shifting is rouge from 3rd to 4th in my 35D

[X5-User]

Looking for some feedback from owner with 35D or 35i with 6 speed automatic transmission with high mileage.

My car has roughly 94k miles and I getting rough shifting from 3rd to 4th gear when engine/transmission is "relatively" cold (i.e after starting car and driving it for 5 to 10 minutes). Once engine and transmission is hot, I don't get the rough shift.

Is this normal behavior or abnormal? and why only from 3rd to 4th gears.

[smass]

Check fluid level first but you may have a bad solenoid. Each gear shift is controlled by a different solenoid on the valve body. A complete set is $350 and can be changed by dropping the pan and valve body.

There are a bunch of youtube videos on this job. Search ZF-6HP solenoids. You have a ZF6HP28x which is similar to the 19, 21, 26 and so on.

[MDeeJs]

Originally Posted by X5-User

Looking for some feedback from owner with 35D or 35i with 6 speed automatic transmission with high mileage.

My car has roughly 94k miles and I getting rough shifting from 3rd to 4th gear when engine/transmission is "relatively" cold (i.e after starting car and driving it for 5 to 10 minutes). Once engine and transmission is hot, I don't get the rough shift.

Is this normal behavior or abnormal? and why only from 3rd to 4th gears.

Do mechatronic sleeves so they can hold the pressure when they are still "cold"

[9vapors]

Originally Posted by MDeeJs

Do mechatronic sleeves so they can hold the pressure when they are still "cold"

I think this is your problem as well. If it hasn't been done, do the tranny service. Drop the mechatronics, do all of the sleeves and gaskets and should be back to normal.

[X5-User]

Originally Posted by MDeeJs

Do mechatronic sleeves so they can hold the pressure when they are still "cold"

Originally Posted by 9vapors

I think this is your problem as well. If it hasn't been done, do the tranny service. Drop the mechatronics, do all of the sleeves and gaskets and should be back to normal.

Do you guys have picture of what you are referring to for mechatronics sleeves?

Also I am experiencing this jerkiness at all lower gears when I put gear selector to Sport mode. Is that expected?

[9vapors]

Originally Posted by X5-User

Do you guys have picture of what you are referring to for mechatronics sleeves?

Also I am experiencing this jerkiness at all lower gears when I put gear selector to Sport mode. Is that expected?

This video has a nice lit view of them about halfway through. Basically over time the gaskets on the sleeve, and the grommets shrink from use and act up when cold as they don't seal as well until they heat up and expand. This is why you're feeling it so strange things while cold and then it's fine when warmed up. That's a common symptom for these parts starting to go bad. I have to do mine too. Look on this forum for Jandref123's how to. He has a parts list for everything you need if you want to DIY.

Linked it below:
https://www.xbimmers.com/forums/show....php?t=1502982

[9vapors]

Here's a good explanation on it and also gives some diagnosis based on different symptoms.

[smass]

For clarification, when I fixed mine, everyone said to do the sleeves/filter/fluid which I did. That did not fix the issue so I had to go back in for the solenoids. Not a big deal but I wish I had just done it all the first time.

[X5-User]

Originally Posted by smassey321

For clarification, when I fixed mine, everyone said to do the sleeves/filter/fluid which I did. That did not fix the issue so I had to go back in for the solenoids. Not a big deal but I wish I had just done it all the first time.

Can you describe the symptoms you had to see if it is similar to mine?

From my research, if problem was consistent and rough shift happens every time regardless of temperature then it could be the solenoid but If it is only when it is cold then solenoid would be fine. I am not sure yet how to pinpoint the problem.
I have even read one thread that it is a software problem and it just needs a software update

[smass]

Originally Posted by X5-User

Can you describe the symptoms you had to see if it is similar to mine?

From my research, if problem was consistent and rough shift happens every time regardless of temperature then it could be the solenoid but If it is only when it is cold then solenoid would be fine. I am not sure yet how to pinpoint the problem.
I have even read one thread that it is a software problem and it just needs a software update

Software would be a good place to start as it is an easy quick flash. You should always make sure you are on the latest software before troubleshooting a modern BMW. Since you have a diesel, you got new software with the EGR recall so you probably are on new enough software.

I have changed solenoids on 3 of our 6 speed ZF now. One had a big bump going from 2-1 when hot. Another would sometimes refuse to downshift to 2nd and go from 3rd to 1st which was abrupt. Also when hot. And the 3rd would sometimes bang into 1st if you accelerated without coming to a complete stop.

All of my issues were worse when the transmission was hot. Your issue is cold related which can sometimes be as simple as fluid level which goes up when hot. The seals between the valve body could also leak more when cold.

When servicing these transmissions the cost of fluid and pan is not cheap. It is my opinion that when dropping the pan you may as well also drop the valve body and change the seals/sleeves and solenoids. It is 8 extra bolts to get a valve body out. As this is an expensive electronic part this is not without risk so ideally you only do it once. So if you are doing selves/seals you may as well do solenoids.

There are lots of you tube videos on the 6 speed ZF rebuilds. Many of the techs sent out the solenoids for testing and most of time, one or many failed the testing.

[X5-User]

Originally Posted by smassey321

Software would be a good place to start as it is an easy quick flash. You should always make sure you are on the latest software before troubleshooting a modern BMW. Since you have a diesel, you got new software with the EGR recall so you probably are on new enough software.

I have changed solenoids on 3 of our 6 speed ZF now. One had a big bump going from 2-1 when hot. Another would sometimes refuse to downshift to 2nd and go from 3rd to 1st which was abrupt. Also when hot. And the 3rd would sometimes bang into 1st if you accelerated without coming to a complete stop.

All of my issues were worse when the transmission was hot. Your issue is cold related which can sometimes be as simple as fluid level which goes up when hot. The seals between the valve body could also leak more when cold.

When servicing these transmissions the cost of fluid and pan is not cheap. It is my opinion that when dropping the pan you may as well also drop the valve body and change the seals/sleeves and solenoids. It is 8 extra bolts to get a valve body out. As this is an expensive electronic part this is not without risk so ideally you only do it once. So if you are doing selves/seals you may as well do solenoids.

There are lots of you tube videos on the 6 speed ZF rebuilds. Many of the techs sent out the solenoids for testing and most of time, one or many failed the testing.

I do understand the concept that if I am there might as well do solenoids but I believe in the theory if it is not broken, don't fix it.

I will perform transmission service (oil & filter change) and then give it a try before doing anything extra. I also just confirmed that I am on the newest software as you mentioned. I am also consider tuning the transmission as I have heard, transmission tune will fix all of these issues.