Gearing 6MT vs 7 DCT?

[kinimod]

Are the gears 1-6 equal in both transmissions, while 7th in DCT is just an extra for highways? Or is gearing actually adjusted for 6MT?

I was wondering about this and how it affects fuel economy on the highway if that 7th gear is not available for 6MT.

[rubber_ducky]

I'm fairly certain that the gear ratios are listed in the new issue of roundel. Which I don't have with me at the moment. But unless somebody else beats me to it, I'll try to remember to post tonight

[JoeFromPA]

Gear ratios are different, but 5th and 6th are the same in both IIRC.

[01ON19]

http://f80.bimmerpost.com/forums/sho...&highlight=DCT

[01ON19]

Per Roundel:

________DCT________MT
1st____4.806______4.11
2nd____2.593______2.315
3rd____1.701______1.542
4th____1.277______1.179
5th____1__________1
6th____0.844______0.846
7th____0.671

Final
Drive___3.462____3.462

[Zoli007]

Interesting, so based on that the DCT will turn fewer revs in 7th vs the MT in 6th.

[JoeFromPA]

Originally Posted by 2015F80M3

6MT gets better mileage too. Probably because of the gearing.

Let me edit that for you:

6MT gets better fuel economy in EPA testing, but not in EU testing, and since it is essentially geared the same as the DCT with the same final drive, it's not likely due to the gearing.

Instead, it is likely due to drivetrain efficiency in the manual trans vs. the DCT.

[chiplee]

What's the rear diff ratio?

[Milban]

The way I read it, 3.4 (final drive) is the rear end ratio on both, and 7th on the DCT is more advantageous than 6th on the 6mt.

[StealYourFace]

It would be nice if BMW would gear their torquey 6 speed stick cars similar to the way GM does. No need for 6th gear to be so short.4th should be 1 to 1, 5th .85 and 6th .6

[kinimod]

So does it mean that gears 1 through 4 on MT convert slightly less revolutions to the wheels than DCT? Doesn't that mean that the engine has to work harder to maintain constant speed (operate at higher engine rpm)?

If so what are the benefits of this?

[CanAutM3]

See here for good discussions on the F8X gearing

EDIT: just realized Kanuk beat me to it