Car vibrating under acceleration and louder than usual road noise

[tmh88]

I have a 2005 S4 and my car is vibrating quite a bit when accelerating between ~55-70 mph. I can feel it a tiny bit before those speeds, but it becomes very obvious right around 55 mph and stops right after 70 mph and only happens when accelerating. If I lift off the accelerator at 65 mph the vibration immediately stops, but even just lightly pressing it the vibrations start again. It feels to be originating from the front driver's side area and the whole car shakes, not the wheel/brake pedal.

There's also a rubbing/resistance noise coming from the same area which becomes very noticeable above ~30mph, and almost sounds like a bad wheel bearing, but it's a steady noise, not the oscillating sound that usually happens. I don't really know how to describe it other than much louder than usual road noise, as if the typical road noise is just significantly amplified. It doesn't sound like metal on metal, or any kind of grinding/scraping. I replaced my pads and rotors yesterday, but the noise existed prior to doing that, so I'm pretty sure my brakes are out of the question (also doesn't explain the whole car vibrating while accelerating). I don't think my wheels are out of balance because it only happens under acceleration and only around ~50-70 mph. I had my front wheel bearings replaced about 20k miles ago, but I suppose it's always a possibility that one has gone bad.

I noticed the boot on my driver's side CV joint is starting to pull back and there's a bit of grease on the outside of it, but it's not making any clicking noises nor does turning seem to affect the noise. I know that has to be replaced, but I'd like some thoughts on what else needs to be checked out so I don't have to disassemble components in that area twice. I don't have a CEL, although people have reported coil pack problems and not having any CEL's either. Regardless, that doesn't explain the loud rubbing/road noise, although that could be entirely unrelated.

Any thoughts? Thanks

[roboto_1337]

I have a 2005 S4 and my car is vibrating quite a bit when accelerating between ~55-70 mph. I can feel it a tiny bit before those speeds, but it becomes very obvious right around 55 mph and stops right after 70 mph and only happens when accelerating. If I lift off the accelerator at 65 mph the vibration immediately stops, but even just lightly pressing it the vibrations start again. It feels to be originating from the front driver's side area and the whole car shakes, not the wheel/brake pedal.

There's also a rubbing/resistance noise coming from the same area which becomes very noticeable above ~30mph, and almost sounds like a bad wheel bearing, but it's a steady noise, not the oscillating sound that usually happens. I don't really know how to describe it other than much louder than usual road noise, as if the typical road noise is just significantly amplified. It doesn't sound like metal on metal, or any kind of grinding/scraping. I replaced my pads and rotors yesterday, but the noise existed prior to doing that, so I'm pretty sure my brakes are out of the question (also doesn't explain the whole car vibrating while accelerating). I don't think my wheels are out of balance because it only happens under acceleration and only around ~50-70 mph. I had my front wheel bearings replaced about 20k miles ago, but I suppose it's always a possibility that one has gone bad.

I noticed the boot on my driver's side CV joint is starting to pull back and there's a bit of grease on the outside of it, but it's not making any clicking noises nor does turning seem to affect the noise. I know that has to be replaced, but I'd like some thoughts on what else needs to be checked out so I don't have to disassemble components in that area twice. I don't have a CEL, although people have reported coil pack problems and not having any CEL's either. Regardless, that doesn't explain the loud rubbing/road noise, although that could be entirely unrelated.

Any thoughts? Thanks

wondering if the excess load under acceleration is affecting your CV shaft... the fact that you say it's pulling off the boot on the outer makes me think that it's the inner joint.... it could also be a mount. Best to get under the car and check it out... pull on stuff see what's tight and see what wiggles.

[badger.]

CV was my guess, that is the only component of the front wheels directly impacted by engine load.

[924Carrera]

I'm hoping that the issue is the axle because my car is doing more or less the same thing. I bought it from a shop that replaced the front inner boots with what I later found were A4 parts (a whopping $8 savings per each, I believe). The boots actually appeared to be compatible and to fit fine, but while in the middle of a road trip in which my power steering hose ruptured (a very fun experience), I was crawling around under there and noticed tons of CV grease splattered everywhere that had not been there before. Somehow, despite not being torn, the LH inner boot had basically vacated all of its grease. I replaced it with the correct boot, but only after returning from my 1000+ mile road trip. I'm guessing that didn't do the inner tripod any favors. I plan to replace the axle while doing control arms at the same time, but have not gotten around to it yet. Like OP I have the same sort of vibration (it gets significantly worse over 80) despite having nicely balanced wheels. I also have the "increased road noise" that can almost be felt more than it is heard, that seems to be coming from the front left and is particularly noticeable under deceleration/engine braking.

[tmh88]

Just ordered a full cv/axle assembly from Raxles, hopefully this fixes the problem. For those of you who have done this before, what tools will I need? Just want to make sure I have everything before taking half my car apart.

[demonmk2]

Check your control arms
Different platform but had the same symptoms and it was that.

[tmh88]

Hmm, maybe I'll buy control arm bushings and replace them at the same time. I'd rather spend more money up front on parts that may or may not be defective than troubleshoot for a month and take it apart several times.

[tmh88]

My cv/axle didn't come yet, but I'm more confident than ever it's the problem. Today I noticed that when turning and accelerating the vibrations stop almost completely, and when straightening out again they come back.

[gojcaj]

Here's one easy check you should try to eliminate or confirm some things. Turn your steering wheel all the way in one direction and check your tires in the front and also rear. Run your hand across the inner tread and feel for irregularities and bumps. My tires looked great until I felt a crazy amount of waviness in them which led to a similar noise. Everyone I talked to thought it was wheel bearings as well.

[Dolphin S4]

Something tells me 90% it's a front cv joint had the same problem.. car would shake like crazy under hard throttle