Automatic Transmission Bug

this is unrealistic, the Transmission isn't supposed to cut half of the throttle to shift up ,beamng.drive dev should remove this asap..

you clearly see whats going on. that not how automatic Transmission work.




at least make it as an option in gameplay if its there to help automation car..

 

it say unavailable source. also I still got a point here im sure of that at 100% it shouldn't cut half of the throttle when shifting up.

 

I also have experience with automatic transmission, mostly with 3 speed transmission I worked a lot on these and beated a lot of these to know enough of how it work and how to rebuilt them,also I worked a lot on 4 barrel and smaller carb,and the carb is not going at 50% when shifting up while doing donnut all around the road
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this was a couple year ago , I was there, its not to far from where I live, and trust me when he floor it and it shift up it stay at 100% throttle

 

yeah probly an age thing ! even in 2000 a lot of vehicle doesn't go half throttle when shifting up, like honda civic, Pontiac grand prix, and a lot more

 

It is those pesky modern cars, they do all sort of weird things that at old ages would of been witchcraft or at least sorcery

Old cars (50's and so) did not have even kick down cables, after those came in, it was lengthy period until electronics started to come sometime at 80's I believe.

Those 60-70's cars have only kick down (not all) to shift down when throttle is applied certain amount which varied a bit and pretty much nothing else.

Hitting rev limiter caused almost immediate shift up and if rpm range was correct pushing throttle down 2/3rd or fully depending a bit, caused shift down, ease up on throttle was way to shift up and push little more was to keep gear, but it was just mechanical stupid box that did not know anything about outside world.

I think that in this BeamNG version it can be made to work really well, needs just proper tune.

I have these kind of parameters in box that is on my video:
"throttleCoefWhileShifting":1,
"wheelSlipUpThreshold":999999, // I guess here you have to balance experience vs realism, those old boxes didn't know about wheelspin so I set it high, added one more 9 for a good measure
"gearChangeTime":0.75,
"shiftEfficiency":0.75,

I might want to increase gear change time a bit and lessen "transmissionGearChangeDelay":2.5 as it is causing too much rev limiter hammering.

Anyway most important is "throttleCoefWhileShifting":1, for anything before 80's or with good old non electronically controlled gearbox. I think that throttle cut on shifting has been a thing more at DCT era, after 2000's ? I guess some data could be found, if one has hours to spend, but that is my guessing, you better do your own guessing, you are better at it

 

It still sounds a lot like it shouldn’t be on as default.
A good test to do is to drive a automatic vehicle on sand. It should not lose its momentum between shifts, it is one of the huge benefits of the automatic.
Look at this comparison between manual and auto: (5:50)

 

I was literally writing something like this in the general discussion tab

Older vehicles, or more specifically, shifts that don't lock up the TC (more explanation below) do not need throttle cut..

Going into a locked up gear (say 3rd in a 4 speed auto) needs to have the throttle cut, so it is revmatched, as the torque converter is locked up (in an idea world beamNG would simulate torque converters and not just lock up in specific gears, but rather throttle points and engine rpm/load). When the TC is locked up, it behaves like a manual transmission almost, and so if you don't cut throttle between shifts then it will feel jerky.

But like in old cars, the TC is not locked up, and shifts into unlocked gears are fine when the throttle is being applied. The torque converter can absorb the shock of the gear change, and whilst doing so the engine is kept at a nice steady RPM, which in the moonhawk used to be around 2000RPM, where it is quite happy going up through the gears.

 

My Olds did have TC lockup and certainly no any kind of throttle cut.

TC lockup has nothing to do with that, usually TC lockup opens up, then locks up again.

You would need computer controlled throttle plate for throttle cut for any shifting related effect and that is throttle by wire, but not even all throttle by wire has such feature.

 

Welp... guess I should throw my hat into the ring for this one.

Back in the day of barberation (so I typed carburetion and my computer changed it to this... I would change it but it fits so well and is to funny for me to take out) they didn't have all this fancy shmancy technology. Throttle cuts were not a thing, but then how does one get smooth shifts between gears? Simple... really long drawn out gear changes and no TC lockup. The torque converter can take most of the blow out of a shift and make it really smooth, but the transmission can also help by smoothing up its own gear changes and shifting in ways that there is a minimal cut in power.

