Well, that defeats the purpose of the parking brake. Ha ha. That clunk can be a little annoying, but perfectly normal and harmless. It's due to the little play there's in the shaft. It only happens when direction of torque is reversed, so either when parking uphill or downhill (don't know). I almost always park on flat surfaces (no parking brake), and my truck has never made the clunk in those conditions. I've only heard it once in 6,700 miles. It's better to let the parking brake do its job, than risking transmission issues due to a stuck parking pawl that requires tons of force to dislodge, but to each his own .

 

You sound like a Ford service department employee. There is absolutely nothing normal about the clunk noise during start up.Mine does it on hills and on flat surfaces. First truck out of 20 that does this and it's "normal", I don't think so.

 

You’re wrong. Ford engineers will tell you the transmission has multiple clutches engaged at all times. This is the cause and there is nothing they are going to do about it.

 

Mine has only done it on flat surfaces when I apply the parking brake before releasing the brake pedal. If I don't apply the parking brake at all, it won't make the clunk noise, so if you yourself don't use your parking brake, you probably wont hear the clunk since your truck is most likely moving slightly to engage the parking pawls.

After your truck is warm, stop, set the parking brake, put it in park, then release your brake pedal. Start it up 15 minutes later and it will likely make the clunk...at least once out of every 5 times. It won't do it if the truck has been parked for a while, if I never set my parking brake, or if I do it as I described in my previous post.

It's still pretty annoying since this is another normal characteristic that I've never had to deal with on any other car I've ever owned.

 

I very rarely use a parking brake. Only on a steep hill or at a boat ramp. My truck makes the clunk probably about 3 out of 5 warm start-ups.

 

At some point you just have to come to terms with the idea that these new vehicles make noises they shouldn't make. Is the clunk good? Most definitely NOT! However, these things live forever while making bad noises. I have just decided to drive and enjoy my truck. I came to that conclusion with my last vehicle and my wife's current car. Neither had any actual failures. Just odd noises, but they kept running just fine.

 

You just might be correct. Only time will tell. Of course these 10 speeds and Auto start/stop are still quite new to the F150 so we will have to see how these strange noises play out.

 

There has to be lash in the driveline, and that's what that clunk is. If the truck rolls backwards a little, then the driveshaft turns a little when started. The only difference is Ford is less refined than others, and you can hear the clunk. But it's absolutely harmless. It's like worrying about a motorcycle with a wet clutch making the awful clunk they make when engaging 1st gear. You'd think something is going to break, but it's harmless too. It's a freaking Ford, and a truck at that, not a Bentley, so a little research would ease the obsession that these things have to be church quiet. Yeah, there're some disturbing noises I wouldn't slip under a rug, but not this, or the VCT deceleration ratcheting when cold. Annoying? Yes, but not harmful. Yes, I'd prefer they were not there, but it's just crazy to try to do something about it when there's nothing wrong in the first place, so even new parts or a new engine or tranny would make it too. I consider myself **** retentive, but man, I feel for some folks here who are 100 times worse. Must drive the family crazy. Ha ha.

 

Did u ever find out what is was i have a 2018 ford f150 is doing the same thing and i only have 8000 miles on it.

 

Yeah, it's not pleasant. My 2017 5.0/6R80 didn't do this, my Canyon LGZ/8L45 didn't do this. It seems to be pretty random, even on warm starts.

But with so many larger problems on the table with the cursed 5.0 Gen3/10R80, I haven't worried too much over this one.

The only thing I can say is that the clunk feels very similar to the "downhill" clunk on the 10-speed. Park yourself on any significant incline (15%+) and then release the brake pedal (or sometimes it's necessary to rest foot on gas). Feels like the DS suddenly "caught" on something.