ZF 8HP transmission rough downshifts while braking

[vinu_neuro]

My 2013 Q5 3.0T is around 97k miles now. Following the ZF procedure and using ZF Lifeguard 8 fluid/filter, at 85k I drained and refilled the trans twice (few hundred miles between each, with new filter during the first fluid change). The vehicle has mostly seen highway miles and the factory fill was still relatively light/clear. After the first fluid change, shifting was super smooth. After the second change shifting was noticeably rougher, so I reset the adaptions and did the relearn procedure which smoothed shifting completely.

In the last 1k miles I've noticed rougher 3-2 and 2-1 while braking. If I let it coast down it downshifts smoothly. It's intermittent but seems to be becoming more frequent.

Any advice?

 

[The Critic]

Fluid level adjustment?

 

[andyd]

Critic beat me to it Is it old enough to have a dipstick?

 

[BMWTurboDzl]

My 2013 Q5 3.0T is around 97k miles now. Following the ZF procedure and using ZF Lifeguard 8 fluid/filter, at 85k I drained and refilled the trans twice (few hundred miles between each, with new filter during the first fluid change). The vehicle has mostly seen highway miles and the factory fill was still relatively light/clear. After the first fluid change, shifting was super smooth. After the second change shifting was noticeably rougher, so I reset the adaptions and did the relearn procedure which smoothed shifting completely.

In the last 1k miles I've noticed rougher 3-2 and 2-1 while braking. If I let it coast down it downshifts smoothly. It's intermittent but seems to be becoming more frequent.

Any advice?

Double check fluid level. Assuming you're aware that the vehicle must be level and the fluid must be within a specific temperature range.
I'm also assuming that you made sure the o-ring for the snorkel came out of the mechatronics with the old pan.

Worst case: ZIP KIT, but I think I'm getting too far ahead of myself.

Zip Kit® - ZF8-ZIP

Sonnax Zip Kit ZF8-ZIP targets the root cause of multiple complaints by sealing the critical circuit pressure losses in the ZF8HP45/55/70 and Chrysler 8

www.sonnax.com

 

[nicholas]

Lubegard did wonders for our audi trans.

 

[panthermike]

Agreed on all points of checking fluid level and ensuring everything fit together well. I will also second the Lubegard recommendation as it has helped a couple of transmissions I've serviced specifically with that issue

 

[Craig in Canada]

Ordinarily I would add to your list - check for intake leaks. In BMW circles anyways, a pre-turbo intake leak (e..g allowing unmetered air, not a post-turbo boost leak) can contribute to rough downshifts under braking even if they aren't bad enough to set an engine code. Check all of your clamps, seals, and smoke the intake if you have the tools to do so.

It doesn't make a lot of sense (fuel injection should be off while coasting/braking etc..), but it has been reported and discussed enough times that I've seen that it's worth investigating.

Because you had sudden onset of the symptoms after a second fill - I'm with the others on fluid level check. Get up to temperature and check it again, being ready to add more. You may have already seen that adaptations should not be reset unless hard parts (solenoids, seals, clutches) are changed but I'm surprised/glad that it seemed to do good things in your case. That isn't always the case.

However, adaptation resets require re-adapting, and I've seen documentation that this isn't just a matter of getting in and driving. There is a procedure from ZF. I think it includes light throttle from stop until 8th (usually 100kpjh+), then coasting (not braking) all the way to a stop. It would be a challenge for me to find a place to actually accomplish this without being in the way or encountering the need to brake. There are also posts online from people debunking ZF's document as baloney. xHP (HP6 and HP8 software tune vendors) have written articles urging caution against adaptation resets for fluid-only service. YMMV

 

[Vitamin Yoda]

Any advice?

What about when you go up a hill slowly and accelerate, do you get a rough and sudden upshift?

 

[dumkid]

Some zf8s downshift while braking to provide engine braking. Especially in sports mode

 

[Vitamin Yoda]

Some zf8s downshift while braking to provide engine braking. Especially in sports mode

We have a 2016 RAM 1500. It kicks every time you come to a stop and it does a 2-1 shift.

 

[dumkid]

The zf8 in the few tuned BMWs I've ridden in will shift to up the rpms to above 3 grand if you brake hard enough. It's to keep the engine in its power band and to help you slow down. OP's audi might be doing the same thing (or it might be broken)