Z4 SMG Question

[Jimbeaux]

My 2004 Z4 has an SMG with the stick and the wheel paddles. What years was this option offered, and is it still? If not, why...problems or just not accepted?

[Jimbeaux]

Does anybody have any knowledge on this?

[bar_steward]

My understanding of it is that this an automatic gearbox with "manual" paddles and not an SMG gearbox as fittedto the M3 which was a hydrauliclly operated manual gearbox. The main difference being that the G/box fitted to the Z4 has a torque-convertor type clutch and thus will give smoother (but not quite as brutally fast) gear changes - which by all accounts in no bad thing!!

Good luck with the Z - i get my on wednesday!!!

[Andrew D]

bar_steward said:

My understanding of it is that this an automatic gearbox with "manual" paddles and not an SMG gearbox as fittedto the M3 which was a hydrauliclly operated manual gearbox. The main difference being that the G/box fitted to the Z4 has a torque-convertor type clutch and thus will give smoother (but not quite as brutally fast) gear changes

That isn't the case of "SMG" Z4's. The SMG box (technically known as "H-SMG" ) is fundamentally the Z4's six-speed manual fitted with a hydraulic system for making gear movements and operating the clutch. At facelift (in 2006) the SMG option was dropped and the steering wheel paddles given to the automatic (which had previously been available in line with SMG and the manual, but with only the stick to operate the steptronic fixed-ratio option).

I'm not sure why it was dropped, I haven't heard of any inherent mechnical problems with it, but I know it wasn't very popular. Presumably BMW reasoned that the number of customers lost as they wouldn't accept the auto rather than SMG was outweighed by cost savings of stopping SMG production. Or perhaps the SMG box wasn't upto taking the M Roadster's torque output and they didn't want to offer SMG on the lower cars but not on the M Car.

As the SMG box is a manual underneath it lacks the smooth movement between gears of a true auto, but also lacks transmission slip under power. But in normal driving it's pretty smooth, although it sometimes slips the clutch more than you would in a manual when moving off from slow speeds in second. In the car's "Sport" mode, however, changes are pretty much instant and fairly savage, which is nice when you're in the mood but it's good to be able to turn Sport off for more mundane driving.

In my opinion the SMG transmission is the most suited to the car, for two primary reasons. Firstly it makes the fullest use of the Sport mode that tightens steering and throttle response, maximising the flexibility of the car between cruiser and sports tool. The steptronic auto box goes into a sports (read: high-revving) mode also, but the SMG does that and shortens shift times. Secondly, the Z4 is fundamentally a roadster; a car for both sports driving and refined crusing. SMG promotes that flexibility, when a manual is more suited to hardcore head-banging as in a Boxster S, and an auto is more suited to a waft-mobile that dabbles in sports driving such as an SLK.

[Jimbeaux]

Andrew D said:

bar_steward said:

My understanding of it is that this an automatic gearbox with "manual" paddles and not an SMG gearbox as fittedto the M3 which was a hydrauliclly operated manual gearbox. The main difference being that the G/box fitted to the Z4 has a torque-convertor type clutch and thus will give smoother (but not quite as brutally fast) gear changes

That isn't the case of "SMG" Z4's. The SMG box (technically known as "H-SMG" ) is fundamentally the Z4's six-speed manual fitted with a hydraulic system for making gear movements and operating the clutch. At facelift (in 2006) the SMG option was dropped and the steering wheel paddles given to the automatic (which had previously been available in line with SMG and the manual, but with only the stick to operate the steptronic fixed-ratio option).

I'm not sure why it was dropped, I haven't heard of any inherent mechnical problems with it, but I know it wasn't very popular. Presumably BMW reasoned that the number of customers lost as they wouldn't accept the auto rather than SMG was outweighed by cost savings of stopping SMG production. Or perhaps the SMG box wasn't upto taking the M Roadster's torque output and they didn't want to offer SMG on the lower cars but not on the M Car.

