As it decides whether to open an investigation into complaints about Volvo front axles, the National Highway Traffic Safety Administration is upgrading its investigation of a separate problem with Volvo VNs.

NHTSA has upgraded its Preliminary Evaluation to a Engineering Analysis of 1996 to 2000 Volvo VN trucks, investigating suspected U-bolt failures on drive axle assemblies.
According to NHTSA documents, drive-axle (rear suspension) U-bolts have allegedly cracked and in some cases totally failed. The preliminary evaluation was opened based on two reports of U-bolt failures. During the Preliminary Evaluation, NHTSA learned of 530 additional reports of such failures from fleet contacts. Volvo also has reported 453 warranty claims pertaining to the U-bolts failing.
NHTSA notes that "maintenance may be an issue in this investigation, as Volvo requires periodic re-torque of the U-bolt nuts. However, [NHTSA's] discussions with fleet managers indicate that maintenance requirements were being met."
This investigation is unrelated to a petition filed by the Owner-Operator Independent Drivers Assn. in March, asking the agency to look into a number of problems related to the front end of Volvo trucks, including excessive vibration, premature tire wear and premature parts failure. In response, Volvo Trucks North America asked the agency to expedite its decision on whether to open a Preliminary Evaluation, the first stage of any NHTSA investigation. NHTSA officials told Truckinginfo.com they plan to determine whether to proceed with that request for an investigation "soon."
The agency also recently opened a Preliminary Evaluation into problems with doors on some Peterbilt trucks. Some owners of Peterbilt Model 379s, model years 2000 and 2001, are allegedly having problems with the driver's cab doors opening unexpectedly when the truck is under way or sticking shut and being hard to open. NHTSA documents say the problems are reportedly caused by incorrect clearance between the driver's cab and the sleeping compartment. Peterbilt is aware of the problem and has recently released a repair kit to address it, according to the agency.
To report truck safety problems to NHTSA, call 1-888-327-4236. Or you can file your vehicle complaint online at www.nhtsa.dot.gov/hotline.