Or simply going to this sort of website: Central Valve Bodies - Remanufactured Valve Bodies

Thanks for the info guys! It makes sense that the valve body cleanout would be essential to a proper transmission service, since any debris in those passageways, springs, and check valves would lead to poor shifting and weird behavior.

Has anyone on the board had success with a valve body service? i.e. the trans was operating poorly before the service was done, then operating normally after?

There's many posts related to "Changing the fluid vs. Not changing the fluid". I'm suggesting here that the fluid change PLUS valve body service is the right way to go.

My visit at ZF Dortmund for Gearbox maintenance.(very, very long!) HUGH RESULT!!
I found this on Bimmerboard e38
this man took his 735i to a ZF service centre .
this is how to service a transmission , enjoy .:thumbup:

If you are going that route, then you should start with obtaining as much technical information on the transmission as possible. You can begin buy purchasing the $100 technical CD-ROM from ZF; for example for the 6HP26 the cd is p/n 1068 766 701.

Fantastic link, thanks for sharing. I can't believe how big the ZF transmission's are in real life. Probably all that lifetime fill bratwurst.

I have performed the service under supervision of a specialist and the ATSG repair manual for the 5L40E transmission. This is something the dealer will not perform, only transmission shops. I had a 5th Gear incorrect ratio code and car would go into fail safe mode. After researching and diagnosing the possibilities, I came to the conclusion it was the valve body that was the problem. I'll document more when I get this write up together. I've been thinking about the forum while figuring out the problem, just need to put it all together.

This CAN be a DIY if in the right hands. This is not something you can make a mistake with and expect things to go fine. I really dont suggest this to be the average joe wrenching on the weekends type of job. I would understand what you're getting into before even thinking about dropping the pan to remove the valve body.

Oh, and those with the 5L40E trans and experiencing the "No Reverse" issue....The culprit is right there. The EPC and TCC solenoids get clogged from the sediments that make trans fluid dirty, preventing these parts from switching into reverse. If not this, the check balls aren't allowing fluid to pass through due to them being jammed in place from the dirty fluid passing thorough the valve body. Almost 95% of the time a refurbished or new valve body will fix the issue.

And to refurbish a valve body....leave it to the pros. There are tools that specifically need to be used to properly re-sleeve the valve bores and they are not cheap. Precision is absolutely necessary because these parts cannot be off by any margin if expected to function correctly.

:thumbup: Thanks for contributing to this informative post guys! This should give us all an appreciation for what's going on inside the transmission and how important that valve body is to smooth and precise operation.

here is his other half
the family are all named Hugh , I wondered why until I discovered they use their last name first and first name last .
here are their names
Hugh Jass
Hugh Jaynus
Hugh Jenuts
Hugh Jehans
Hugh Jappetite .

I had a 2000 X5 4.4i that was exhibiting hard downshifts from 2nd to 1st while approaching a stop. My mechanic diagnosed it as a faulty valve body. He replaced it and the problem disappeared. While not an actual service of the VB the VB was the cause of the problem.