BMW X3 Forum
BMW X3 Forum
Welcome to the ultimate BMW X3 community.
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
XBimmers | BMW X3 Forum BIMMERPOST Universal Forums Off-Topic Discussions Board What's the difference between semi-automatic and automatic nowadays?

Post Reply
 
Thread Tools Search this Thread
      Yesterday, 12:12 PM   #1
Fentomized
Registered
Belgium
0
Rep
1
Posts

Drives: BMW X3 M40i (G01)
Join Date: Dec 2018
Location: Oost-Vlaanderen, Belgium

iTrader: (0)

What's the difference between semi-automatic and automatic nowadays?

I've been wondering lately what truly the differences are between semi-automatic and fully automatic. I know that they both work a bit differently, and that back in the days only a semi-automatic would allow the driver to change gears manually, but nowadays, especially in BMWs we are also able to put our ZF-autos into manual mode, even with optional paddleshifters.

So what are the main differences nowadays between them for the driver?

Thanks,
Fentomized
Appreciate 0
      Yesterday, 12:19 PM   #2
ScottSinger
Brigadier General
1519
Rep
4,261
Posts

Drives: M235i 6spd
Join Date: Dec 2013
Location: Mid-Atlantic

iTrader: (0)

I think nowadays semi-auto usually refers to a mode as opposed to a the basic operating design.
Appreciate 0
      Yesterday, 12:48 PM   #3
Fentomized
Registered
Belgium
0
Rep
1
Posts

Drives: BMW X3 M40i (G01)
Join Date: Dec 2018
Location: Oost-Vlaanderen, Belgium

iTrader: (0)

Quote:
Originally Posted by ScottSinger View Post
I think nowadays semi-auto usually refers to a mode as opposed to a the basic operating design.
I guess so too, but then again we have the single clutch and double clutch tranmissions, like BMW's DCT or Volkswagen's DSG.

What's the main advantages of those compared to say the ZF? As far as I know the newer F90 M5 even ditched the DCT for the ZF.
Appreciate 0
      Yesterday, 03:16 PM   #4
ScottSinger
Brigadier General
1519
Rep
4,261
Posts

Drives: M235i 6spd
Join Date: Dec 2013
Location: Mid-Atlantic

iTrader: (0)

Quote:
Originally Posted by Fentomized View Post
I guess so too, but then again we have the single clutch and double clutch tranmissions, like BMW's DCT or Volkswagen's DSG.

What's the main advantages of those compared to say the ZF? As far as I know the newer F90 M5 even ditched the DCT for the ZF.
This is a great site https://www.zf.com/products/en/cars/home/cars.html

there are so may configuration of transmissions now, some of the dual clutch banged but are capable of very quick shifts, some with torque converters handled extreme power better and creep in traffic better.
Appreciate 0
      Yesterday, 03:33 PM   #5
Banana Hammock
Beefcake
Banana Hammock's Avatar
3245
Rep
701
Posts

Drives: E92 M3
Join Date: Apr 2016
Location: Los Angeles

iTrader: (2)

I've always interpreted it as a semi-automatic transmission has a mode that allows you to shift manually either via flappy paddles or the gear lever while a fully automatic one's are just stuck in boring mode.
__________________
Akrapovic | Alpha-N | ARC | IND | KW | Varis | Volk | Vorsteiner
@kontradictions
Appreciate 0
      Yesterday, 03:43 PM   #6
ScottSinger
Brigadier General
1519
Rep
4,261
Posts

Drives: M235i 6spd
Join Date: Dec 2013
Location: Mid-Atlantic

iTrader: (0)

chk out this manual with automated controls

https://www.zf.com/products/en/cars/products_29280.html
Appreciate 0
      Yesterday, 03:47 PM   #7
dinonz
Colonel
United_States
1460
Rep
2,350
Posts

Drives: 2016 M3 MWM ZCP
Join Date: Mar 2013
Location: Austin

iTrader: (0)

