Are manufacturers ditching dual clutch for torque converters
Discussion
I have just been reading some random reviews recently and noticed quite a few new performance cars coming out are single clutch torque converter gearboxes.
The new S5 Sportback has an 8 speed torque converter, Lexus LC500 has a 10 speed and there's the ZF gearboxes in quite a few others.
The reviews seem to praise the better developed gearbox and say they pretty much are on par for speed/smoothness and economy with dual clutch but I guess they are cheaper to develop/maintain and more reliable.
The new S5 Sportback has an 8 speed torque converter, Lexus LC500 has a 10 speed and there's the ZF gearboxes in quite a few others.
The reviews seem to praise the better developed gearbox and say they pretty much are on par for speed/smoothness and economy with dual clutch but I guess they are cheaper to develop/maintain and more reliable.
I would agree, the Torque converter boxes have become way more efficient, rather than a massive slush heat pump that they always were.
Once the clutch is locked up it's no longer wasting energy through the torque converter (a propeller in a bath of oil) & now most are locked up unless stationary, pulling away or changing gear.
With some clever control of the solenoids you can also have two gears providing torque for a brief moment so technically there is no loss of drive during a gearchange. The Planetary gears are always meshed & just change direction for a ratio change.
It's also a lot easier to get multiple gearing through multiple sets of planetary gears to keep the engine at peak BSFC etc. Obvious advantages with smooth drive-ability too. The Mazda Skyactiv autobox was one of the first to do this, it's also almost half the size of a normal auto. with ZF & Aisin etc now following suit in the mainstream.
Once the clutch is locked up it's no longer wasting energy through the torque converter (a propeller in a bath of oil) & now most are locked up unless stationary, pulling away or changing gear.
With some clever control of the solenoids you can also have two gears providing torque for a brief moment so technically there is no loss of drive during a gearchange. The Planetary gears are always meshed & just change direction for a ratio change.
It's also a lot easier to get multiple gearing through multiple sets of planetary gears to keep the engine at peak BSFC etc. Obvious advantages with smooth drive-ability too. The Mazda Skyactiv autobox was one of the first to do this, it's also almost half the size of a normal auto. with ZF & Aisin etc now following suit in the mainstream.
PositronicRay said:
cptsideways said:
With some clever control of the solenoids you can also have two gears providing torque for a brief moment
Wow, I did not know that. Planet gears are wonderful things, you can also think of them like a differential & a traction control system using the brakes to slow the wheel speed, its exactly the same principle!
Just don't take one apart & expect it to go back together the same way autoboxes though simple in the mechanics have hundreds of valves, ports, pressure valves, springs etc all controlled by a few solenoids & loads of horrid little things that you WILL loose.
An Aisin three/four speed is the epitomy of simplicity though, simple pressure makes it all work rather well even to this day still one of the nicest changing boxes ever & autolockup above 40mph.
saaby93 said:
cptsideways said:
An Aisin three/four speed is the epitomy of simplicity though, simple pressure makes it all work rather well even to this day still one of the nicest changing boxes ever & autolockup above 40mph.
Whats got that ?I had heard the same, the only thing the dsg in my Skoda has over a conventional auto is shift speed and even then its tenths of a second .
In stop start traffic I far prefer a conventional box, in fact I cant think of any time i prefer the dsg although they do make a nice noise at full throttle upshifts, I'm certainly not a hater of the dsg but the reliability and bork factor does worry me slightly
I have a ZF8 in my Jag and it really is an excellent gearbox
In stop start traffic I far prefer a conventional box, in fact I cant think of any time i prefer the dsg although they do make a nice noise at full throttle upshifts, I'm certainly not a hater of the dsg but the reliability and bork factor does worry me slightly
I have a ZF8 in my Jag and it really is an excellent gearbox
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