TCC lock up in 3rd

[damanx]

Running the ATKX bin.

3rd gear TCC lock up occurs at 27mph.

4th gear at 26.

Seems like the extra 2-250 rpm drop when the TCC locks up in 3rd at normal/moderate acceleration bogs down the engine a little more than it should.

Oh, running the 700r4 and 3.73 rear.

Bump the 3rd mph to 32 mph maybe?

[RobertISaar]

certainly could.

[buddrow]

I adjust mine to 35 in 3rd and 38-40 in 4th. Good for around town

[EagleMark]

Sometimes your better off without 3rd and let the motor run easy with no TCC load for fuel mileage.

[damanx]

Sounds good, I'll turn it off on the next bin burn.

[RobertISaar]

Sometimes your better off without 3rd and let the motor run easy with no TCC load for fuel mileage.

i think that will be highly dependant on the converter you're running.

GM, in all of their infinite wisdom, decided that 94-95 3100 cars shouldn't lock their TCC in 3rd until the same MPH that they would lock at in 4th. this isn't so bad in the smaller platforms that got ~1600 stall converters, but the W platform cars got ~2100 stall units. instead of locking in 3rd around 30-35, they shift into 4th at 35 and spin against the converter until 45, then lock. REAL gutless feeling in 4th until the converter locks. of course, keep putting your foot into it to reach 45 and you're at the 2100 stall point the entire time.

i much prefer locking in 3rd around 30, then shift into 4th between 40-45 keeping the converter locked. it's all preference at that point though.

[EagleMark]

Preference, weight, aero dynamics, gear ratio, engine torque, tire size and probably a few more things like Robert mention torque converter lockup.

Like my truck has plenty of power in town at 35 MPH with 3;73 gears so at low TPS the TCC locks up, I do a lot of 35-45 driving so it works good for driving and MPG. SHifts to fourth at 45 MPH... Same truck with V6 or 2:73 gears is another story.

[Fast355]

Preference, weight, aero dynamics, gear ratio, engine torque, tire size and probably a few more things like Robert mention torque converter lockup.

Like my truck has plenty of power in town at 35 MPH with 3;73 gears so at low TPS the TCC locks up, I do a lot of 35-45 driving so it works good for driving and MPG. SHifts to fourth at 45 MPH... Same truck with V6 or 2:73 gears is another story.

I never liked how my 3.42 geared Express shifted with the 4L60E. The stock 80E tune was even worse. Running mostly stock 4.8/4L80E shifts now. The only way I get 3rd gear TCC is in 3rd gear and I don't lock 4th until 50 mph.

[ony]

I had a 2.2 Corsica, locked 35mph in 3 didn't have a 4th or over drive if I feather footed it. 1989 model