2013 750xi Loud bang then no forward or reverse.

[Korywiesner]

Driving down I-40 today about 80ish I heard a loud pop (Clue #1) and then noticed that the car would no longer accelerate... Just revved up(Clue #2)....
Jumped off onto the upcoming exit and with enough luck managed to get it rolled into a parking spot at a fuel station.

Engine sounds great.... When I rev it up in gear, it makes kind of a whining noise from under about where the drivers butt goes (Clue #3). I put it in park and jumped out to see if anything was leaking and the car started rolling..... Transmission in park but the car still rolls(Clue #4)...

Had it hauled back to our workshop and dropped in the bay. When I got back this evening, I started the car then put it in gear...It didn't take off BUT if you rev it, it will slightly creep as long as it is on level concrete(Clue #5). I had to turn it sideways to get it where I needed and not block the door and was able to creep it until it hit the slight incline.

The transmission switches into P, R, N and D..... So long as you put it in neutral first and then whatever gear or Park, otherwise it complains about needing to wait for the car to not be in motion before shifting into park(Clue #6)......

There were no indications that anything was wrong with the car until the loud pop.....
3 weeks ago I changed out both guibo joints.....

Here is my line of thinking..

Shouldn't be transmission...... Seems to operate properly as far as I can tell.
I am curious if a broken rear driveshaft (or Guibo) would cause this? If so, why doesn't the car move via the front wheels? (Not Likely I think)
Would a rear CV cause this? Again, why wouldn't the other wheels move the car? (Not likely Either I think)

So far what I come up with is transfer case..... Since the car will not stay still when put in park (E-Brake use required and holds car still). I am curious as to why it would still creep?
Could this be something as simple as a flud issue? ( I give it a %15 chance)
My leading theory (I know ZERO about BMW transfer cases but have tons of experience in auto diagnosis and repair) is that the input shaft on the transfer case shapped! Could possibly be the transmission output shaft I suppose.....

Admittedly I haven't investigated anything yet, I got in late and didn't feel like messing with it after a long lousy (Probably expensive) day. I will start diving into it in the next few days after putting front axles in a F-550.

I was hoping that you guys that are in the know may have some clue as to where to start or maybe someone here has maybe had a similar experience.

Thanks for any assistance or suggestions.

P.S. I may also Cross-post this in the f10 forum as well since they use the same(ish) engine-trans-Tcase set-up.

[conroyt]

I would start with the Guibo.

[Korywiesner]

UPDATE:

Jacked the car up and looked around......

Put it in gear and the rear driveshaft and guibo both turn but not the nut on the differential.....

Put car back in park and spin wheels the same direction and the nut at the front of the differential turns but not the driveshaft.........

So is the pinion gear coming directly out of the rear differential or is that an easily replaceable flange that the guibo bolts to from the rear differential?

[Korywiesner]

So ... UPDATE....



What a nightmare...... When I got the differential out... The front 3 hole flange would spin but not the larger 16? sided nut.....



For the life of me.... I could not get the flange out of the end of it.... I turned everything i had the strength to turn..... Managed to get the flange pushed out a few turns of the smaller nut and it was like it started catching splines again.....



My assumption is that the splines inside the flange are toast......



So.... Ordered a nice replacement differential (and urethane bushings) and put it in.... FLANGE WAS DIFFERENT.... 115MM SPACING WITH 19MM RECESSES.... Had a guibo custom machined to work, stretched the 110 to 115 (NIGHTMARE BTW) and viola.....



NOT SO MUCH... CAR FREAKED OUT....



Reset EVERYTHING with ISTA.... Did well for 3 days of moderate driving then drivetrain malfunction... Turns out there is some difference between RWD and X-drive rear-ends....



Pulled it out and sent it back....



Ordered another.... Never showed... Got refund...



Ordered 3rd.... Same year, X-drive 750i (NOT Li) UPS lost it.... Finally showed up tonight.... NO FLANGE.....



I can't find the 105\12 flange with 22mm recesses ANYWHERE....



PLEASE HELP!