Triumph Repair: triumph spitfire 1972 vibration, shaft vibration, axle bearings

Question
Hi Howard, My 1972 triumph spitfire develops a vibration and noise when traveling on the highway. It only occurs when I let  the car coast without giving it any gas (i.e. going down a hill and letting off on the gas pedal.)I had a mechanic check all U-joints and they seem ok. It seems to be comming from the rear-end. All fluid levels are OK. Any suggestions,   Wayne.....

Answer
Hi Wayne,

That does sound like a "U" joint on an axle. However, You need to carefully check the stub axle bearings in the side of the differential. Also take a large pry bar and start checking for free play in the outer hub area. The outer axle bearings are noted for going bad but that is usually noted by a lot of bearing noise when driving with or without throttle.

Any vibration in a axle and/or wheel will be a "Wheel Speed" vibration and noise. But a drive shaft vibration due to a drive-shaft "U" joint will be a finer vibration then wheel speed. Check for any up/down play in the differential pinion bearing too.

Howard