E39 2.8 ZF Trans Issue

[39KiwiTouring 2]

Hi guys. Any help appreciated here, Here are symptons of my trans potential issue.

1. Is very tall in first when cold changes to 2nd at 3500rpm and when i'm at 40k.

2. I have had to use the tiptronic or manual part to change into 5th when doing 100k as it seem to be sitting at 2500rpm so dropped to 1700 odd once in 5th, had to do that a dozen times not all the time.

3. Has started not dropping back in to 1st when stopped at lights done this a few times probably half a dozen times then takes off slowly pinking abit because it's in 2nd or even third, then realises and kicks down and gives the diff a whack while it's at it.

181k kiwi new so I might explore BMW service records if they have changed the trans fluid but it looks like the lifetime seal sticker is still in tact.

Suggestions please.

[Allanw 1071]

Have you checked tyre pressures, diameters and wear? They can upset the trans.

[39KiwiTouring 2]

It has 55 on front and 50's on the rear, as in 225x55x16

[Allanw 1071]

Hmmm... that could be it. They don't much like different rolling diameters.

[39KiwiTouring 2]

Yes sounds like it is engine and trans have always run superb FSH etc. Just noticed the tyre size difference since this thread.

[39KiwiTouring 2]

And I only put those tyres on a few months ago

[FuManChu 2]

I'd check if the trans has had a service too. I did mine at 160km nz new and the oil was black! Yeah on the tyre thing too. My trans guy said he come across a worn spare tyre on the rear throwing the trans out of sync.