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With all due respect the S2 pinion gear set are weaker and break. The pinion is not as strong as the turbo pinion. Here is a picture of my 951 when I got it. It had an AOR with the "S2" pinion swap. That cost me $3332 to have sent off and rebiult. I also found a welded input shaft but that's a different story.
I'm willing to bet your previous owner installed the S, not the S2 R&P. That one is indeed weaker than the Turbo. The S2 R&P mod has been done on half a dozen cars down here that all see the track. So far none have failed. The first one that did the swap mistakenly did the S R&P and that failed just like yours.
How is the S2 different? Hardened pinion gear? Same small pinion gear right? Why not just use an S2 transaxle and not waste time putting the S2 ring/pinion into a turbo transaxle which has the same 1-5 gear ratio as the S/S2?
That's an option although I thought the S2 and Turbo w/ S2 r&p still had different gear charts. Don't have them to hand at the moment. The S2 rp is definitely stronger than that of the S though. The 1st gear in the turbo is hardened also.
I agree with Cole. It's largely in the gearing. The turbo does have long gearing in stock form but with the S2 rp mod it's a totally different beast. I have in car video of my car back in 2009 / 10 with that gearbox setup and you can see how quick it rows through the gears. This is with a stock 2.5 motor with larger cam and a GT3076 turbo. The cam actually would have hurt response as it shifted the powerband across to higher rpms. Still, you can see just how lively this gearbox mod made the car.
The stronger S2 ring and pinion is 8/31 teeth, the S and NA are 9/35, the final drive in the S2 is ever so slightly taller at 3.875, to the NA/S 3.8888.
Then I would just use a S2 transaxle over having the work done to a turbo transaxle if someone wanted shorter gears with a stronger differential. Having a hardened first gear won't matter because the turbo won't be able to biuld much if any boost with how fast I goes thru that 1st gear. Wow someone realy hacked my AOR before I had it fixed to stock form, wonder if it still has hardened first and second gears now.
The cooler can be added to the S2 transaxle I believe. Would need the proper oil cooler side cover and proper oil pump gear depending if it's a open or LSD with the cooler loop and the transaxle end cap with the hole in for the return. Or make a home made setup if it's a race car like this thread shows which is real nice because it has a temp switch for the pump vs running all the time like the stock tranaxle coolers, which in cold weather may keep the trans fluid too cold and make the trans whine(from what I've heard). https://rennlist.com/forums/924-931-...on-cooler.html
3.0 NA is sweet for sure... but anyone who says it's almost as fast, similar hp, etc. etc. clearly has not spent much time on-boost in a 951. Countless cars have good torque and throttle response: 350Z, 3-series, G35 the list goes on. But when that boost comes on you'll forget all about NA. Maybe in a drag race or road coarse they will be similar stock-4-stock, but IMO that rush of boost at 3500 rpm is an a whole other level. And that's before you mod it. A tuned 951 can break traction UPON roll-on boost in 2nd and 3rd. I've had all kinds of high end cars, and the one that makes most people say 'holy bajeezes' is my stock 951... at 3500 in 2nd on a spring day.
Keep in mind if you drive a Turbo, try to find one you know is sorted, even if not for sale (some RL member, cars-n-coffee, etc) because unlike with NA, one that is off even a little, vaccuum leaks, boost leaks, will run like a wet basset hound.
Nice rational post Molly. Off-on light switch like power is an addictive rush for sure. I get mine from my Kenny Roberts Yamaha RZ350 (1984). It would do 0-60 in 4.8 seconds before being hopped up Crank the throttle and when the power band (3500 rpm) hits you better be leaning forward and holding on. Now it's closer to a 4 second trip with expansion chambers replacing the catalytic convertor equipped restrictive exhaust , power valves locked open and 34mm Mikunis. Not bad for a little 350cc two stroke twin and a world away from my Harley.
I got my first 2-stroke dirt bike (KX-80) in about 1984. I know your bike well. Same logic applies with bikes. My last dirt bike was a 2013 WR250R and before that a DRZ400SM. (Then I redesigned my collarbone and cuff, so no more bikes) Those 4-strokes are bad *** for sure... but that 2-stroke power band hit of my last RM125 full race bike was, like boost, a whole other level. Front tire comes right off the ground.. any speed.. any time.. you have no choice in it.. weight forward and enjoy. Just like boost ; )
Boost is definitively addictive. When I was first looking at getting a 944 I had my heart set on an S2. I test drove one but didn't end up buying it. A couple weeks later I decided to go and have a look at a Turbo, just out of curiosity. One test drive and I was sold, put a deposit on it the next day. Even now I am falling more and more in love with the little beast, and when I look back I am very glad I didn't buy an S2 instead.
Though, having said that, maybe one day I will get myself an S2 or even a 968...but only so I can build a 3 Liter turbo!
Boost is definitively addictive. When I was first looking at getting a 944 I had my heart set on an S2. I test drove one but didn't end up buying it. A couple weeks later I decided to go and have a look at a Turbo, just out of curiosity. One test drive and I was sold, put a deposit on it the next day. Even now I am falling more and more in love with the little beast, and when I look back I am very glad I didn't buy an S2 instead.
Though, having said that, maybe one day I will get myself an S2 or even a 968...but only so I can build a 3 Liter turbo!
Reminds me of my story. I almost bought a stock green 944. It was an NA and came without a battery for $1000. The deal didn't go through because the guy wouldn't agree to smog it before sale. Can't tell you enough: glad I didn't buy. The next 944 I looked at was my Turbo and everything was right about it. Put deposit on it that same day...was too anxious to even want to negotiate.
Now I know how big of a deal that was. I love the car more and more. Boost power is the most insane thing. Can't imagine my 944 without it ... it's just a whole different beast than any non-turbo.
I have been looking for about a year for a low mile S2/968 for weekend driveability. I found a pretty good one in Boston a few month ago, but the guy didn't want to sell it to me because I was an out of state buyer. One of my 951's is to rare to drive. The other has 350hp, which makes it a little hard to live with sometimes, so it depends on how you intend to use it.
12-07-2015, 05:42 PM
Crank the throttle and when the power band (3500 rpm) hits you better be leaning forward and holding on. Now it's closer to a 4 second trip with expansion chambers replacing the catalytic convertor equipped restrictive exhaust , power valves locked open and 34mm Mikunis. Not bad for a little 350cc two stroke twin 
