Whole car vibrating
 

So only recently my entire car is vibrating on the freeway. Like I got BASS but without the audio to go with it and it's a continuous hum not thum thum thum. It must be in gear, foot on the gas pedal, and on rough road for it to happen. All 3 only. If it's not in gear and thus not gassed either, the shifter will vibrate way more than it does when the problem happens, like an electronic device, and the chasis won't vibrate at all. If my foot's not on the gas pedal, there's absolutely no chasis vibration even if it's in gear. If it's on a smooth road, there's almost nothing, but I can hear a similar hum so low that I only notice it b/c I'm listening for it. If I rev the engine in neutral nothing at all happens. It still happens on rough city streets but the lower speeds reduce the vibration from annoying to perfectly tolerable. Throttle and rpms make no difference at all; the slightest tap on the gas pedal will instantly change it from nothing to full vibrations. In fact I'd be tempted to think that higher rpms and throttle aren't as bad, but I'm probably imagining that. I think I'm hearing it from somewhere in the drivetrain. The heavily vibrating shifter in neutral (which gets dampened when it transfers to the entire car) makes me guess that the problem is somewhere from the tranny to the drive-axles and putting it in gear and applying a little gas creates a stiff link to transfer the vibration to the entire chasis.

So what kind of trouble do I have to look forward to?

My first thought was driveshaft u-joints, but the more I read, the less confident I felt that is your problem. Especially since you say even the shifter vibrates when in neutral. Some of your symptoms almost sound like a tire tread that is failing. I've had that happen before and it shakes the whole car above a certain speed, but road conditions usually don't factor into that - neither would throttle position, if it's above the speed for vibration, none of that would matter.

Have you made sure all under car, drivetrain and suspension related fasteners are tight? That would be my first move, if you haven't already done so.

My tires need to be changed badly, I can start there. The shifter vibration in neutral isn't noticeable unless you put your hand on it, then it's like a phone on vibrate. As I said the noticeable problem is in gear, gas pedal pressed and rough road. I suspect the path is rough road => drivetrain => engine => whole car. The road doesn't need to be that rough to cause the problem. Anything short of perfectly smooth will do it. By failing tire tread do you mean a failing steal belt?

For each of the possible scenarios, how much danger am I in? Do I need to address this around today, or within a couple weeks?

I would check u joints.

A tire tread failing would have dire consequences. It would delaminate from the carcass and cause a complete tire blow out. A tire tread came off of my fiance's car and did some damage when it separated, mainly scuff marks around the wheel well and a broken piece of side skirt.

I would start with tires. If that doesn't correct it, then start looking at replacing the transmission and engine mounts (neither are very expensive, but both are a pain to replace).

So the shifter doesn't shake in neutral. That must have been a fluke or an extra rough road. I've also noticed the vibration on smooth roads as well as rough, So I dunno what was making it stop intermittently. Replacing the tires didn't fix it. Recent work was a pilot bearing replacement and air conditioner work. The mechanic who did the pilot bearing said my tranny might need a rebuild but it wasn't vibrating so it may be fine for now. I hope it isn't that. I think he said the old pilot bearing chewed up a shaft or something like that but he ground it back down, dunno if that's related.

id check your spare tire compartment.

I have serious virations when the car reaches 4k rpm to 4.4krpm.

Thats where all my vibration comes from. I work at DCTire so i ripped off all my tires and rebalanced and i did see any bent rims or anything abnormal. Granted my fronts are in need of replacement but it didnt solve my vibration problem. :/

Im thinking its the bolt that holds the spare isnt tight on mine.

its the tires. Mine are really bald and thread is falling off. They are also probably not balanced ether.

I already replaced the tires. Still vibrating. Should have included a balance but I didn't check. EDIT: Ya one of the rims has two weights on it now. All of them had only 1 before. All the weights may look different than the old ones too, but I could be imagining that.

drive shaft man all the way i had the exact thing happen to me
its simple to take off and inspect
4 bolts and a good tug
check that quick b4 it breaks cuz wen it does it suck i had to replace my trans wen mine broke cus it came up and broke my shifter surrond
if that dont work check ur u joints
but while u have it up go ahead and replace all bushings u can possibly find full set
just to eliminate that as the problem
drive shaft is any wer from 200 and up trans just find a good frind to sell u 1 i baught mine for 60$
full bushing set always varies but is always a good thing to replace
and the plus side is its always a good idea to get a new shaft the newer the better

Busted U joint on the drive shaft thanks for the help.

I needed the tires anyway and they saved my life in the recent rain storms heh.