I have a 2006 325i Steptronic. Is it possible to damage the transmission if I manually downshift from say 3rd to 2nd if I were already driving in 3rd at a high rate of speed, or is there some kind of limiter that will stop the engine from damaging itself if it looks like the downshift will redline the tranny?
In theory no.
but in practice...
wrote
I virtually certain that the transmission won't downshift if it would over-rev the engine. Same goes for the SMG transmissions.
Floyd
If I were screaming along anywhere near the Red Line, the very last thing I'd be considering is a downshift. Maybe what you need is an Ejection Seat to launch your ass out of the car if you downshift while at red line.
If you mix up pushing and pulling (down and up) it wont down shift if it would be near the red line.
No. You can neither over-rev or labour the engine with Steptronic. Nanny state rools. ;-)
With my old E34, I'd often leave it in third for town use start and stop, and it didn't complain.
Describe.
I broke a 4 speed box in a [1983] 735i in 1991 by shifting from reverse to drive while dong ~3,000rpm*.
This was supposed to have interlock to prevent this sort of damage, just like the Steptronic.
Not a Steptronic, then?
It's not possible to select reverse when in Steptronic mode. Or neutral or park. Just the forward gears.
BTW, I'm surprised you broke any auto by selecting reverse at speed - or the other way round. Usually, the wheels just break traction. Or a driveshaft breaks.
Steptronic is just a bit more technically advanced than your '83 box! I'd wager that the '83 box was fully mechanical, whereas the steptronic is electrically controlled. Much less chance of the computer accepting an incorrect signal than there is of you forcing a physical link into the wrong place. Don't think you can really compare them.
Both gearboxes, however, are just as effective in propelling your car forward and over said criminal ;-)
As he came towards me I reversed and he stuck and broke the [laminated] windscreen, then he went round the side of the car, but despite three tries could not angle the blow properly to smash the side screen.
That's right, steptronic won't let you do anything naughty. It's actually quite irritating and makes the manual mode not worth bothering with. If, say, you are in third and try to engage second at what it thinks would be too high an engine speed, the display briefly changes to "2" but then goes back to "3" without doing anything. I would rather it beeped or something (if it physically blocked the lever from being moved back, that would be great, you could really drive it enthusiastically in manual mode). Also, if I remember, it changes up if you redline. I would prefer if it just cut out at the limiter. After all, if you wanted auto mode you probably wouldn't have engaged manual.
Yup - my main problem with it.
If you have a manual box, you can hold it on the limiter as long as you like. But with the Steptronic, hit the limiter and it changes up. Not what you want when darting between corners on a twisty road. Indeed, positively dangerous.
How did you get away finally? I mean, with a broken gearbox?
It's an auto which is said to provide manual control. There's no intrinsic reason why that manual control is over-ridden under some circumstances. My previous 5 speed ZF fitted to an E34 525 stayed in the gear you selected manually regardless, and a third gear start for example could be useful in slippery conditions.
Only when BMW finally adopts the twin clutch system used by Audi, etc. The present SMG just isn't much good in auto mode. Whilst I'm happy with 'snappy' changes when pressing on, I want near seamless changing in town, or when driving gently.
You must be a bank manager or a solicitor;-) jack
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