Quote:
Originally Posted by Power Hungry
Cody,
What you said is exactly the reason we have to be very careful how torque reduction is handled. There are programs where the torque reduction is reduced or eliminated to achieve a specific feel, but it should never be removed on towing programs where a significant load is being pulled. It's a quick way to overstress the hard components as well as the clutches.
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I guess I don't see this because I don't understand how cutting transmission input torque momentarily during a shift is bad (GM has been using it on the Duramax/Allison combination since '01, and it's REALLY noticeable). Unless there are other things at work here in addition to slightly reducing engine torque that is happening in the code at the same time that I am not observing, I don't see a downside.
I guess I shouldn't say that I have reduced the values in the torque reduction maps much if any under high load (the upper right corner of the table) but primarily in the low load portion (where stock values are at 100%). This has made for seamless shifting at light acceleration that isn't jerky. I can increase the TV pressure during the shift (hence the shift occurs very quickly and positively) and still have a great shift feel.
Concerning the 2-3 shift, I have found that commanding low torque output during a shift (in the 60% range) makes for an especially harsh upshift and actually
increasing the torque output back into the stock range will soften the shift a little. The shift seems to get better the lower you go until the values are lower than about 75%; then the shift feel improvements appear to get counter-productive (on the 2-3 shift).
Here's a question. Why do the 02-03 transmissions have a horrible flare if the torque reduction values
aren't increased to 100% while the earlier trucks do not (even when running close to stock power output)? What is changing here that has nothing to do with engine torque output? Is this why the values we are discussing shouldn't be decreased due to side-effects NOT related to engine output?
Quote:
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Originally Posted by Bill
Installing a modified valve body has a significant advantage because it allows the transmission fluid to flow more easily through the programming orifices and results in faster flow into the clutches and more responsive clutch activation. Also, because the fluid no longer needs to be forced through at higher pressures, there is also a resultant drop in tranny fluid temps... often as much as 25-30 degrees.
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Well said. There still is ZERO strength addition to the transmission though.