What’s causing the annoying vibration in my Acura?

My 2007 Acura TSX with 160,000 kilometres on it has an annoying vibration coming from the front end at more than 80 km/h. It’s worse when I step on the gas pedal. I have had the tires balanced and ball joints replaced but my mechanic can’t find the problem. – Bob R.

Front-wheel drive cars use CV axles consisting of an inner CV joint, axle shaft and outer joint to deliver power from the transmission. When the vehicle hits a bump in the road, the suspension moves upwards, forcing the CV shaft to shorten. The inner joint located at the transmission is designed to allow for this length change. It accomplishes this using a tripod with three bearings sliding back and forth within the inner joint housing.