I work with a guy who owns a foxbody and we've basically become dragstrip buddies. So when we aren't "working" we're bsing cars and ripping on each other. Todays discussion was converters. In his situation he's using a AOD with a nonlockup converter. Long story short he asked me what would happen if I ran a nonlockup in my 4l60E. I didn't have an answer. Any thoughts?

Both are street/strip cars and get driven at most about 75 miles a week in very little stop and go traffic. Usually to the strip(45min of highway) and to work once or twice a week(15 miles round trip on rural roads.) We pretty much agreed gas mileage would go down but weren't sure of any other setbacks. He's been running his for about 2 years with no problems.

I'm not thinking about doing it just posing a what if so I can sound edumacated next time.

 

It can be done. A local friend with a 95 Formula had his trans rebuilt and the rebuilder talked him into a non-lockup, said he had to shorten the input shaft. It works well and didn't seem to affect his mileage much. But to go back he'd need a new input shaft.

 

The biggest reason for lockup is for gas mileage.

My converter only locks half the time right now because of a random misfire. I have noticed no change in mileage.

 

I don't know about 4L60Es, but I know a lot of Grand National guys (200-4R trans) like to modify it so that it locks up at WOT in 2nd and 3rd. It generally improves trap speeds by a few MPH, which makes sense, because there should be less drivetrain loss (and therefore more power to the ground) through a locked converter.

 

Yeah, but this ain't the norm.

 

That works on a TURBO car because the resistance builds more boost. Does't work that well on NA cars.