[E91Noob]

I'm trying to diagnose the following issue and I've already searched the forums for some sort of plausible answer/direction for mechanic as this issue is over my head.

I installed a front drive shaft(items 1 &2 in diagram) yesterday and now when accelerating I can feel a (violently) slipping. It's almost as if the front wheels are fighting for traction, but I fear it's the gears in the front diff are worn.

When decelerating I can hear a clunk noise around the transfer case once the car is nearly stopped.

The rpms feel like they're stepping rather than gradually climbing. The car will hang at 2.2K rpms for half a second and then jump up to 2.4k. You can feel a distinct lurch inside the cabin when this happens..

I'm unsure if it's coming from the front diff, the transfer case, or if something is wrong with the driveshaft itself.

How can I go about diagnosing the cause of the issue? I have Bimmergeeks standard tools on my laptop and a K+DCAN cable. There are no codes nor warning lights in the dash, but should I be looking for faults in the logs?

I'm going to remove the front driveshaft again, since I don't have any problems driving without it, but wanted the full power available by having it connected. Or should I leave it connected and try to get Xdelete working instead?

Backstory:
I purchased the car a few months ago and the front drive shaft was not connected. I asked the previous owner why it wasn't connected and they "had no idea"(of course not). I'm just trying to get this car back in shape after being neglected for too long and want to do most of the work myself.

[Brian86]

That's kind of a unique problem. My first instinct is to blame it on the transfer case... but the wet clutch mechanism shouldn't cause 'surging' or 'binding' even if it's grabbing somewhat erratically. The computers are usually really good at picking up T-case actuator problems.

To clarify, the car drives perfectly normally with the front driveshaft removed? That would suggest the surging/stepping isn't related to the engine or transmission.

Is there fluid in the transfer case?

How does the front diff feel. You should be able to feel something just operating it by hand if it's that far gone.

Is it possible the rear diff was changed out to one with a different ratio?

I dunno, just kinda throwing out ideas.

[E91Noob]

I should add to my original description of the issue that I don't feel the issue everywhere while accelerating. It's only noticeable only under moderate/heavy throttle in the 2-3.5k rev range. If I'm super smooth (slow af), and hold the revs around 3.5k+, there is no noticeable issue.

To clarify, the car drives perfectly normally with the front driveshaft removed?

I've been driving the car for about three months now without the front driveshaft connected with no issues. As soon as it was installed I can feel the jerky acceleration.

Is there fluid in the transfer case?

I haven't checked if there is or on the quality of the fluid in the t-case. I will make sure to do that early this week.

How does the front diff feel.

Feeling the front... the driver's side is a little 'tight' but feels more like a bearing nearing the end of its life. It still moves easily but doesn't freely spin as long as the passenger-side wheel. I can see the gear turning where it would be connected to the drive shaft when moving the wheels.

Is it possible the rear diff was changed out to one with a different ratio?

I'm unsure, how would I be able to check on that? Out of curiosity: What would influence someone to make the decision to change out a rear diff with a different gear ratio than stock?


The previous owner did replace the oil pan gasket, so I know that the front diff has come out at least once for that job. There shouldn't really be any room for error since it's a sealed component right? If that's the case, I should narrow my investigation to the transfer case for the time being, and order a bunch of aluminum fasteners for the driveshafts.

[E91Noob]

I've pulled Fuse #40 in the glovebox and I am no longer having the issue I was describing. This is good enough to get me around town to run groceries for the time being.

However, traction control is disabled as a result. This has narrowed the issue no further, but I will be taking it to a new shop on Thursday. My normal mechanic said that this job would be over his head and referred me to a shop on the edge of town.

[E91Noob]

Update:

The shop determined that the wheels were outside of the tolerance allowed by x-drive. I thought that I had the same size on fronts and backs but I've been known to be forgetful. I'm going to swap my winters on early this year and change the t-case oil and check that I didn't damage the gears.

If they're damaged, I can't really afford the repair before the winter so I'll be having some fishtailin' fun until the snow melts.

[woodex m.e.]

Crazy question....... But what size tires are you running front and rear? I bought a car with a blown front diff. And all the front end was disconnected so similar story. Once I got it all repaired and back together I found there were issue similar to what you state. It ended up being because the kid had mismatched tire diameters between the front and rear. Likely the cause of the blown diff. Got new tires in the proper size and if solved the problem.

[E91Noob]

Originally Posted by woodex m.e.

Crazy question....... But what size tires are you running front and rear? I bought a car with a blown front diff. And all the front end was disconnected so similar story. Once I got it all repaired and back together I found there were issue similar to what you state. It ended up being because the kid had mismatched tire diameters between the front and rear. Likely the cause of the blown diff. Got new tires in the proper size and if solved the problem.