Quote:
Originally Posted by ScottSinger View Post
chk out this manual with automated controls

https://www.zf.com/products/en/cars/products_29280.html
Dad's motorhome has one of those. It's weird. Like a slow driver driving a manual.
Appreciate 0
      Yesterday, 03:53 PM   #8
ScottSinger
Brigadier General
1519
Rep
4,261
Posts

Drives: M235i 6spd
Join Date: Dec 2013
Location: Mid-Atlantic

iTrader: (0)

Quote:
Originally Posted by dinonz View Post
Dad's motorhome has one of those. It's weird. Like a slow driver driving a manual.
Ferrari had something similar in their Mondial if I recall correctly
Appreciate 0
      Yesterday, 04:36 PM   #9
GuidoK
#buildnotbought
GuidoK's Avatar
1279
Rep
2,335
Posts

Drives: Z4 3.0i ESS TS2+
Join Date: Jul 2012
Location: Tinkering in the garage

iTrader: (0)

Quote:
Originally Posted by Fentomized View Post
especially in BMWs we are also able to put our ZF-autos into manual mode, even with optional paddleshifters.

So what are the main differences nowadays between them for the driver?
I think technically the 'zf auto' is a manumatic and not a semi automatic.
And a dual clutch gearbox or a SMG is a semi automatic:

https://en.wikipedia.org/wiki/Manumatic

https://en.wikipedia.org/wiki/Semi-a...c_transmission

I think in the end the biggest difference is whether you let a computer choose the gear (automatic) or that you do it yourself (semi-automatic, manumatic or manual).
Because the thing a computer can't do is anticipated driving. For that the human mind is by far superior (if you know how to drive and understand vehicle dynamics of course).
computers get smarter and smarter, for instance use GPS map data to predict if a corner is coming up, but they can't anticipate on where you want to go or, most of the time, what happens on the road (obstacles, traffic lights etc), that still dictate on what gear one should choose.

Quote:
Originally Posted by ScottSinger View Post
chk out this manual with automated controls

https://www.zf.com/products/en/cars/products_29280.html
Thats basically an SMG I think?
Note that this is not similar to the mondial valeo clutch. Thats an automated clutch afaik.
__________________
Z4 3.0i | ESS TS2+ | Quaife ATB LSD | Brembo/BMW performance BBK front/rear | Schrick FI cams | Schmiedmann headers+cats | Powerflex/strongflex PU bushings | Vibra-technics engine mounts | H&R anti rollbars | KW V3 coilovers | Sachs performance clutch

Last edited by GuidoK; Yesterday at 09:01 PM..
Appreciate 0
      Yesterday, 07:25 PM   #10
Redd
Major
483
Rep
1,155
Posts

Drives: 2010 BMW E92 M3 Dakar Edition
Join Date: Jul 2015
Location: Malaysia

iTrader: (0)

Fully automatic refers to a gearbox that does all the shifting for you. Think of the automatics in older cars with just the P, R, N, D, 1, 2 options. Semi automatic refers to a gearbox that also gives you the option to select your own gears but does not require you to use a clutch pedal.

Fully automatic cars with a semi-auto mode have been around for a long time, with various methods of gear selection. Some use a gated shifter like the Alfa Romeo Q-system (uses an Aisin gearbox). Nowadays nearly all automatic cars have paddle shifters to give you a semi-auto mode.

This is different from the actual type of gearbox mechanism. Traditional auto gearboxes used to be torque converter gearboxes. Then they added buttons or paddles to introduce a semiautomatic mode to torque converter gearboxes. Tiptronic falls in this category. After that came the robotised manuals (aka single clutch auto) which was basically a manual gearbox with a computer controlled actuator which worked the clutch for you. BMW SMG, Alfa Selespeed, Ferrari F1, fall into this category.

Then came the dual clutch gearboxes, pioneered by VW. BMW DCT, Porsche PDK are dual clutch gearboxes, with complex gear trains with two clutches, each operating alternate odd/even gears, to allow faster shifting.

