How to make better use of your semi...
Discussion
...Automatic gearbox.
What?
Well, what else were you expecting the title to be? *Tuts*
This is something you won't find in Roadcraft - a guide to using semi-automatic gearboxes. I've never read a proper guide to using them, so the advice I'm giving is based solely on my own experiences. Obviously, every manufacturer's systems are slightly different, and have their own idiosyncrasies, so if you're an owner of a car with one of these gearboxes, please feel free to share your experiences on here.
Let's set the guidelines for the article first. I'm not going to be writing about switchable automatic gearboxes. A traditional fully automatic gearbox works via a torque converter, and there is plenty of information knocking about on how to use those correctly. What I am writing about are the more modern style of semi-autos, which incorporate a mechanical clutch and a traditional gearbox which has automatic (usually hydraulic) operation of the gearchange and clutch. They're two-pedal cars in which the gearchange is operated with either a gear-lever style switch on the centre console, or "paddles" behind the steering wheel, or a combination of the two. The gearchange is generally sequential (i.e. you have to go through each individual gear on the way up and down the 'box), but there are ways to effectively "miss" gears out, which I'll cover.
Now, my experience of these gearboxes isn't vast, but I own an M3 with the SMG1 gearbox, and I've had a reasonable amount of time behind the wheel of a DSG equipped Golf GTI, so I think I'm experienced enough to comment, but if anyone wants to let me have a go in an F1 equipped Ferrari (for comparison reasons only, of course), then I'd be happy to do so.
Setting off
The first thing to remember with gearboxes of this type is that they are not automatics. They have a mechanical clutch, and you should drive them with as much mechanical sympathy as you would a manual car. In a traditional automatic, the car is happy to sit on a hill with a small amount of power applied, keeping it stationary or just moving forward slightly - that's because the drive is being transmitted through a fluid coupling, and it creates no wear whatsoever if you drive it in that manner. Try that in a semi-auto, however, and you're effectively slipping the clutch. Drive like that all the time in traffic and you'll need a new clutch much sooner than you'd like.
Semi-autos don't "creep" either. Put a traditional automatic in drive, and it's tendency to creep allows you to carry out almost all your low speed manoeuvring by just releasing and pressing the brake pedal. If you put a SA car in gear and release the brake, nothing will happen. That's because the car has, in effect, pressed the clutch, put the car into gear, and is waiting, clutch down, for your next input. The car requires you to actually press the accelerator and apply some revs before it will release the clutch and start to move.
This is another area where you need to demonstrate some mechanical sympathy, and not quite in the way you might think. If you apply a small amount of throttle, the clutch will be released gradually and the car will slip the clutch for you. This is fine on the odd occasion that you're doing some parking or manoeuvring, but if you set off from stationary like that every time, again, you'll quickly wear out the friction plates of your clutch and face a large bill. I find that it's actually more mechanically sympathetic to set off with a little more throttle, so that the car almost immediately fully engages the clutch, rather than slipping it. I'm not saying you should set off with full-bore acceleration every time, but rather with a positive press of the accelerator, as opposed to feathering the pedal.
Most SA cars have some form of "launch control" system built into their software. In the M3, I think it's called "race start" or something similar. It requires the driver to push and hold the gear lever forward, which holds the clutch down, and then apply 4,000 to 5,000 revs with their right foot. Releasing the gearlever effectively "sidesteps" the clutch and the car takes off like a rocket. Now, don't get me wrong - it's an effective system, and it's great for impressing/frightening passengers, but it feels very rough on the whole transmission and in an RWD car, it can kick the rear-end sideways on all but the driest, best-quality tarmac. Other than trying it out a few times, I don't use it on the road, and I don't recommend it for anywhere other than the track.
So the best advice I can give you when setting off in a SA car is to remember that it's a manual gearbox with a proper clutch, and to drive it like that.
Changing up
I've discussed the merits of smooth gearchanges in another thread, so I won't flog that dead horse any more, but new users of SA gearboxes (myself included), find that the quality of gearchange is a little poor. I suspect (as was the case with me) that that's because they don't drive it like a manual, and expect the cars elastictrickery to sort it all out for them.
