Ask Pete

[#1]

I recently spoke with a member who complained of a vibration while braking, telling me that the vibration began after having the tires rotated at a local repair shop. While it seemed the connection between the recent service and the current symptom was unlikely, after asking a couple of questions I realized the two were very much related.

The servicing technician used a pneumatic impact gun to remove and install the wheel lug nuts when rotating the tires. While this is a practice that has been going on since impact guns became the tool of choice in many facets of auto repair, using one of these guns to take lug nuts off isn’t as impactful as using one to put them on. I have seen many techs use straight airline pressure at the gun, and if the gun has the capability to deliver 180 foot-pounds (ft-lbs) of torque, 180 ft-lbs of torque is what will get delivered to the lug nuts.

All vehicle wheel lugs have a specific torque specification—most of them around 90 ft-lbs of torque. So if the gun is unregulated and delivering 180 ft-lbs of torque, the lugs are being severely over-tightened. This over-tightening can warp the hub and rotor, which will then cause a vibration while braking—and sometimes just while driving.

The proper way to tighten wheel lugs is with a torque wrench adjusted for the recommended torque of the vehicle being serviced. Some techs use “torque sticks,” which are extensions used on an impact gun. These sticks come in different lengths and thicknesses, the size of the stick dictating the amount of torque the gun delivers. This allows the tech to use the gun without regulating it, as the torque sticks deliver only the amount of torque they are designed for.

Whenever your vehicle is getting wheel service of any type, make sure the tech properly torques the wheels to the manufacturer’s recommended tightness. This will maintain the ride quality and braking efficiency.

[#2]

I have a 1991 Pontiac Sunbird.  After driving continuously for two or three hours, in city or Interstate, I turn the car off and when I get ready to turn the car back on it doesn't start back up.  It's almost like the battery is dead but all the electrical is working.  An hour to hour and a half later, it starts back up like nothing was ever wrong.  Every time I call a AAA tow truck, by the time they get there my car starts on it's own.  This has happened three times now in the past six months and no one can tell me what is causing this to happen.

[#3]

It sounds like you may be having an issue with the starter solonoid once it gets hot. I know it may be tough to coordinate but it's best to have your place of repair replicate the failure to ensure a proper diagnosis.

[#4]

My experience with torque sticks is poor.  I always retorque lug nuts after having new tires installed or old ones rotated and have found large varancies in the torque sticks would insist on torque wrench being used.