OEM-level 8HP swaps in E-series cars

[V8bait]

Doing a swap in a 2008 335xi (6HP21X) using a 8HP45X from a 2015 328xi. The bellhousing had one bolt hole that had to be drilled out and matched up otherwise. Using a N55 torque converter and old N54 flexplate.

Issue I ran into is that the old 6HP21 is around 25 1/4" long, the 8HP45 is 26 1/4" long. Anybody ever see this before? From my research, all of the 8HP45 are 670mm so right around what I'm seeing at just over 26" long, and as far as I can tell the 6HP21 never changed for LCI.

That extra inch makes the mount fail to line up and the driveshafts not fit.

Edit- from measuring multiple transmissions and some help from Josh from Guru Autowerks, it turns out the N55 8HP45X is shorter than the N20 version by almost exactly one inch. Everything else is identical, except for one bellhousing bolt hole that is provisioned but not drilled. Could make it work but not worth it, use a N55 trans. Thanks BMW.

 

[EJLew3221]

Today was first runs with this billet internal 8hp70 turbolamik 2.0 3500 stall converter.

there was few issues on this 6hp to 8hp swap, struggled with them some extra 8-10 hour before solved everything out.
Lamiks complete wiring is awesome, work like charm and it`s very good quality, installation few hour.
Lamiks circuit board to reroutine orginal TCU fits like glow, installation with mechatronic few hour.
turbine mod to get 8hp turbine to n54 few hour.
installing gear display and program switch including diagnostic display prox 1 hour
Lamik adaptor fits well, no wuss on that.

then the struggle started, first i had some small issues to get my laptop connect to Lamik, it was about tunerpro comnnections and took me 2 hour to resolve, just testing untion it connected (dummy me)

paddles started to work without gear selector 1x e84 but when selector was connected, it blocked those flaps too.
double and triple checked everything including Lamik TCU cabling, Lamik pin layout, 6hp to 8hp connector, measured everything many times.. until... spoiler alert...

they did a mistake on Lamik homepage in manual--1X e84 wiring picture, it`s totally wrong pin layout, pins numbered fron wrong end of connectoe and ign feed and ground is crossed..

The right one is to be found on HTG similair picture where cables are right
-pin1 green +12v feed
-pin2 empty
-pin3 yellow canL
-pin4 white canH
-pin5 grey +12v ignition
-pin6 brown ground

that took me 8 hour to find out where the fault was that selector don`t wake up..

i did inform Lamik that they fix that on their homepage

I have a N55 will it still work?

 

[135boost]

Lenght of my 6hp21x was indeed 15mm longer than my 8hp70x and there was that adaptor plate between trans and engine what
equalize that pretty much.

i found a crack on my block so i pick it up for repair, 8hp trans with 3500 stall trans seems to work as charm ...

 

[wheela]

Lenght of my 6hp21x was indeed 15mm longer than my 8hp70x and there was that adaptor plate between trans and engine what
equalize that pretty much.

i found a crack on my block so i pick it up for repair, 8hp trans with 3500 stall trans seems to work as charm ...

You found a crack on your block? That sucks, any details you can share?

 

[135boost]

Crack is horizontal on the left side of the block in level of bottom end of water jacket and leaking water out from block and in to one of oil drain channels. I will recieve a new block in a week or so with fixed that weak spot of block.