6 Speed Manual Tranny Question?

[rmorin49]

Is the 6 speed tranny in the Z4 unique to the E89? I recall reading this somewhere. If so, what is unique about it?

[ChuckB]

Yes it is unique from the other 6MT in the BMW paddock, the big difference is the short throws but includes better matched gear ratios to the power curves, but as demostrated in the 135/335 Performance Kits, torque is limited to 317lbs/ft to protect the clutch vs the normal 332lb/ft on either the Auto or DCT transmissions, but all kits get the upgrade to 320HP. I'll check with my folks and see what they will tell me next week.

[siscobmw]

different also the weight, they saved 6.5 kgs from other units and ratio are different and matched to different differential ratio....in the end they changed a lot of stuff but the final ratio is about the same ...

[rmorin49]

Thanks for the info. When I test drove an s30i with a 6MT followed by an s35i with the DCT, I really liked the feel of the 6MT. The throws were short and the gear ratios were excellent. This helped me make the decision to get an s30i with the 6MT since I have an R32 with DSG and missed shifting gears.

[Alext]

Anyone have any ideas what the gear ratios are for a manual 35i?

[Memphis1]

Originally Posted by Alext

Anyone have any ideas what the gear ratios are for a manual 35i?

23i
I - 4.32
II - 2.46
III - 1.66
IV - 1.23
V - 1.00
VI - 0.85
R - 3.94

30i
I - 3.5
II - 2.0
III - 1.31
IV - 1.00
V - 0.81
VI - 0.70
R - 3.19

35i
I - 4.06
II - 2.40
III - 1.58
IV - 1.19
V - 1.00
VI - 0.87
R - 3.68

[Alext]

great thanks memphis i been searching everywhere for that...looks IDENTICAL to the ratios in the 135i! SO it means the 35i doesnt have a unique 6 speed.

[Memphis1]

maybe it feels different because it's shorter throw, i'm sure Dinan and others could mess around with the ratios if you really wanted to.

[cdeslandes]

Originally Posted by rmorin49

Thanks for the info. When I test drove an s30i with a 6MT followed by an s35i with the DCT, I really liked the feel of the 6MT. The throws were short and the gear ratios were excellent. This helped me make the decision to get an s30i with the 6MT since I have an R32 with DSG and missed shifting gears.

The clutch/shift action combination on that car are amazing. Yes there are "better" clutches and gearboxes out there (Porsche/Nissan/Mazda) but none that have that perfect mix of fun and everyday drivability in my opinion.

(This coming from someone who learned to shift manually on a farm tractor back in 1974...)

[teagueAMX]

Originally Posted by memphis2012

23i
I - 4.32
II - 2.46
III - 1.66
IV - 1.23
V - 1.00
VI - 0.85
R - 3.94

30i
I - 3.5
II - 2.0
III - 1.31
IV - 1.00
V - 0.81
VI - 0.70
R - 3.19

35i
I - 4.06
II - 2.40
III - 1.58
IV - 1.19
V - 1.00
VI - 0.87
R - 3.68

memphis2012, do you know what the rear gear set ratio is for each of the three models? I looked on BMW Features and Specification page for the 35i and it didn't show the ratio.

It's interesting that the engine with the most torque has a higher numerical 1st gear ratio. This must mean they put a numerically lower rear end gear in the 35i, giving it a better top speed. But it's just a guess without knowing the rear differential gear ratio.

Note: Most everyone likely knows, but for those that don't, a high gear number or ratio means the gear is actually "low", like a tractor low gear.

[zEdP]

Hi teagueAMX,

The end gear ratios.
23i - 3,64
30i - 4,27
35i - 3,08

It's interesting that the engine with the most torque has a higher numerical 1st gear ratio.

This makes for the gearbox and end gear the following ratios:

23i I-15,72 II-8,95
30i I-14,95 II-8,54
35i I-12,50 II-7,39

EdP

[teagueAMX]

Thanks EdP,

The 30i rear end ratio is really steep, but it's torque is much less than the n54 so it needs it. The 35i final drive ratio makes sense, and sort of what I expected given the n54's has much more torque than the 23i and 30i.

So even though the 30i MT 6th gear has an overdrive ratio of .7, when the final drive ratio is calculated it is 2.99. Compare that to the 35i is 2.68. So the 30i MT gear set is actually a closer ratio gearbox, and is designed to keep it in the right RPM range right up to highway speeds. The 35i can stretch it's legs a little more around town and ultimately on the highway.

Has anyone done the same calculation for the DCT?

They say that 35is has the M3 DCT, which would be expected given 35is' overboost torque of 369 ft lbs, so that's another scenario to consider.

[zEdP]

Copied from the new 2010 E89 catalog.

35is:
I-4,78 / II-3,06 / III-2,15 / IV-1,68 / V:1,39 / VI:1,20 / VII:1.0
End gear ratio 2,56.

http://www.belux.bmw.be/newmedia/doc...dster_BENL.pdf on page 22.

So if this info is correct, the DCT 35i and 35is have both the same gear ratios.

EdP

[s2000jan]

Originally Posted by zEdP

Copied from the new 2010 E89 catalog.

35is:
I-4,78 / II-3,06 / III-2,15 / IV-1,68 / V:1,39 / VI:1,20 / VII:1.0
End gear ratio 2,56.

http://www.belux.bmw.be/newmedia/doc...dster_BENL.pdf on page 22.

So if this info is correct, the DCT 35i and 35is have both the same gear ratios.

EdP

from the look of this picture below, it is NOT the same as the one from the 35i (taken from the same brochure) .... or am I missing something ?

[Memphis1]

Originally Posted by s2000jan

from the look of this picture below, it is NOT the same as the one from the 35i (taken from the same brochure) .... or am I missing something ?

what ZedP quoted is the DCT ratios for both, what you're looking at is the 6 speed on the 35i vs the DCT on the 35is...

[s2000jan]

Originally Posted by memphis2012

what ZedP quoted is the DCT ratios for both, what you're looking at is the 6 speed on the 35i vs the DCT on the 35is...

Your right ! my bad ! was comparing 2 different things ....