[KingLT1]

So for a couple years now I have had my TCC slip tables zero'd out. I did it before I ever had any converter shudder. The only thing I never cared for about doing this is it makes the trans down shift a bit harshfrom any gear. The other night I decided to try putting the Slip tables back to stock and I noticed some oddities with the transmission. I don't get the rumble strip vibration, but the rpms were flaring when cruising steady with the converter locked. That is another symptom of the converter shudder. So I guess mine has it with the stock settings, but with my Tune the trans acts fine.

That being said, I decided to try and modify the TCC slip tables. I started by reducing all the cells populated with 10 to 5, and the cells with 5 to 3. That removed 90% of the anamolies I was seeing with the stock TCC slip settings. So I went a step further and reduced all the cells that were currently 5 to 3, and the cells with 3 to 2, and left all else the same.

The results seem to be good. No issues and the trans down shifts smoother compared to having the tables completely zero'd out. It's still a bit firmer then stock, but much better then being zero'd out.

I have to take my car in for a steering recall, my service advisor said they would run the 18-na-355 fluid flush under my warranty even though I am modded now that GM doesn't require any diagnosis prior.

Either way, just figured I would share for those that like to tinker. If you try these settings make sure to change all gears "AC off 1-8".

[Trochoidal]

Thanks for the information.

Are these the same slip tables you posted about in this thread?

https://www.camaro6.com/forums/showthread.php?t=540913

While we’re on this subject, do you have a thought why the line pressure spikes when in gear and not moving?

I posted about this a few months back.

https://www.camaro6.com/forums/showthread.php?t=554779

You also mentioned in that thread about other changes you made. Will you share those changes with me?

[KingLT1]

Yes those are the tables. Zeroing them out doesn't allow the converter to slip a certain percentage during throttle transition which makes down shift much more aggressive. Pretty sure GM did this to make transition from 4cyl mode smoother and the part throttle down shifts more seamless.

Far as the line pressure spike, I am not sure why it does that.

The other changes are as follows.

Shift inertia
Shift time
Shift pressure TCC on/off
Max kpa
Trans peak torque and limit
Torque management switches

All those tables need adjustments to maximize the trans tune for best performance. I don't believe you need to make all those adjustments for the TCC slip tables if trying to prevent converter shudder.


Do you have HPtuners?

[Trochoidal]

Originally Posted by KingLT1

Yes those are the tables. Zeroing them out doesn't allow the converter to slip a certain percentage during throttle transition which makes down shift much more aggressive. Pretty sure GM did this to make transition from 4cyl mode smoother and the part throttle down shifts more seamless.

Far as the line pressure spike, I am not sure why it does that.

The other changes are as follows.

Shift inertia
Shift time
Shift pressure TCC on/off
Max kpa
Trans peak torque and limit
Torque management switches

All those tables need adjustments to maximize the trans tune for best performance. I don't believe you need to make all those adjustments for the TCC slip tables if trying to prevent converter shudder.


Do you have HPtuners?

Great to know what tables need attention. That crazy spike could just be some kind of erroneous data. Yes I have HPtuners.

Thanks again for sharing.

[parbreak]

I've had mine zeroed out for over 1 1/2 years and kind of like the crazy downshifts. Guess I just got used to them and certainly can deal with that better than the rumble strip slip. But maybe I'll give your mod a try. Thanks for the info.

[EMTNLSS]

I've had mine zeroed for a while also. I'll try these settings out and see how it feels.

[cooper1965]

Interesting KingLT1 , now are you using the added slip with your full trans tune, or this is a mostly stock trans tune?

[KingLT1]

Originally Posted by cooper1965

Interesting KingLT1 , now are you using the added slip with your full trans tune, or this is a mostly stock trans tune?

Full Trans Tune.

Originally Posted by parbreak

I've had mine zeroed out for over 1 1/2 years and kind of like the crazy downshifts. Guess I just got used to them and certainly can deal with that better than the rumble strip slip. But maybe I'll give your mod a try. Thanks for the info.

Yea I could easily live with the tables zeroed out, I just like to tinker. I had a "I wonder if I tried this" moment LOL. I figured I would post up for others to try and see what they thought.

[grampa_ss]

speaking of tinkering....i extended my normal driving shift points about 4mph higher. And i don't shift into 8th now until about 54. I hate driving around at 1200 RPMS

[Joshinator99]

Originally Posted by grampa_ss

speaking of tinkering....i extended my normal driving shift points about 4mph higher. And i don't shift into 8th now until about 54. I hate driving around at 1200 RPMS

Agreed, changing the part throttle upshift TCM tables made for a very nice improvement in around-town driving.

[cmitchell17]

For the harsh/rough closed throttle downshifts, I disable TCC lockup at 0% TPS for gears 1-5 or 6, I found this helps the torque converter absorb some of the downshifts tieing up and binding when on the brake slowing down (especially when coasting or slightly on the brake).

I know I have seen some SAE papers about improving NVH (noise, vibration, and harshness) characteristics for downshifting on clutch to clutch automatics, so I think its a industry problem. However, I think GM could have tuned it way better and eliminated a lot of the sorry and harsh zero/part throttle shifts, or either they did this on purpose to improve durability as a trade-off, or they are just so bureaucratic no one bothered to make it any better.

[grampa_ss]

Originally Posted by cmitchell17

For the harsh/rough closed throttle downshifts, I disable TCC lockup at 0% TPS for gears 1-5 or 6, I found this helps the torque converter absorb some of the downshifts tieing up and binding when on the brake slowing down (especially when coasting or slightly on the brake).

I know I have seen some SAE papers about improving NVH (noise, vibration, and harshness) characteristics for downshifting on clutch to clutch automatics, so I think its a industry problem. However, I think GM could have tuned it way better and eliminated a lot of the sorry and harsh zero/part throttle shifts, or either they did this on purpose to improve durability as a trade-off, or they are just so bureaucratic no one bothered to make it any better.

can you post a screenshot. thanks

[KingLT1]

Originally Posted by cmitchell17

For the harsh/rough closed throttle downshifts, I disable TCC lockup at 0% TPS for gears 1-5 or 6, I found this helps the torque converter absorb some of the downshifts tieing up and binding when on the brake slowing down (especially when coasting or slightly on the brake).

I know I have seen some SAE papers about improving NVH (noise, vibration, and harshness) characteristics for downshifting on clutch to clutch automatics, so I think its a industry problem. However, I think GM could have tuned it way better and eliminated a lot of the sorry and harsh zero/part throttle shifts, or either they did this on purpose to improve durability as a trade-off, or they are just so bureaucratic no one bothered to make it any better.

my TCC lock up is disabled until 8th gear 55mph.

[cmitchell17]

Originally Posted by grampa_ss

can you post a screenshot. thanks

I like to keep 6, 7, and 8 still locked up since the clunks and clanks seem to be a little more amplified in the lower gears. However, it seems like i'm getting more and more clunking and clanking but it could just be me noticing it. It can do it bad at around 40-45 when you're at very light throttle and it goes from 8-7. The very bad NVH qualities of the driveline and pinion gear I think are about 90% to blame for the problem, since you wouldn't notice any of this if it weren't for the whole driveshaft and carrier bearing clunking during the downshift when there is a sudden torque spike or reversal.