997 transmission?

I've begun tracking my 996 - but one issue is the REALLY tall gearing (I suppose for EPA milage). Gear sets are pretty expensive, and I'd want to change 3,4 and 5. But then I thought - 997 gearing is way lower, and might help with more 'torque' coming off the corners. With a little looking, you can find a used 997 trans for about $2500. Has anybody here done this? I've heard anecdotal evidence that it works out pretty well, for not a lot of money. Any thoughts?

Interesting... 997 C2 Gear ratios: 1st gear: 3.91 2nd gear: 2.32 3rd gear: 1.61 4th gear: 1.28 5th gear: 1.08 6th gear: 0.88 Ring and pinion: 3.44 996 C2 Gear ratios: 1st gear: 3.82 2nd gear: 2.20 3rd gear: 1.52 4th gear: 1.22 5th gear: 1.02 6th gear: 0.84 Ring and pinion: 3.44

Not sure the marginal performance increase would be worth the cost. If you go through with it, find a way to reliably record 0-60 times and maybe some 3rd or 4th gear highway pulls. I'd love to be proven wrong!

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I tend to agree with this. Another option would be to just increase final drive ratio and while you're in there, add a LSD.

This is an old trick for getting more useful performance out of older auto-trans cars at the drag strip, since the older cars typically have only a few forward gears. Reducing top speed in exchange for keeping RPM higher in the top gear(s) makes sense. Once you get into 6- and 7-speed transmissions with sufficient gearing for you to be able to keep the RPM up at almost any speed, tinkering with gear and/or final drive ratios has less benefit (so, in my opinion, hanging a 997 transmission off of a 996 wouldn't be worth the effort). GBox advertises adjusting the gear ratios as a way to make your car accelerate "like a race car" - but you'll almost certainly be significantly reducing your final drive/top speed in exchange for getting to the lower top speed more quickly.

Great info!! Talking to racer guys. It's only the 997.1 (because of the bell housing change). And a lot of attention must be applied to condition. Interesting stuff!

So a 997 6 speed tranny can be swapped into our 996? What years are the 997.1 that will work? There appears to be more 997 used trannys around than 996, so the prices are considerably lower

I'm all for finding the best bang-for-buck gearing upgrade for these cars. It's the one of the things I dislike most about the car - the tall gearing. But wouldn't it be more cost-effective (and a bit less work) to change the ring & pinion instead?

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What I hear is that's expensive and unreliable. The gears are stacked on the Pinion, and 996 is a press-fit (means using a 50 ton press).

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Yes - on my Corvette, for example, I swapped out the D36 rear end for a D44 with 3.73 gearing. This significantly reduced the car's top speed, but it now pulls like a freight train. Note that changing the drive ratio will also cause the speedo to be wrong, perhaps quite wrong. I can program variables in my Corvette ECU (like tire size) to get the speedo to calculate the correct speed, which is a LOT easier than changing out the speedo gear in the transmission. My (admittedly limited) understanding of the 996 suggests that this isn't possible - at least not by a mortal.

Hmmm. Still approaching these cars with my M3 mindset but I guess I can see why the R&P swap isn't a very common upgrade. Other than the one company I know of that makes a set (Albins, almost $3k), I'm finding it hard to come up with any other aftermarket options anyway. It's looking like the 997.1 trans is the more cost-effective option. Any idea if the 997 gear set will fit in the 996 housing? Or does this upgrade necessitate the whole 997 trans, housing and all?

I believe the 996 (and newer) speedo reads off the front wheel ABS ring, so changes to gear ratios would have no effect.

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And Albins only makes 4.00 any more...

I'm also looking for shorter gear ratio on my 996, so that it's more fun to drive in twisty mountain roads. Does anyone have more information about the compatibility of 997.1 gearbox on a MY2000 996? How much shorter would that make 2-3-4 gears? Thanks!

I think it is compatible for sure...When I put a 997 S 3.8 in my 996, we at first used the original transmission. However, once we decided to go back in and beef up the LSD and clutch I decided to just go with a 997.1 S tranny (from Norspec dismantling). Frankly, it is so much better now and just the way it shifts is so much more precise. I would think it is a great upgrade all around. If you have questions about compatibility, reach out to Charles at Dundon motorsports who did the work on my car. He may even pipe in here. Good luck

Does the 2nd gear of the 997 transmission top out at around 62 mph (100 kph) and 3rd at around 90 mph like most cars? A little off topic, but doesn't an Audi transmission fit onto the Boxster engine? I thought I wrote that down in my notes. I couldn't remember if the Audi transmission was just a cheaper option of if it also had ratio benefits.

Many audi engines have the same bellhousing bolt pattern as the boxter/996... The critical part of the equation is if the transmission mount is in the same place. The 996 has three points of contact with the engine/transmission, so the transmission mount is pretty important.

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my 996 2nd gear tops out around 74mph. it kinda sounds like the swap might be worth it if converting a c4 to c2 or replacing a bad 996 box since used boxes r so much cheaper.

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997.1 = 2005-2008. 997.2 arrived for 2009 model year with the 9A1 motor.

