Low speed gear change issue

[Jpdv]

I'd be grateful for any observations:

2015 D4, TDV6 with 8 speed box. Well maintained, FSH. Now at 198000k. Transmission oil changed at 128k (Sep2019).

I'm a 'gentle' driver, not hammering the vehicle. When I slow down, I've noticed that as I coast/brake to a halt, the final gear change is a little harsher than any other (which is basically not noticeable unless looking at the rev counter). But this one is like a cross between a surge and 'soft jolt', if that makes sense. It's not engine surge - no rev flicker - but a sort of feeling that the car doesn't want to stop quite as quickly as it should, and a gentle push. I'm not clear if it's just me being very gentle on the brakes, so the gear change becomes more noticeable at very low speed, or an indication of something wrong...

Planning a partial flush within the month - any other things to look at?

Thanks...

[scarry]

I would do a full flush and see how it goes.

[Geedublya]

I'd be grateful for any observations:

2015 D4, TDV6 with 8 speed box. Well maintained, FSH. Now at 198000k. Transmission oil changed at 128k (Sep2019).

I'm a 'gentle' driver, not hammering the vehicle. When I slow down, I've noticed that as I coast/brake to a halt, the final gear change is a little harsher than any other (which is basically not noticeable unless looking at the rev counter). But this one is like a cross between a surge and 'soft jolt', if that makes sense. It's not engine surge - no rev flicker - but a sort of feeling that the car doesn't want to stop quite as quickly as it should, and a gentle push. I'm not clear if it's just me being very gentle on the brakes, so the gear change becomes more noticeable at very low speed, or an indication of something wrong...

Planning a partial flush within the month - any other things to look at?

Thanks...

I had a transmission service when I bought my RRS at 89K and intended to go for 40K between services. The pandemic and workload meant that it didn't happen until 50K later. Shifts (up and down) were becoming harsh and it would hang onto gears longer than before.
After the service everything is nice again, much much smoother shifts doesn't and hang on to gears. The service used 8l of fluid.
I think your problems will be resolved with a service.

[PerthDisco]

The 1-2 or 2-1 clunk is evident on the 6 speed also. First step if not already done at next oil change is change also the seals between the mechatronics plate and gearbox. They are rubber bridges that transfer oil and become hardened and leak pressure. At 200k this is very normal they are ready to change and do this before considering any rebuild kit for the mechatronics. Very cheap these parts like $40 but a messy job and also change the seal for the harness plug into gearbox at same time. Helped me and assume same applies on 8 speed.

ZF 6HP 6 Speed Auto Transmission Troubleshooting! Common problems - YouTube (https://youtu.be/aX0bhui8UXA)

[DiscoJeffster]

Even just a reset of the gearbox adaptation can help. I’ve done this before when it’s been a bit harsh on gear changes and it relearned and was improved. You do this with a tool like the GAP IID TOOL.
I did a mechatronic rebuild to try and improve it as well but that really didn’t make any difference. Admittedly I didn’t vac test all the ports and simply replaced the seals with a kit so I may have missed some issues.

As others have said, give it a fluid change and reset the adaptations and you’ll probably find it improved.

[Jpdv]

Thanks to all; I'm leaning to a seals and fluid change, will see how that goes...