I'll refer you back to the advice I gave before - drive it like a manual. If you don't adjust your throttle position during an up-change, then the engine speed won't match the road speed for the next gear, and there will be an inevitable jerk when the clutch is released and the engine speed is brought back down through the transmission. So, the trick for up-changes is to release the throttle a bit during the gearchange. It doesn't have to be much, but allowing the revs to drop slightly during the up-change nicely matches engine speed to road speed, and eliminates almost all the jerkiness from the change.
This is obviously easier with slower gear-changes than it is with quicker ones. My SMG 'box is an early one which only has one speed of gearchange, which is quite slow. It suits my driving style, and allows me to change nice and smoothly - almost seamlessly. Newer SMG set-ups, together with other manufacturer's systems allow the driver to choose the gearchange speed. In those cars, I'd recommend perfecting your changes in a lower-speed setting, before turning the gearchange speed up. In the fastest settings, I think you'll always lose some smoothness, and these are best suited for track use, or spirited drives on your own.
Downchanges
Downchanges in SA cars are much easier to perfect, as the car's software usually incorporates a system which raises engine revs - "blips the throttle" on downchange. The SMG system is very good, and I've heard open-exhausted 360 CSs running at Fiorano, and they sound like they match the revs on downchange seamlessly.
One aspect which will be alien to the more traditional advanced drivers is that SA cars - particularly those with paddle gearchanges - allow gearchanges to occurr much easier whilst the driver is braking. One of the main reasons that Roadcraft recommends separation of braking and gearchanging is that it allows the driver to keep both hands on the wheel whilst braking. Paddle-shift setups obviously allow the gearchanges without removing the hands from the wheel. Despite that, though, I still drive mine almost to the system in that I leave my gearchanges to the end of the braking period, as I'm still a big believer in separation.
The only car I've driven so far in which I would overlap more was the DSG Golf. This gearbox is a marvellous piece of kit, and the gearchanges are almost perfect - on upchanges, there is no perceptible drop in acceleration and the downchanges are virtually seamless. I'd feel confident changing down through the box with a DSG setup, as the software doesn't allow selection of too low a gear.
Automatic Mode
Apparently these cars have a fully automatic mode.
I've never tried it.
What?
Well, what else were you expecting the title to be? *Tuts*
This is something you won't find in Roadcraft - a guide to using semi-automatic gearboxes. I've never read a proper guide to using them, so the advice I'm giving is based solely on my own experiences. Obviously, every manufacturer's systems are slightly different, and have their own idiosyncrasies, so if you're an owner of a car with one of these gearboxes, please feel free to share your experiences on here.
Let's set the guidelines for the article first. I'm not going to be writing about switchable automatic gearboxes. A traditional fully automatic gearbox works via a torque converter, and there is plenty of information knocking about on how to use those correctly. What I am writing about are the more modern style of semi-autos, which incorporate a mechanical clutch and a traditional gearbox which has automatic (usually hydraulic) operation of the gearchange and clutch. They're two-pedal cars in which the gearchange is operated with either a gear-lever style switch on the centre console, or "paddles" behind the steering wheel, or a combination of the two. The gearchange is generally sequential (i.e. you have to go through each individual gear on the way up and down the 'box), but there are ways to effectively "miss" gears out, which I'll cover.
Now, my experience of these gearboxes isn't vast, but I own an M3 with the SMG1 gearbox, and I've had a reasonable amount of time behind the wheel of a DSG equipped Golf GTI, so I think I'm experienced enough to comment, but if anyone wants to let me have a go in an F1 equipped Ferrari (for comparison reasons only, of course), then I'd be happy to do so.
Setting off
The first thing to remember with gearboxes of this type is that they are not automatics. They have a mechanical clutch, and you should drive them with as much mechanical sympathy as you would a manual car. In a traditional automatic, the car is happy to sit on a hill with a small amount of power applied, keeping it stationary or just moving forward slightly - that's because the drive is being transmitted through a fluid coupling, and it creates no wear whatsoever if you drive it in that manner. Try that in a semi-auto, however, and you're effectively slipping the clutch. Drive like that all the time in traffic and you'll need a new clutch much sooner than you'd like.
