Auto 'box Kickdown
Discussion
Superhoop said:
No, the button in that picture is tio limit pedal travel.
Kickdown is purely a function of throttle position in an auto box
It certainly used to be a physical switch - the box would have a connection for a kickdown cable. None of my autos are around at the moment but I seem to recall they still have at least the sensation of pushing a little switch down at the bottom of the throttle travel, even if it's actually all done with the throttle position sensor.Kickdown is purely a function of throttle position in an auto box
SO no, not a myth. Anybody who says or claims kickdown is a myth obviously has no experience whatsoever of driving an automatic. Even s
tty automatic Yaris's and the like have it.I'm sure that today they are all electronic and measure some parameters and then react accordingly.
Obviously in the days before computers it was mechanical. Now I suspect that there were also differing systems as well.
Certainly some kick downs would always happen once the throttle reached a certain position but others would only occur if you moved the throttle quickly enough to the floor.
I wouldn't have thought that any system would be a visible button though.
Obviously in the days before computers it was mechanical. Now I suspect that there were also differing systems as well.
Certainly some kick downs would always happen once the throttle reached a certain position but others would only occur if you moved the throttle quickly enough to the floor.
I wouldn't have thought that any system would be a visible button though.
My dad's SLK350 auto has a switch behind the accelerator that seems to cause it to kickdown. It's not simply a pedal travel limit as I've taken a close look at it and it's definitely a switch.
He didn't even know he had until he accidentally pressed it one day. It's quite a firm switch so you have to be quite firm on the pedal to activate it.
Looked on a few Merc forums and they all say its a kickdown switch.
He didn't even know he had until he accidentally pressed it one day. It's quite a firm switch so you have to be quite firm on the pedal to activate it.
Looked on a few Merc forums and they all say its a kickdown switch.
My dads mate had a Rolls Royce with kickdown. As it used silly fuel in kickdown, he never used it but come sale time, dad knew he'd show it off to a potential buyer.
So he fixed a stink bomb to the back of the throttle pedal. The results contained every swear word ever invented. Tee hee!
So he fixed a stink bomb to the back of the throttle pedal. The results contained every swear word ever invented. Tee hee!
The first autos I drove in the 70's and 80's had a sort of switch - there was a detent at the end of the pedal which you had to push through to get the box to kick down.
The more recent autos I've had (BMW and Merc 7G) seem to go down the box if you push the pedal rapidly to anywhere near full throttle, so it's obviously all done with electronic wizardry.
The more recent autos I've had (BMW and Merc 7G) seem to go down the box if you push the pedal rapidly to anywhere near full throttle, so it's obviously all done with electronic wizardry.
Vladimir said:
My dads mate had a Rolls Royce with kickdown. As it used silly fuel in kickdown, he never used it but come sale time, dad knew he'd show it off to a potential buyer.
So he fixed a stink bomb to the back of the throttle pedal. The results contained every swear word ever invented. Tee hee!
'the fuukc did I just read? So he fixed a stink bomb to the back of the throttle pedal. The results contained every swear word ever invented. Tee hee!
Edit... Just re read and got it.... With friends like your old man who needs enemies!
I read it as though your dad owned the car and sabotaged his own sale.
Edited by dave_s13 on Thursday 29th August 09:28
Vladimir said:
My dads mate had a Rolls Royce with kickdown. As it used silly fuel in kickdown, he never used it but come sale time, dad knew he'd show it off to a potential buyer.
So he fixed a stink bomb to the back of the throttle pedal. The results contained every swear word ever invented. Tee hee!
Your second name isn't Putin is it? So he fixed a stink bomb to the back of the throttle pedal. The results contained every swear word ever invented. Tee hee!
dave_s13 said:
'the fuukc did I just read?
Edit... Just re read and got it.... With friends like your old man who needs enemies!
I read it as though your dad owned the car and sabotaged his own sale.
In the mid 80s a prank thing got a bit out of hand. We couldn't go anywhere without expecting our front door to he bricked up or similar! Funny looking back on it though.Edit... Just re read and got it.... With friends like your old man who needs enemies!
I read it as though your dad owned the car and sabotaged his own sale.
Edited by dave_s13 on Thursday 29th August 09:28
I think the term kick-down is really best used for the old autos. In these simpler days of 3 speeds, the road speed was the determinant when an autobox would change gear. ie if road speed drops below 25 mph engage 2nd. Kick-down changes the speed, hence causing the box to select a lower gear. ie select 2nd if below 45mph. Kickdown was selected by throttle postion.
Now, some computer will be monitoring hundreds of parameters, to decide which of the which of the seemly dozens of gears to select. for example, ISTR that Porche determined when a driver lifts off the throttle suddenly, its typically for a corner or to slow down, so the autobox keeps the lower gear, rather then change up. When a driver reduces acceleration because he has achieved his desired speed, he lifts off more slowly, so the box changes up.
Now, some computer will be monitoring hundreds of parameters, to decide which of the which of the seemly dozens of gears to select. for example, ISTR that Porche determined when a driver lifts off the throttle suddenly, its typically for a corner or to slow down, so the autobox keeps the lower gear, rather then change up. When a driver reduces acceleration because he has achieved his desired speed, he lifts off more slowly, so the box changes up.
My X350 xjr is relatively modern and has a kick down switch at the end of the throttle travel. It is quite firm. The car will kick down depending on how you drive it without pressing the switch but no where near as aggressively. If you do use the switch it generally changes down up to 3 gears to near maximum revs. Apparently having the kickdown switched pressed also extends the upper rev limit before a change by 500rpm or so.
In sport mode the use of the kickdown switch is generally not necessary as it is that aggressive pretty much all the time.
In sport mode the use of the kickdown switch is generally not necessary as it is that aggressive pretty much all the time.
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