olsen said that the gearing wouldn't match the 3.6 power curve.

However, since then I have driven a 930 with a NA 3.6 Varioram with the original 4 speed and I really liked it. It felt much better that the 915. The guy did the transplant work himself. I am trying to get him to post some pics to the BBS. His car is really sweet.
He was a former BOOST-O-HOLIC.

IMHO, the 915's stock 1st. gear is a waste when mated to the 3.6 Vram. I would like a much taller 1st in a 915. It would make the car much more fun for me. I would like to be able to get to 60 in 1'st gear.

Embs · Embs's Garage

The other problem is finding a good 930 tranny. There just doesn't seem to be many around. Of course I think there is a fresh one on my garage floor in the corner

beepbeep · 05-14-2003, 12:10 PM

pre -78 930 boxes bolt straight in. post -77 boxes have longer clutch housing (to accomodate rubber-damped clutch) so they have to get shortened as 930 back end is actually longer than SC (so engine sits further back)!!

Otherwise than that...930 boxes are impossible to break, even with 935 engine... 3.6 with it's spinky torque cannot do anything to its gears. Synchros get worn with time and should be replaced in time.

We bought clean and rebuilt long 930 box for 1200$... short ones are somewhat more expensive as they aren't so common. Apart from the clutch housing, they are the same...

1fastredsc · 05-14-2003, 01:24 PM

For the kind of price you'd pay for a 930 trans, or at least a good rebuilt one, why not just rebuild the 915 and put in gears that are accustomed to your standards?

ChrisBennet · ChrisBennet's Garage

Quote:

Originally posted by 1fastredsc
For the kind of price you'd pay for a 930 trans, or at least a good rebuilt one, why not just rebuild the 915 and put in gears that are accustomed to your standards?

The 915 really isn't built to handle the torque of a 3.6 though I guess street driving might not tax one that much.
-Chris

89911 · 05-14-2003, 02:29 PM

Do you really wany to take your fantastic 993 engine that was meant to run with 6 speeds and cram it into just 4 gears??? You can beef up a 915 to handle it but a G50 is the way to go.

beepbeep · 05-14-2003, 03:43 PM

915 box sucks, rebuilded or not. It's the sad truth.

ChrisBennet · ChrisBennet's Garage

Quote:

Originally posted by beepbeep
915 box sucks, rebuilded or not. It's the sad truth.

Amen, bro.
-Chris

rdane · rdane's Garage

Embs...did you put the 930 box in your 3,6 yet?

look 171 · 01-18-2005, 01:45 AM

Quote:

Originally posted by beepbeep
915 box sucks, rebuilded or not. It's the sad truth.

Hey the 930 box sucks too, but boom proof. The shifting into 2nd is just have to be done ever so slow, or else click click and slight grind then into second. Who does 60mph in first? Can you see yourself slamming the gear lever into 2nd at 6800rpm on boost. It's a horrable feeling. Chaning the ring and pinion may work ok and cheaper too. Stock 2nd and 3rd was my favorite gear. Now it's just 3rd.

Jeff

look 171 · 01-18-2005, 01:47 AM

I mean bomb proof, sorry

real550A · real550A's Garage

"915 box sucks, rebuilded or not. It's the sad truth."

All those threads on "which is better, G-50 or 915", are being summarized here in one short sentence.
I have one of each, and prefer the G-50.

PorscheGuy79 · PorscheGuy79's Garage

Quote:

Originally posted by look 171
Who does 60mph in first?

On a side note, the new Z06 does which directly relates to its very quick not to sixty time of 3.9.

lendaddy · 01-18-2005, 05:41 AM

After my 930 box was rebuilt by Gary Fairbanks, the 1st to 2nd shift was great. Before the rebuild it was a slow process to "get" second.

beepbeep · 01-18-2005, 07:21 AM

Quote:

Originally posted by look 171
Hey the 930 box sucks too, but boom proof. The shifting into 2nd is just have to be done ever so slow, or else click click and slight grind then into second. Who does 60mph in first? Can you see yourself slamming the gear lever into 2nd at 6800rpm on boost. It's a horrable feeling. Chaning the ring and pinion may work ok and cheaper too. Stock 2nd and 3rd was my favorite gear. Now it's just 3rd.

Jeff

930 box uses same synchro design as 915, so shift-feel and wear-tear are apporoximately the same. But it's built much stronger and will stand any naturally aspirated Porsche engine 'till the cows come home. No chance in hell that the housing will twist and gears fail.

If shifted frequently, it's synchros will get worn just like in any other (porsche synchromesh) transmission. In Europe, itäs usually 3:rd gear (due to highway overtaking 2:nd to 3:rd on-boost syndrome) that is toast. If driven mostly in town with enforced 55mph limit, it might be 2:nd that's worn.

IMHO it's better transmission than 915 if you don't need to play red-light "who's faster" game...