Since autos have the option, they can start to engage the next gear before the previous gear is actually done engaging... usually it doesn't actually do this until the previous gear is about 80% disengaged... but once it gets that far, it starts slipping in the clutch packs for the next gear until full engagement. This lowers the jolt of gear changes substantially and was used A LOT in American automatic transmissions. (perhaps this isn't how they originally shifted... but after a few years of wear and tear... they all ended up doing this, so I just assume that they were designed like that)

Fast forward a few years and fuel efficiency starts becoming an issue... No longer can you just slip gears between each other as this then puts unnecessary strain back onto the engine, so that's out the window... we also need more gears as well seeing as 3 speeds just aren't as efficient as 5 or 6... plus, real slippery TC's put a huge damper on efficiency by just making a lot of heat and not a lot of movement, so those are widely replaced as well. This all combined in the late 80's to early 90's to get cars that had a bit rougher shifting... were they jerky? No... but they definitely were nowhere near as smooth as the boats used to be.

Then more fuel efficiency stipulations came along to the point that cars now needed to try and use TC lockups AS MUCH AS POSSIBLE to try and keep their fuel efficiency up. My 88 Mustang had a rough shifting transmission that tried to keep the TC locked up as much as possible below a particular RPM. First gear was off limits, but everything else was fair game. If you punched it though, it would unlock and allow use of the TC to get the revs up in each gear. These things were clunky... again... not bad... but definitely not smooth.

With the advent of fuel injection right around the corner, manufacturers started to mess with computers and did figure out that cutting throttle can be used to quicken and smooth shifting in automatics. This was mostly only implemented in the mid 2000's by sports cars and supercars though as their automatics needed to shift as fast and smooth as possible (ok maybe not smooth... but definitely fast... and this helped)

Move up into the 2010's and a lot of cars started to do this trick in the search for fuel efficiency... the more time your in a gear, the more time you are using fuel and not wasting it. I think a lot of cars use this nowadays... not actually sure, but my parents 2018 definitely feels like it has and that's just a lowly Equinox.

This tech mostly wasn't used until FBW throttle became commonplace. In older cars that had it, they would actually cut the fuel injectors for a moment to get an RPM drop. This worked, but was only really effective when performance was needed and not really useful when just galavanting around town.

So the feature is both realistic and not realistic at the same time. It just needs to be implemented in such a way that the cars that have it have it and the ones that don't don't. (that makes sense right?)

 

see my grey text... in the ideal world BeamNG would have proper TC simulation, and it would only lock up dependant on engine load, rpm etc.
The earliest one was the Packard Ultramatic, in 1949 where they used a governor on the rear axle that locked up the torque converter anywhere from 15-56mph (dependant on rear axle ratio). This probably wouldn't have been silky, but it's better than BeamNG's previous shifting where it would go straight to a locked gear (so big shift shock), these systems were in top gear, then locked up, not shifting and locking at the same time.

 

I always like to reproduce ford transmissions. (I tune mostly Fords IRL)

I always like to play around with "4R100" all the time (gear ratios = 2.71, 1.54, 1.00, 0.71)

IMO its been getting closer and closer every update. (Before in 0.12 and older versions) gear shifts and lockup was unpredictable.

Now in 0.13, shifts and lockup seems to be on point.. There is always room for improvement but I must say from where the shifting logic started to now is a huge improvement.

in 0.12 and older versions, I always had to hit my TCC lockup "switch" but I rarely do now.. Unless its in a drag situation

 

The 4R100 is electronic, and yes shifts and lockup are on point, the throttle cut works perfectly on the 4 speed autos. And also on the new ETKs, just old cars with no lockup don't need the throttle cut.

*edit* i still think there should be no throttle cut in non lockup gears, for example from 1st to 2nd on 4 speed autos, no throttle cut is needed, the TC would absorb it

 

Agree, I posted because one of the posts was talking about ford transmissions (mustang)

Maybe @Diamondback can add something to the logic that can exclude older non electronic autos and throttle cuts with a jbeam parameter.

in electronic transmissions and no throttle cut in non lockup gears, maybe something added to the logic and a jbeam like this "throttleCoefWhileShiftingMinGear": X, <----- gear