10spd trans issue or possibly rear diff?

[blankman]

2023 10r80 37k now. Last year I was having an issue with pulling into my driveway. Car is lowered and had 19s at the time. Slowing down to pull into a small transition incline from the roadway to my driveway, it would slam/clunk into gear it seemed. Not sure what gear it was downshifting to and from, but i learned to either give it more gas to pull in or slow to almost a stop so it wasn't as harsh. So that I got used to and could deal with. Talked to the dealership about it and they gave me an estimate of about 4 months till they could look at it. Said screw it I can deal with it, the car would be in the garage for winter by then.

Fast forward to upgrading to 20" wheels, the issue is still there but more manageable. But now that its warmer out, the trans gets to a hotter temperature and im having a new issue at running temp. Whenever I slow down to take a right turn onto my street, if im completely off the gas or slightly on throttle it seems the car will just slam into the lower gear it seems. Ive noticed the same behavior when approaching a roundabout, slowing down to make it than itll either slam into a gear or shift up another gear and chug for a second than slam into a gear.

I did a relearn last year and it was good for a month, but still succumbed to the slamming into a gear pulling into my driveway. So im looking for some suggestions on exactly how to explain this to the dealer, as I've gotta call them for the steering recall.

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[sirben711]

I too had harsh downshifts.

The only thing that fixed it was the FP Tune I got.

Are you tuned in anyway?

 

[blankman]

I too had harsh downshifts.

The only thing that fixed it was the FP Tune I got.

Are you tuned in anyway?

I am not. I havent even gone back into forscan to correct the tire diameter. Im not sure hiw the systems work but I figured even woth a larger diameter set to account for the larger wheels and tires wouldn't do much other than fix my mph. Again I don't know how the systems work , so im not sure if that would affect down or upshifts.

 

[compprep]

Check fluid level in tranny. It's a HUGH PITA. Wear fireproof gloves as it needs to be at operating temp.

 

[sirben711]

I am not. I havent even gone back into forscan to correct the tire diameter. Im not sure hiw the systems work but I figured even woth a larger diameter set to account for the larger wheels and tires wouldn't do much other than fix my mph. Again I don't know how the systems work , so im not sure if that would affect down or upshifts.

I don't know for sure, but I think shifts happen based on many factors such as engine RPM, wheel speed, throttle, etc. Adjusting to the correct tire diameter might help.

When it comes to checking the fluid, its an awful task. I was losing my mind on this transmission so early on I took my car in for bad downshifts (extremely violent downshifts) they checked the fluid, upgraded some parts, cleared KAM, did a full relearn......and nothing got better. I was about ready to get rid of the car. Then I decided to give it one last chance. I bought the FP Tune and suddenly the shifting became pretty good. Not perfect, but finally useable and mostly enjoyable.

I cant tell you what to do. But a tune of some sort that includes a transmission shift strategy might be beneficial for your problems.

 

[diambo4life]

100% trans

 

[Joe Gonsalves]

Get the Ford M-9603-M8B kit. It's the FP tune mentioned already. It fixes the transmission shifts. It's not 100% but it is 98% improvement. Best money I spent on my car, and it shifts soooo much better now.

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