TCC 3rd gear lower/upper limit vs. TPS%

**HaulnA$$** · 03-03-2014

Gonna chip in my two cents for what its worth. When tuning TCC lookups it is a good idea to reference transmission fluid temperature while tuning either by using a gauge or datalogging the "e" trannies. Rising temps can be an indicator of locking too soon or releasing too late. The data doesn't lie.

**steveo** · 03-03-2014

i still hold that lockup should be low load cruise only, and disengage on acceleration so the torque converter can do its job.

if you need it for anything else, you're working around the fact that you have the wrong stall point

**EagleMark** · 03-03-2014

Originally Posted by steveo

i still hold that lockup should be low load cruise only, and disengage on acceleration so the torque converter can do its job.

if you need it for anything else, you're working around the fact that you have the wrong stall point

Me too... I think someone misunderstood me earlier?

**RobertISaar** · 03-03-2014

i hate the feel of the converter slipping against its stall point, especially for long periods of time. a 2100 stall is just fine in 1st and 2nd, but above that, i'm not making enough torque to get out of the stall range. spinning at 2100 in 4th gear at ~35MPH makes the engine feel gutless, but TCC locked in 3rd at the same MPH is ~1500RPM and the engine actually feels like it's pulling the car up to speed until i'm able to shift into 4th and lock the TCC then.

stock cal would have shifted into 4th around 32 and spun against the converter until ~45, then locked.

i like a very manual feel in my automatics.... i realize not a lot of other people do though.

**Roadknee** · 03-03-2014

Originally Posted by RobertISaar

i hate the feel of the converter slipping against its stall point, especially for long periods of time. a 2100 stall is just fine in 1st and 2nd, but above that, i'm not making enough torque to get out of the stall range. spinning at 2100 in 4th gear at ~35MPH makes the engine feel gutless, but TCC locked in 3rd at the same MPH is ~1500RPM and the engine actually feels like it's pulling the car up to speed until i'm able to shift into 4th and lock the TCC then.

stock cal would have shifted into 4th around 32 and spun against the converter until ~45, then locked.

i like a very manual feel in my automatics.... i realize not a lot of other people do though.

With my personal preference I could not agree more. I spend a lot of time driving my 1995 K1500 around town at 35 mph. The stock tune shifts into OD at light throttle at 29 mph. I upped this to 44 mph and engage the TCC in third gear at 32 mph light throttle. This is much more enjoyable, requiring much less throttle driving around town compared to stock.

**Fast355** · 03-03-2014

Originally Posted by Roadknee

With my personal preference I could not agree more. I spend a lot of time driving my 1995 K1500 around town at 35 mph. The stock tune shifts into OD at light throttle at 29 mph. I upped this to 44 mph and engage the TCC in third gear at 32 mph light throttle. This is much more enjoyable, requiring much less throttle driving around town compared to stock.

I agree with Robert and you with this. The stock shift mapping in my 4L60E was horrible in my Express with 3.42s. Did not use 3rd gear/ TCC locked nearly enough. The 4L80E stock tune actually locks in 2nd gear above 50% TPS at 45+ MPH as well. I also like a very manual like feeling from the automatic. Even keep my torque converter locked at 0% TPS and during DFCO.

By holding 3rd to higher speeds with the locked converter, I can keep the RPM lower, keep the transmission running cooler, and use less throttle to move around.

**Roadknee** · 03-03-2014

Originally Posted by Fast355

Even keep my torque converter locked at 0% TPS and during DFCO.

I haven't looked at $OD yet to see if this is possible. I imagine keeping he TC locked on decel would use a bit more fuel, but well worth it IMO to reduce TCC cycling.

**RobertISaar** · 03-03-2014

i've done it on the MC, coasting downhill in 4th with the TCC locked and DFCO active is really effective at cutting speed.

had an interesting side-effect though.... if in 4th/locked/DFCO and you move the shifter down into 3rd..... that causes a rather interesting thing to happen, one i've since learned to avoid. now when i downshift into 3rd, i tap/hold the brake first to cause the TCC to unlock(PCM reads the switch and current options are setup to command TCC off whenever brake is detected, most of the older stuff has the brake switch open up the TCC circuit, so the same method would work), move shifter, then let off the brake. TCC will then PWM apply and very shortly after, DFCO will continue. makes my glasspacks quite obvious.

but uh....... don't TCC locked 4-3 downshift with DFCO active, you won't like the result. if i had to guess, i'd say the 4-3 with TCC locked is what causes the problem, the DFCO just makes it worse.

**EagleMark** · 03-03-2014

Originally Posted by Fast355

I agree with Robert and you with this. The stock shift mapping in my 4L60E was horrible in my Express with 3.42s. Did not use 3rd gear/ TCC locked nearly enough.

Me too! Around town here there is a lot of 35-45 MPH driving and stock 4L60E settings just pain sucked! It'd be in OD and TCC locked and I was going to fast, let off gas and TCC will unlock (I think all 4L60E is TCC unlock at 0% TPS and no parameter to adjust? Mine is anyway) coast, hit gas, coast hit gas etc... YUK!

