A customer visited the 4 wheel alignment geometry bay at the garage this week complaining that his Mercedes Benz ‘C’ class was pulling to the left hand side of the road and the steering wheel alignment was incorrect (not straight). The customer had been experience problems with the steering wheel alignment since he purchased the car two years ago and had taken the vehicle to numerous garages within the Manchester and Bolton area to have the tracking and four wheel alignment assessed with no success. Here at Drury Lane Services (The Garage), our expert vehicle technicians began with an initial assessment of the condition of the tyres and set the tyre pressures to the Mercedes manufacturers settings. In addition, we undertook full suspension and steering checks in order to identify any abnormal wear. The suspension and vehicle checks revealed nothing unusual but the technicians did notice that the near-side-front (front left-hand side) brake was binding on (sticking). The technician recognised this as a common cause of steering wheel pulling.
Following this initial investigation into the cause of the poor steering wheel alignment and pulling to the left, one of our experienced technicians conducted a 4 wheel alignment and geometry check on the vehicle using our Hunter DSP600 imaging system. The Hunter DSP600 imaging system is used to check a range of geometry and alignment angles including front and rear toes, front and rear cambers, caster angles, thrust angle and king pin inclination. The DSP600 readings did not reveal any significant faults in the alignment but the technician proceeded with the adjustments.
To restore the four wheel alignment on the Mercedes Benz to the manufacturer’s settings, the technician freed off the near-side-front (front left-hand side) brake caliper and conducted a road test. During the road test, the technician noticed an improvement but reported that although the alignment of the steering wheel was now correct, the Mercedes Benz was still pulling to the left hand side of the road.
With a great deal of experience in 4 wheel alignment and geometry testing, the technician was able to identify that the rectification of the steering wheel alignment but not the near side pulling was due to the correction of the rear geometry and the thrust angle.
So far, thanks to the accuracy of the Hunter DSP600, we had eliminated the braking system and the 4 wheel alignment and geometry. The investigation continued. ..
We proceeded with a more in depth investigation of the suspension and steering checking the front and rear antiroll bars for pre-load and also ensuring that the condition of the shock absorbers and springs were within the manufacturers tolerances. With all the suspension points freed, we then swapped the wheels and tyres around on the vehicle resulting in better handling of the vehicle but the problem was still not resolved 100%.
Coincidently there was a similar Mercedes Benz in the garage undergoing repair which drove without steering pulling and whose steering wheel was straight. The alternative Mercedes Benz also had 100% accurate four wheel alignment and geometry. With the customers permission we swapped the wheels of the two vehicles and took the car for a test drive. During the test, the Mercedes Benz ‘C’ Class drove perfectly without and pulling to the left hand side and with a perfectly straight steering wheel.
Not all vehicles we have in Drury Lane Services (The Garage) for a four wheel alignment are this difficult to solve, but by going through a logical process and having the correct equipment and expertise, we normally get to the root of the problem – and solve it of course!
If we hadn’t checked and verified the 4 wheel alignment using out Hunter DSP600 imaging system in the first place we could have been going around in circles.