You cannot go off of current gear as when the shift has happened, you have to look at engine RPM. Your RPM settles at 4:41.357 and around a second later you are at 48mph. The current gear that you are looking at is when the trans actually commanded the shift. The 80E does not shift as fast from command to shift completion as a 65E as all the parts are heavier. Based off of math you are not getting slip in those frames. Regardless of what the converter is doing, if you know the current gear and the input and output speed on the trans you can calculate to find slip if in 1-3 gear.

 

So is this "normal" then? I really wish someone could take a test drive with me because I find it very hard to believe everything is functioning as it should during that downshift/acceleration.

 

You can increase the shift pressure if necessary, I would make conservative steps though until you like the shift feel? Far as your downshift from a 40 roll, you need to remember that your 1st gear ratio has been reduced by just under 24% with the 80 swap. This is why so many guys complain about their trucks feeling like a pooch out of the hole after the 80 swap. Now throw a looser converter into the mix and you just multiplied the issue. Until you have the t/q to get you through that rpm range, you'll have to deal with your current 40 roll downshift to 1st gear complaint.

 

I have no problem dealing with this issue until the boost. I was just worried there was a problem somewhere and didn't want to compound the issue with extra horsepower. Thanks Chuck!