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      03-19-2020, 02:06 PM   #170
fastboatster
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Drives: 2009 bmw 328i
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Quote:
Originally Posted by upsidedownfunnel View Post
A big reason why Porsche must use PDK is because mid/rear engine cars pretty much have to because of packaging. Modern torque converter planetary automatics are too long. This is also way performance front engine FWD cars (or FWD based AWD) use DCTs or manual only as well. Cars like the GTI/Golf R, the Focus RS, Civic Type R, Veloster N, Civic Si, either are DCT or manual only because a torque converter automatic in a transverse configuration is severely compromised for use in a performance car.

Obviously Porsche and other mid engined cars are longitudinal, but they drive the rear wheels so need a transaxle with limited space in the back. Look at the new C8 corvette. They go mid engine so they changed from torque converter auto to DCT. That's why cars like the RS4/5/6, M3/M4/M5/M8 can all use torque converter automatics since they use a front engine RWD layout. Audis are a bit weird but since they have longitudinal engine configurations and it's easier to fit a long transmission in the front of the car, we can just pretend they are RWD cars.

Finally, I'm sure Porsche could fit a ZF 8HP in the back if they really wanted to. But they're Porsche. They charge a lot of money for the little things.
In Porsches, the transmission is pointed towards the inside of a car, so length doesn't matter too much. Besides, awd pdks are very similar in length to Audi's longitudinal dcts, and these are definitely NOT short, yet they fit them just fine. RWD zf8 is a very small transmission, same size as 6hp. 6hp is not gigantic either. Porsche previously had torque converter autos, the shift to dct was because dcts were quicker at a time and 1.5 lawyers driving these cars wanted to feel like they are some kind of enthusiast drivers.
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