[Mike02z]

Originally Posted by Dawgz

Yea I get that, However I never had that situation on my X3M. The driveline is similar if not exactly the same.

I had a ‘22 X3MC and I noticed it. SA said totally normal.

Put it in 2WD mode and see if it happens.

[RichardGM4]

My G82 x-drive does it but pretty much only when it's cold weather and/or I'm turning slowly at near / full lock on uneven ground, like a ramp into a driveway and/or wet leaves, etc

It's been like it since I've had it - I spoke to a friend of mine who's had a number of AWD Porsche 911s and he said his cars used to do it too, so I'm not worried that it's a fault or issue with my car

[Needsdecaf]

Originally Posted by Dawgz

Yea I get that, However I never had that situation on my X3M. The driveline is similar if not exactly the same.

That's because it's not the driveline that causes it, it's the suspension geometry.

It is possible to get this effect on a pure 2wd car with aggressive geometry / alignment like a Corvette or a Porsche. Your X3 likely had a less aggressive alignment, perhaps softer or narrower tires.

Berzerker is correct, it's likely just the Ackermann effect.

Originally Posted by RichardGM4

My G82 x-drive does it but pretty much only when it's cold weather and/or I'm turning slowly at near / full lock on uneven ground, like a ramp into a driveway and/or wet leaves, etc

It's been like it since I've had it - I spoke to a friend of mine who's had a number of AWD Porsche 911s and he said his cars used to do it too, so I'm not worried that it's a fault or issue with my car

Bingo Bango. My RWD 911 did it as well.

[PVC]

I've had the same issue, and I suppose it's not really an issue. When you turn the wheel all the way to the left or right, it feels like something needs to snap into gear for the car to move. This happen in AWD mode or RWD mode.

[g80z]

I have this problem too, and I feel it most when the car is cold, it’s violent sometimes, makes me cringe at how aggressively it skips sometimes

[turbojg]

I think there are two different (but similar) situations happening here witn RWD vehicles and AWD vehicles.

I have been investigating this myself as I experience the same thing with my X-Drive as others and in fact created a thread about it a couple weeks ago. I did get a very useful response regarding the Ackerman effect with a video explaining it.

Let me start with RWD cars. A differential is needed in the rear so that power can be applied to both wheels but will allow the wheels to spin at different rates when making a turn (as both wheels travel through arcs of different Radii). That fixes one problem but creates another in that if one wheel looses traction all the power goes to that wheel. Therefore a clutch (mechanically or electronically actuated) is added to lock the two wheels together when the car is going in a straight line under power. However, If you try to make a turn under power the wheels will be locked together. So one of two things needs to happen. A tire will need to slip or the clutches need to slip. Sometimes the clutches slip smoothly but depending on the power that is applied sometimes the clutches will release and grab with a jarring effect.

With AWD (if the rear axle is a clutch type) the same thing will happen in the rear as with the RWD car. However with AWD there is now driven front wheels to deal with. When making a turn the front wheels (because they travel through arcs of different radii than the rear wheels - Ackerman effect) there needs to be something to allow for that difference in speed between the front and rear axle. The BMW is rear wheel biased so that means that under low power situations the front and rear axles are not connected (so no problem when making a turn). But the minute you start to apply power to where the rear tires might slip the clutches in the transfer case (between the front and rear axles) start to lock up. If making a turn at the same time the same thing happens between the front and rear xles as happens between the 2 rear wheels (with a clutch setup).

A Chevy pickup truck with full time 4WD truck that I owned actually (instead of a clutch) had a differential (like in the rear axle) to account for any difference in speed between front and rear axles. It also had a way to lock out the transfer case differential when in low traction conditions so power wouldn't be lost to the axle with the least traction. The idea was that since the conditions were low traction that the tires could slip a little to release the binding in the driveline from the front/rear speed differences while making turns.

I know it can get confusing but I hope that helps explain why all this happens.

[Dawgz]

Originally Posted by turbojg

I think there are two different (but similar) situations happening here witn RWD vehicles and AWD vehicles.

I have been investigating this myself as I experience the same thing with my X-Drive as others and in fact created a thread about it a couple weeks ago. I did get a very useful response regarding the Ackerman effect with a video explaining it.

Let me start with RWD cars. A differential is needed in the rear so that power can be applied to both wheels but will allow the wheels to spin at different rates when making a turn (as both wheels travel through arcs of different Radii). That fixes one problem but creates another in that if one wheel looses traction all the power goes to that wheel. Therefore a clutch (mechanically or electronically actuated) is added to lock the two wheels together when the car is going in a straight line under power. However, If you try to make a turn under power the wheels will be locked together. So one of two things needs to happen. A tire will need to slip or the clutches need to slip. Sometimes the clutches slip smoothly but depending on the power that is applied sometimes the clutches will release and grab with a jarring effect.

With AWD (if the rear axle is a clutch type) the same thing will happen in the rear as with the RWD car. However with AWD there is now driven front wheels to deal with. When making a turn the front wheels (because they travel through arcs of different radii than the rear wheels - Ackerman effect) there needs to be something to allow for that difference in speed between the front and rear axle. The BMW is rear wheel biased so that means that under low power situations the front and rear axles are not connected (so no problem when making a turn). But the minute you start to apply power to where the rear tires might slip the clutches in the transfer case (between the front and rear axles) start to lock up. If making a turn at the same time the same thing happens between the front and rear xles as happens between the 2 rear wheels (with a clutch setup).