I'd say stock tranny programming was designed around slush and coast. Now it feels more like a performance car shift and I can drive it. No noticeable loss of MPG either...

IIRC I've got it set to 3rd gear, then TCC lock till 45, then OD... anyway it drives real nice in town and at these speeds, still low RPM, but I can drive it and stay on gas with TCC locked and have control.

**lionelhutz** · 03-04-2014

It's all nice to have big discussions about shifting and TCC lockup with e transmissions, but the OP can't chose the exact shift points with his 700R4 so the TCC lockup has to suit the shifting of the transmission. With the 700R4, you may have to compromise between keeping the TCC unlocked at lower speeds or manually shifting between 3rd and 4th so that you don't get both 4th gear and the TCC locked lugging the engine.

The '8051 LT1 TCC control is decent, you can set downshift unlock, upshift unlock, low %TPS unlock and rapid %TPS decrease unlock.

It's fine to lock the TCC on light acceleration. I have my TCC capable of locking in 3rd starting at 30mph and the earliest the 3-4 upshift can happen is 46mph. But I 100% want the TCC to unlocked as soon as I open the throttle enough that I must want to accelerate. No stepping on the gas more and more trying to reach enough throttle to get the transmission to react. For this, I find about 20% higher then the cruising %TPS is a good place to start.

**Fast355** · 03-04-2014

Originally Posted by lionelhutz

It's all nice to have big discussions about shifting and TCC lockup with e transmissions, but the OP can't chose the exact shift points with his 700R4 so the TCC lockup has to suit the shifting of the transmission. With the 700R4, you may have to compromise between keeping the TCC unlocked at lower speeds or manually shifting between 3rd and 4th so that you don't get both 4th gear and the TCC locked lugging the engine.

The '8051 LT1 TCC control is decent, you can set downshift unlock, upshift unlock, low %TPS unlock and rapid %TPS decrease unlock.

It's fine to lock the TCC on light acceleration. I have my TCC capable of locking in 3rd starting at 30mph and the earliest the 3-4 upshift can happen is 46mph. But I 100% want the TCC to unlocked as soon as I open the throttle enough that I must want to accelerate. No stepping on the gas more and more trying to reach enough throttle to get the transmission to react. For this, I find about 20% higher then the cruising %TPS is a good place to start.

Actually with the 700r4 you can get the governor recalibration kit to dial in the governor and you can also get the Bowtie Overdrives TV MadeEZ kit to adjust part-throttle. I had on one on my TPI. I was able to dial in the shift RPMs I wanted for WOT 1-2 and 2-3 very easily. With the 700r4 I found the weights changed the 1-2 shift speeds more and the springs the 2-3 shift. I was also able to use the adjustable TV setup to dial in where I wanted the part throttle shifts in normal driving. Finally dialing in the TCC setup also helped. Keep in mind that the early 700r4s lock TCC in 2nd gear as well.

**EagleMark** · 03-04-2014

Originally Posted by lionelhutz

But I 100% want the TCC to unlocked as soon as I open the throttle enough that I must want to accelerate. No stepping on the gas more and more trying to reach enough throttle to get the transmission to react.

Made me laugh, stepping on throttle more and more and then WHAM! Downshift!

Originally Posted by Fast355

Actually with the 700r4 you can get the governor recalibration kit to dial in the governor and you can also get the Bowtie Overdrives TV MadeEZ kit to adjust part-throttle. I had on one on my TPI. I was able to dial in the shift RPMs I wanted for WOT 1-2 and 2-3 very easily. With the 700r4 I found the weights changed the 1-2 shift speeds more and the springs the 2-3 shift. I was also able to use the adjustable TV setup to dial in where I wanted the part throttle shifts in normal driving. Finally dialing in the TCC setup also helped. Keep in mind that the early 700r4s lock TCC in 2nd gear as well.

That's a lot of work compared to an E trans.

This was a good conversation but we sure went off topic for 700R4 TCC...

**lionelhutz** · 03-04-2014

Sure, you can mess with a 700R4 and get it to shift mostly how you want. But, it's not even close to an electronic transmission where you can set all the upshifts and downshifts exactly where you want them. For example, how do you set the speed a 700R4 drops back out of OD without messing up the rest of the shifting so that when you drive into a reduced speed zone you're not lugging the engine with OD and the TCC locked?

**RobertISaar** · 03-04-2014

you make a stepper/servo motor that controls the TV cable and program it to work how you want it to?

of course, that only controls one aspect of line pressure. i've had a similar thought using a vacuum pump and the modulator on my 4T60E to play with line pressure, but it was just what popped into my brain when it was idling.

**damanx** · 03-05-2014

For the time being, I won't be playing with the parameters in question.

Frankly speaking, I know absolutely nothing about how the tranny in my truck is setup and I'm not even sure of how much life is left. Realistically, if the 2.8 engine condition is any indication, then I don't expect much longer on the tranny.

So, I am going to finish getting all the parts together for the spare 700r4 and rebuild it with better components than stock and revisit this if needed.

I am also going to consider replacing the 3.73 rear with a 3.42.