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      09-05-2021, 08:22 PM   #1
IronCore864
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DCT Gear Ratio Much Higher than Manual / Torque Converter?

I'm reading the technical data from MINI, and it seems the gear ratios of the DCT is much higher than the manual:

I 3,615 15,741
II 1,952 9,284
III 1,241 5,899
IV 0,969 4,129
V 0,806 3,196
VI 0,683 2,558
VII – 2,073
Rückwärtsgang(reverse?) 3,538 14,220
Achsübersetzung(final drive?) 3,421 3,789

Any reason for this?

I think the mini DCT is getrag 7DCT300; getrag also produces DCT for BMW; iirc the M2 DCT is getrag too, but the numbers for M2 is much more reasonable:

Getriebeart 6-Gang manuell (7-Gang M Doppelkupplungsgetriebe mit Drivelogic)
Getriebeübersetzung
I 4,110 (4,806)
II 2,315 (2,593)
III 1,542 (1,701)
IV 1,179 (1,277)
V 1,000 (1,000)
VI 0,846 (0,844)
VII – (0,671)
R 3,727 (4,172)
Hinterachsübersetzung 3,462 (3,462)

I'm not sure if I've read some data sheet from VW, but I vaguely remember that the DSG gear ratios are also close to the manual.

Why on earth does mini DCT have such a high gear ratio? Because it has a ridiculously small primary drive???

Tried to google this but couldn't find much useful info; the only thing that come close is from a honda bike forum where the final drive is (slightly) different because of manual/DCT difference.

Anybody could answer this?

Thanks in advance.
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      09-05-2021, 10:50 PM   #2
Humdizzle
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no clue. The F80 is like this too. the ratios don't make much sense for the dct and seem to be better for the manual. 1st gear on the dct is short and useless, and 7th gear is just an overdrive gear. My guess is that they made 1st gear short on these cars to prevent people riding the clutch in low speed situations ? but idk.

https://f80.bimmerpost.com/forums/sh...d.php?t=949959
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      09-08-2021, 05:00 PM   #3
brad850csi
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They've made a mistake and multiplied the gear ratio by the final drive. If those ratios were correct the top speed would be about 100kmh
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      09-12-2021, 11:37 PM   #4
IronCore864
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Quote:
Originally Posted by brad850csi View Post
They've made a mistake and multiplied the gear ratio by the final drive. If those ratios were correct the top speed would be about 100kmh
Impressive! Your math must be really, really good...
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