Semi-autos don't "creep" either. Put a traditional automatic in drive, and it's tendency to creep allows you to carry out almost all your low speed manoeuvring by just releasing and pressing the brake pedal. If you put a SA car in gear and release the brake, nothing will happen. That's because the car has, in effect, pressed the clutch, put the car into gear, and is waiting, clutch down, for your next input. The car requires you to actually press the accelerator and apply some revs before it will release the clutch and start to move.
This is another area where you need to demonstrate some mechanical sympathy, and not quite in the way you might think. If you apply a small amount of throttle, the clutch will be released gradually and the car will slip the clutch for you. This is fine on the odd occasion that you're doing some parking or manoeuvring, but if you set off from stationary like that every time, again, you'll quickly wear out the friction plates of your clutch and face a large bill. I find that it's actually more mechanically sympathetic to set off with a little more throttle, so that the car almost immediately fully engages the clutch, rather than slipping it. I'm not saying you should set off with full-bore acceleration every time, but rather with a positive press of the accelerator, as opposed to feathering the pedal.
Most SA cars have some form of "launch control" system built into their software. In the M3, I think it's called "race start" or something similar. It requires the driver to push and hold the gear lever forward, which holds the clutch down, and then apply 4,000 to 5,000 revs with their right foot. Releasing the gearlever effectively "sidesteps" the clutch and the car takes off like a rocket. Now, don't get me wrong - it's an effective system, and it's great for impressing/frightening passengers, but it feels very rough on the whole transmission and in an RWD car, it can kick the rear-end sideways on all but the driest, best-quality tarmac. Other than trying it out a few times, I don't use it on the road, and I don't recommend it for anywhere other than the track.
So the best advice I can give you when setting off in a SA car is to remember that it's a manual gearbox with a proper clutch, and to drive it like that.
Changing up
I've discussed the merits of smooth gearchanges in another thread, so I won't flog that dead horse any more, but new users of SA gearboxes (myself included), find that the quality of gearchange is a little poor. I suspect (as was the case with me) that that's because they don't drive it like a manual, and expect the cars elastictrickery to sort it all out for them.
I'll refer you back to the advice I gave before - drive it like a manual. If you don't adjust your throttle position during an up-change, then the engine speed won't match the road speed for the next gear, and there will be an inevitable jerk when the clutch is released and the engine speed is brought back down through the transmission. So, the trick for up-changes is to release the throttle a bit during the gearchange. It doesn't have to be much, but allowing the revs to drop slightly during the up-change nicely matches engine speed to road speed, and eliminates almost all the jerkiness from the change.
This is obviously easier with slower gear-changes than it is with quicker ones. My SMG 'box is an early one which only has one speed of gearchange, which is quite slow. It suits my driving style, and allows me to change nice and smoothly - almost seamlessly. Newer SMG set-ups, together with other manufacturer's systems allow the driver to choose the gearchange speed. In those cars, I'd recommend perfecting your changes in a lower-speed setting, before turning the gearchange speed up. In the fastest settings, I think you'll always lose some smoothness, and these are best suited for track use, or spirited drives on your own.
Downchanges
Downchanges in SA cars are much easier to perfect, as the car's software usually incorporates a system which raises engine revs - "blips the throttle" on downchange. The SMG system is very good, and I've heard open-exhausted 360 CSs running at Fiorano, and they sound like they match the revs on downchange seamlessly.
One aspect which will be alien to the more traditional advanced drivers is that SA cars - particularly those with paddle gearchanges - allow gearchanges to occurr much easier whilst the driver is braking. One of the main reasons that Roadcraft recommends separation of braking and gearchanging is that it allows the driver to keep both hands on the wheel whilst braking. Paddle-shift setups obviously allow the gearchanges without removing the hands from the wheel. Despite that, though, I still drive mine almost to the system in that I leave my gearchanges to the end of the braking period, as I'm still a big believer in separation.
The only car I've driven so far in which I would overlap more was the DSG Golf. This gearbox is a marvellous piece of kit, and the gearchanges are almost perfect - on upchanges, there is no perceptible drop in acceleration and the downchanges are virtually seamless. I'd feel confident changing down through the box with a DSG setup, as the software doesn't allow selection of too low a gear.
