So, I've put just under 2700 miles on my FLT Level 4-4L80E with billet input shaft. It's been running extremely well until the last 100-200 miles. I started noticing that it would carry first gear under part throttle. It'll carry it to 30ish mph, and then shift into second with a very firm shift. It does this in other gears as well. Also, when I put it in reverse, it takes a few seconds to engage. It does this even after being warmed up and driven for a bit. I thought maybe the friction components in the tranny had worn in, and whatever debris might have clogged the filter, creating a low line pressure issue. So, I drained the pan, replaced the filter with an OEM filter, and put new fluid in it.........still the same issue. Any help would be appreciated.

 

Did you put enough fluid in? Also, any corrosion on the wiring connections?

 

It shifts into reverse and forward gears like mine did when I first installed it and didn't have enough fluid in it. His is full though and just started doing this. It seems like it has low line pressure causing the hesitation to shift into reverse or forward gears. Then when it builds enough pressure it grabs the commanded gear. I think this slide into gears is causing extra wear on it's clutches.

What regulates line pressure for the 80E into reverse and forward gears?