'99-'01 vs '02-'05 manual transmission differences

All, I did some searching to learn more about he differences between these two transmissions. I didn't run across much. Hoping this thread can compile as much information in a single thread. I see that the clutches for each generation are different. Does anyone know what the differences are? Is the main difference the flywheel? If so, are the flywheels interchangeable? If so, what are the benefits/cons of each style? Also, based on my research, I came across some information about the shifter cable differences. Is that the only external difference? I am trying to find out these things: -How to physically install an '02-'05 transmission with a 3.6L engine into a '99-'01 chassis, and how to install a '99-'01 transmission with 3.4L engine into an '02-'05 chassis. -Can a '99-'01 trans fit a 3.6L engine and vice-versa? If so, do any parts like the flywheel/starter/slave cylinder/axles need to be changed with a different version? Any assistance you can provide is greatly appreciated.

That's a lot of questions. I think you should see if these guys could help answer your questions http://www.gboxweb.com/

Hi, I don't have a lot of facts for you, but based on recent research I did, and people I spoke with when I was looking to replace my blown motor, upgrading to the 996.2 engine takes a lot more work than just a engine/transmission swap. Physically, you should find the newer assembly will bolt right up. Assuming you have the e-gas/throttle 2000 and newer, there is an updated DME, you need to change brake lines, update ABS sensors (unless you alreadyy have a C4), cluster and wiring changes (or retain your cluster and do more wiring changes), and to make it more doable, you may want the key/ignition/immobilizer. That and the fuel system switched to returnless, so you will want to update that. It ended up being more than I was interested in, but a few people have done it successfully. If it was me, I'd want the engine donor car side by side with the recipient to make sure I got it all. Good luck with whatever you decide.

Thanks for the information! I will be using this information for really only testing purposes. Some of my cars will be torn apart to test. I really enjoy stuff like this. I've spent countess hours reading about random brands like Hondas, Nissans, and BMWs where people hodge-podged parts from different models and years for a better outcome. Hoping to see what I can find with these cars since most owners don't experiement. All in the interest of satisfying curiosity. I will say, I am a little shocked that things like the braking system will need to be changed to a newer version, speedometer, etc. I read how you can swap in a 3.6L into a 2003 Boxster without doing all of these modifications. Can you elaborate more on the C4? What is so different of the C4? Does the C4 have the necessary newer brake lines, ABS sensors, etc? Thanks so much for the help!

My understanding is that the C4 already has the newer version of the Bosch abs.

I can answer a few of your questions about the similarities/differences of the 996.1 and 996.2 trans/clutch. The 996.2 trans has 3 support bearings on the input shaft compared to the 996.1 trans has only 2, the extra support bearing is near the clutch side of the input shaft. The flywheels will interchange, as will the starter. The clutch pressure plate for the 996.1 are .200 shorter in length , the 996.2 release bearing is .200 longer. While they could be interchanged the 996.2 clamp load is a bit higher to handle additional torque. The clutch disks are the same diameter , spline,and thickness and are interchangeable. While the 996.1 and 996.2 trans have the exact same bolt pattern and will bolt to the engine, I can not say for sure if the overall length, axle bolt pattern, mounting points are the same, I have had no need to investigate this, but a side by side comparison would quickly determine this.