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View Full Version : Why Are Auto Gear Ratios Different?

DrivingTheDream
27-07-06, 10:58
To manuals?
Paul@SWZ
27-07-06, 10:59
Mainly because the auto box has less gears I believe !
Pete
27-07-06, 11:09
Indeed. Also why the diffs are different ratios.
DrivingTheDream
27-07-06, 11:09
I know that! lol! I meant why do they have less gears too?
Pete
27-07-06, 11:18
I'm guessing - Because they're so hidiously complicated inside and it's very expensive to make with more gears? It's only fairly recently that BMW etc have had the cool proper sequential manual gearboxes - I bet they cost a fortune.
Paul@SWZ
27-07-06, 11:22
It also due to size and weight as there is valves, solenoids and more fluid for each gear causing it to need a bigger sump etc
garethr
27-07-06, 12:07
Mercedes have a 7-speed auto now, but they can't use it on the big power AMG cars because it won't handle the torque, so maybe it's a good thing that the Toyota box is only 4-speed :-)
imi
27-07-06, 12:10
not to mention that the Auto gearbox design is over 10 yrs old....technology has moved on since.....
paul mac
29-07-06, 00:41
not to mention that the Auto gearbox design is over 10 yrs old....technology has moved on since.....
10 years try 15-20 years, i tried a flappy paddle gear box in a saab turbo hired when i was away with work, it was laughable the ecu would wait about 10 seconds while it took in the scenery THEN change up with the engine bouncing of the rev limiter, i was glad to get back in the no nonsense 3 speed supe
Ark
29-07-06, 11:12
I'm guessing - Because they're so hidiously complicated inside and it's very expensive to make with more gears? It's only fairly recently that BMW etc have had the cool proper sequential manual gearboxes - I bet they cost a fortune.

Plus the SMG's lunch themselves with frightening regularity - I knew a chap who went through three of them on his M3...
geoffvalenti
29-07-06, 12:48
I know that! lol! I meant why do they have less gears too?

Mainly because the slippage in the torque converter enables the engine to be in a more efficent part of the toque curve than a locked up system, (clutch/manual 'box) therefore negating the need for more gears (except in extreme high performance applications)