I have a 2003 Screw 4X4 with the 5.4, 3.73's, 4r70 with 305 70 16's. When I get on the highway it seems to go about 1 mile or so before the torque converter locks up. It seems to be irregardless of the temperature or grade. Is this normal?

 

For taller aftermarket tires with no gear change, yes that is a normal effect!! Detrimental?? No. Mine was worse... I had 305/70's with 3.55 gears and it drove me bonkers. I just got used to it over time. When I finally got 4.10 gears installed, it immediately returned the tranny to "normal" performace. I couldn't believe what I had been missing. Yours shouldn't be too bad with 3.73's, but that's all it is. No harm will come.

 

TCC lockup was to wait for the fluid to reach operating temperature anyway.

Steve

 

Not this condition. This will happen any time during driving with a taller tire/stock gear combo...well after the fluid is up to normal temp. Converter lock up is not to make fluid reach a certain temp, if that's what you were implying. My apologies otherwise. There is a fluid temp reference involved with when the thing actually locks, yes, but it is extremely low and not relative to this condition/thread. It is also only one of many variables controlling converter lock up and I believe the lack of temp alone will not prevent the converter from locking under normal driving conditions.

There are also waay to many variables to what "operating" temp is between two given trucks to be a huge factor when the converter locks up. For example...by no means do I mean to start an argument/discussion, kick a dead horse, or any of that, but it's been stated that the fluid must reach 90* before the converter will lock. I completely, 100% disagree with that and have proven daily, at least on my truck, that that number alone is not a deciding factor.

 

If I'm really light on the gas I can feel mine lock halfway through third no sweat.

Like the other guys said it's just because of a bigger tire and rim combo, I thought mine would suffer a bit just because of the rotational mass of my rims but it wasn't too bad. I bet bigger tires are heavier though, I wouldn't know for sure.


EDIT: Also, like Galaxy said I can feel the torque converter lock even from a cold start on a cold morning. (Well 45 is a cold morning in Arizona )

 

Thanks for the responses. The weird part is that it usually happens on the first shift into overdrive when I get on the interstate. Whether it is the first time or later after driving around town. When I kick it down and then back out of it it locks up quicker. I assumed it was the larger tires, but you guys reinforced it.