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+--- Thread: Lets talk automatic transmissions: To creep or not to creep? (/showthread.php?tid=33055)
Lets talk automatic transmissions: To creep or not to creep? - Marty_Deslions - 2020-10-11 18:07
So I was thinking about the "best" (automatic / two-pedal) transmission.
Lots of automatic transmission out there are equiped with a torque converter. This will continuesly send some power to the wheel when its in gear, the driver can hold the car in place by pressing the brake pedal. My car (Toyota corolla yay) does this too, and i'm used to it. It can come in handy when you need to park it slowly, even more on an uneven surface-> "One foot parking".
So nowadays you see the double clutch transmission automatics, which usually have a "creep" function when you let go off the brake in gear. Same goes for some of the semi-automatics. Its seems manufactors have this programmed into the transmissioncomputer thing. Maybe so it "behaves like a traditional automatic"?
However, the problem (or my "autistic" problem, if you wanna call it that way) is a matter of principle: A car should not be able to move without the driver making it. In gear, the "default" action of the car (without the driver doing anything) is crawling forward at around 5-8kmh. This somehow grinds my gears (get it?).
But,
There is an alternative. Not all semi-automatics (or automated manuals) have a creep function. For example older Smart Fortwo's don't creep, also Alfa/Fiats "Selespeed" transmission doesn't creep. Also trucks/semi's/coachbusses with automated manuals usually don't creep. They go when the driver presses the "go"pedal. This seems more logic to me, in principle.
However, the downside of this, is that without a hill-hold/brake-hold function on an semi-automatic, the vehicle can move backward/forward if its on a slope, and you let go of the brake. Imagine being in Drive, standing at an incline hill, and the light turns green, you let go of the brake and immediately the vehicle starts rolling backwards.
When switching from the brake to the gaspedal, its like a "dead point". Like, for a second, the vehicle is not being held still by brakes, nor is it being pushed by the engine to move in a direction the drivers want, it simply is left to the laws of nature.
A solution would be a brake hold system that will not only hold the vehicle in place, but also when you come to a stop by just rolling it out (poor english), i mean you dont press the brake pedal, you just let it come to a stop like on a uphill section, the brake hold system will also kick in to prevent it from rolling back. (if im not mistaking the BMW i3 has some sort of principle build in. It doesnt creep in gear, but the car will prevent it from going the opposite direction of the gear its in)
So lets go back to cars I can afford, without any hillhold system. Is there any reason/arguments/situation that I am forgetting to choose the creep-automatic or the noncreep-automatic?
Please let me know your thoughts!
RE: Lets talk automatic transmissions: To creep or not to creep? - Clas - 2020-10-11 18:36
Pretty interesting discussion actually. I have also though about this before. Whats even more interesting is about electric cars. Should an electric car creep? Seems pretty odd to me. But at least Tesla has an option for the driver to choose, creep or not creep. Maybe that would be the answer to all of this? Let it be an option for the driver.
RE: Lets talk automatic transmissions: To creep or not to creep? - Marty_Deslions - 2020-10-11 19:09
(2020-10-11 18:36)ClasK_03 Wrote: Pretty interesting discussion actually. I have also though about this before. Whats even more interesting is about electric cars. Should an electric car creep? Seems pretty odd to me. But at least Tesla has an option for the driver to choose, creep or not creep. Maybe that would be the answer to all of this? Let it be an option for the driver.
Yep, I already found discussions on Tesla forums about creep on or off. Some have it on, but I think most people like it off. However, in Tesla's there is a hillhold to prevent you from rolling back.
RE: Lets talk automatic transmissions: To creep or not to creep? - Barney - 2020-10-12 16:18
Autocreeping comes in very handy in heavy trafficjams. Also, driving off from standstill might feel smoother for some people. Maybe back in the days when the automatic transmissions weren’t so well developed, the start was too rough or it just had technical reasons and was since then just kept like that...
