[Scott@Radar-Mirror.com]

Hi I'm having a couple of issues with my transmission and looking for some help. Car is a 2016 550i with 57k miles.

When coming to a stop, like 1 mph and last 5-10 feet before full stop I feel 3 or 4 quick pulses or surges, presumably something going on with the transfer from 2nd to 1st gear. The problem is intermittent. It does not occur if I manually shift to 1st when stopping.

Other issue is very harsh shifts from 1st to 2nd under certain conditions. Driving in comfort mode the shifts feel normal in all gears. In Sport mode (The button Sport, not the Sport where you move the shifter to the left) if I pull off from a start without much throttle 1st gear hangs and then very abruptly shifts to 2nd. In manual mode shifting from 1st to 2nd anywhere under 2k rpms seems ok, if I shift above 2500 rpms I get the same violent shift. Shifts from 2-8 feel generally less smooth than normal but 1-2 is killing me.

I don't know if the two issues are symptoms of the same problem. Any input greatly appreciated. Thank you.

[Conserve]

Presumably this ZF 8 speed automatic transmission. Did you just purchased this car or you have had it for some times. What you know or don't know about car's past, etc. First thing comes to mind is sounds like clutch plates are worn or slipping, which is hard to believe if the car has not been abused. Is the trans fluid up to level should be? 57K miles, you are due for trans fluid change or that is already done? Or possibly one or more solenoids are going bad.

[Scott@Radar-Mirror.com]

I bought it 5 years ago with less than 10k miles. It's been driven normally. I have not changed the transmission fluid or checked the level. I was planning to change the fluid soon and wondering if I should just go ahead and replace the seals and solenoids while I'm at it since the mechatronic will already be out. I checked fault codes and there's nothing there related to the transmission unless I'm misreading it.

[Conserve]

I would probably take it to dealer or an indy shop and let them diagnose it first and perhaps pick up some tips/ ideas from them and cost. Upon that information decide if want to do it yourself or not.
BTW, found this link if that helps any. Good Luck!
https://f30.bimmerpost.com/forums/sh....php?t=1663803

and this video starting @ 32:59 showing how to change solenoids, circuit board, etc. on BMW E70 X5. It is not the same but you will get the idea.

[Scott@Radar-Mirror.com]

Thank you! I will check this out.

[Unspec]

Change the fluid, but it's a well known issue in this generation of ZF8HP's that 1-2 and 2-1 is just a herky-jerky shift when it's in sport mode and encountering specific RPM shift zones. I've noticed that shifts are smoother if you're really giving it the beans, which to me suggests that sport mode trans tuning is expecting heavy load, and thus increasing clamping pressure, but when you're not actually giving it the beans it "complains".

But yes, shifts in sport mode are going to be harsher than comfort in general, since it's prioritizing performance (e.g. shifting quickly) over comfort.

[Scott@Radar-Mirror.com]

I found the transmission pan and oil and Sonnax kit. The solenoids and mechatronic seal kit/parts are surprisingly difficult to locate.

[obiltagi3]

Originally Posted by Scott@Radar-Mirror.com

I found the transmission pan and oil and Sonnax kit. The solenoids and mechatronic seal kit/parts are surprisingly difficult to locate.

I was told by a local Indy the typical solenoids/sleeves/seals are unserviceable on the F10 550i transmission mechatronic unit. Instead, the whole mechatronics unit needs to be changed. I have not confirmed this info yet, let us know if you find anything.

[Scott@Radar-Mirror.com]

Originally Posted by obiltagi3

I was told by a local Indy the typical solenoids/sleeves/seals are unserviceable on the F10 550i transmission mechatronic unit. Instead, the whole mechatronics unit needs to be changed. I have not confirmed this info yet, let us know if you find anything.

I was able to find everything I was looking for. I'm getting a new pan/filter, fluid, sealing sleeve kit and solenoids from thectsc.com. I'm also getting a Zip Kit from Sonnax https://www.sonnax.com/parts/4590-zip-kit Hopefully this will solve the problem.

[Scott@Radar-Mirror.com]

Here is a very cool video

[obiltagi3]

Originally Posted by Scott@Radar-Mirror.com

I was able to find everything I was looking for. I'm getting a new pan/filter, fluid, sealing sleeve kit and solenoids from thectsc.com. I'm also getting a Zip Kit from Sonnax https://www.sonnax.com/parts/4590-zip-kit Hopefully this will solve the problem.