A Chevy pickup truck with full time 4WD truck that I owned actually (instead of a clutch) had a differential (like in the rear axle) to account for any difference in speed between front and rear axles. It also had a way to lock out the transfer case differential when in low traction conditions so power wouldn't be lost to the axle with the least traction. The idea was that since the conditions were low traction that the tires could slip a little to release the binding in the driveline from the front/rear speed differences while making turns.

I know it can get confusing but I hope that helps explain why all this happens.

This was helpful, thank you.

[MJBO]

Notice it reversing out of my car space at my office, hard lock crawling in reverse. Never felt it was an issue, and that’s the only time it’s felt.

[turbojg]

Originally Posted by MJBO

Notice it reversing out of my car space at my office, hard lock crawling in reverse. Never felt it was an issue, and that’s the only time it’s felt.

I did not want to over complicate my previous explanation of forces created in RWD and AWD drive systems during turns but there are other driveline and forces generated by the wide tires that build up while making tight radius turns that build to a point and need to release. The build up and release of all these forces during tight radius turns can be more noticeable during cold weather as the tires are more likely to skip (slip) and suddenly release built up forces.

As I mentioned this subject is very complicated and I am still learning myself. The diagram below with give you an idea. Car designers are well aware of all this but due to the handling requirements of high performance cars choose to not design these effects out. You can learn more by doing a search on "Ackerman Steering".

[Dawgz]

I also have a Transfer Case code CF5573 so thats also why im wondering if thats related to what im feeling. For those who have felt this, can you scan your car and see if there is a T-Case code? It would show under LMV-G70.

CF5573: Signal (Target distribution of longitudinal torque, 97.1.2) invalid, transmitter VIP

[turbojg]

Originally Posted by Dawgz

I also have a Transfer Case code CF5573 so thats also why im wondering if thats related to what im feeling. For those who have felt this, can you scan your car and see if there is a T-Case code? It would show under LMV-G70.

CF5573: Signal (Target distribution of longitudinal torque, 97.1.2) invalid, transmitter VIP

Where would I find the transfer case code?

From what I am seeing this characteristic isn't seen with just one particular model year 'M' or for that matter just to BMW.

[Dawgz]

Originally Posted by turbojg

Where would I find the transfer case code?

From what I am seeing this characteristic isn't seen with just one particular model year 'M' or for that matter just to BMW.

I did a full scan via Protool on my car and that code came up under the LMV-G70 module which is for the Tcase.

[turbojg]

Originally Posted by Dawgz

I did a full scan via Protool on my car and that code came up under the LMV-G70 module which is for the Tcase.

I have BuimmerCode, BimmerLink and BimmerUtility but didn't get the Protools because when I emailed them to check compatibility with the 2024 models and they replied that there was limited functionality because of BME going to online coding (or something like that).

[Dawgz]

Originally Posted by turbojg

I have BuimmerCode, BimmerLink and BimmerUtility but didn't get the Protools because when I emailed them to check compatibility with the 2024 models and they replied that there was limited functionality because of BME going to online coding (or something like that).

Any one of those should be able to pull a code if there is any. just make sure its not reading just the DME and reading all modules. This TCASE code is not stored in the DME.

I have an appointment for the dealer next week, will follow up with what's found.

[turbojg]

Originally Posted by Dawgz

Any one of those should be able to pull a code if there is any. just make sure its not reading just the DME and reading all modules. This TCASE code is not stored in the DME.

I have an appointment for the dealer next week, will follow up with what's found.

Thanks. Learning to use those apps is next on my list of things to do.

Please keep us updated regarding the outcome of your dealer visit.

If it is normal I wonder if there is a way to minimize the effects. It does take away some of the enjoyment of driving the car as the temperatures get colder.

[ChrisM4]

I haven’t experienced the symptoms above (yet) but I did have a street legal F-body race car with a full spool in it and that was hilarious parking with drag radials 😄

[Dawgz]

So SA got me an update.

1) the CF5573 code/fault is for communication. They are updating the software for it which should resolve it.

2) the binding effect, the SA said that X5 and some other models have a service bulletin that requests to use a different type of Tcase fluid. Although that SB doesnt call out the M3 or M4..... they have done this fix on other M3/M4 and it has fixed the issue. SA told me to drive it for 300 miles or so, if it still happens then they will contact BMW NA to look at it further. He said several cars have come in for this and they have only had to replace ONE Tcase; Others have had resolution with the SB fix.

SIB 20 02 20 Calls out several cars, including the M5 which uses the same Tcase so makes sense.

https://static.nhtsa.gov/odi/tsbs/20...76367-9999.pdf


SITUATION
There is a jerking or shuddering during either or both of the following:
Cornering or accelerating from low speeds
Driving with low to medium loads
There are no warning lights or Check Control messages.

CAUSE
Unevenly worn or incorrect fitment tires are installed on the vehicle, or the factory-filled transfer case oil
does not meet BMW specifications.

[Dawgz]

Picked up the car from the dealership yesterday, drove it for 150 miles so far and have had tried to replicate the issue again and I cannot. Even on when the car is cold.

Hopefully this is also the fix for everyone else!