4.8is transmission journey from broke to ballin'

[Junkycosmos]

PropellerHead,
Thank you! I wanted to post a quick note back. Using a bunch of what you posted as motivation and tips my X (2005 x4.8is) is shifting better than I ever knew it could. While I would not have outright said before this that I had a broken transmission but it was clearly not performing as designed and had started to lag more in recent months.

No more kicking when shifting from 1st to 2nd. No more hanging in 2nd and 3rd and overall more consistent shifting overall. As a result my driving has is now more spirited. Not crazy but enough so that I'm also shocked for my mileage to have also increased. Yes, no kidding 5% or so. Clearly it was hanging in the lower gears more than I realized.

I have had good success with recent steps I took of swapping trans fluid and the parts plastic sealing parts between valve body and trans. All of the plastic tubes were shorter from age 1-2mm. The theory here is high pressure fluid leaks between valve body and trans due to these $20 in plastic parts shrinking. No special tools other than to drop trans pan. Valve body unbolts and drops even easier.

My Medtronic seal had a very slight leak too. I also think my overall fluid was low too as it took 7 liters to refill first time and second fluid swap only took 5.5 liters.

Trans oil change 7 liters life guard6 (bav auto)

dropped pan,
new filter (BMW parts counter)
dropped valve body
New metatronic seal (round electrics plug seal)
valve body seal , 4 tubes within trans (BMW)
took 2 liters into pan with engine off,
took 5 more with engine running, gear shift and 42C
Reset trans adaptations
Trans shifting much better now

Drove a 2 thousand miles and then for good measure changed trans filter and pan gasket 2nd time. Added fluid Zf lifeguard 6, took 5.5 liters at temp 40c
Trans resets adaptations again due to new fluid. If I were recommending to someone else I would not recommend 2nd pan drop but I would do 2nd fluid change.

Drives much better now. Shifting smooth and quick like I expect from a 2.5 ton sport truck.


Here are some other research links I complied looking into this.


Zf site directions
http://www.zf.com/na/content/media/u...28_Catalog.pdf

Zf lifeguard 6 fluid per zf site
Amazon $23

Bav auto $23 / liter
Welcome to bavauto.com | ZF Lifeguard 6 fluid - for 6-speed automatic transmissions

More on our trans
Everything about your ZF 6HP26 transmission issues | BMW Logic7 site

6hp26 tear down and history
Post 6 here shows the 5 seals (1 rectangle and 4 round tubes) valve body and trans plates
ZF 6HP26 Teardown

[fmugur]

Great to hear guys. I also have the 1-2 hard shift when cold on the 4.4 and on the 4.8 not too bad but it's there. I will change the gaskets and I hope that fixes it. I added the part numbers. As far as I could find, other than the four tubes all are BMW parts.

new filter BMW part:
24117543550

new oil pan gasket, BMW part:
24117543484

New metatronic seal (round electrics plug seal):
24347588725

valve body seal - BMW part number:
24347588727

4 tubes within trans (BMW) - from the ZF catalog you posted. I believe these cannot be purchased from BMW, only from the ZF transmission parts supplier?
2x BMW 24107519314 ZF 01.050
BMW 24107519315 ZF 01.060,
BMW 24107520715 ZF 01.064

Note: I found and added the BMW part numbers for the ZF SEALING SLEEVE

[PropellerHead]

This is great to hear from the folks that are solving their problems with the experience in this thread!

I can also report that my X5 has been running *great* since this set of repairs. We did the Wild West '15 trip with nary a whisper of troubles. I came home for a week and dropped another 1,200 miles on the next week! Since it's been a few months that I've taken it in, I am ready for what is becoming my Fall checkup. I seem to have been doing them in Spring as well.

Anyway, I like to take it in, tell them to look it over and replace anything that leaks, squeaks, whines or wails. I usually leave the wife at home for fear that they'll try to get me into a younger model.