Chassis Auto Parts Minneapolis MN

Any new-car dealership technician will tell you that diagnosing chassis noises can be one of the most frustrating problems a technician can be called upon to deal with. Although modern quality-control measures on the production line have vastly reduced the number of chassis noise complaints, they still exist. In response, many auto manufacturers have devised noise, vibration and harshness (NVH) diagnostic techniques and equipment designed to quickly pinpoint the source of a noise.

Technicians working in aftermarket shops generally don’t have the need for this level of diagnostics, due in part because most new vehicles have already been “de-bugged” under warranty and because the causes of noises change as the vehicle ages. In the ­aftermarket, repair oversights, worn parts and normal wear most often cause noises. See Photo 1 .

GATHERING INFORMATION
Customer interviews are critical to the noise location process. Keep in mind that the grinding noise that you hear might not be the squeaking noise that the customer hears. In most cases, a test drive with the customer might help to identify the noise with which he or she is most concerned.

If the noise is intermittent, use a checklist to help identify the conditions under which the noise occurs. Is it a cold or warm-weather noise? Does it occur when the wheels hit a tar strip or does it occur more frequently on a gravel or washboard surface? Is it a squeaking, chirping, rattling, knocking or clunking sound? Or is it a wheel-speed or an engine-speed noise?

Last, it’s important to consult auto manufacturer TSBs before approaching a difficult noise diagnosis. At times, a noise can be so difficult to locate that the diagnosis has to be done in an engineering laboratory. TSBs are also the culmination of inputs from hundreds of technicians and field engineers working to solve noise problems. 

SHOP PROCEDURES
Successful chassis noise diagnostics require a methodical approach. The best procedure is to perform a bumper-to-bumper undercar inspection and not stopping with the first problem you find.

If it’s an older, high-mileage vehicle, I generally start by lubing the hood, hatch, trunk and door latches and checking for smooth, secure operation afterward. This reduces the possibility of these parts being randomly stuck in a half-latch position. Rubber door seals and plastic parts should be routinely lubricated with an aerosol silicone spray. Windows should also be checked to make sure the channels are secure in the doors and that the window fits the channels.

Underhood checks should include unsecured batteries, hoses or other hard parts that might cause a rattle under some driving conditions. Similarly, the trunk or rear hatch area should be checked for loose spare tires, j...