I will certainly give it a try. I should note that when we have arrived at our destination, we always stop the truck, keep right foot on the brake pedal, put it in Neutral, engage the parking brake with the left foot, realease the brake pedal so that the trucks weight is now resting on the parking brake, then move the shifter to Park. My dad ingrained the parking procedure when i started driving, and we have a steep driveway. We can try waiting longer in Neutral.

 

I use the same portal except for when parking in my garage which is dead level. Mine clunks so bad I can feel it throughout the truck when it happens.

 

Yeah, the big/hard clunks are brutal, i dont see how they can call it normal at all. Especially when you can hear it 50 or more feet away! In case you havnt seen this video i posted:
https://youtu.be/5fgkiOLhCEU

 

Here are 2 videos of the clunk on my F150. 2018 Lariat 5.0L 10spd 4x4. The video with the "clunk" noise was with the parking brake on and the transmission in park (the parking brake was engaged BEFORE the transmission rolled into park). The second video without the "clunk" noise was with the parking brake on and the transmission in park (the parking brake was engaged AFTER the transmission rolled into park). I get a normal start every time with no clunk if I engage the parking brake after allowing the transmission to roll into park.

 

That makes total sense; of course there is no clunk when the truck's weight is permitted to rest against the parking pawl, and apply holding torque to the transmission's output shaft. I would venture a guess though, that even though you're not hearing a clunk, upon start up, torque is being applied to the transmission's output shaft, the same way as if it weren't under holding torque. You're just not seeing or hearing the sudden stop (and shock loading of the gears). The question is, why? Perhaps first, we need to re-frame the question, and ask it among a more ubiquitous automotive audience without eluding to any specific transmission or vehicle...

"Hey transmission expert guy, I have seen reports of an automatic transmission momentarily (<1second) applying output shaft motion and/or torque under the following conditions: 1) The vehicle is in park, 2) The vehicle was running when placed into park, 3) The engine and transmission are at or slightly below operating temperature, 4) The vehicle is Off and being started to On (typical turn-key start-up).

Would you or would you not consider that to be normal behavior in a modern automatic transmission? If not, please speculate as to a cause."

After feedback from a general audience of automotive engineers and techs, you can ball all that feedback up, with videos, and drop the "It's a F150 with a 10R80 transmission" bomb.. see what happens then. The general argument in my opinion, is that permitting any transmission to apply free-wheeling motion and/or torque to the output shaft while in park AND during start-up (and thus the prop shaft of the truck) not only will cause premature wear of the gear sets in the transmission and rear end, it also presents a possible safety hazard. If the general consensus from the question above is that "hey, it's totally normal for any automatic transmission to do that.. why aren't you letting the parking pawl load up first?" or whatever the specific scenario may be... then I guess we all get to get over it.

 

I'll have to respectfully disagree, my truck still clunks when resting on the transmission. The shaft moves very little if any, but still clunks.
https://youtu.be/O8u0sdnags0

 

That's why I was saying that I'd venture a guess that even though the other poster might not hear it, it's still there.. I think it'd be best to start fresh with an understanding of the condition being normal or not, regardless of make or model.. I don't know what you could expect to achieve with Ford if you get a boat load of information saying that "NO.. this definitely IS NOT characteristic of ANY Automatic Transmission."... but it might be a start to an interesting Twitter post or something.

 

Mine's headed to the dealer next week. Ran some errands yesterday and only had a few minutes between starts and it sounded like gunshot went off. Combine that with "bang" downshifts under low load it needs to be checked out.

 

JMHO, but I think MarkA has a valid point. This issue seems to somewhat center around momentary torque being applied through the transmission with sufficient force to suddenly take up slack in the ring and pinion. It would make sense that it would happen if the parking brake were set before the park pawl were fully engage, or if the vehicle were in neutral and the park pawl never engaged. I can see where under these circumstances an automatic transmission with clutch pack may grab a bit before clutch packs release. Something very similar happens on motorcycles with multi-plate wet clutches. You can get a brief torque output just before the plates unstick, even with the clutch lever pulled in. Sounds like it might be similar and possibly normal. Next question would be, what about that huge slack in the ring and pinion? Maybe all the trannys are the same and the difference is the ring and pinion clearances.

 

With a transmission in park, or neutral, why should it be transmitting power all the way through and with enough force to knock the ring gear, quite loudly?

And the other factor here is whether or not the transmission is hot. In the morning, it's almost not noticeable. If it's up to operating temp, and only a short stop, it slams the ring gear like a gun shot. It's like something is letting go that should because it swells when hot. And then when it gets cool again, the gap or whatever forms and it's not as noticeable.