Why a 7 speed gearbox...

Ashok Arora · 14th September 2004, 19:11

Some reviews say that the 7 speed SMG gearbox is overkill and just a marketing gimmick.

I disagree. The relatively low torque of the new M5 means that the engine needs extra gearing to get the best performance out of it, especially from a standing start.

Thoughts about this?

vndkshn · 14th September 2004, 19:21

Well, at least one of those articles said that there was plenty of low end power, negating the need for the 7 gears in that aspect.

However, my guess is that they went for 7 to get the most acceleration they could get out it to win the stop light war and provide the right gear at the right time in the turns.

However, the downside with this will mean more shifting in normal driving. At least that is one benefit of SMG in this case. I wonder how SMG will handle skipping gears?

flynhawaiian · 14th September 2004, 20:51

I was kinda thinking that they were meeting fuel economy regulations by putting in the 7th gear, which I assume is some super overdrive. Would be cool if on the highnway the car got 25 mpg

Quote:

Originally Posted by vndkshn

Well, at least one of those articles said that there was plenty of low end power, negating the need for the 7 gears in that aspect.

However, my guess is that they went for 7 to get the most acceleration they could get out it to win the stop light war and provide the right gear at the right time in the turns.

However, the downside with this will mean more shifting in normal driving. At least that is one benefit of SMG in this case. I wonder how SMG will handle skipping gears?

chuckg · 14th September 2004, 21:08

Quote:

Originally Posted by flynhawaiian

I was kinda thinking that they were meeting fuel economy regulations by putting in the 7th gear, which I assume is some super overdrive. Would be cool if on the highnway the car got 25 mpg

According to the post with the specs in Deutsch, 6th is direct and 7th is .833 which is not terribly high for an overdrive gear.
ChuckG

chuckg · 14th September 2004, 21:09

Quote:

Originally Posted by flynhawaiian

I was kinda thinking that they were meeting fuel economy regulations by putting in the 7th gear, which I assume is some super overdrive. Would be cool if on the highnway the car got 25 mpg

According to the post with the specs in Deutsch, 6th is direct and 7th is .833 which is not terribly high for an overdrive gear.
ChuckG

flynhawaiian · 15th September 2004, 00:45

Not teribly, but probably good for a sport car. I will take a guess at 6th gear being 1:1. Whats the rear end on this 4.10:1?? or are they going taller like 3.73??

Quote:

Originally Posted by chuckg

According to the post with the specs in Deutsch, 6th is direct and 7th is .833 which is not terribly high for an overdrive gear.
ChuckG

MEnthusiast · 15th September 2004, 02:29

Quote:

Originally Posted by vndkshn

However, my guess is that they went for 7 to get the most acceleration they could get out it to win the stop light war and provide the right gear at the right time in the turns.

This is my guess as well.

Ferrari-Bmw · 15th September 2004, 09:32

Quote:

Originally Posted by chuckg

According to the post with the specs in Deutsch, 6th is direct and 7th is .833 which is not terribly high for an overdrive gear.
ChuckG

true but the engine revs to ~~~~>> 8000+ so thats ,,why the car is capable to go 200 mph +

chuckg · 15th September 2004, 16:46

Quote:

Originally Posted by flynhawaiian

Not teribly, but probably good for a sport car. I will take a guess at 6th gear being 1:1. Whats the rear end on this 4.10:1?? or are they going taller like 3.73??

6th is 1.1 (i.e. direct) and the final drive ratio appears to be 3.62 if I'm interpretting the German specs right.
ChuckG

Suretyagent · 15th September 2004, 17:27

The answer will be revealed the first time you drive the new M5. I have no doubt that the gearing will seem perfectly spaced for the engine and that BMW would have designed eight or even nine speeds if they felt it would have enhanced performance.

If launch control works as well as I believe it will (think F1 car launching from a stand-still after a pit stop) the first three gears should snap off some seriously quick acceleration that will continue into higher speeds with each successive well-spaced gear. But it will probably take some re-programing of our brains to get used to the more frequent and frenetic action.

Unfortunately the top gears will not be fully appreciated without removal of the electronic top speed limiter.

Derek