I've been experiencing a strange phenomenon on my '09 MCS. The car has a slight pull to the right but only when going less than 18 MPH. Anything above that the car pulls straight ahead and does not drift to the left or right. I can even let go of the wheel and the car will stay straight and true. This is really driving me nuts and I'd like to get some opinions. Here's some other info: -Had alignment 3 months ago and still exhibited the problem even the day after the alignment. No I didn't hit a huge pothole. -Checked for excessive rubbing in the front passenger side wheel well and there are no rub marks on the inside of the tire and wheel. -Car has factory mechanical LSD. -I know the steering angle sensor isn't working. Whenever I start the car the DSC immediately turns off and I get warnings on the dash about it. Whenever using the turn signals, making a 90 degree turn, I have to manually shut off the turn signal instead of it going off automatically. -I have replaced both front wheel speed sensors. -Car exhibited issue BEFORE I reflashed ECU. Not tuners fault! I have a couple of theories. First, I think there is some stupid logic in the ECU that may be applying my front passenger side brakes during this speed range and making the car pull to the right. I can't verify this since there isn't excessive wear on that rotor and also the pull isn't excessive enough to probably cause that wear. The only other thing I can think of is the LSD itself. Could there be something mechanically in the differential that is doing this? This could get expensive! This is kind of an annoyance more than anything. The car drives perfectly on the track and during spirited street driving. It's when I'm in stop and go that it's kind of irritating.
More clues. Just had the car up on jack stands and started engine with car in neutral. Right wheel is spinning almost at an idling pace and the left wheel is stationary. WTF?! Isn't neutral supposed to me literally that... neutral?!
Too late. Car is back down on the ground after I found a new problem to deal with. Leaking brake piston seals. It's scootched over to let the wife park in the garage with me. Gotta love the track day abuse repairs.
Maybe that is the issue that causing the pull at low speed. Due to small leak the piston is not coming back quickly one side? Maybe...possibly...
My highly knowledgeable dad and I were discussing this last night and he knew exactly what the problem was. Not really a problem but something that I never even thought of. I'll admit I only have basic knowledge of transmissions compared to engines... This is not unusual as the the gears are engaged all the time but rotating on their bearings. When in neutral there is enough drag to cause the output shaft to rotate. The differential will then send that to whichever wheel has the less drag; doesn't take much. With that said, I think the issue with the steering is down to the steering angle sensor. The dealer already wanted to charge me $200 to even start looking at the problem so I think i'll wait till i sell the car someday to fix it.
Don't ya just love the stealers...$200.00 to just look at it? Yep very normal to have a little tire rotation on the stands.
The DSC cannot function if either the steering angle sensor or wheel speed sensors are not working. I know the wheel speed sensors are good since ABS is still functioning perfectly. The two sensors talk to eachother and the computer knows how fast each wheel should be turning with respect to what angle the steering wheel is turned at. I'm not concerned at all since I don't drive the car in the winter and at the track that last thing I want is another electronic nanny like DSC.