So I haven't found it yet, but, has anyone documented up the swap a little? My 2nd gear has the feel of a gear headed south.. Just the details, Mounts - any changes needed? Electrical connection (Backup lights) Clutch slave plumbing? Drive line connection? Cheers.

I too am considering this very thing. My 996 is in need of rebuild and a friend has a 997 S trans available. What I have today in a '99 996 body with G96.00 trans with factory LSD mated to 2002 3.6L engine. It seems the 997 S trans will bolt but that I need new cables because the shift linkage is on the driver's side (instead of the passenger's side) so the length is different. The cable connection might be different also but not sure about that. The unknown is the transmission mounting brackets opposite the engine side. Will my mount work? Do I need to make mods or find a different mount and if so what mount? Thanks, Gary

I've also seen comments about retrofitting a 997 shifter to a 996 so at least that bit sounds plausible. The upside is the front mount is pretty simple,. I was wondering of a turbo trans would fit , I kinda like the larger wide mount it uses..

I remember reading on another thread that the 997 transmission is actually bigger / longer than the 996 unit, making it a little tricky to install. From what I understand the main difference is you have to use 997 shifter cables because they are a different length. They also run on the other side so you have to get them away from some coolant lines. The only part I don�t understand is how the mount works but I assume worst case if the 996 mount doesn�t line up you have the use a 997 bracket.

The front mount is sort of T shaped, two studs on the body at the top of the T and then the front rubber mount has 2 bolts that go cross ways through the rubber mount at the lower leg of the T. Either way the mount in front doesn't look too mad to change the length or width of. Probably easiest way would be to get the mount with the 997 trans so you have both and can sort the hole alignment out.. I'm looking a the C4 transmission, which adds the different front diff assembly.. I'd probably keep the 996 diff, and just adjust the driveline length if needed. Be awesome if someone had the actual length from the bell junction to the front of the nosecone of both.. I keep looking at the used ones, but from what I can tell the 996 getrag is kinda like the 996 engine, some small glitches that add up to a 3-5K pain in the rear..

Gents, I have successfully put a 997 C4S 6-Speed (G97.31 AISIN) trans into my 996 track car - a C2 that "identifies as a GT3" but is decidedly not. The stock trans was a G96.00 6-speed that started popping out of first, then second, started grinding going into 2nd when down shifting and rev matching. When I emptied out the oil there was "glitter" in the oil. Anyway, she is in need of a rebuild and a friend offered me a used 997 C4S trans for a very accommodating price and promised it would fit. Yep. It fit but it was a tight fit. Mainly the top of the trans oppose the engine side was a little higher than the 996 trans and was pushing up against coolant pipes, the front power/drive shaft "flange" was hitting some coolant rubber hoses, and the shift linkage is on the opposite side. It was a bit of a bugger to get to fit and make clearance but I got it. I haven't road tested it yet all seems to shift and engage properly. There is a little more stiffness in the shifting and that is probably due to the junkyard 997 shift cables being router around coolant lines and the transmission mount which caused a few higher stress bends. Not a show stopper but a difference. I did not try the 996 cables because folks on this board said you needed the 997 ones so I never compared them. I also called and emailed Numeric to talk to them about this conversion and how their cables might support this. Well, after 4 days of calls, emails, and voice mail with out a return call or email I gave up and bought the used 997 cables as per this forum indicated they would work and they were $125 with the body plug and insulation whereas the Numeric set was $500 or so. In retrospect the numeric cables probably would have made life much easier and the shifter feel smoother but they did not answer so I rolled the dice and went with the supposedly proven (and cheaper) option. The real trouble with the cable routing was the last bend to get under the transmission mount and align with the cable holder bracket. I could make plastic notched cable sheath cap fit into the bracket but it was with extreme force and a lot of residual tension in the cable assembly. I did not like that so I though (wrongly) I could rebend the bracket to give up an 1/8" to 1/4" favorable to relieve the stress. My tools and I did not have the talent to pull that off so I ended up cutting the bracket between the two mounting "forks" where the cable sheath cap locked in. I then cut and bent each piece individually to where I felt very little cable stress when bolted up. The only problem is one bolt hole is insufficient to hold the now individual bracket in place. Over time that would surely loosen up so I put a piece of metal between the two pieces and welded them together, as well as put a few dollops of weld to strengthen where I had cut and weekend the bracket. It felt very solid afterwards and with two bolt holes the bracket would now be fixed. Again, if the Numeric cables were more flexible to aid with the routing and long enough to use the stock bracket w/o stressing the cable, that might have saved a ton of work and been a better solution - however since I don't know their length and flexibility to deal with the more tortuous routing path, I don't know. May have been the same problem in the end. Sadly I did not take many pictures as I was working through this but I did take some. I will see if I can start a new thread title something like "997 Manual Trans into 996 Success." Give me a few days to get the pics that I do have and see how to edit them with arrows and such and then I will upload. I did want to give you guys my quick synopsis here as this thread did help me decide to do it and figure it out.

*weakened* the bracket...dang auto correct