Shift Quality

[907DAVE]

What is the preferred method to firming or softening shift feel?

Is it by changing slip time, torque reduction, or TV pressure?

What are the negative affects of each?

I like the torque reduction feel for light driving, but dont like the "burn time" that comes along with it, what is best for my tranny?

[cleatus12r]

The easiest way to get a more firm but yet comfortable shift is to change the target slip time by reducing the values (it's time) by about .25-1 ms. The TV pressure is a baseline that gives the shifts a "head start" so to speak in the adaptive strategy. The PCM can compensate up to about 20 PSI in most cases to achieve the desired slip time. That's the easiest way.

Bill and I have differing thoughts on the torque reduction during the shifts. I won't get in on his side of the coin, but I prefer to use the stock reduction or even a little lower values in the low APP ranges simply because I think it's better for the transmission. Bill doesn't believe that's true and it may not be but he can explain to you his thinking on the deal and you can make a choice for yourself.


Negative effects? I can't give you any as a slightly quicker shift is always better for the friction elements inside the transmission. A "mule kick" in the seat during a shift is obviously not good. As long as you can get a quick shift, minimize burn time, and keep it comfortable, it's a good shift.

I can show you a couple of my shift parameters if you'd like to try them.

[907DAVE]

That would be awesome.

[cleatus12r]

Oh, and I forgot to mention that the OBS and E99 guys are SOL on the adaptive stuff.

I was kind of curious as to the TV pressure offsets and TV pressure slopes in the parameters menu. I tend to leave those alone but I assume they actually dictate the solid state line pressure in each gear. They do make the shifts harder when changed. I don't know though. I was actually trying to save that question for the tuning class......

But if you know, or Bill freely divulges the information, I won't argue with it.

[cleatus12r]

I will be right back. I'm busy making some screenshots...............

Give me about a half an hour.

[cleatus12r]

Ok here they are, in no particular order.............

Bill, I am not saying that these tunes are perfect so if there is something amiss, then please feel free to offer suggestions. These do work very well for me and the way I drive though.

[907DAVE]

Thanks Cody, gonna have to study and compare these. I did not know anything about the "torque table" but will have to look at that, and I was wondering what that was for.