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Bordom
02-16-2014, 09:33 PM
There is a rumbling sound/vibration coming from the rear end of my car. It is very deep and aggressive sounding in person, but in the provided video it is quite faint. You will hear it just after 30 seconds in if you are wearing headphones, or a similar type of listening device with the volume all the way up.

It does not sound like a wheel bearing, or CV shaft. There is absolutely no play in any of the axles, and the wheels are stiff. It is a rotational sound of sorts and does not emanate from the front of the vehicle. The associated vibration comes from the center arm rest area, leading me to believe it is the center bearing. (substantial play but not enough to knock around) When starting from a stop, there seems to be a delay in the drive line where much slack is picked up before any forward motion is achieved.

There is however a distinct metallic clunk when I was checking the prop shaft the other day. I spun the wheel back and forth and heard a clunking from the rear prop shaft CV joint connecting to the diff. I do not know if that is normal but it doesn't seem like it is. My other theory is that the CV on the prop shaft has gone dry and is creating these deep rumbling sounds I am hearing in the cabin, as well as the clunking while spinning the wheel back and forth.

I have a replacement diff and rear axles that I will be getting once funds are accessible, and will see if that takes out much of my sounds.

Here's the video:

http://www.youtube.com/watch?v=9QpQ9HxOKR0&feature=youtu.be


Help and opinions would be greatly appreciated.

ricekikr
02-17-2014, 03:24 AM
Couldnt hear anything.

Does it happen under load or all the time? What speed?

Could be any of the ff

Center diff mount (which one do you have?)
Broken exhaust mount, causing exhaust leak or rubbing in tunnel
Plus all you said

When cv fail, it starts to tick. If really bad can cause vibration and lotsa racket.

Bordom
02-17-2014, 08:47 AM
It happens at 60km/hr and noticeable at 80. It always occurs in fourth and fifth gear at 2-3k rpm. If I go above 3000 in 4th, the sound will disappear. Likewise for 5th.

I still have the stock diff mount and all of the exhaust mounts are intact with no leaks. There's no up and down, or side to side play in the diff. None of the CV boots have ever been changed on the car, nothing has been regreased and they don't tick. When rev matching and engine braking, the car shudders and replicates the deep aggressive noise.

If it was a cv joint, wouldn't it make a bunch of noise regardless of speed?

ricekikr
02-17-2014, 10:01 AM
Is this under load (boost) or just cruising part-throttle/off-throttle in-gear?

Does it happen in other gears at the same rpm also or just at higher speed/load?

Bordom
02-17-2014, 10:17 AM
It occurs cruising at those speeds on or off throttle. It gets slightly more noticeably if I jam the throttle.

At 60 in 3rd, there's no sound. As soon as I shift into 4th, maintaining speed, I can hear it noticeably. I don't think it's a trans issue, but could it be the synchros on 4th and 5th are pitted and transmitting this vibration to the rear?

Bordom
02-18-2014, 06:57 AM
bump