SORRY FOR THE LONG DESCRIPTION
So i need some help, when i first got my car it had a bad shaking problem. It would start around 40 and get worse around 65 and it also had a sound that would appear. I suspected front bearings so i had them replaced. After having them replaced i noticed the tie rods were bad so i replaced those and just got it aligned a few days ago. Anyways it now rides somewhat decent until i hit 70 mph. Im no speed demon but the interstate speed limits to get home is 70 and of course you have to speed up to pass people, anything higher than 70 feels like my car is gonna fall apart. Ive also replaced the drivshaft with a balanced aluminum one and i know the front tires are balanced cause i had new tires put on a few months ago and had them balanced. Sorry for the long post but this is really driving me crazy and as of right now im thinkin i should just save a couple thousand and take it to a shop after december. So any ideas of what i should check would be great, also the front tires even after having the bearings replaced still have a lil 12 to 6 play, i think they just didnt tighten the center nut enough?

 

Could be caused by a bad belt in a tire, a bent wheel, or possibly a bent alxe or rear axle bearing. I would be inclinded to belive its wheel/tire related

 

were can you feel the vibration? does the steering wheel feel likes its going to fall in your hands or does it feel like its in the seat or from the rear seats? if its worse in the steering wheel its coming from the front, check tire wear, wheel balnce, or for a bent wheel.(some bent wheels will balance out) also check front suspension for loose parts that were maybe missed in the alignment inspection. if its from the rear which it most likely is, check for bent rim or axle shaft. those two are the most common in the rear since these cars can get tail happy in the hands of people who dont know how to drive especially in the wet.rear wheels smacking a curb happens all the time and WILL warp/bend the axle flange.since it can be felt at high speeds it will be related to wheels/tires or axles.a small amount of 12 to 6 bearing play is normal, but it is possible that it wasnt adjusted properly, some loose ball joints can feel like minimal wheel bearing play.

 

Is the only way to check for a bent axle to actually pull the axles? I'll also go ahead and check the rims tomorrow

 

I see you got your car alined but was that just the front ?
How old are your rear springs ? If they're stack and sag you rear end will be off set about a half inch or more. this will cause the car to be miss alined and that is not figured in when you have your car alined. and at higher speed it will cause you to feel a shimy.
You say your front tires are new and ballanced , What about your rears?

 

the way i do it is leave the wheels on lift the rear tires put the trans and neutral , spin the tires by hand and watch which one is out of whack. then i like to swap the wheel to the other side to see if the wheel wobble moves with it, if it doesn't its the axle.

 

The rears were new when i bought it and they have weights on em, they could be misbalanced though and i had never hears of a rear alignment so i'll look into that as well

 

i have the same problem with vibrations above 70 but i can feel the vibrations through my shifter. like my sifter is vibrating itself off the car.

 

The vibration could also be caused by bad(warped) brake rotors. You said you replaced the bearings, but you didn't say anything about the rotors. I would have them replaced next, I know this from experience.

 

transmission tailhouse bushing and/or worn slip yoke caused this in my car

 

thats only during braking, but anything is possible.

yes that might cause it to but not very common.

 

Years ago I had a set of aftermarket Cobra rims that caused this. I tried everything until I couldn't take it anymore and took the rims off the car and I put the stock ones back on. What kind of rims are you running?

 

i would rotate the tires and have the old tires re balanced if the shaking goes to the front than its either a bad tire or bent rim if shaking stays in the rear than start from there, axles or the spring thing