Wish I had all those tools in that video! Let us know how your process goes!

[Scott@Radar-Mirror.com]

Originally Posted by obiltagi3

Wish I had all those tools in that video! Let us know how your process goes!

Me too! You have to drop the fluid pan to get the part number off the separator plate (apparently these are unique to the valve body on your car) so I'm going to start with a basic fluid/pan change and see if this makes any difference. If the issue persists I will order the rest of the parts including a new separator plate and cross my fingers.

[Scott@Radar-Mirror.com]

The fluid change did not help but I was able to find the part number for the separator plate. It looks like I will be rebuilding the valve body. For reference if anyone needs instructions for removing the ZF 8HP valve body I found a video with some helpful info. I've seen some variations in the layout for this valve body. Note the cylinder behind the solenoids, this is a hydraulic impulse storage device. This part is missing in most of the other information I have seen. The transmission in the video is a ZF 8HP55 from an Audi and may be slightly different from the BMW 8HP70.

Here I found this on the HIS storage device https://www.greencarcongress.com/200...ng%20operation.

[itsnota2ma]

I was having this issue with my 550, and it was not a transmission issue at all, I had a leak in the seal between the intake and the turbo. Before you go through all of the trouble with the transmission, have this checked. If this is not the issue, then no harm done. I would also check for codes, even though there isn't a CEL, it will still throw a code.

[Scott@Radar-Mirror.com]

I'm going to clear the multitude of codes I have and see what comes back before working on the valve body. I got Bimmerlink to erase the faults and for some reason it will not delete anything. I got Ista yesterday so hopefully I will have better luck.

[Scott@Radar-Mirror.com]

So Ista so far is not playing well. Bimmerlink has a total of 70 faults yet Ista isn't reading ANY faults -0-. I even deleted BL from my phone and reinstalled and it is finding the exact same faults plus a couple more this time. These codes (or some of them) should be found in Ista!? Anyone knows what I need to do let me know.

[ChiltiCoatl89]

Any excessive vibrations or noise in the car? You should check your mounts as well make sure they are not worn and torn. I Definately appreciate and respect someone who is willing to do all types of work (Especially Transmission) also, do not forget what itsnota2ma mentioned as well. He could be well right on the money, check very carefully!

[Scott@Radar-Mirror.com]

I ordered all of the parts and have been up all night working on this. I have very good instructions and overall it's been pretty easy. I'm almost finished just need to reinstall the valve body and I'm pretty much done.

[Surly73]

Very interested in your progress, results, parts sources and tool list

Thanks for keeping the community updated with your progress. My F10 has not been kind to me this fall so I don't feel like working on it "for fun" at all, but I have been contemplating a complete solenoid, valve body etc.. job on my 8HP just to improve manners and fix some potential minor issues that came from the factory.

[Scott@Radar-Mirror.com]

In case anyone is following the thread replacing the solenoids and installing the Sonnax kit does not seem to have changed anything except the pulsing/shudder coming to a stop is now a single clunk. The problem does not occur if I am in manual shift mode. I originally thought this was because I was manually downshifting to 1st before coming to a stop but manual shifts to 1st or just letting the car downshift itself from any gear eliminates the clunk, as long as I am in M shift mode. I will probably get the XHP software to force the car to stop in 2nd gear until I can figure out how to solve this.

[NikMN]

XHP has a black Friday sale.

Check you pcv/intake system like itsnota2ma suggested. Much better 1st to 2nd shift after i replaced both inlets and pcv hose.

[Scott@Radar-Mirror.com]

I have a quick update. With adaptations catching up to the conditions in the valve body and transmission the car is actually shifting really well in normal (comfort) mode. I'd say it's about 90%. Now sport mode (where I prefer driving) the issues persist. I spoke with a rep from ZF and wasn't terribly helpful but pointed to the "mechatronic" as the likely problem and told me to replace the entire assembly - this is the tcu and valve body and about $5000 from BMW. No thanks. The adaptation for clutch C is now beyond the recommended range for fill pressure suggesting the corresponding valve isn't holding pressure. Before I get too far into the weeds I'm ordering a remanufactured valve body tested to operate properly and hoping this is the solution.