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Auto trans vs manual


wtreat

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All the new high peformance cars are automatics. Specifically, an automatically-shifted manual transmission. Like Ferrari, BMW, Porsche and almost all the others.

 

So even they prefer manuals.

 

Nope, Mostly what these manufacturers are using is dual clutch transmissions(DCTs). While DCTs are similar to automated manuals, they are not the same. A DCT has two wet clutches rather than one dry clutch, and it is basically two separate three speed manuals in the same case. Gears 1,3,5 are in one trans, and gears 2,4,6 are in the other. This allows the transmission to select the next gear up or down in the other transmission (not literal transmission, but effectively they are separate). This allows the car to be in the next gear, so all that needs to happen is one clutch disengages and the other engages. These systems are often accompanied by flappy paddles, but they can also be fully automated. But complete manual control would be way too difficult for normal drivers.

 

An automated manual is just what it sound like a normal standard (lol) transmission. With constant mesh gears, synchros, and a single dry clutch. No planetaries, no clutch packs, no band clamps, and no torque converters. Both the shifting and the clutching are controlled by the car, not the driver. This allows for the ease of an auto, with the efficiency of a manual. (Talked to a friend recently that drove an E46 M3 with an automated manual, he said it was very strange, because you knew what the car was doing, and felt like you should be a part of it, but you weren't).

 

 

Edit: with a little research, you were also right. BMW, Porsche, Ferrari, etc. have made the move to DCTs, but for a couple years before that, they were also using automated manuals.

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I stand corrected about manually shifted automatics.

 

Back to the original post. It is in reference to a 520, unknown year. Assuming "bolt in" engine swaps, the transmission choices are 3 speed torque converter, band and clutch pack automatic, four and five speed dry clutch syncro shifted manual.

 

If driven the same way, the five speed would potentially be the best choice for gas mileage. No torque converter slippage, no oil pump losses from the automatic. Additionally, the extra gear with the five speed should make it possible to keep the engine closer to the most efficient operating RPM.

 

A manual transmission also has the possibility of down hill coasting, with the engine off. Not recommended with power brakes, or power steering, but if the old truck or car has manual steering, and brakes, a possibility.

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