Clunk sound when shifting to D or R and car jerk when shifting to 5th gear

[Gaz142]

Update: Car taken to dealership and all issues were caused by a weak battery, dealership changed the battery and everything run fine now. No clunks, no jumps, no jerks, no rpm issues and everything run smooth.


Greetings,

Model: Mustang GT - 2018

I'm feeling so demotivated. I don't know if the problem is within the transmission or not but I have the following issues:
- Clunk sound and car jump when shifting from [N to D] - [ N to R] and sometimes when shifting back to [ P ].
- Car jerk when gear shift into 5th gear.
- Car hard-shift from 3rd to 1st gear.

They seem to happen randomly but 90% of the time. Sometimes its so smooth that even the car jumps feel light and nice.

I took it to mechanic and he did the following.
- Changed rear left AXLs
- Greased rear right AXLs
- Cleaned throttle body [car used to have unstable RPM when idle, its fixed]
- Changed the spark plug [car used to have unstable RPM when idle, its fixed]

The mechanic said it will take time for the car to relearn how to shift better since the changes. So I did a KAM reset and still nothing changed. The only noticeable improvement is the RPM is so stable on idle. So he told me to keep driving the car until Saturday and if the problems still persist, he will check them over again. I'm seriously worried that this is a transmission fault. Any thoughts what might culprit be ?

Videos:

- Gear shift clunk:

- Gear shift into 5th:


Thanks, Gaz.

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[NGOT8R]

Could it be that the transmission needs to be recalibrated electronically?

 

[Cobra Jet]

Sounds like valve body is the issue. Did you review the very large 10R80 thread here:
https://www.mustang6g.com/forums/th...tions-to-harsh-or-no-shift-conditions.135463/

Check level of trans fluid (how to in above thread). Many early S550 10R80 owners found that the trans fluid was low.

Valve body failure was most common in some early (2018) 10R80's.

You can ask the Service Center to do a 10R80 software reflash, but if the issue persists after that (or comes back), it's not a software issue, it's a hardware issue.... Usually a "relearn" is smoothed out within 500-1k miles as the trans adapts to your driving style as well as averaging of speed/RPMs. The relearn procedure is also outlined in the above thread.

Take it to Ford and demo the issue to a Tech, Shop Foreman or Service Writer by taking them out for a lengthy drive and replicate the issue. Then let them drive it back so they can experience it for themselves.

 

[Gaz142]

Sounds like valve body is the issue. Did you review the very large 10R80 thread here:
https://www.mustang6g.com/forums/th...tions-to-harsh-or-no-shift-conditions.135463/

Check level of trans fluid (how to in above thread). Many early S550 10R80 owners found that the trans fluid was low.

Valve body failure was most common in some early (2018) 10R80's.

You can ask the Service Center to do a 10R80 software reflash, but if the issue persists after that (or comes back), it's not a software issue, it's a hardware issue.... Usually a "relearn" is smoothed out within 500-1k miles as the trans adapts to your driving style as well as averaging of speed/RPMs. The relearn procedure is also outlined in the above thread.

Take it to Ford and demo the issue to a Tech, Shop Foreman or Service Writer by taking them out for a lengthy drive and replicate the issue. Then let them drive it back so they can experience it for themselves.

Thanks a lot !! I will take a look on it

 

[Gaz142]

Update: Car taken to dealership and all issues were caused by a weak battery, dealership changed the battery and everything run fine now. No clunks, no jumps, no jerks, no rpm issues and everything run smooth.

 

[AkiKoulouris11]

Update: Car taken to dealership and all issues were caused by a weak battery, dealership changed the battery and everything run fine now. No clunks, no jumps, no jerks, no rpm issues and everything run smooth.

Hello, I just picked up my 2018 Gt premium and I’ve noticed the same problem. My car at low speed in normal mode when it shifts from 4th to 5th you can hear the clunk, but on high rpm and sport mode you feel a jerk. I was really worried that it is transmission. The car only has 21k miles and it was serviced yearly. Wondering if this is an issue I should be worried about.

 

[Gaz142]

Hello, I just picked up my 2018 Gt premium and I’ve noticed the same problem. My car at low speed in normal mode when it shifts from 4th to 5th you can hear the clunk, but on high rpm and sport mode you feel a jerk. I was really worried that it is transmission. The car only has 21k miles and it was serviced yearly. Wondering if this is an issue I should be worried about.

I sold the car to be honest with you.. It was just a source of stress of constant issues. Good luck with yours man and hopefully its nothing serious

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