As the SMG box is a manual underneath it lacks the smooth movement between gears of a true auto, but also lacks transmission slip under power. But in normal driving it's pretty smooth, although it sometimes slips the clutch more than you would in a manual when moving off from slow speeds in second. In the car's "Sport" mode, however, changes are pretty much instant and fairly savage, which is nice when you're in the mood but it's good to be able to turn Sport off for more mundane driving.

In my opinion the SMG transmission is the most suited to the car, for two primary reasons. Firstly it makes the fullest use of the Sport mode that tightens steering and throttle response, maximising the flexibility of the car between cruiser and sports tool. The steptronic auto box goes into a sports (read: high-revving) mode also, but the SMG does that and shortens shift times. Secondly, the Z4 is fundamentally a roadster; a car for both sports driving and refined crusing. SMG promotes that flexibility, when a manual is more suited to hardcore head-banging as in a Boxster S, and an auto is more suited to a waft-mobile that dabbles in sports driving such as an SLK.

Good write-up; thanks.

[bar_steward]

Andrew D said:

bar_steward said:

My understanding of it is that this an automatic gearbox with "manual" paddles and not an SMG gearbox as fittedto the M3 which was a hydrauliclly operated manual gearbox. The main difference being that the G/box fitted to the Z4 has a torque-convertor type clutch and thus will give smoother (but not quite as brutally fast) gear changes

That isn't the case of "SMG" Z4's. The SMG box (technically known as "H-SMG" ) is fundamentally the Z4's six-speed manual fitted with a hydraulic system for making gear movements and operating the clutch. At facelift (in 2006) the SMG option was dropped and the steering wheel paddles given to the automatic (which had previously been available in line with SMG and the manual, but with only the stick to operate the steptronic fixed-ratio option).

I'm not sure why it was dropped, I haven't heard of any inherent mechnical problems with it, but I know it wasn't very popular. Presumably BMW reasoned that the number of customers lost as they wouldn't accept the auto rather than SMG was outweighed by cost savings of stopping SMG production. Or perhaps the SMG box wasn't upto taking the M Roadster's torque output and they didn't want to offer SMG on the lower cars but not on the M Car.

As the SMG box is a manual underneath it lacks the smooth movement between gears of a true auto, but also lacks transmission slip under power. But in normal driving it's pretty smooth, although it sometimes slips the clutch more than you would in a manual when moving off from slow speeds in second. In the car's "Sport" mode, however, changes are pretty much instant and fairly savage, which is nice when you're in the mood but it's good to be able to turn Sport off for more mundane driving.

In my opinion the SMG transmission is the most suited to the car, for two primary reasons. Firstly it makes the fullest use of the Sport mode that tightens steering and throttle response, maximising the flexibility of the car between cruiser and sports tool. The steptronic auto box goes into a sports (read: high-revving) mode also, but the SMG does that and shortens shift times. Secondly, the Z4 is fundamentally a roadster; a car for both sports driving and refined crusing. SMG promotes that flexibility, when a manual is more suited to hardcore head-banging as in a Boxster S, and an auto is more suited to a waft-mobile that dabbles in sports driving such as an SLK.

Ahh... I did find it a little confusing about the switch at 06MY so just assumed that the (very few) people that did advertise an SMG Z4 were just trying to make their auto Z4 sound a bit more sporty! Isn't it the same one that's fitted to the E46 M3?? If so the torque theory doesn't stand but never-the-less thanks for setting the record straight!

[Jimbeaux]

Getting the feel of it fine now. I love the SMG, the control of a manual without needing a clutch foot. Additionally, the "sport" mode makes a very noticable difference in throttle speed and shifting times. I hear people talk about their SMG in an "auto" mode. I would not want this, but was that an option, or did it come with all SMGs? I don't seem to have such a choice.