Automatic Mode
Apparently these cars have a fully automatic mode.
I've never tried it.
Edited by R_U_LOCAL on Monday 23 April 19:57
R_U_LOCAL said:
Automatic Mode
Apparently these cars have a fully automatic mode.
I've never tried it.
I have in the SMG II equipped M3. It's very weird as unless you're at full throttle it does its best to change up all the time, so getting the right amount of acceleration in most circumstances is more by luck than judgement.
I've found that a firm push on the go peddle with my DSG Audi (3.2 V6) produces a rather nasty jerk forward. I appriciate the point about clutch slip and wear but wonder hows this relates to the wet clutch on the DSG system - both of them?
Also found that the DSG box will creep forward, but not on a gradient, I assume that the software will only allow so much resistanced before declutching.
Also found that the DSG box will creep forward, but not on a gradient, I assume that the software will only allow so much resistanced before declutching.
Edited by medicineman on Monday 23 April 22:57
StressedDave said:
R_U_LOCAL said:
Automatic Mode
Apparently these cars have a fully automatic mode.
I've never tried it.
I have in the SMG II equipped M3. It's very weird as unless you're at full throttle it does its best to change up all the time, so getting the right amount of acceleration in most circumstances is more by luck than judgement.
I was being sarky.
I've tried it several times in my own car and I hate it. You can't anticipate when the gearchange will happen, so you can't time your throttle lifts to smooth out the gearchanges.
It's amazing isn't it - the car has a drive-by-wire throttle pedal, so incorporating an automatic lift in the software would be relatively trivial. After all, they've got an automatic blipper for downchanges.
They could be even cleverer and monitor the rate of change of the pedal position, so that when you ease pressure slightly it would comand a change, as on more conventional automatics.
They could be even cleverer and monitor the rate of change of the pedal position, so that when you ease pressure slightly it would comand a change, as on more conventional automatics.
interesting stuff .
I have a F1 CS and it did take a bit of getting used to after a manual 355 I've been assured that leaving car in gear at lights or in traffic does clutch no harm , cos as you point out the clutch isn't engaged till accelerator's depressed. Hill start's are a mission tho and i hate loss of clutch when reversing. I don't lift on up or downshifts tho i know other owners do 
I have a F1 CS and it did take a bit of getting used to after a manual 355
I've been assured that leaving car in gear at lights or in traffic does clutch no harm , cos as you point out the clutch isn't engaged till accelerator's depressed. Hill start's are a mission tho and i hate loss of clutch when reversing. I don't lift on up or downshifts tho i know other owners do tony h said:
interesting stuff .
I have a F1 CS and it did take a bit of getting used to after a manual 355 I've been assured that leaving car in gear at lights or in traffic does clutch no harm , cos as you point out the clutch isn't engaged till accelerator's depressed. Hill start's are a mission tho and i hate loss of clutch when reversing. I don't lift on up or downshifts tho i know other owners do
I have a F1 CS and it did take a bit of getting used to after a manual 355
I've been assured that leaving car in gear at lights or in traffic does clutch no harm , cos as you point out the clutch isn't engaged till accelerator's depressed. Hill start's are a mission tho and i hate loss of clutch when reversing. I don't lift on up or downshifts tho i know other owners do Thanks Tony - the lift on upshift is obviously driver choice - I prefer a smoother change, but keeping the throttle pressed throughout a gearchange certainly feels more sporting. Some people would obviously prefer that kick in the back that comes with the up-shift. There are some benefits to smoothing out the gearchange though, particularly in road driving. The weight balance of the car is moved around more progressively during a smooth gearchange, which has obvious positive implications for the overall balance of the car. If you ever take a gear whilst cornering, smoothness is essential to keep the car settled in a corner.
Lucky bugger *mutter mutter* 
Though apparently you did own a 205 gti, so I'll let you off.
Incidentally, (and off-topic) what did you think of your 355? Keep it long? A lad I know wants one (and yes, I dare say soon he will be able to afford it).
Though apparently you did own a 205 gti, so I'll let you off.
