Clunking noise from the transmission when slowing down!

[thornclaw]

Applying grease to my transmission output shaft splines and the I.D. of the output flange splines resolved my clunking noise. The output flange is connected to the driveshaft. Mine has the stock exhaust. Only takes about 15 minutes to apply the grease if you have a lift. Good Luck

can you detail how the job was done? specifically how did you get the flange off?

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[Xiaoqian]

can you detail how the job was done? specifically how did you get the flange off?

You can take a look at this Ford TSB from 5 years ago. Same issue and same fix. Very detailed.

 

[Cobrakit]

You can take a look at this Ford TSB from 5 years ago. Same issue and same fix. Very detailed.

Do you have a copy of the WSM, Sections 307-01 and 205-01, as called out? The output shaft flange P/N needs to be updated for your vehicle.

 

[Will2]

Do you have a copy of the WSM, Sections 307-01 and 205-01, as called out? The output shaft flange P/N needs to be updated for your vehicle.

Not that poster, but I believe the part is: JL1Z-7089-B

Also curious how to DIY this.

 

[Cobrakit]

but I believe the part is: JL1Z-7089-B

Yes JL1Z-7089-B is current p/n and supersedes older numbers. Concern i have is this is the part that my car came with.

 

[slip10]

I noticed that I do not get a "clunk" when it is in sport mode. Any one else seeing this?

 

[Barstoolman]

I noticed that I do not get a "clunk" when it is in sport mode. Any one else seeing this?

Same here! I have an automatic dark horse with handling package, and for whatever reason no clunk in sport mode

 

[Will2]

If you have continuous gear display enabled, I would monitor the gears to see if it's going 3 --> 2 --> 1 in Sport mode, versus 3 --> 1 in Normal mode. I would get the clunk when it downshifted from 3 --> 1.

 

[Cipis]

Mine GT PP goes 1-3 3-1 even in sport mode

 

[WrekEE]

My DH automatic is in the shop. I gave them the info for the TSB's. They are saying its a bearing issue in the rear differential. and Part is backordered to May 10th. So it sits.... and i wait. And then i will probably have to tell them to do the TSB's if the clunk is there. Sucks... i only have 500 miles and haven't really been able to drive it hard.

 

[D/\rK•650]

My DH automatic is in the shop. I gave them the info for the TSB's. They are saying its a bearing issue in the rear differential. and Part is backordered to May 10th. So it sits.... and i wait. And then i will probably have to tell them to do the TSB's if the clunk is there. Sucks... i only have 500 miles and haven't really been able to drive it hard.

Sorry to hear this. Mine had the clunk and they fixed it so far its ok. They greased the output shaft. I guess your has a different issue though. Goodluck with the fix.

 

[AZ_Ryan]

Mine GT PP goes 1-3 3-1 even in sport mode

The grear selection is throttle dependant. That said mine only skip shifts in normal mode. Also the transmission does take some mileage to learn your driving habits and smooth out. Sport mode in mine was super touchy at first. Now its really nice.

 

[Cipis]

The grear selection is throttle dependant. That said mine only skip shifts in normal mode. Also the transmission does take some mileage to learn your driving habits and smooth out. Sport mode in mine was super touchy at first. Now its really nice.

I believe it is throttle response related. Honestly, I never go hard from stop. That is maybe why my trans. shifts over 2. even in sport.. …

 

[Will2]

When I had this issue on my '25 GT and would listen very carefully, I could also get the noise accelerating slowly from a stop. Whenever I hit 2-3mph either slowing down or speeding up (1-->3 or 3-->1) it would make a clunk and you could feel it in the floorboard. It would even sometimes happen ~17mph from a different gear change, though you'd have to be sensing extremely carefully in a quiet area (and without extreme exhaust mods) to notice.

The Ford Expedition/Navigator TSB 20-2253 posted in this thread fixed it, or at least the sound became quieter and more of a "chuff" sound at the 1/3 or 3/1 shift. Now on my '25 Eco I also hear the "chuff" on 1/3 3/1 so I presume this is a characteristic of the 10R80.

What I call the "5th gear stumble" is another characteristic I've noticed on the 10R80 on multiple Mustangs.

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