[Chief_Bimmer_Fan]

I'm up for a trans flush on my F34 which has the ZF 8HP45 transmission. This is different then most F3x models that have the 6HP variant.

Basics:
2015 F34 N26 xDrive @ 78k miles.

I want to change the valve sleeve and rings on the valve body. BMW only sells this as a kit also available from ECS Tuning.

https://www.ecstuning.com/b-genuine-...d/24508612902/

I can only find two sellers with the right set of rubber seals and sleeves for the 8HP. I don't get it, this transmission is used by many othe manufacturers?!?

I stupidly got the filter only thinking there was a separate valve body rebuild kit, so I'm already out the cost of that unless I don't do the valve body rubber. >

Why am I going that deep and not just doing a fluid flush? Well when I come to a stop, sometimes the car has a jerk between first and park. Maybe 2 to 1. Its just having occasional hard shift. I have reset the driving habits memory. Either case I am sure it due to worn fluid for sure, but is the wear on the valve body sleeve and rings necessary? I mean rubber does harden and crack.

This kit, as named, comes with the shift rod unlike any other I've seen.
I'm nervous about changing it without any reference on how to do it but it obviously must wear, otherwise why would it be a kit.

So am I over thinking this and should just do the fluid flush?
Has anyone got behind the valve body on a 8 speed? or know about the wear on parts?

Any actual experience would be sage.

Thanks!

[mbanck]

I think all F3x have a ZF 8HP?

I've only ever heard of people exchanging the fluid as a matter of defensive maintenance, but also haven't seen people do it themselves, but bring in the car to a ZF shop (not sure whether those exist in the US).

[Vortex8]

Hello, I did the fluid change myself. It\s not that hard if you have the proper tools. Note that you need to monitor Oil temperature for correct level adjustment. I followed the Service procedure in ISTA, which has it written pretty okay and basically tells you what to do and won't let you (unless you force it) go to next step until oil temp is reached etc.

After that I cleared the adaptations, and the difference is significant. Especially at colder temperatures. There is still slight jerk at certain very low speeds, but I guess you can not eliminate that 100%.

[Chief_Bimmer_Fan]

Originally Posted by Vortex8

Hello, I did the fluid change myself. It\s not that hard if you have the proper tools. Note that you need to monitor Oil temperature for correct level adjustment. I followed the Service procedure in ISTA, which has it written pretty okay and basically tells you what to do and won't let you (unless you force it) go to next step until oil temp is reached etc.

After that I cleared the adaptations, and the difference is significant. Especially at colder temperatures. There is still slight jerk at certain very low speeds, but I guess you can not eliminate that 100%.

How many mile were you at?? I can see the change after a flush and drive style reset gets smoother shifting. I am apprehensive about not doing the valve seals though.

My brothers 335 did get the infamous "can't shift out of park" scenario that happens because he waited on changing the valve body seals.

Aside the COVID situation, I put alot of miles on my car, so skipping that could yield a nasty event, but it doesn't cause permanent damage and wouldn't happen for a long time from now.

So I guess I'll just do the fluid change and drive style reset.

Thanks

[Chief_Bimmer_Fan]

Originally Posted by mbanck

I think all F3x have a ZF 8HP?

I've only ever heard of people exchanging the fluid as a matter of defensive maintenance, but also haven't seen people do it themselves, but bring in the car to a ZF shop (not sure whether those exist in the US).

I very well could be wrong on that. I just made the presumption due to the abundance of 6HP info & videos and seemingly no 8HP info.

No ZF shops here in US that I know of. Closest to me is Montreal Canada; long trip from Boston.

[Vortex8]

I've had around 80k km so you can say something about 50k miles. I am planning to keep this interval.

Here is a cut out from their official service information:

ZF automatic transmissions are filled with specially developed semi-synthetic oils. At very high operating temperatures, the oil ages faster than under nomal conditions. Example: Many trips at high speeds, Many trips while towing a trailer, Sporty driving. Depending on the driving style, ZF recommends a transmission oil change every 80,000 to 120,000 km or after eight years at the latest.