4L80E downshift firmness question

[Wolfie]

Did search, but can't find what I am trying to look for...
07 Express 2500.
When manually downshifting, is there somewhere to look to make the downshift happen quicker?
When downshifting from 3 > 2 or 2 > 1 it seems to take way too long to make the downshift.

[Taz]

Hello Wolfie,

Take a look at your settings for:

• D0928 (Manual downshift 2>1 shift speed)
• D0933 (Manual downshift 3>2 shift speed)
• D2003 (Abuse mode speed enable)

Regards,
Taz

[Wolfie]

(I hope this works, I'm sending this from my iPhone while at work)

Thanks Taz, but that's not what I mean.
I have the tranny shifting when I want it , in part to a trans tune from a hummer.
I mean the time from when the downshift begins, and when it is fully downshifted.
Almost like a slipping tranny on an up shift.

[Taz]

OK .. now I understand ... my apologies for my confusion.

No direct parameter in the calibration that comes to mind for manual downshift times. If you are manually downshifting at low % TPS or while coasting - the TC will be unlocked in a truck tune -and this will make the shift feel longer. At high % TPS or WOT the manual downshift should be quicker.

I generally use TransGo kits in 4L60 and 4L80 - haven't tuned a stock 4L80 in a while. Nothing comparable here right now to log.


Regards,
Taz

[slow67]

This seems to be one of the few tables "The other guys" have, but is not in EFILive. The table is called "Brake shift pressure vs Torque vs Gear". It looks backwards from a normal shift pressure table (low torque input is high pressure) because the transmission is mostly only de-applying clutches. Yes, the overruns and bands get applied sequentially, but these aren't important to operation, as they only keep the engine from over-running the transmission, they aren't really holding any power.

[Wolfie]

sigh..... ok.... thanks for the answers...

[joecar]

This seems to be one of the few tables "The other guys" have, but is not in EFILive. The table is called "Brake shift pressure vs Torque vs Gear". It looks backwards from a normal shift pressure table (low torque input is high pressure) because the transmission is mostly only de-applying clutches. Yes, the overruns and bands get applied sequentially, but these aren't important to operation, as they only keep the engine from over-running the transmission, they aren't really holding any power.

When I get a chance I'll ask Ross/Paul if this can be made available.

[Wolfie]

Thanks Joe!

[slow67]

X2!

[GMPX]

I'll be honest guys, I just don't know when I can go back and look at the T42 stuff again, I mean, I'll put it on my list, but that list is very big.