[Andrew D]

bar_steward said:

Isn't it the same one that's fitted to the E46 M3?? If so the torque theory doesn't stand but never-the-less thanks for setting the record straight!

As far as I'm aware H-SMG was a Z4-only transmission, as it was fundamentally based on the Z4's manual gearbox. So the torque theory depends on whether the M Roadster has the same ZF manual gearbox as the rest of the range. However, H-SMG is certainly a different system to the Siemens SMGII transmission available on the E46 M3.

Jimbeaux said:

Getting the feel of it fine now. I love the SMG, the control of a manual without needing a clutch foot. Additionally, the "sport" mode makes a very noticable difference in throttle speed and shifting times. I hear people talk about their SMG in an "auto" mode. I would not want this, but was that an option, or did it come with all SMGs? I don't seem to have such a choice.

Glad you're getting to grips with it. A lot of those who criticise semi-automatics haven't really driven them much and expect to be able to jump straight in and drive them smoothly, like in an auto. The fact is that if you hadn't driven a manual before, you'd not drive that smoothly either, and it's a damned shorter learning curve on SMG!

Sport mode is certainly a good laugh, but I'd be careful about using it too often. Apart from drinking more fuel due to the throttle map (as mine seems to do in Sport), I suspect that the savage gear changes might result in quicker clutch wear than in the non-Sport mode.

The automatic mode was integrated to all SMG boxes. You can tell if you're in automatic by looking at the gear indicator between the speedometer and tachometer dials; if the gear number is preceded by "D" it's in automatic mode, and will shift on it's own according to your driving style. If it just has a number then it's in manual and will only shift if you tell it to, if it hits the rev limiter or is going to stall. You can switch between auto and manual by pushing the gearstick to the right (away from Reverse) when you're in drive (it doesn't stay in that position, it's only a toggle switch). When in automatic you can go straight to manual by changing gear with the paddles or gearstick, and it then remains in manual until you push the gearstick to the right again.

[Jimbeaux]

Andrew D said:

bar_steward said:

Isn't it the same one that's fitted to the E46 M3?? If so the torque theory doesn't stand but never-the-less thanks for setting the record straight!

As far as I'm aware H-SMG was a Z4-only transmission, as it was fundamentally based on the Z4's manual gearbox. So the torque theory depends on whether the M Roadster has the same ZF manual gearbox as the rest of the range. However, H-SMG is certainly a different system to the Siemens SMGII transmission available on the E46 M3.

Jimbeaux said:

Getting the feel of it fine now. I love the SMG, the control of a manual without needing a clutch foot. Additionally, the "sport" mode makes a very noticable difference in throttle speed and shifting times. I hear people talk about their SMG in an "auto" mode. I would not want this, but was that an option, or did it come with all SMGs? I don't seem to have such a choice.

Glad you're getting to grips with it. A lot of those who criticise semi-automatics haven't really driven them much and expect to be able to jump straight in and drive them smoothly, like in an auto. The fact is that if you hadn't driven a manual before, you'd not drive that smoothly either, and it's a damned shorter learning curve on SMG!

Sport mode is certainly a good laugh, but I'd be careful about using it too often. Apart from drinking more fuel due to the throttle map (as mine seems to do in Sport), I suspect that the savage gear changes might result in quicker clutch wear than in the non-Sport mode.

The automatic mode was integrated to all SMG boxes. You can tell if you're in automatic by looking at the gear indicator between the speedometer and tachometer dials; if the gear number is preceded by "D" it's in automatic mode, and will shift on it's own according to your driving style. If it just has a number then it's in manual and will only shift if you tell it to, if it hits the rev limiter or is going to stall. You can switch between auto and manual by pushing the gearstick to the right (away from Reverse) when you're in drive (it doesn't stay in that position, it's only a toggle switch). When in automatic you can go straight to manual by changing gear with the paddles or gearstick, and it then remains in manual until you push the gearstick to the right again.

Good info all around; thank you sir!