Why is my Subaru acting funny (moving, car, mechanic)

[Metlakatla]

There seem to be a few posters here who know something about cars. My Subaru starts knocking a little somewhere toward the back end when I go over 35 or so. Going to take it to one of the local quacks, but I'd like to have some idea of what might be wrong so I won't get fleeced too bad.

[stiffnecked]

Could be a loose bracket on the muffler or one of the rear cv joints. Kinda hard to diagnose without seeing or hearing it.

[RayinAK]

That will be difficult to tell unless you can figure if the knocks are inside, or outside the car. Things that make knocking sounds inside the car (back and front) are the seatbelt buckles hitting something when the car is moving. For the time being, buckle all the seat belts in the back and see what happens. Also look inside the back door pockets (if your car has any of those), and make sure all are empty. The mechanic will have to take care of knocking sounds if these are outside the cab. Sometimes the CV joints make knocking sounds, specially when making turns, and get better in straightaways.

[riceme]

Another thing to secure for troubleshooting purposes is the jack and tire iron... usually in a little compartment in the back of a car like that, and make sure the spare is properly secured as well. Those things can make quite a racket if they come loose.

...but I kind of doubt it's a loose something or other in the cab.

[Metlakatla]

I haven't driven it for over a month; I suppose I should start it up or something. It has very few miles, so it probably isn't anything serious. Thanks for the help. I know it can't be diagnosed on a forum, but I just want to sound at least somewhat informed when I talk to a mechanic because I was just burned by one about my truck.

[riceme]

Other things that come to mind are struts and the differential (if there is anyone you pray to, you should begin praying that this is not the problem. Maybe follow it up with sacrificing a chicken or a goat, just to cover your bases), and like Ray said, the cv joints. But these things would have a tendency to make noise when you execute a turn, not necessarily going straight at a certain speed, which I'm sure is why Ray suggested securing things first... and I am a big fan of Keep It Simple Stupid.

[Metlakatla]

It just seems to happen after I hit 35 or so on the road into town (which is paved and fairly straight). It doesn't seem to affect the actual driving at all; it just makes this odd noise.

[riceme]

Does the car shake or vibrate after you hit 35 or so?? Or is it just a knocking sound?

[riceme]

"just," ha.

[Metlakatla]

Just kind of a dumbass knocking sound that seems to be coming from the rear. It seems to happen after it shifts into 3rd.