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FIXITMAN
FIXITMAN, Master Technician
Category: Mercedes
Satisfied Customers: 17462
Experience:  ASE MASTER CERTIFIED, AA DEGREE DIESEL/AUTOMOTIVE
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My 2008 C300 when at hihway speeds seems to be, of

Customer Question

My 2008 C300 when at hihway speeds seems to be, for lack of a better description, "notchy". By that I mean I have to constantly correct the steering. When I do it seems to have a slight resistance then the steering wheel moves. We have checked all the ball joints and the rack for the steering but all appear to be good.
Submitted: 2 years ago.
Category: Mercedes
Expert:  FIXITMAN replied 2 years ago.
Hello, my name is Bobby. Thank you for the question. Can you tell me if the car is stock? Does it have the factory wheels and tires on it? Has it been in an accident? Did this start all of a sudden?
Customer: replied 2 years ago.
Yes the car is stock with factory wheels and standard size tires. It has not been in an accident. I have owned this car for 5 years. I believe that it started all of a sudden. I first noticed it when I was on the highway at about 100 km/h. The problem is not as apparent at city speeds but I do find that when I go around a corner I have to steer the car back to straight or else it would just keep going around in a circle.
As an example, at highway speed the car wants to track in a line that takes it first to the left and then when I correct there seems to be a resistance and then the steering wheel moves to the right but then the car tracks to the right so I need to correct the line again by moving the steering wheel to the left. Once again I get resistance and then the steering wheel moves and the car tracks back to the left. I am constantly making small adjustments as I weave my way down the road..
Expert:  FIXITMAN replied 2 years ago.
Thank you for getting back with me. From what you are describing it sounds like this is occurring because of the tires. Due to the way that the tires are wearing or due to the tread design your tires are grabbing just about every imperfection in the road. This tends to happen more on tires with a very open tread pattern. It can also be that the caster on the front end alignment is way out. If it is then this will occur also. If you can tell me the brand and model of the tires I can look them up and let you know if this is the type of tire that I see issues with.
Expert:  FIXITMAN replied 2 years ago.
Please let me know when you can and we can continue if needed.
Customer: replied 2 years ago.
Tires are Michelin MXV4 225/45R17.
Is it possible that I may have accidentally recalibrated the steering angle sensor when backing a trailer into a very tight spot? When doing so there is a lot of turning the wheel lock to lock but not going back to centre.
Expert:  FIXITMAN replied 2 years ago.
That really should not have affected it. If you have a calibration issue then you should have a service light coming on. Are they the Primacy or Energy line?
Customer: replied 2 years ago.
Primacy
Expert:  FIXITMAN replied 2 years ago.
Thanks. Typically those tires are not too bad. I would try either crossing the front tires from one side to the other to see if anything changes or change the psi up 10 psi and then down 10 psi. If it continues to be the same then I would suspect that the caster is too low and it needs to be increased.
Customer: replied 2 years ago.
Sorry about the delay. I tried over and under inflating the tires. It made no difference. The steering feels "heavy" even when moving slowly (almost at a stop) with the same resistance and then movement when turning the steering wheel.
Expert:  FIXITMAN replied 2 years ago.
Does the steering wheel feel better when you rev the engine?
Customer: replied 2 years ago.
I'll try that tomorrow but my initial reaction is "no'.
A couple of other items:
When I go around a corner and let go of the steering wheel the car will continue to go around the corner. That is, the steering is not returning to the center position by itself. (That resistance thing again?)
I sometimes hear a very slight creaking noise when i turn the steering wheel.
Expert:  FIXITMAN replied 2 years ago.
I would get the vehicle on a rack and unhook the outer tie rod ends from the knuckles. I would then move each tire back and forth feeling for binding. It is possible that you have a dry tie rod or ball joint that is binding causing this.
Customer: replied 2 years ago.
Already did that. Everything is smooth and not binding. The rack is new.