Strange feeling from rear of car

[AVIMAX]

I was driving my '86 Carrera this weekend after having a 4 wheel alignment done as well as a new rear wheel hub and bearing. I had this done after I lowered the car. The car has been driving great, smooth and straight on the highway, and city streets. However, last night I decided to go for a drive, and went down the highway and was feeling a strange roughness from the rear end. It was almost like the road surface was rough like a dirt road, but I know the road well and even on a new patch of pavement, the roughness did not go away. It stayed at any speed, and applying the brakes did not make any change either. The steering wheel was rock solid, no vibrations so the front was OK. When I got off the highway, the feeling went away. It has not come back, and driving on the same stretch of road did not reproduce the feeling. I probably put about 60km on the car since the alignment before feeling this, and another 10km of smooth driving after this happened. Any thoughts what it might have been? I am 99% sure it was not the road. Odd things like this make me worry on old cars.

Thanks.

[911st]

Check your lug nuts! This has happened to me.

Also, the rear bolts on the rear spring plate require a lot of torque to hold every thing to together and sometimes they come loose right after an alignment. This happened to me also.

Of course it could be the rear bearings.

Good luck.

[AVIMAX]

Lugs nuts are good. I once made that mistake on my MGB. Did a brake job, and forgot to check the lug nuts. Lost a front wheel while making a turn. Expensive mistake, I had to find a new front fender! Luckily I felt something was wrong and had slowed down to a crawl and was turning onto a side street to check things out when it happened. Won't make that mistake now, however whenever there is a strange feeling, I get worried about the wheels! I will check the rear bolts on the spring plates.

Thanks.