[pw0n]

Originally Posted by F32Fleet

You don't go through each gear at 2k rpms.

Run though the gears place the transmission in park and then rev to 2k rpm. The gear dance should take all of 3 min

See questions in the FCP DIY on the ZF8HP fluid change.

I can run through the gears, but the guide clearly says to hold each gear at 10s (or 3s, depending on gear). My car immediately reverts to the first gear if I manually shift to any gear above the second. Is there some trick/setting to hold the gear?

I believe andino also faced a similar issue as he pointed out he defaulted to the service function as he wasn't able to shift beyond the second gear.

[pw0n]

Originally Posted by eugene89us

Here is the info directly from ZF:

Let the engine run at idling speed and then select positions R and D one after the other. Afterwards, shift gears according to the table below, depending on the transmission variant (A, B or C).

Transmission variant /Gears to be selected /Hold gear for /Additional operations
A/ 1st to 3rd/ 3 sec./ -
B/ 1st to 4th/ 10 sec./ -
C/ all/ 10 sec./ Keep the engine speed at 2,000 rpm for 30 seconds to fill the torque converter with oil.

Thanks, do you have any more info on which variants fall under A, B, and C?

[F32Fleet]

Originally Posted by pw0n

I can run through the gears, but the guide clearly says to hold each gear at 10s (or 3s, depending on gear). My car immediately reverts to the first gear if I manually shift to any gear above the second. Is there some trick/setting to hold the gear?

I believe andino also faced a similar issue as he pointed out he defaulted to the service function as he wasn't able to shift beyond the second gear.

Try hold the gear with the paddle shifter.

[thejeremyman9]

Originally Posted by pw0n

I can run through the gears, but the guide clearly says to hold each gear at 10s (or 3s, depending on gear). My car immediately reverts to the first gear if I manually shift to any gear above the second. Is there some trick/setting to hold the gear?

I believe andino also faced a similar issue as he pointed out he defaulted to the service function as he wasn't able to shift beyond the second gear.

Are you building wheel speed? I believe there is a minimum wheel speed for each gear. So for example you can't go into 7th gear if your wheel speed is only 5mph.

[pw0n]

Originally Posted by F32Fleet

Try hold the gear with the paddle shifter.

I'll give that a shot - thanks!

[pw0n]

Originally Posted by thejeremyman9

Are you building wheel speed? I believe there is a minimum wheel speed for each gear. So for example you can't go into 7th gear if your wheel speed is only 5mph.

No wheel speed - I had the brakes firmly pressed when I was doing this as my car is on jack stands.

[thejeremyman9]

Originally Posted by pw0n

No wheel speed - I had the brakes firmly pressed when I was doing this as my car is on jack stands.

I honestly don't think you can go above 2nd... maybe 3rd with zero wheel speed. Unless there is a workaround i am not aware of.

[pw0n]

Originally Posted by thejeremyman9

I honestly don't think you can go above 2nd... maybe 3rd with zero wheel speed. Unless there is a workaround i am not aware of.

For sure, I found that bit on FCP's guide a bit strange as well, but could be due to the different variants (A, B, or C) mentioned in an earlier post (FCP might've used a variant that could hold gears above second gear?) or the trick mentioned above - haven't tried it yet but will report back when I get a chance (will be awhile as I had a little incident...)

[pw0n]

Originally Posted by F32Fleet

Try hold the gear with the paddle shifter.

This did the trick - thanks F32Fleet ! Got way more in this time, but unfortunately, car hit 46 C before I could finish, so gonna let it cool before continuing the refill.

[IraHayes]

While somewhat involved, performing the trans service isn't that complicated, and you don't need ISTA, or need to reset trans adaptations. You just need to follow the directions from ZF and have a way to monitor trans fluid temperature. The best way to monitor is with the transmission's own temp sensor IMO. For that you'll need a diagnostic tool such as the Schwaben unit sold by ECS tuning, or bluetooth connector and the Bimmerlink app.

The three critical parts are to make sure the car is level and monitor the trans temperature, because that's what going to dictate the proper amount of fluid to add, and equally if not more important, use the correct fluid. I was a dealer tech many moons ago and saw more than a few transmissions that got ruined because the owner used the wrong fluid, or serviced it somewhere where they used the wrong fluid. I know that ZF lifeguard 8 isn't exactly cheap, but I wouldn't cheap out on the fluid myself. That ZF8HP transmission costs some serious coin.

[pw0n]

Just wanted to report back - changed the transmission fluid (along w/ the transmission fluid pan, both from ZF) and the rear differential fluid (from BMW) @ 64k mi on my 435i, and car definitely feels much smoother.

Both fluids were pretty nasty, and I even saw some sizable black flakes in the diff fluid.

In case anyone needs links to parts,
1) transmission fluid kit: https://www.fcpeuro.com/products/bmw...-24118612901kt
2) rear differential fluid (you'll need ~1L, I used about 750-800mL): https://www.fcpeuro.com/products/bmw...ml-83222295532

[_bdiddyb_]

@pw0n, question for you. If you did this at home garage (which is usually some degrees slope), how do you know your car is "leveled"? Beside filling at the proper temp range, having the car leveled is another critical step. First time around, I "top off" at 42 degrees and call it a day. But then I could hear the transmission "pump noise" at startup. It quickly goes away as soon as car warms up, but i thought it was an indication of low fluid. I had to go thru the whole process again. 2nd time around, i didn't hear pump noise anymore. Just something to look out for. Too much fluid - trans overheat. Too low fluid - gear damage or shifting issues.

[pw0n]

Originally Posted by _bdiddyb_

@pw0n, question for you. If you did this at home garage (which is usually some degrees slope), how do you know your car is "leveled"? Beside filling at the proper temp range, having the car leveled is another critical step. First time around, I "top off" at 42 degrees and call it a day. But then I could hear the transmission "pump noise" at startup. It quickly goes away as soon as car warms up, but i thought it was an indication of low fluid. I had to go thru the whole process again. 2nd time around, i didn't hear pump noise anymore. Just something to look out for. Too much fluid - trans overheat. Too low fluid - gear damage or shifting issues.

My bad for getting back to you so late. That's a good question, but I honestly didn't check/measure how leveled my car was. I probably should've considered it beforehand!

Silly question, but did you only jack up only one side your first fill? I had my car on all four jack stands - doesn't mean the car was perfectly leveled, but wanted to point out the obvious.

It's been over a month since I've done the fluid change, and everything feels fine. That's not to say the refill was perfect - I'm sure I'm over/under a bit, but it's probably still within some tolerable range. Again, all speculation here, so do so at your own risk.

Only thing I'm iffy about is torquing the fill plug. Couldn't torque it to spec so had to hand-tighten, but considering it's just a fill plug, I'm guessing I should be fine. Just thought it was weird that a fill plug had such a high torque spec relative to what I expected.