Clunk/bang when coasting uphill- low RPMs.

[freewayman]

Anyone else get a clunk/bang when coasting uphill at low rpm?

It happens somewhat consistently for me as I live on top of a hill. Basically there is a school zone in the middle of this hill, and so typically I let off the gas to slow down to 20mph (30km/h).

However when I get back on the gas to maintain this speed, the transmission will clunk into 3rd gear from 5th. Sometimes it will do this on the downshift even when I don't give any throttle. This scenario is it the only time it does it (not always but often) but I suspect there's been a few times when it's done it in other low rpm conditions, when low rpm coasting to a stop with no throttle and no brake.

Also, I "hear" this clunk more so than I feel it. It can also be described as a "pop" sound as well.

This is my only gripe with the transmission, otherwise it shifts buttery smooth.

Edit: the truck is a 23 Tremor- 3.5 Ecoboost with 10R80

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[freewayman]

A thought just came to mind..

Could this be because at low RPMs the transmission fluid pump puts out less flow and the valve body doesn't like these lower pressures?

 

[Samson16]

Don’t know about that. Perhaps try sport or tow/haul and see if the behavior improves. Normal mode might be lugging the drivetrain in order to wring the last drop of fuel efficiency from it.

 

[Ford Motor Company]

Anyone else get a clunk/bang when coasting uphill at low rpm?

It happens somewhat consistently for me as I live on top of a hill. Basically there is a school zone in the middle of this hill, and so typically I let off the gas to slow down to 20mph (30km/h).

However when I get back on the gas to maintain this speed, the transmission will clunk into 3rd gear from 5th. Sometimes it will do this on the downshift even when I don't give any throttle. This scenario is it the only time it does it (not always but often) but I suspect there's been a few times when it's done it in other low rpm conditions, when low rpm coasting to a stop with no throttle and no brake.

Also, I "hear" this clunk more so than I feel it. It can also be described as a "pop" sound as well.

This is my only gripe with the transmission, otherwise it shifts buttery smooth.

Edit: the truck is a 23 Tremor- 3.5 Ecoboost with 10R80

Could you please send over a message with your VIN and the name/location of the Ford dealer you have been working with? I would like to take a closer look at your clunking concerns on my end.

 

[Kelvin]

I had this exactly same issue before. When slow speed on a very slight uphill road, it went form 3 to 4 first, then after some distance, it gear down from 4 to 3 again, that is big clunk happens. And it almost can reproduce every time.

After lots of researching, there is some theory that make sense to me.
It is because of leaking pressure in valve body channel, and I did tried to fix it myself using after market parts

https://www.f150gen14.com/forum/threads/fixed-my-clunky-down-shifting.26184/

After that fix, this uphill clunk issue never happen, and my transmission almost no more clunk

 

[freewayman]

I had this exactly same issue before. When slow speed on a very slight uphill road, it went form 3 to 4 first, then after some distance, it gear down from 4 to 3 again, that is big clunk happens. And it almost can reproduce every time.

After lots of researching, there is some theory that make sense to me.
It is because of leaking pressure in valve body channel, and I did tried to fix it myself using after market parts

https://www.f150gen14.com/forum/threads/fixed-my-clunky-down-shifting.26184/

After that fix, this uphill clunk issue never happen, and my transmission almost no more clunk

interesting, ill take a look. i suspected it was something to do with the valve body. i wonder if putting the transmission through the same scenario repetitively would help the issue as well by having adaptive adjust for the conditions under this specific engine speed and power demand scenario. only reason i mention this is because I just moved here from a very flat area with no hills, and so it could be plausible the adaptive tables weren't ready for this so to say. I have noticed that it's gotten a bit better over the past couple days, so there's that as well. will monitor and see if it disappears eventually.

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