Funny enough, I'm running 225/45R17 on 8" wide rims. I took it to a shop and they slapped on a known good set of wheels from another 328xi they had on the lot and claimed the issue went away. I have no idea why this is the case, but my all seasons are due for a changing anyways so I'm going to shop around this winter for some aftermarket wheels and tires.


I'm waiting two weeks to put my winters on, but I'm currently driving with the fuses for the Transfer case and traction control pulled.

[CheesecakeInjection]

Originally Posted by E91Noob

Funny enough, I'm running 225/45R17 on 8" wide rims. I took it to a shop and they slapped on a known good set of wheels from another 328xi they had on the lot and claimed the issue went away. I have no idea why this is the case, but my all seasons are due for a changing anyways so I'm going to shop around this winter for some aftermarket wheels and tires.


I'm waiting two weeks to put my winters on, but I'm currently driving with the fuses for the Transfer case and traction control pulled.

Did you get it solved? I have this exact issue. Thinking its diff tcase or an axel maybe?

[E91Noob]

Originally Posted by CheesecakeInjection

Did you get it solved? I have this exact issue. Thinking its diff tcase or an axel maybe?

I had to get 4 new tires. The two in the back were worn down much more than the fronts which was throwing off the system.

You have three options at the moment, two are temporary fixes.

1. Pull the fuse for your transfer case, there should be two listed in the fuse diagram for your MY.

2. Pull your front half/drive shaft out.

3. Get properly sized tires.

[E91Noob]

Originally Posted by woodex m.e.

Crazy question....... But what size tires are you running front and rear? I bought a car with a blown front diff. And all the front end was disconnected so similar story. Once I got it all repaired and back together I found there were issue similar to what you state. It ended up being because the kid had mismatched tire diameters between the front and rear. Likely the cause of the blown diff. Got new tires in the proper size and if solved the problem.

What was the cost to have the front diff repaired? I have properly sized tires on now and I'm not having any issues with awd so maybe I caught it before doing any major damage.

I'm going to have a shop do a fluid change on the front diff and transfer case to make sure that nothing was chewed up.

[DoJu3]

Originally Posted by E91Noob

What was the cost to have the front diff repaired? I have properly sized tires on now and I'm not having any issues with awd so maybe I caught it before doing any major damage.

I'm going to have a shop do a fluid change on the front diff and transfer case to make sure that nothing was chewed up.

Let me know how that goes, I had a double whammy of front driveshaft flange failure and transfer cause actuator like 2 weeks apart, I pulled the front driveshaft and while waiting for the weather to get better and waiting for the part the actuator went, now I'm waiting for the actuator to arrive so I can do both at once and I hope I didn't damage anything driving with no front driveshaft.

[CheesecakeInjection]

Originally Posted by E91Noob

I had to get 4 new tires. The two in the back were worn down much more than the fronts which was throwing off the system.

You have three options at the moment, two are temporary fixes.

1. Pull the fuse for your transfer case, there should be two listed in the fuse diagram for your MY.

2. Pull your front half/drive shaft out.

3. Get properly sized tires.

Mine happens with regular tires too.

Local bmw specialist mechanic thinks its just wheel hop from a bad strut. I asked a buddy to watch as i drove by him and he said it spins and hops for like 1 second. (After one second of flooring through it, on the gas it goes away) the mechanic says the front end is too bouncy when he pushes on it.

So I'm pretty sure he's correct, it's only as the car jerks forward and weight is transferred to the back, the front end lifts a little, and hops until it falls back a second later.

I bought adjustable coil overs, and will update if it solves the issue. With winter coming soon it may be hard to find enough grip to re-create it. (Live in canada)

[E91Noob]

Originally Posted by DoJu3

Let me know how that goes, I had a double whammy of front driveshaft flange failure and transfer cause actuator like 2 weeks apart, I pulled the front driveshaft and while waiting for the weather to get better and waiting for the part the actuator went, now I'm waiting for the actuator to arrive so I can do both at once and I hope I didn't damage anything driving with no front driveshaft.

How did the actuator service go?

Unrelated, now my dash is lit up now with ABS, Traction Control, Brake (CC-ID 369), and TPMS(CC-ID 50). I'm hoping the t case actuator didn't die on me and it's just a case of being cold out. I'm going to get the laptop out in the morning and see if I can get any more information out of the car's computer.

[E91Noob]

Originally Posted by E91Noob

I'm going to have a shop do a fluid change on the front diff and transfer case to make sure that nothing was chewed up.

I really need to stop procrastinating on this one. I think I'm just scared to know.

[E91Noob]

Following up on this, 2 years later.
I did chew up the internals on the Tcase and it imploded, leaving me without any drive.
Had to get a junkyard one for $500 because anything new or rebuilt was incredibly expensive.

I did do the Tcase oil chance in Feb 2022 but the damage was done and it died May 2023. The car has now found a new owner.

/THREAD