Of late there's been a renaissance of sorts for the old torque converter automatics, led by the new ZF 8 speed that's found in many of today's high performance cars. Make no mistake, this new ZF has a torque converter like in the automatics of old, but has been tweaked to shift as quickly as a dual-clutch while retaining the reliability and ability to handle power like a torque converter.
Appreciate 0
      Yesterday, 07:26 PM   #11
HFW003
Colonel
HFW003's Avatar
Australia
1798
Rep
2,637
Posts

Drives: MY19 LBB M2 Comp
Join Date: Apr 2013
Location: Newcastle, Australia

iTrader: (0)

One, you pull the trigger and rounds keep coming until you let your finger off and the other, you pull the trigger and only one round comes out.




Sorry, I misread the question
Appreciate 2
SherM4n384.00
kscarrol1968.00

      Yesterday, 11:18 PM   #12
yco
ignorance is bliss..
yco's Avatar
594
Rep
852
Posts

Drives: E71 X6M '10
Join Date: Jan 2018
Location: Istanbul & Kyiv

iTrader: (0)

Semi Autos: same principle with manuals, a robotized clutch is being used, often dont have an "Park" on the selector and instead of D there is generally an A.. they re around for almost 100 years.. SMG is a "sequential" transmission with robotized clutch.. it cant change gear from 6 to 2 for example.. more like a race car sequential.. so SMG is not like Easytronic and other that lets you feel like an old nanny changing gear for you.. semi autos ll sound like manual transmission on a flyby with slower shifting speed depending on the transmission model..

Full autos: they dont have a traditional clutch.. they have torque convertor.. torque convertor has a clutch inside though but different than traditional one.. so it uses wet clutch system.. they have PRND and sometimes L for low gear or gears only.. like in new M5.. even though it is much faster than traditional torque convertors but still.. automatic ll sound like on a flyby, softened dramatic rev drop while changing gears.. recent sporty torque convertors may sound like a double clutched though..

double clutched transmissions: they re around less than 20 years in traffic.. their gear layout is different and using 2 clutches for 2 different sets of gears.. they re more complicated.. you ll feel the clutch on first few meters as well but the rest you wont.. dual clutch gear box'ed car ll sound like crazy fast gear changes on a flyby..
__________________
"Race car driving is like sex. All guys think they're good at it." Jay Leno
Appreciate 0
      Yesterday, 11:42 PM   #13
Nivarox
Quadrex
Nivarox's Avatar
340
Rep
1,187
Posts

Drives: BMW G30 530 XDrive
Join Date: Jun 2016
Location: Close To BMW Dealer

iTrader: (0)

I have driven various automatic transmissions from "quaint" torque converter to fully electronic ones . I must say difference is minimal to me just like or in the same way the difference between minimal deep tech and tech house .
However, one car with EDC (semi auto ) seems to have a tendency of being jerky during launch .I don't take it as a gripe but this is rather something I have noticed .
There's also CRT ,I have not driven one but from what I read it behaves like a semi auto rather than fully automatic tranny

Besides, fully automatic should shift up / down when driver hits red line but semi auto when driver selects manual mode should not interfere with the shifting even driver hits red line . If a driver don't use manual mode in semi auto then it should act like a fully auto .This is my understanding as well
__________________
Comparing BMW i8 to Tesla Is Like Comparing Apples to Pineapples
Appreciate 0
      Yesterday, 11:45 PM   #14
Ross61
Private
65
Rep
69
Posts

Drives: 2004 GTO (soon to be an M4)
Join Date: Sep 2014
Location: A Place that Begins with "W"

iTrader: (0)

Quote:
Originally Posted by HFW003 View Post
One, you pull the trigger and rounds keep coming until you let your finger off and the other, you pull the trigger and only one round comes out.




Sorry, I misread the question
^^^This^^^
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 03:01 AM.




xbimmers
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST