[2one3E90]

How reliable is the auto trans zf in the 335i? Anyone with a lci 335i mated to a n54 have issues? Tuned or not tuned? How does it shift and does it shift the same way it was new?

[Cloverdale]

Approaching 130k kilometers with one recent fluid / filter change (Valvoline Max Life) operates flawlessly (500 hp kit from Arm with JB4).

[whyzee125]

Keep your fluid changed and make sure your sleeves etc don't leak and you'll be good!

[BRG_N54]

I have two 335's. I got the second car, an '07, on the cheap about a year ago. I noticed different shifting than the '08. It was slow to shift up, but it was the downshifts with the paddles that were bothersome. It would almost coast for a few seconds after changing gears, really unnerving, the way I drive.

I recently did the whole service; New fluid, pan and shift solenoids. Also replaced all the mechatronic sleeves. Old pan was dated 2006, so had never been changed. I also assume perhaps the fluid was never changed, it was nasty looking and smelling. Cleared adaptations and ran most of the re-learn process.

WOW! Such a huge difference. It drives like new now, shifts are almost seamless in D, and my paddle shifts are crisp and direct. I think it has also improved fuel consumption, not by much, but every little bit helps.

I had purchased two of everything, but the shift solenoids, so I can do the same on the '08. Just got my ZF6 fluid in, so that's next on my to-do list!

[2one3E90]

Originally Posted by BRG_N54

I have two 335's. I got the second car, an '07, on the cheap about a year ago. I noticed different shifting than the '08. It was slow to shift up, but it was the downshifts with the paddles that were bothersome. It would almost coast for a few seconds after changing gears, really unnerving, the way I drive.

I recently did the whole service; New fluid, pan and shift solenoids. Also replaced all the mechatronic sleeves. Old pan was dated 2006, so had never been changed. I also assume perhaps the fluid was never changed, it was nasty looking and smelling. Cleared adaptations and ran most of the re-learn process.

WOW! Such a huge difference. It drives like new now, shifts are almost seamless in D, and my paddle shifts are crisp and direct. I think it has also improved fuel consumption, not by much, but every little bit helps.

I had purchased two of everything, but the shift solenoids, so I can do the same on the '08. Just got my ZF6 fluid in, so that's next on my to-do list!

ahh yes okay. Did u diy with? Im gonna be looking for that kit now. I have a 09 335i wirh zf 6 also.

[BRG_N54]

Originally Posted by 2one3E90

Did u diy with? Im gonna be looking for that kit now.

Yes, I did the work myself. I also got the bits from various places, but FCP sells a kit.

The weirdest part was filling the trans with the car running, never been under a running car before! If you DIY, pay close attention to the trans temp while filling. Plenty of YouTubes out there for guidance.

[Sgop335]

One tip for transmission fluid, if one has Protool is to watch the transmission fluid temperature displayed on screen while car is running and filling fluid...

[2one3E90]

Why do people and even techs say not to change your trans fluid? Will it mess up if it hasnt been changed in 150,000?

[Cloverdale]

Originally Posted by 2one3E90

Why do people and even techs say not to change your trans fluid? Will it mess up if it hasnt been changed in 150,000?

You should research fluid condition advice cause it is the case that in a trans fluid application that possesses significant metal and debris you may well experience slippage and/or increased slippage upon introducing new fluid if trans internals (clutches for example) are worn to the point of having become dependent on the dirty fluid to operate.

[BRG_N54]

These ZF6HP19's are complex beasts. I think it just opens up so many opportunities for poor execution that it's easier to leave it alone than become an expert and service it correctly.

The fluid must be correct, the fill process is very particular. You may need to service/replace the shift solenoids and/or mechatronic seals. Then you really need to clear adaptations and perform the re-learn procedure. If any of those things are missed or don't go correctly, it may not solve anything and could make the transmission worse. Then you have an angry customer or disappointed DIY'er, some might find it easier to just say leave it.

Every fluid in every car will degrade over time. Personally, I would always prefer new, correct fluids to old ones. However, when auto trans fluid is used it will suspend the worn clutch friction material and supplant the materials that are missing from the clutches. This can aid in operation, if the clutches are heavily used. When you put fresh fluid in it does not have this additive and can cause the clutches to work less effectively, and wear even faster. These transmissions electronically lock the torque converter in every gear, which can also add to wear. At this point the transmission should really be overhauled and new friction material put in, but that is expensive and time consuming. Everyone nowadays wants a quick, cheap fix, so this alternative is last resort. Often blame goes to the transmission, rather than driving style or service intervals.

TLDR: Like anything mechanical, the more complex, the more scary it can be.

[lookalikehuuh]

well well well... finally came to the dark side with the 335i eh hahaha!

I have the auto trans in both my cars since SD traffic and I bought these cars back when I used to have to commute 45min to an hour every day in gridlock traffic of course.

I'm tuned on E50 with "Stage 2+" looking at like 127K miles and the transmission is rock solid. I do regular maintenance on the transmission with the seals/sleeves like every 50-70K and it hasn't missed a beat so far. I use the ZF fluid (kit) from FCP Euro which isn't too expensive.

I know others sometimes do the mechatronic solenoids at the same time but I haven't done them yet... maybe this next time I will do the transmission solenoids.

If you haven't tuned your 335i yet, get all the maintenance out of the way and light that baby up, it makes such a HUGE difference in how the car feels.

[Nando_e90]

Originally Posted by BRG_N54

Then you really need to clear adaptations and perform the re-learn procedure.
TLDR: Like anything mechanical, the more complex, the more scary it can be.

Just a question:
Clearing adaptation and re-learn procedure must to be done? or can it not be done without any issues?

I have seen many say NOT to clear adaptations, and many saying the opposite.

I personally did it and performed the relearn procedure when I serviced the transmisión 5 years ago with all seals and solenoids as well, but I'm asking because in the next days I'm changing fluid and seals again since the kick at a stop came back after the XHP Flash install. I was thinking of not clearing adaptations.

[BRG_N54]

Originally Posted by Nando_e90

I'm changing fluid and seals again since the kick at a stop came back after the XHP Flash install. I was thinking of not clearing adaptations.

All of my mileage and experience will be on a 100% stock car. Once you go altering the firmware there are no guarantees anything will act predictably any longer. You altered the code and now you have an issue, I would advise to alter it back.

I think the advice is to clear adaptations and re-learn any time you service the HP19. There is also a fluid quality counter that should be reset. I'm no transmission expert, this is all just IMHO.