Incidentally, (and off-topic) what did you think of your 355? Keep it long? A lad I know wants one (and yes, I dare say soon he will be able to afford it).
Edited by leon_t on Tuesday 24th April 20:09
leon_t said:
Lucky bugger *mutter mutter*
Though apparently you did own a 205 gti, so I'll let you off.
Incidentally, (and off-topic) what did you think of your 355? Keep it long? A lad I know wants one (and yes, I dare say soon he will be able to afford it).
Though apparently you did own a 205 gti, so I'll let you off.
Incidentally, (and off-topic) what did you think of your 355? Keep it long? A lad I know wants one (and yes, I dare say soon he will be able to afford it).
Edited by leon_t on Tuesday 24th April 20:09
Pug GTI was my 1st car and turned me into a petrolhead . I had the 355 5 yrs and would still have it if CS wasn't made
As the owner of a manual E46, with considerable experience of an SMG one, I far prefer the manual in all circumstances! and certainly in stop-start traffic. It can be difficult to start smoothly but briskly.
The SMG simply does not suit anyone who cares about smoothness - it is more difficult to get the revs well matched on up shifts when you are not in control of the timing of the release of the clutch. Even on down shifts, in spite of the fabled electronic blip, there are sometimes difficulties. The blip is good for downchanges on the overrun, but not if you like to change down when you are ready to start accelerating. Or that's what I have found.
PS I am thrilled that the new M3 (apparently E90) is coming with a manual. But will an RS5 be better?
The SMG simply does not suit anyone who cares about smoothness - it is more difficult to get the revs well matched on up shifts when you are not in control of the timing of the release of the clutch. Even on down shifts, in spite of the fabled electronic blip, there are sometimes difficulties. The blip is good for downchanges on the overrun, but not if you like to change down when you are ready to start accelerating. Or that's what I have found.
PS I am thrilled that the new M3 (apparently E90) is coming with a manual. But will an RS5 be better?
Edited by waremark on Thursday 26th April 21:37
waremark said:
As the owner of a manual E46, with considerable experience of an SMG one, I far prefer the manual in all circumstances! and certainly in stop-start traffic. It can be difficult to start smoothly but briskly.
The SMG simply does not suit anyone who cares about smoothness - it is more difficult to get the revs well matched on up shifts when you are not in control of the timing of the release of the clutch. Even on down shifts, in spite of the fabled electronic blip, there are sometimes difficulties. The blip is good for downchanges on the overrun, but not if you like to change down when you are ready to start accelerating. Or that's what I have found.
PS I am thrilled that the new M3 (apparently E90) is coming with a manual. But will an RS5 be better?
The SMG simply does not suit anyone who cares about smoothness - it is more difficult to get the revs well matched on up shifts when you are not in control of the timing of the release of the clutch. Even on down shifts, in spite of the fabled electronic blip, there are sometimes difficulties. The blip is good for downchanges on the overrun, but not if you like to change down when you are ready to start accelerating. Or that's what I have found.
PS I am thrilled that the new M3 (apparently E90) is coming with a manual. But will an RS5 be better?
I disagree - I find the SMG box perfectly useable in traffic and I can execute very smooth gearchanges with it. It did take me a couple of months to fully acclimatise myself to it. It requires you to think ahead of the gearbox slightly, which, in all honesty isn't a bad thing, but I can see why it isn't everyone's cup of tea.
I didn't want an SMG when I was shopping round for my car, but I bought it because it was in lovely condition and had a flawless service history. I decided that I would stick at it with SMG and I'm now glad that I did. If I were to trade up to an e46 M3, I'm almost certain that I'd choose another SMG - canging gear with paddles rather than the "gearstick" really appeals to me.
Oh, and I've always got the MX-5 if I fancy some traditional three-pedal driving!
Futuramic said:
Interesting reading and up to Reg's usual standards of unembellished, but comprehensively informed and clear, writing. But has anyone considered that all this thottle lifting, feathering and trick starting sounds like more effort than just driving a manual?
isnt it just what you do in a manual anyway? except your only waving one foot about?Gassing Station | Advanced Driving | Top of Page | What's New | My Stuff