A few questions :
- Are you sure tires a identical in size, wear and inflation?
- Are your ABS sensors working?
- Are your front lower arms in good shape?

If the arms (silent blocs) are worn, it can cause this. It did on mine sometimes.

As for the tires and sensors, I'm guessing the xDrive uses the sensors to determine in a wheel is slipping so if they're worn, it'll engage and hence dribble at low speed while turning enough to make a difference in actual speed.

I don't own an xDrive but a 2002 but if its even partly mechanical, it probably uses a viscous coupling (as do Range Rovers since the 1990's) and those can go bad either from oil contamination or excessive use on road (driving with runflats is a known problem if not taken care of quickly).

You've got some checking to do and it can't hurt to change the fluids in the diffs and transfer box, they're no more lifetime than the gearbox.

So then XDrive fluid should be looked at as well then? Is this also known as the Transfer box?

Yes, both directions, every time. And I feel it in my seat, not the steering wheel or shifter, which makes me believe it is something in the rear...

Tires are brand new 255/55/18 all around, ABS sensors are working as far as I know... I heard and felt them working the other day coming to a stop, so I would assume the ABS is functional.

As for the front lower arms, they do not have any play in them. Had my mechanic check the entire suspension setup when I did the Hardrace Camber & Toe arms in the rear.

So just to recap, I should be doing a flush and fill in both front and rear diffs and the transfer box? (XDrive fluid?)

Any other suggestions while I'm getting all of that done?

I'm not convinced changing fluids is the solution. Not saying it isn't but I would continue to troubleshoot. It won't hurt to change fluids.

Can you feel the shudder turning the steering wheel back and forth sitting still?

Does the shudder get worse the faster the turn?

Does it make any noise?

Speed while shudder is key. Slow not likely control arms fast quite likely


Sent from my iPhone using Tapatalk Pro

That's the reason for asking if speed makes a difference- is a part of what I consider necessary troubleshooting before drawing a conclusion. Even if it gets worse the faster the turn I wouldn't conclude the problem is control arm(s). I wouldn't be spending a dime at this stage of diagnosis. Note that this shudder has gone on for "years". I would think it would be much worse by now if it is a control arm problem.

No shudder while turning the steering wheel while sitting still.

Shudder goes away as the speed goes up and I straighten out. Like I said, it only happens turning left or right, from a complete stop. No noise either, just feel the shudder in the seat of my pants.


Yeah don't think it can be the control arms based on the above ^^


Well my X is new to me as of August 2017, and I felt this shudder when I first got it and ever since, but I had just shrugged it off as the XDrive just doing it's thing....

I'm not spending a dime until we figure it out :thumbup:

Also another point to note, when I press the DSC button to turn traction control ON or OFF, I do not get any response from the dash, no little yellow triangle light at all, even if I press and hold it for a while. DSC is definitely working, as it has stepped in and caught itself while I was trying to do donuts in the snow... :rofl:

A little bit of shudder when turning
 

When DSC kicks in the light on the dash lights. When abs kicks in, no light.

The DSC button on dash will disable DSC and illuminate the triangle. Verify your DSC triangle lights when you start the car.
Are you on a low friction surface when you experience this?

A couple of diagnostic concepts:

1) pull the fuse that disables the front drive. You can confirm if the problem is from the front wheels.

2) disable DSC: if you are correct and it's working but the light isn't, you can determine if some part of the system is working or not

3) as mentioned earlier, in pretty sure it's some form of the differential trying to turn the inside wheel faster than the left; drive in a circle on low friction surface: sand on assphalt is perfect: properly operating did will allow the inside wheel to lay down a clean tire track, if the dif is putting too much torque to the inside wheel the track will not be clean.

If there is just a tiny bit of over rotation on very tight turns, as long as your tires aren't wearing it could be ok. My Camaro spun the inside wheel (with shudder) any time the surface wasn't perfect since the dif was set up to give equal power to both drive wheels.

When I lost the shudder it was time to have the dif serviced because one wheel would spin and the other would get no power. Possibly you could have less than optimal grip tires? The tires that came on wife's car I wouldn't put on an old vw bug.

So when I try to kick it out and slide, I have yet to see the DSC yellow triangle light up. When I start up the car, it definitely lights up and goes away. When I press the DSC button, I get nothing on the dash...

I have felt this in complete dry conditions in the summer, and I feel this in low friction surfaces such as snow and ice that we are dealing with now. No difference, same shudder.

Will have to try some of the diagnostic options you mentioned. Where is this fuse that disables the front drive? So it would be a complete RWD system then? Any adverse effects of driving it like this?

How to disable DSC, if I am not able to get it to light up. I know you can hold the button down for 10-15 seconds and turn it off completely, but if it doesn't light up, what else can I do?

Will try the driving around in tight circles later on today and see what kind of tracks it is laying down.

Tire grip should not be an issue, because I just installed brand new Bridgestone Blizzaks!

Thanks!

A little bit of shudder when turning
 

I've only recently heard about the front drive disable. My understanding is it won't cause harm but you lose ABS and DSC so it's only meant for testing. I don't know the fuse but it's well established on the forum

If you aren't getting the light it sounds like a wiring or switch problem. I would test the switch and wiring.

I will do a couple. Tight turns and drifting on some snow wirh and without the DSC to compare and see if you can use as reference


Sent from my iPhone using Tapatalk Pro