ZF8 autobox (in BMW 340i) - change-down probs

[Staterunner]

Or maybe not a problem, just a thing. I'm just out of run-in period, and notice that after kick-down or very vigorous acceleration, the box remains in a lower gear after I've released the throttle. So, say, accelerate hard for a few seconds - box is in 2nd/3rd up above 5k, then remains in 2nd/3rd after I've fully released, screaming away. Even as the speed reduces (and thus the revs lower too), it doesn't not change up. Scenario is regardless of Sport+/Sport/Comfort settings.

Is this normal in the ZF8?! I'm new to it, but seems unlikely...

Thanks

[MrBen1]

I think they all do that - designed to hold the lower gear presuming you are driving quite hard and might well nail it again any second. If you start using much more gentle throttle as opposed to simply lifting off it seems to realise you've stopped pressing on and changes up. Alternative which I use quite often is simply to use the paddles to change up a gear or two.

[Staterunner]

Thanks MrBen. I'll try that lifting gently thing. (I did guess that it might be the gearbox being cleverer than my driving - but never seen it in an auto before).

[Pica-Pica]

335d here, so not sure about petrol versions. I am surprised it does not do what you expect, the ZF8 is spookily similar to as the driver would select. It will hold a lower gear if accelerating hard, or if going downhill. It does differ according to mode. In sport mode it will hold a gear for longer than if in comfort. If it is not doing as you expect, I suspect an issue.

Edited by Pica-Pica on Thursday 3rd January 19:21

[stuart_83]

Does the same to me occasionally in mine, kind of annoying as it leaves the engine screaming when you're only doing 30-40mph!

I sometimes just tap the paddle to change up manually.

[CBflatsix]

I've had a 430d m sport for the last 2 years from new with 35k done and every so often the 8 speed just holds on to a gear. When it does I just change up with the paddles and it seems to sort itself out, Other than this I think it's a great gearbox.

[Staterunner]

Thanks, Pica, Stuart, Flat b. Very helpful sharing.

Just drove it home, heeding advice above to lift off gently and not suddenly. That definitely helped it move up the gearbox straight away, and stop the screaming. Also note the flappy paddle manual intervention suggestion. Thanks; leaning on that too. Seemingly with lever over to the left for sport shifting, you can't use paddles to bet back to auto by holding up paddle. But justing flicking lever to right and back left for now.

[Agree; great gearbox - just need to learn its manners, I guess. And maybe not drive on-off throttle like a 17 year old. Pleased with the new car all round, actually. First BMW of my own... v good.]

[Pica-Pica]

Staterunner said:

. Seemingly with lever over to the left for sport shifting, you can't use paddles to bet back to auto by holding up paddle. But justing flicking lever to right and back left for

If you have already flicked the gear lever to the left - into sport mode, as soon as you use an up or down paddle, you are then into fully manual mode. The transmission will only change down if you go down below a stall speed, or change up if you are at the rev limit. As you have discovered, flicking central lever back right and then left will put you back into sport mode with auto-changing at a higher rev. Alternatively you can use the gear stick to manual change up and down (as an alternative to using paddles).

It is a very good and very versatile transmission, it takes a bit of practice to get the best out of the auto and manual modes, but that will reward you.

[MarkJS]

I have that same gearbox in an Alfa Giulia Veloce. I don’t think there’s anything wrong with it at all going by your description. It will hang onto a (lower) gear if it senses that ‘you’re on it’ and will resume to a more normal state when it senses the madness is over.

I can’t imagine the Diesel users in previous posts will have felt quite the same characteristics due to the ‘box being programmed differently due to their engines more torque-rich behaviour (But I could be wrong).

I really wouldn’t worry about it.

[Wills2]

MarkJS said:

I have that same gearbox in an Alfa Giulia Veloce. I don’t think there’s anything wrong with it at all going by your description. It will hang onto a (lower) gear if it senses that ‘you’re on it’ and will resume to a more normal state when it senses the madness is over.

I can’t imagine the Diesel users in previous posts will have felt quite the same characteristics due to the ‘box being programmed differently due to their engines more torque-rich behaviour (But I could be wrong).

I really wouldn’t worry about it.

I would agree with this if you sharply open the throttle and then sharply come of the throttle the gearbox will think your "on it" and hold the gear for the next input, diesel versions perhaps still do this but you've got less revs to play with so perhaps not as noticeable and with such a narrow power band it's better to just let the box do its thing.

My MDCT would behave the same if I was sharp on the throttle, but gentle inputs off and on would allow you to change gear using the throttle rather than it holding when you lifted off.

The ZF8 in the 7 series is so imperceptible you don't even notice its there never mind knowing or even caring what it's doing.

[Pica-Pica]

MarkJS said:

I have that same gearbox in an Alfa Giulia Veloce. I don’t think there’s anything wrong with it at all going by your description. It will hang onto a (lower) gear if it senses that ‘you’re on it’ and will resume to a more normal state when it senses the madness is over.

I can’t imagine the Diesel users in previous posts will have felt quite the same characteristics due to the ‘box being programmed differently due to their engines more torque-rich behaviour (But I could be wrong).

I really wouldn’t worry about it.

I assure you 335d diesel with ZF8 will do the same, that is it will go to the rev limit if in sport and floored.

[Scobblelotcher]

M135i auto owner here and my car behaves in the same way whereby sometimes it will sit at high revs which I think is it anticipating more hard acceleration like your waiting for a gap to pass a car and thus is ready for more, after about 20 seconds if you don’t accelerate hard again, it just changes up normally.

I found it a bit disconcerting at first that it was happy to thrash itself and sometimes even now use the paddles to change up for it! It can sometimes make you look like a bit of a plonker if you’re in a town centre and it’s holding gears like that if you come out of a junction quickly.

[Staterunner]

Great advice, all. Thanks so much. I've put a few more miles in and the stuff above is exactly right. Will try and learn to be less leaden-footed, and get the most out of the gearbox.

[Pica-Pica]

Staterunner said:

Great advice, all. Thanks so much. I've put a few more miles in and the stuff above is exactly right. Will try and learn to be less leaden-footed, and get the most out of the gearbox.

Enjoy!
Another tip. If you are in slow crawling traffic, try manual mode to give you a bit more engine braking. Knock lever left, then shift into 2 or 1 (M2 or M1 on display). You can then drive on the throttle using engine braking - that is very useful for tedious crawling traffic. If you are in 2nd but you have to stop to a halt, the box will shift down to 1st on its own (M1 on cluster display).
If the traffic speeds up a little, use the right paddle to upshift to M3.

That all sounds a bit ‘I have bought an auto, why should I do all that?’. However, that is the versatility of the ZF8 sportauto, and once practised, is easier to do than to describe and gives a finer degree of control without all the tedious left leg pumping and slipping the clutch.