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      05-29-2020, 12:30 PM   #1
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Truth about using Kickdown?

So... iam fairly new to the F8X world but iam seeing people say in posts to NOT use the kickdown because you'll SCH. Is this happening ONLY on tuned cars?

This ( kickdown ) is one of the reasons i like the dct and like to use it from time to time.

Is this myth or is there some truth here?
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      05-29-2020, 12:51 PM   #2
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plenty of other posts about this. Have people spun it using kickdown? yes. But that's not the only cause for it spinning. its happened to stock cars and tuned cars, 6 speed and DCT. It seems more likely to happen on tuned DCT cars though.

personally I wouldn't use it. Use auto for cruising, manual mode if you want to do pulls.
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      05-29-2020, 01:04 PM   #3
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This is a gray subject from what I gather here.
If it’s under warranty, one shouldn’t care.

I’m also commenting to subscribe because I remember seeing somewhere here that the later models were tuned to have less torque down low. Also the way the power is put down has changed.

On my 2019 for example, using kick down in efficient mode is extremely dramatic and the car just takes the f’off on the highway. If in sport or sport plus, it will not drop into a super low gear and the car doesn’t seem to move as fast.

Either way, I don’t use it that much to care either way.
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      05-29-2020, 01:17 PM   #4
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Quote:
Originally Posted by Humdizzle View Post
plenty of other posts about this. Have people spun it using kickdown? yes. But that's not the only cause for it spinning. its happened to stock cars and tuned cars, 6 speed and DCT. It seems more likely to happen on tuned DCT cars though.

personally I wouldn't use it. Use auto for cruising, manual mode if you want to do pulls.

Why wouldn't you use it?....why is it there if it shouldn't be using it in a stock NON tuned car?
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      05-29-2020, 01:37 PM   #5
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Quote:
Originally Posted by 65fastback View Post
Why wouldn't you use it?....why is it there if it shouldn't be using it in a stock NON tuned car?
same reason why its not a good idea to cruise for 30 minutes at 5k rpm. Sure you 'can' do it. But that doesn't mean its ideal for the car. Same reason I never launched my old GTR more than a handful of times. not worth the gamble...

the m3 will pull just as hard manually going down to 2nd and then flooring vs using kickdown from 7th to 2nd. so why not just do that for piece of mind
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      05-29-2020, 02:30 PM   #6
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Quote:
Originally Posted by Humdizzle View Post
same reason why its not a good idea to cruise for 30 minutes at 5k rpm. Sure you 'can' do it. But that doesn't mean its ideal for the car. Same reason I never launched my old GTR more than a handful of times. not worth the gamble...

the m3 will pull just as hard manually going down to 2nd and then flooring vs using kickdown from 7th to 2nd. so why not just do that for piece of mind
Not sure anyone thinks thats ok. or why you used that as a comparison?

If guys are getting a SCH using the kickdown seems like the clutches and driveline are doing exactly what they are designed to do.

Is there proven damage being done when using the kick done on a STOCK car??
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      05-29-2020, 02:56 PM   #7
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Using kickdown is a hyper aggressive car feature.

Launch control is also a hyper agressive car feature

Red lining the car is a hyper agressive move

Anything hyper agressive puts a big strain on the car, the kickdown should be used very sporadically the same way launch control is.

Why on earth would you keep launching unless you are doing passes at the strip or showing off.

No reason to use kickdown unless under emergency, if you are cruising manually stick it into gear and cya later, if you need power drop a gear and dissapear.

We don't know if kickdown is a cause of SCH but it definetly isn't a feature you should be using 10 times a day cause you think it pulls harder. Drop from 6th to second sequentially and floor it, it will pull the same.

If you think using launch control everyday on your routine drives is reasonable then use the kickdown and red line the car all day. SCH or not you are significantly wearing the car out.
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      05-29-2020, 03:33 PM   #8
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Quote:
Originally Posted by 65fastback View Post
Not sure anyone thinks thats ok. or why you used that as a comparison?

If guys are getting a SCH using the kickdown seems like the clutches and driveline are doing exactly what they are designed to do.

Is there proven damage being done when using the kick done on a STOCK car??
https://f80.bimmerpost.com/forums/po...ts&pollid=9445

here is a poll you can take a look at. In almost every year of production there are guys who spun there hub on a stock car. the poll doesn't say if it was just a defective hub from factory or they did a kickdown. Regardless, it is more prevalent in a dct car vs 6MT (stock vs stock).
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      05-29-2020, 03:58 PM   #9
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Just use your car as intended and don't worry about it.
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      05-29-2020, 04:40 PM   #10
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Quote:
Originally Posted by deeldoo View Post
Using kickdown is a hyper aggressive car feature.

