What do you mean by bind? Do you mean like wheels completely lock up? Or just talking about clunking? It sounds like the low/reverse clutch is disengaging since you said it happens at around 3 mph. The 1-2 shift in the 6L80 is not synchronous, all the others are though, when it shifts to second it just applies one clutch, then the low reverse sprag clutch (not the same as the low/reverse clutch, since that is a friction clutch and the sprag is a one-way mechanical clutch). It's programmed to always start from a standstill with the low/reverse friction clutch applied since if not full engine torque, multiplied by the torque converter stall as well, would be going through the mechanical low/reverse sprag. Once it hits around 3-5mph or something like that, it disengages the low/reverse friction clutch. I am thinking that is what you feel. If I remember correctly there are some not so obvious things you have to remember when putting in the low reverse assembly in the case. One way to check would be to start off in manual 1st gear mode, which fully locks at all times, the low/reverse friction clutch at all speeds. As for HP Tuners being able to turn it off, unfortunately I have never seen anything in HP Tuners that will do that. Like what he is showing in the videos, unfortunately most of the parameters and settings don't do anything. About the only thing you can do is set proper shift speed. Even trying to reduce the torque reduction on upshifts doesn't work, you have to go into the ECM and trick the system by limiting the lowest timing value it can use for any torque reduction event, which can cause issues elsewhere. I think a lot of people get the placebo effect and think HP Tuners can just do anything and fix everything, but the reality is they just release a bunch of parameters that either aren't defined properly, or only work for specific operating systems, or just aren't properly tested to ensure functionality. They obviously have a lot of liability so any safety related parameter will work, for example throttle control type stuff, but most other stuff is just kind of fluff unfortunately.

@@cmitchell17a1 Thanks for the reply. Yes it's more of a bump not a complete bind. I was told that the "air bleed" function could be causing this. However while looking at the flow chart in my ATSG book I did see that the low/reverse clutch applies momentary. In manual low it doesn't bind so I think you are on to something. In fact last week it started doing it more often. At first it was only one time after the key cycle. Now it randomly does it and it seems to be getting worse. I'm probably going to pull the unit back out next week.

Not sure how much a 6L80 video is going to help with Ford's 6R80, maybe it'll help with some of the transmission concepts

@@gunshipproduct2 well, the 6R80 and the 6L80 are very similar transmissions, as they were codesigned. There's even a Ford patent referenced in the video. The clutch to clutch shift strategy is likely largely the same.

@@Akya2120 Huh, more you know. I do know the 6R80 is almost identical to the 6HP ZF unit, I didn't know the 6L80 was condesigned, that pretty cool, did you have any reading or articles on that? I can't find any but it would be cool to look into it

I wondered about that initially, but at that point in the shift, the apply piston would have already stroked. The piston should have stroked in the fill phase, which is the first third of clutch application.

@@Akya2120 didn't see any pat ref you have a timestamp?, do you mean the codesigned 10 speed that everyone is aware of?