Details-
'99 k1500 4WD Suburban Silverado
5.7L, 4L60e, 3.73 rear dif.
Location- Fairbanks, AK

The tranny finally gave it up after 148,800 miles, including 2 round trips on the Alaska highway pulling an overloaded 7,000 pound travel trailer and 6 kids in the past 3 years.

At what point in modifying the engine to gain more horsepower and realizing more torque, do I need to switch from a 4L60e to a 4L80e? It's not the fastest 1/4 mile that's important. It's keeping the cruising speed while towing an elephant uphill;-)

This is really a question of torque vs speed. It seems as though I need more torque pulling the trailer. But pulling is only occasional compared to regular street use. A 4L60e will give a little more speed, whereas a 4L80e will yield a little more torque. However, most pulling is in 3rd gear, so both trannys will pull the same with a 1.00 gear ratio in 3rd. If I rebuild the 4L60e, what would I need to do to increase the torque. Or is money better spent on the engine?

 

If you are going to pull often then at the least have a huge trans cooler but the 80e is the way to go.

 

The 60e with a little more converter would be good and the 60e lower first is and advanatage when pulling

 

Top Jimmy Performance in Palmer just did my 4L60E and it's amazing. He does great work at great prices and stands by all of his work.