It is still better than transmissions developed earlier, because it moved away from pure mechanical control with no compensation at all to electronically controlled one!dikidera wrote: ↑20 Oct 2024, 14:44 The other subject I want to touch on is again the transmission. Our 5-speed transmissions are driven by algorithms, models which:
A) Were developed in the 90s and are not as advanced
B) Expect that the condition of the gearbox will be immaculate the whole time. Perfect TC clutch, perfect friction plates. Non-sticking solenoids.
C) Approximate many physical phenomena without measuring most of them.
Because these algorithms were developed a time where compute power was not that great, the algorithms are sometimes very simple and not that accurate. I don't claim to understand them. This is why these gearboxes die all of a sudden and had no codes prior.
On the other hand we have the 6-speed TF80SC which features entirely different algorithms. The code is denser(by a factor of 4 at least), uses a lot of floating point math(the 5-speed does not) as such it probably has a better approximation of various physical phenomena, torque transfer etc. More is not always better, but in this case it probably is. I expect the 6-speed to be more durable and resist wear.
The adaptation algorithm for the 5-speed is very "simple", I am speaking from memory, but it's something along the lines of a static table of oil temp regions and gears. The oil temp regions are -15, 0, 15, 40, 65 and 110 if I remember correctly. Then these tables have a value between 0 and 4.
And depending on this value, the adaptation of one temp region and gear is added with that from another.
Now because there is no finer granularity here, when the transmission adapts a shift say at 100c, it will use that adaptive value at 65c because they are both of the same temp region, because, again, no finer granularity. What about that table and summation of the adaptations? It's static and not very adaptive.
The adaptations are also not grouped by RPM, no such concept.
Finally, the TCM firmware assumes that when it commands 70 psi of pressure for main lube, that it will in fact be 70 psi, but any sticking solenoids, pressure loss from internal leaks or not as good oil characteristics, it can all go downhill from there.
TF80 in wife's ex XC60 wasn't very smooth. In fact, when we bought it knew, it was banging so hard that I found pieces of clutches doing ATF drain and fill. It required a TCM software update later. The word was Volvo did a crappy job replacing 3.2l I-6 engine with yet another iteration of I-5 turbo.
Same era Aisin-made A760/AB60 are hit or miss. The one in my Tundra has a slight problem with 2nd gear when cold and a lot of kicking when stuck in traffic, which reminds me AW55 so much. The same engine/transmission combo in wife's Sequoia is always silk smooth. They're also are not know for premature death and are good for like 0.5M miles.
Reports on newer 8 and 10-speed Aisins are anywhere from "shudder" to silk smooth, on brand new vehicles.
Nothing replaces a human being who shifts a manual gearbox. Humans adapt quickly.
