’66 Volvo – Things that go bump in the night

I noticed the car had a bumping noise going down the road. It sounded like someone was hitting the bottom of the car with a rubber mallet. I placed the rear axle on stands, pulled the choke and let it go in 4th gear. Looking under the car the issue was very apparent, one or both of the drive shafts were bent. It was jumping around like crazy where the two shafts meet in the middle. I am not sure how I did not notice this on the trip back from Seattle. But, you cannot feel the bumping, just hear it. Also, at speed the frequency of the bump almost matched the exhaust note perfectly; so it just sounded like part of the exhaust noise. I pulled both drive shafts, replaced all three u-joints with greasable u-joints. There is a place in North Little Rock that specializes in drive shaft balancing, Dynamic Driveline. The guys said they were both bent, they straightened the shafts perfectly. The car sure drives a LOT better now. Since the drive shafts were already out of the vehicle I replaced the center support bearing and the two bushings that support the center support, and of course did a little painting of the parts.

Products used: