If your truck does this in neutral, I would be very curious what happens when duplicating while on jack stands with the parking brake off? If it drives the tires we are now talking about a safety issue rather than reliability.

 

I wasnt able to duplicate in Neutral, but i tried early on. I'll try again. Any of you open a case with Ford??? You really need to if you havnt!

 

I picked up a 2018 with the 5.0L just over a month ago and it has the clunk but I haven't approached the dealer about it yet.

 

Does anyone here who has the clunk also have the pop\clunk during transmission up shifts? I am wondering if they might be related.

 

Rey
Sorry for the delayed response.

Ford had the truck for about a week. At first they were leaning hard to removing the transmission and looking for issues. After multiple tech looked at it and reading the ford tech pages they decided to go a different route. They conducted line pressure tests and other test on the transmission. They determined the pressures were high at start up. They found an available firm ware update for the Trans control unit and valve body (as they called it). So they flashed it and drove it to re-lean the shift points. Driving the truck it shifts much better except for an occasional issue. However 3 days later the clunk has returned. I am going to reach back out to the service manger and see what the next steps are.

But what was odd was the service manager was all about pulling the transmission and check for factory defects and other issues. But after speaking with Ford he backed away from that, wonder if they said not to?

 

I have a 2018 5.0 3.73 and I am experiencing the clunk at startup as well as when I let off the gas at around 40 mph. I am not sure they are the same but they sound similar.

 

 

Here is a video of the driveshaft moving during the clunk at startup.

 

So.. I have the 2018 FSM, and it's documentation on the 10R80 is exhaustive.. I flipped through it and inevitably put myself to sleep. What interested me was what valve positions were where when going from 1st, through reverse and neutral, then park. I'd have to go back and try again.. but I'm just thinking:

Nothing happens in this thing without pressure being applied to a clutch pack, somehow, some way. I would speculate that these transitions occur at some kind of delay too, albeit slight. Clearly, as Magma indicated by Ford tech admission, the pressures were high somewhere or another. I propose an experiment:

Over a period of days, when going from Drive or Reverse to Park.. shift to Neutral first, wait a few seconds, then shift to Park. This may introduce enough delay to bleed down whatever pressure is accidentally being maintained on the drive gear clutch arrangements. See if it still happens during this period. I don't know what we could glean from this, other than that "Ah Ha!" moment.. it'd still be up to Ford to re-write a piece of code, somewhere in the bowels of Ford.. but it might be a beginning to an end.

Years ago, I was working on a pneumatic machine that was cobbled together by some other folks. Their valving setup was total garbage, and you can't honestly expect to get precision control out of a pneumatic cylinder. They were driving a 4" diameter cylinder with 100PSI air, and couldn't get it to stop where they wanted. My solution to the problem was to, upon a stop command, rapidly shuttle the valves on each side of the cylinder to equalize the pressures on both sides, thus making the piston truly stop. The accuracy improved, and they weren't trying to maintain a pressure in either direction.. they just wanted it to stop on a dime (or a quarter dollar.. whatever).

In my imagination, this 10R80 scenario is reminiscent of that. Or... it's a total garbage thought.

 

Sounds like a good plan....