Anyone who can help? Please, I need it!!!

I own a 2002 wrx. It is making some horrific vibrations coming from the rear end of the car. The Subaru techs couldn't find anything?? Let me explain... put yourself in my car...I've got a light load (no passengers, low fuel tank). I'm sitting a stop. I rev up and get on it, but not too much. I get no vibrations and the car drives as it should. Now say I've got a heavier load (passengers, a full tank). Same scenario, but this time when i get on it I get this loud, heavy vibration like the whole rear end of my car is gonna rip off! It likes to occur while turning and accelerating at the same time and also sometimes when I'm creeping up an incline, but mostly when the car is heavy. It only happens when accelerating from a slow speed. Never at 3rd gear or higher. What is it? Bad rear diff? Bad CV joint? Bad drive shaft? Tranx mounts good. Engine mounts good. CV boots good. Fluids constantly checked. Before I start throwing down some cash I'd like to pinpoint the problem. Thanks for reading. Input desperately needed.

This may seem like a stupid question, but did you check to make sure your lugs are tight? How rapid is the vibration? Does it matter if you are turning left or right?

Thanks for the reply. Yeah the lugs are nice and snug. Direction doesn't matter. The vibration fells like I'm hitting thousands of potholes on a dirt road doin 50mph and sounds like someones hitting the back of my car with a couple 3 or four hammers. I'm getting so frustrated. I've done so much research and still no answers from anything or anyone. Surely someone has had this problem. I even drained the rear diff and put a magnet in for shavings and found none. The right rear axle does have a lot of play in every direction. I know it can have very slight in and out. I hope it is the axle and not some differential problem. Subaru quoted me $370 for one axle! If you have anymore thoughts I'd love to hear em. Good reply though. I know I look over the easy stuff when I get frustrated. Thanks. I've got thousands in my car and I can't even drive it like I want to. Did somebody say trade it in and buy a 2008?????haha

Have you replaced anything in the rear part of the transmission recently?

Hit something that may have bent a side shaft? Damaged the main drive shaft?

If it's only above certain speeds it suggests it's harmonic and related to rotating components.

I have done no parts replacement on transx or diffs. As far as I can tell I have no damage to main drive line or side shafts. It has got to be affiliated with rotating parts somewhere on the car. Another scenario: I can be at a stop in front of my driveway which has about a 30% up grade. As I move forward and up my driveway which is as slow as I can without stalling I will start to hear and feel deep pops as if something is slipping. These pops happen about 2 times per wheel rotation. Maybe my main drive line is slipping in the rear diff?? This is when I'm heavy remember. Those pops will turn into a violent shudder if for example I punch it around a tight corner. It's almost like one of my wheels is hopping. I've babied this car since I've owned it at 15,000 miles due to this problem that I can't seem to figure out. I'm so used to it now I know how far I can push it before the ungodly vibration begins. Wish I knew how the first owner did to this thing. I appreciate your interest in my problem. More replies are more than welcome. Thanks

I'd start with the relatively cheap: check your wheel balances and maybe get an alignment.

I have done no parts replacement on transx or diffs. As far as I can tell I have no damage to main drive line or side shafts. It has got to be affiliated with rotating parts somewhere on the car. Another scenario: I can be at a stop in front of my driveway which has about a 30% up grade. As I move forward and up my driveway which is as slow as I can without stalling I will start to hear and feel deep pops as if something is slipping. These pops happen about 2 times per wheel rotation. Maybe my main drive line is slipping in the rear diff?? This is when I'm heavy remember. Those pops will turn into a violent shudder if for example I punch it around a tight corner. It's almost like one of my wheels is hopping. I've babied this car since I've owned it at 15,000 miles due to this problem that I can't seem to figure out. I'm so used to it now I know how far I can push it before the ungodly vibration begins. Wish I knew how the first owner did to this thing. I appreciate your interest in my problem. More replies are more than welcome. Thanks

Your drive shafts are rotating parts, sounds like you have one either bent or the CV joint on it is worn out - it can happen.

It's impossible for the drive shaft to slip in the rear diff, for that matter, the only way anything in the diff can slip is if you've stripped something or have some other sort of damage.

Jay's advice is also good.

Thanks so much guys! I just had my wheels balanced and aligned so that elimates the wheels. I will take it in and point out the axles for troubleshooting. I've read a lot of other posts with people with similar problems and most of their problems point to their axles. I just wanted to hear someone bring it up in my specific case. I appreciate everyones time and will get those things checked out. I will post again when I recieve either good news or bad so ya'll can use my experience for other folks with a similar problem. Thanks again.

i had almost the exact same problem. as it turns out my back left cv axel was worn out and didnt get any better when i was on an offroading adventure and found out my car couldnt tackle a boulder. it could be the problem... if it needs to be replaced fix it sooner than later.

What size wheels and tires do you have? Is it possible they are rubbing on the fender?