Adrian

Dear Horst,
For the G50/03 and G50/05 C2 gearboxes as compared to the G64/00 C4 gearbox the differences are in 2nd and 3rd.
2.059:1 G50/03&05 2nd gear
1.407:1 G50/03&05 3rd gear

2.118:1 G64/00 2nd gear
1.444:1 G64/00 3rd gear

The G50/04 and G50/10 and the G64/01 gearboxes are different again.
Final drive ratio is always 3.444 regardless of gearbox
Ciao,
Adrian
911C4

Vrprotti

I have a new track toy, a82 tub with 964 motor.
Once the car is run about 8 minutes on the track it has a big hesitation issues around 4,200-4,800 RPM, I changed both coils, distributor caps and rotor, tested dme and installed new custom Steve wong chip, and new mass air flow sensor, none of which helped. After reading this it sound like it could be 02 sensor.
Could I unplug for a session to test it? Should I spend 130$ to replace

FeralComprehension

FWIW you can get that part cheaper on Amazon; ~$85 IIRC.

stevepaa

failing O2 will cause you to fail smog in cal, if you almost fail, check your O2.

Zingari

I can confirm the symptoms of a failed/failing O2 sensor. I was in the process of getting mine out to swap over into a decatted exhaust section (noted the comments about reduction in bhp as I'm going to use a stripped out cat) but due to a bad thread on the sensor ended up putting it back.

Clearly I damaged it, albeit it looked well worn, car started up fine until it warmed up about half a mile from home. Erratic idle, rough running, no power and cutting out. Fortunately I was able to limp home

boxsey911

Unlucky Brian. It's almost always easier to just buy a new one rather than try and swap out an old one.