Shift adaption time

[MNR-0]

I currently have a 0.3s shift adaption time on my WOT 1-2 shifts. It completes the shift just shy of 6600rpm. Ive set it to 38mph and 6250rpm WOT shift.

No matter what I do to the shift time vs tps tables, it shifts at 0.3 seconds. I absolutely must have it shift faster than that. Is there something I can do?

Have had a shift kit and tranny rebuild done. Using stock shift pressure tables. Only changed the shift MPH and RPM at WOT as well as the shift adaption time vs vs pressure.

[Casey]

I currently have a 0.3s shift adaption time on my WOT 1-2 shifts. It completes the shift just shy of 6600rpm. Ive set it to 38mph and 6250rpm WOT shift.

No matter what I do to the shift time vs tps tables, it shifts at 0.3 seconds. I absolutely must have it shift faster than that. Is there something I can do?

Have had a shift kit and tranny rebuild done. Using stock shift pressure tables. Only changed the shift MPH and RPM at WOT as well as the shift adaption time vs vs pressure.

Shift adaptation:
When GM builds a trans they want the shift as smooth as possible. There are some folks who are harder on cars/trucks than others. Shift adaptation is trans learning (upper time limit).
Before shift adaptation the guys who were harder on parts burned up their clutch packs due to long shift times. Those tables help compensate for that.
They were not intended to be the main focus of shift times, only a compensation when things get ugly.

To get your shift times where you want them, you have to increase your shift pressures. Also don't forget about the Force Motor current table. On some vehicles the 100 column is set to 1245ma which will bleed off pressure.
It's safe to set the 100 column to the same value as the 96 column.

Ken

[Cursed1]

Shift adaptation:
When GM builds a trans they want the shift as smooth as possible. There are some folks who are harder on cars/trucks than others. Shift adaptation is trans learning (upper time limit).
Before shift adaptation the guys who were harder on parts burned up their clutch packs due to long shift times. Those tables help compensate for that.
They were not intended to be the main focus of shift times, only a compensation when things get ugly.

To get your shift times where you want them, you have to increase your shift pressures. Also don't forget about the Force Motor current table. On some vehicles the 100 column is set to 1245ma which will bleed off pressure.
It's safe to set the 100 column to the same value as the 96 column.

Ken

Both the negative and positive tables in my vehicle year are 1245 in the last column. Is this true of the positive and negative tables of the Force Motor? Or should we be changing just one of the tables or both. Thanks

[jimmyblue]

I noticed in my stock setup, that same 1245 column.
However, that's the 100% column and I also see a
max line pressure single-field that had a stock value
of 90 - meaning you can't ever get there?

Wonder what the later models, that have sane 100%
values, have for their max line limit?

[MNR-0]

Thx for chiming in Ken. If I understand this correctly, the Gear vs. Shift Adaption Time vs. Pressure is only a ringfence to protect fom excessively long shifts?

So, rather than modify this table, leave it stock and modify the gear vs. base pressure vs. pressure to get ur WOT shifts at the desired ft-lbs.

If that is correct, then this is even easier than I thought. Once you understand how they map the shift pressures, its a piece of cake.

One other thing, whats the brake pressure table for?

edit: you meant Ken

[Casey]

Thx for chiming in Ken. If I understand this correctly, the Gear vs. Shift Adaption Time vs. Pressure is only a ringfence to protect fom excessively long shifts?

Correct

So, rather than modify this table, leave it stock and modify the gear vs. base pressure vs. pressure to get ur WOT shifts at the desired ft-lbs.

You can still tune that table. I have mine set to .25 sec even though the shift pressure table settings keep my shift below that threshold.

One other thing, whats the brake pressure table for?

Brake shift pressure is only used in the heavy duty truck calibrations. There is a option bit for use of these tables. If your table is full or zeros, it's disabled.

It's an alternate lookup for the base shift pressure table. It's only allowed in certain gears/ user selected gear ranges. There are indexed truth tables for it's use.

Ken

[MNR-0]

Thanks Keith. The Base Shift Pressure has been adjusted and now it shifts firm with wheelsping into 2nd. However, the shift is still bouncing the limiter.

Keith, grateful if you could answer me this:

Will removing Torque Management make your shifts faster (not firmer)? Will it still drop timing during the shift if the reduction tables are all zeroed out?

Im thinking that TM needs to play a part here at 6200+ RPM so it is easier on the box to shift 1-2 without going into too much RPM overrun. If timing is pulled, RPM increase rate is lowered. The box can then shift with less RPM overrun. Is this correct?

If so, then should I reduce the max. spark retard limit from 15 degrees advance to 12-13? Or just Zero it out so TM can pull timing back to 0 degrees? If TM is deleted, then no timing is pulled and so this table becomes redundant for Tranny tuning purposes.

Thanks in advance.

[MNR-0]

Well I answered my own question this week. The VCM can onyl program within the machanical limitations imposed by the transmission. My Shift at 6250 results in an actual shift at 6550 because thats the length of time it takes for the tranny to accumulate enough PSI and start bringing on the bands.

My shifts are set at 6250/6250 and after scanning the real shifts are at 6576/6310. I reckon its the mehcanical limitations of the tranny and also when the VCM polls for a shift command. It takes 2/10s of a second to begin pulling the revs down, and thats nearly 300RPM.

Guess I have an exceptional motor up top. I have noticed that it pulls without losing power till 210kmh in 3rd on the Dyno. Not bad for a stocker.

[Magic_Chicken]

Keith, grateful if you could answer me this:

Ken, not Keith.