Hello everyone. I’ve been reading a couple threads and I seen ppl mentioning trans updates from Honda. What exactly is it that leads to that? What should I look for? and is it something that I should do for precautions?
Transmission Update?
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Torque converter judder caused by prematurely worn ATF. Software update prevents the ATF from wearing prematurely in the future, the 3x drain and fill gets the worn ATF out of there.
Ask a dealer about it, if your vehicle needs it they can do it.
Ask a dealer about it, if your vehicle needs it they can do it.
So in other word pointless to get the update if I don’t have any judder.
I wouldn't say it's pointless. If your vehicle is covered (which doesn't last forever, I believe it's something like 8 years/80k) it's worth getting it done. A headache you won't have to deal with.
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It's not pointless, just not necessarily job number one on the priority list.
If you haven't got any juddering, you can get by perfectly well without the software update as long as you stay at least as disciplined as you have been about keeping the ATF right how it needs to be. Of course, as a vehicle ages its maintenance requirements will change too so you'll only have to get better and better because the transmission sure won't. And that's not a knock against Honda - all vehicles from all manufacturers wear out as they age and get used and need more attention. It's just how it is.
The software update gets you some extra leeway because the ATF doesn't get worn out quite so fast - it's not having to endure the same conditions to get the same job done. If you can get it done for free under the TSB, there is no reason to not do it. If you can't get it done for free, I had it done to my perfectly fine transmission for about a half-hour's labor charge a couple of summers ago and I consider that $75 well spent.
Are we talking about this bulletin? If so, its not about stopping ATF from premature wear (only way to do that is keep it in Honda bottle), but about reprogramming TC lock up clutch.
From what I understood about the update, the TC lock up clutch is what was causing the ATF to wear prematurely, and this wear is what caused the judder (which is why people who are very religious about changing their ATF usually never saw this issue). The update changes the TC lock up clutch behavior to prevent the wear from occurring. This is also why the bulletin states to replace the transmission fluid.
Exactly. Basically, they are bumping up the pressure on the torque converter lockup to make it more aggressive - the judder is a slip that will wear/shear the trans fluid much faster than a fully open or fully locked converter. Likely they originally programmed it to be 'soft' so that your average soccer mom would love the 'smooth' feeling of the transmission...
-Charlie
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These Honda transmissions are like none other.
Years ago I was reading a tech bulletin from a link on a blog that appeared to be sponsored by Sonnax (they manufacture transmission rebuild and repair parts.) It was eye-opening.
If a Honda automatic transmission were to perform a clean shift while accelerating (engaged gear's clutch package disengages, then the next gear's clutch package engages) it would be a bit of a jolting experience. Nobody would buy a car off the dealer's lot that exhibited this on a test drive.
On another note, the above mode of operation really isn't harmful to the transmission.
Honda's approach to making a smooth shift during acceleration: as the previous engaged gear is beginning disengagement, the PCM directs engagement of the next driven gear. There is a brief moment where both are partially engaged, and one result is a much smoother shift. The other result is a lot of localized heating on both affected clutch packages as they are briefly, very briefly trying to be at the same mechanically driven rotational speed.
If this "ballet of disengagement / engagement" timing is off a little (say, longer dwell time involving simultaneous engagement of two gears), you can get a really, really smooth shift....
... you can also get some terrific ATF heating, resulting in thermal decomposition of the ATF. Thermally decomposed ATF most likely has ruined static and kinetic clutch friction characteristics, among other degraded ATF operating characteristics.
Just my somewhat-educated guess on the mechanism for this problem.
Either way, whether it's for the reason @phattyduck postulates, or the above, both do the same thing ... thermally stress the ATF.
OF
P.S. On yet another note, if I'm reading the diagram correctly, our transmissions don't use ATF charge (line pressure) to lock the TCC (torque converter clutch). Rather, they use ATF charge to open the TCC and keep it open until ready for lockup. Amazingly, the TCC is locked up when you start your engine, and when line pressure is sufficient (usually pretty instantly), it's opened (i.e., in a disengaged state).
Years ago I was reading a tech bulletin from a link on a blog that appeared to be sponsored by Sonnax (they manufacture transmission rebuild and repair parts.) It was eye-opening.
If a Honda automatic transmission were to perform a clean shift while accelerating (engaged gear's clutch package disengages, then the next gear's clutch package engages) it would be a bit of a jolting experience. Nobody would buy a car off the dealer's lot that exhibited this on a test drive.
On another note, the above mode of operation really isn't harmful to the transmission.
Honda's approach to making a smooth shift during acceleration: as the previous engaged gear is beginning disengagement, the PCM directs engagement of the next driven gear. There is a brief moment where both are partially engaged, and one result is a much smoother shift. The other result is a lot of localized heating on both affected clutch packages as they are briefly, very briefly trying to be at the same mechanically driven rotational speed.
If this "ballet of disengagement / engagement" timing is off a little (say, longer dwell time involving simultaneous engagement of two gears), you can get a really, really smooth shift....
... you can also get some terrific ATF heating, resulting in thermal decomposition of the ATF. Thermally decomposed ATF most likely has ruined static and kinetic clutch friction characteristics, among other degraded ATF operating characteristics.
Just my somewhat-educated guess on the mechanism for this problem.
Either way, whether it's for the reason @phattyduck postulates, or the above, both do the same thing ... thermally stress the ATF.
OF
P.S. On yet another note, if I'm reading the diagram correctly, our transmissions don't use ATF charge (line pressure) to lock the TCC (torque converter clutch). Rather, they use ATF charge to open the TCC and keep it open until ready for lockup. Amazingly, the TCC is locked up when you start your engine, and when line pressure is sufficient (usually pretty instantly), it's opened (i.e., in a disengaged state).
That doesn't seem like a bad thing - it will get the transmission pump going faster and get the trans ready for operation sooner. All gears should be disengaged, so it won't do anything other than drive the input shaft on the trans.
And yes, I would suspect both gear change timing and torque converter lock characteristics were 'tuned' in the transmission update.
-Charlie
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