€: i used to drive a volvo v70(old version in the 90s, diesel) and i recall it being very unsmooth when i took my foot of the brake and quickly accelerated before it started rolling automatically.
RE: Lets talk automatic transmissions: To creep or not to creep? - Stephen - 2020-10-15 09:21
Automatic transmission equipped vehicles should creep, otherwise it's incredibly annoying if it doesn't. at work we have 2 brands of forklifts that, when in 'gear' one creeps (toyota) and the other (komatsu) doesn't. the komatsu's inability to creep plus the unwelcome addition of a hydrostatic (hydraulic, jerky acceleration)) drive and drive by wire throttle makes it VERY tedious to move in a predictable manner. no creep makes a vehicle very annoying to drive very quickly
RE: Lets talk automatic transmissions: To creep or not to creep? - Marty_Deslions - 2020-10-15 10:03
makes sense. Creep=better control
RE: Lets talk automatic transmissions: To creep or not to creep? - Chuck - 2020-10-15 12:17
Whenever you have to make small, precise movements, the creep function comes in very handy. E.g. when parking or picking up a trailer. Being able to more smoothly, and only few cm is valuable. It's also a lot less hassle if you don't have to switch the pedals all the time,one time to start the movement and then to stop the movement.
I didn't study the history but I think the creep function is actually a waste product of automatic transmissions. The clutch of an automatic transmission will always settle at the bite point, which means that it grinds permanently and therefore always applies a bit of torque. Thus, light vehicles tend to roll, heavy ones, trucks, buses etc, will not.
I'm not sure if this still applies to "modern" cars, and for the electric ones it's simulated anyway, but either way, I don't wanna miss it.
RE: Lets talk automatic transmissions: To creep or not to creep? - Marty_Deslions - 2020-10-23 12:55
(2020-10-15 12:17)Chuck Wrote: Whenever you have to make small, precise movements, the creep function comes in very handy. E.g. when parking or picking up a trailer. Being able to more smoothly, and only few cm is valuable. It's also a lot less hassle if you don't have to switch the pedals all the time,one time to start the movement and then to stop the movement.
I didn't study the history but I think the creep function is actually a waste product of automatic transmissions. The clutch of an automatic transmission will always settle at the bite point, which means that it grinds permanently and therefore always applies a bit of torque. Thus, light vehicles tend to roll, heavy ones, trucks, buses etc, will not.
I'm not sure if this still applies to "modern" cars, and for the electric ones it's simulated anyway, but either way, I don't wanna miss it.
Traditional automatic use a torque converter instead of a clutch. This is what makes it so smooth. Its not a direct drive (although some have a lockup function in higher gears), but a fluid coupling. The engine runs, and the fluid also moves abit, pushing the other end of the converter, which makes that creep movement.
Modern automatics like DSG actually use 2 clutches which emulate that traditional creeping. Maybe its just because people expect that from an automatic.
But yeah for precise manouvering creeping could be very useful.
RE: Lets talk automatic transmissions: To creep or not to creep? - Sky - 2020-10-23 21:39
sometimes if u want a manual, u need a small cheap auto car to take you around especially in traffic
i have a genesis coupe 3.8 thats auto, and i hate that its auto
It shifts automatically even on manual (sport) mode
the auto sport mode doesnt raise enough RPM to be "Sport". it's like they thought this is a car with a trailer attached to it, and they added that mode
if you let of the throttle after a pull it will upshift which is completely wrong, unless i use the paddle shifters then it wont
Changing oil on them is always a touchy move, anything wrong costs the whole transmission
Sometimes torque converter goes bad and you cant do anything about it
Speaking of torque converter, i noticed on Manual genesis coupes you can throw pops and bangs way easier on them because with a clutch and manual trans, you're fully engaged and throttle controlling is precise. whilst in autos you have softness while feathering the throttle and it will only move the car forward rather than throw fuel in the valves
I just hate it atm lol