Launch control is also a hyper agressive car feature

Red lining the car is a hyper agressive move

Anything hyper agressive puts a big strain on the car, the kickdown should be used very sporadically the same way launch control is.

Why on earth would you keep launching unless you are doing passes at the strip or showing off.

No reason to use kickdown unless under emergency, if you are cruising manually stick it into gear and cya later, if you need power drop a gear and dissapear.

We don't know if kickdown is a cause of SCH but it definetly isn't a feature you should be using 10 times a day cause you think it pulls harder. Drop from 6th to second sequentially and floor it, it will pull the same.

If you think using launch control everyday on your routine drives is reasonable then use the kickdown and red line the car all day. SCH or not you are significantly wearing the car out.

Was all that directed toward me?

Was just trying to ask why do i see people talking about NOT using the kickdown on these cars, i use it from time to time while in D on the freeway and dont see any harm in doing so. I dont "roll race" and haven't even tried launch control or race anyone for that matter if you wanna know alittle about my driving habits.
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      05-29-2020, 04:42 PM   #11
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Quote:
Originally Posted by 65fastback View Post
Quote:
Originally Posted by deeldoo View Post
Using kickdown is a hyper aggressive car feature.

Launch control is also a hyper agressive car feature

Red lining the car is a hyper agressive move

Anything hyper agressive puts a big strain on the car, the kickdown should be used very sporadically the same way launch control is.

Why on earth would you keep launching unless you are doing passes at the strip or showing off.

No reason to use kickdown unless under emergency, if you are cruising manually stick it into gear and cya later, if you need power drop a gear and dissapear.

We don't know if kickdown is a cause of SCH but it definetly isn't a feature you should be using 10 times a day cause you think it pulls harder. Drop from 6th to second sequentially and floor it, it will pull the same.

If you think using launch control everyday on your routine drives is reasonable then use the kickdown and red line the car all day. SCH or not you are significantly wearing the car out.

Was all that directed toward me?

Was just trying to ask why do i see people talking about NOT using the kickdown on these cars, i use it from time to time while in D on the freeway and dont see any harm in doing so. I dont "roll race" and haven't even tried launch control or race anyone for that matter if you wanna know alittle about my driving habits.
No not at you lol.

In general for anyone who believes if kickdown is bad or not, i categorize it in the hyper agressive category.

It strains the car in the same vain as many of those things to a slightly smaller degree.

Just not to be used alot.
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      05-29-2020, 04:44 PM   #12
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I personally do not believe that SCH failures are transmission related. Of the 887 forum SCH survey respondents to date, 10.3% of DCT and 10.3% of 6MT have suffered a SCH, an exact match. The vast majority are modified though with 85% of the reported SCH being on modified cars. On stock cars, there are 3.9% reported SCH failures on 6MT and 2.8% on DCT.

The vast majority of owners that have not suffered a SCH will not have voted on this survey, which artificially inflates the numbers, so the probability of it happening is actually much lower than this.

If you enjoy the kickdown feature, use it as you please
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      05-29-2020, 04:45 PM   #13
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Quote:
Originally Posted by Humdizzle View Post
https://f80.bimmerpost.com/forums/po...ts&pollid=9445

here is a poll you can take a look at. In almost every year of production there are guys who spun there hub on a stock car. the poll doesn't say if it was just a defective hub from factory or they did a kickdown. Regardless, it is more prevalent in a dct car vs 6MT (stock vs stock).
Thanks for the link although i did see that while i was searching for threads related to kickdown use, seems the vast majority of responses in that poll are tuned/modified cars and doesn't address the use of the kickdown feature specifically.
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      05-29-2020, 08:11 PM   #14
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Kickdown isn't really the best way to overtake regardless. You're making the engine immediately go into a high load at low RPM before the trans downshifts. This isn't great for engines in general, especially turbo engines.

Best thing is to use the paddles to downshift first. Better to downshift before accelerating hard rather than after. Just takes a little more discipline than using the kickdown but it doesn't cost you any time really.

Although in an M4 you hardly need to kickdown. I find even in D2 mode (and engine in sport), just gradually pressing down the accelerator makes the car downshift very effectively.
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      05-29-2020, 08:33 PM   #15
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Quote:
Originally Posted by Humdizzle View Post
.... It seems more likely to happen on tuned DCT cars though.
...
I'm not so sure about that. Based on the "have you experienced SCH" poll here it would appear that way with DCT cars with it outnumbering manual cars 2:1. But global production numbers have DCT cars outnumbering manual by 5.4:1, which would make them actually less likely to have it. In the end we're just guessing based on a very small sample size that can't even definitively say if any of us really need to worry at all though...
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      05-29-2020, 09:49 PM   #16
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Quote:
Originally Posted by maddmatth View Post
Kickdown isn't really the best way to overtake regardless. You're making the engine immediately go into a high load at low RPM before the trans downshifts. This isn't great for engines in general, especially turbo engines.

Best thing is to use the paddles to downshift first. Better to downshift before accelerating hard rather than after. Just takes a little more discipline than using the kickdown but it doesn't cost you any time really.

Although in an M4 you hardly need to kickdown. I find even in D2 mode (and engine in sport), just gradually pressing down the accelerator makes the car downshift very effectively.
Literally i could not put this into words before, i always thought the issue isnt the kickdown.

Its the lugging of low rpm high load that is the issue, the engine struggles so hard before the downshift.

You have a way with words my friend.

Cheers
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      05-30-2020, 08:43 AM   #17
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Why would the manufacturer include a kick down feature, if they didn't want people to use it and accounted for it in their testing? Unless, it's like Launch Control where they caution against excessive use in the manual, they can't reasonably guard against every customer abusing it and bricking the motor. So, they either thought it was safe enough to include or they performed a cost-benefit analysis on warranty scenarios and came out ahead.
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      05-30-2020, 09:18 AM   #18
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The auto shift doesn't work properly anyway for spirited driving. You kick it down, give it a squirt and back off and they hang in gear revving too hard in overrun for too long. This isn't a F8x thing, my wife's X3 M40i does the same Automatic's for cruising and shopping and the paddle shifts are for spirited driving to manually select the right gear at the right time I think

In auto, the engine's fluffing on traction control holding gears too long where in manual mode, you can short shift it to a taller gear like flat changing with manual dog box. The DCT's a great trans to use manually and much more engaging than auto mode when driving the car hard. As far as spinning crank hubs, I can't find any information about GT4 race cars spinning them that are subject to sustained high revs and driver errors and use the same engine and timing components as the road cars.

Last edited by RevNev; 05-30-2020 at 09:35 AM..
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      05-30-2020, 10:13 AM   #19
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Quote:
Originally Posted by maddmatth View Post
Kickdown isn't really the best way to overtake regardless. You're making the engine immediately go into a high load at low RPM before the trans downshifts. This isn't great for engines in general, especially turbo engines.

Best thing is to use the paddles to downshift first. Better to downshift before accelerating hard rather than after. Just takes a little more discipline than using the kickdown but it doesn't cost you any time really.

Although in an M4 you hardly need to kickdown. I find even in D2 mode (and engine in sport), just gradually pressing down the accelerator makes the car downshift very effectively.
I drive in manual mode the vast majority of the time. I usually select the optimal gear before I need to engage maximum acceleration just as I would on a manual car. I therefore seldom use the kickdown feature.

But I do believe folks over compexify what is going on mechanically and electronically during kickdown. I see it rather simple:
  1. Driver commands kickdown
  2. DCT open both clutches while WOT command is sent to engine
  3. The ECU engages optimal gear based on road speed from a pre-determined table
  4. DCT engages appropriate clutch when engine and wheel rpm match

I don't see how tis can be that damaging...
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      05-30-2020, 10:22 AM   #20
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I used the kickdown feature at will on all three of the F80s I owned. I even used it on one of my tuned cars. If you're worried about SCH, get a different car.
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      05-30-2020, 10:30 AM   #21
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Quote:
Originally Posted by CanAutM3 View Post
Quote:
Originally Posted by maddmatth View Post
Kickdown isn't really the best way to overtake regardless. You're making the engine immediately go into a high load at low RPM before the trans downshifts. This isn't great for engines in general, especially turbo engines.

Best thing is to use the paddles to downshift first. Better to downshift before accelerating hard rather than after. Just takes a little more discipline than using the kickdown but it doesn't cost you any time really.

Although in an M4 you hardly need to kickdown. I find even in D2 mode (and engine in sport), just gradually pressing down the accelerator makes the car downshift very effectively.
I drive in manual mode the vast majority of the time. I usually select the optimal gear before I need to engage maximum acceleration just as I would on a manual car. I therefore seldom use the kickdown feature.

But I do believe folks over compexify what is going on mechanically and electronically during kickdown. I see it rather simple:
  1. Driver commands kickdown
  2. DCT open both clutches while WOT command is sent to engine
  3. The ECU engages optimal gear based on road speed from a pre-determined table
  4. DCT engages appropriate clutch when engine and wheel rpm match

I don't see how tis can be that damaging...
It takes a very short time to drop the car into gear but during that time you are essentially lugging the engine at high load, while with a regular manual you have to first select and then go.
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      05-30-2020, 11:03 AM   #22
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Quote:
Originally Posted by deeldoo View Post
It takes a very short time to drop the car into gear but during that time you are essentially lugging the engine at high load, while with a regular manual you have to first select and then go.
No you're not. Re-read my post: both clutches open as they engine goes WOT, no lugging going on since there's no load on the engine .
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