[bman5150]

I've noticed for the past 6 months that when I'm pulling into my side load garage, or into a parking spot, the car will surge forward. It's almost like the AWD system is binding and the car is lurching forward when I'm barely on the throttle and making a sharp but super slow turn. Lately, it's getting a little more violent if that makes any sense. Almost a bit dangerous as it lurches hard in a tight spot. I don't hear any abnormal noises and have no malfunction indicator lights illuminated. Thoughts? Could it be that little worm gear in the transfer case going bad? My car has 64k miles on it.

[niquehawk5]

A good place to start is the transfer case motor. Try pulling the fuses (20 + 26 I think, it's listed a bunch of places on here) and see if it goes away

[wdeerfield]

Have you thought to change the fluids?

[matteblue3er]

Check CV joints

[hassmaschine]

I have the same thing, posted a thread and found another thread on it.

I believe the suggestion to change the fluid makes sense. CV joints tend to get noisy but I've never felt one bind like this feels - it feels more like a 4wd truck with the hubs locked. I've got the fluid coming, should have it done this weekend.

My theory is the friction modifier that is in the transfercase fluid is worn out, which doesn't allow the clutches to slip when they are supposed to. just like an LSD, it will bind if you put gear oil with no friction modifiers.

Possibly one way to fix it would be to simply add friction modifiers for an LSD to the transfercase fluid, but it's easy enough to just change it out.

[niquehawk5]

Originally Posted by hassmaschine

My theory is the friction modifier that is in the transfercase fluid is worn out, which doesn't allow the clutches to slip when they are supposed to. just like an LSD, it will bind if you put gear oil with no friction modifiers.

Possibly one way to fix it would be to simply add friction modifiers for an LSD to the transfercase fluid, but it's easy enough to just change it out.

interesting theory......it makes a ton of sense.

[bman5150]

Originally Posted by hassmaschine

I believe the suggestion to change the fluid makes sense. CV joints tend to get noisy but I've never felt one bind like this feels - it feels more like a 4wd truck with the hubs locked. I've got the fluid coming, should have it done this weekend.

How'd it go? Does it drive better now?

[hassmaschine]

I have the fluid kit but haven't changed it yet - was busy all weekend. should get to it this coming Saturday.

[Supermoon]

Don't forget to reset the adaptation of your TC after changing fluid.
I got it done at a dealership for 20 minutes of labor charge.

[GTA_G20]

my car is doing this I noticed

[hassmaschine]

Finished it up today. fairly straight forward, but BMW definitely couldn't have made it more of a pain in the ass if they'd tried.

Naturally, since all cars come with a "lifetime" fill these days, you're not really meant to get at the fill plug (drain plug is accessible just by removing some of the undertray/covers).

The fill plug is buried deep up above the transmission brace - rather than fighting it, I just removed it. Well of course, they put a bolt in there so that you couldn't really get it out with the exhaust in the way. But rather than pull the exhaust too, I removed the support from the trans and let it sag a bit - this gave me just enough room to fight the bolt out so I could get the brace out of my way.

Other than that, it wasn't too bad. Well, I hate gear oil - it always ends up getting everywhere and the smell is awful.

When I put it back together, I installed the troublesome bolt from the other side (in case I ever want to do this again), and reset the adaptations once I was done (for free, 20 minutes of labor is like $50?). I've only driven it a short bit but it did seem like the problem is gone.

as far as the gear oil, I'm pretty sure it's really nothing special, but I didn't really pay that much for it anyway so whatever. the real shame is you only need about 2/3 of the bottle - which is OK because after I had pumped it inside the transfercase, I tripped over the open container and spilled the other 1/3 on my garage floor. (fuck!)

[bman5150]

Thx for the update.

[hassmaschine]

drove it about 200 miles yesterday. The binding issue is definitely gone.

[GTA_G20]

So you drained and refilled the transfer case fluid which is gear oil, Correct?

[hassmaschine]

yeah. I used the specific BMW fluid, which is SAE 75w GL4 with some friction modifiers added in. The trick is we don't really know how much friction modifier to add for the clutches to work properly, but basically it's just limited slip diff oil.

[bekanvarov04]

A bit late but when when I first start the car and drive out of my drive way the car is perfectly fine. Once I drive for a mile or two and I take a u turn where I have to turn the wheel all the way the front wheels seem like they drag against the road and once I straighten my wheel the car drives normal again. What could this be?! I replaced the transfer case motor. Could a aftermarket motor cause this? Also when I pull into a parking spot and the wheel drags I put it into park it makes a loud BANG sound from the back causing the car to move a little forward while I feel a drone underneath the car.

[hassmaschine]

Did you even read the thread?

[Corsica1984]

Originally Posted by bekanvarov04

A bit late but when when I first start the car and drive out of my drive way the car is perfectly fine. Once I drive for a mile or two and I take a u turn where I have to turn the wheel all the way the front wheels seem like they drag against the road and once I straighten my wheel the car drives normal again. What could this be?! I replaced the transfer case motor. Could a aftermarket motor cause this? Also when I pull into a parking spot and the wheel drags I put it into park it makes a loud BANG sound from the back causing the car to move a little forward while I feel a drone underneath the car.

Did you find the issue ? I have the same. I changed a cv axle, changed trans fluid. I don’t know how to diagnose it..

[wuoltk]

Check your center carrier bearing. I had almost the similar vibrations before I swapped mine.

[BIMRBOYE90]

Originally Posted by bekanvarov04

A bit late but when when I first start the car and drive out of my drive way the car is perfectly fine. Once I drive for a mile or two and I take a u turn where I have to turn the wheel all the way the front wheels seem like they drag against the road and once I straighten my wheel the car drives normal again. What could this be?! I replaced the transfer case motor. Could a aftermarket motor cause this? Also when I pull into a parking spot and the wheel drags I put it into park it makes a loud BANG sound from the back causing the car to move a little forward while I feel a drone underneath the car.

Where you ever able to diagnose this issue? I took it to the dealership and was told it could be my axle assembly. Had another buddy look at it and he couldn’t figure it out exactly but said my axles seem fine. Been dealing with this issue for some time now. Normally starts acting up after driving 30mins or so. If I continue to drive it without letting that “BANG” happen I get 4x4, ABS, and Brake lights on.