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Noise/Vibration suddenly at 50mph until 80mph


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#1 quiksilver

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Posted 14 July 2010 - 01:59 AM

'Appears' suddenly at 50mph, once over 65mph it starts to disappear till 80mph where it's effectively gone.
It can be felt in the seats, steering wheel doesn't shake. The tires have recently been balanced and a 4 wheel alignment was done at the same time.
I looked through previous posts, and prop shaft/center bearings seem to be the main culprits; is either of those causing this problem?

#2 javadoc

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Posted 14 July 2010 - 03:52 AM

This might not be what you're feeling, but the heat-shield on my car, by the cat, likes to make contact with my driveline and make some mysterious noises. I recently reinstalled it with new nuts (and larger washers) to try and hold it in place better. There's such a little amount of room there that the slightest deformity lets the thin tin contact the driveline. In my case, it'll start making noise around 30mph, and go away around 50-60mph, and sounds like something under there's going to come apart with a speed-variable thwacking sound. HTH!

OTOH, a vibration that can be felt in the seats, but not in the steering wheel can indicate a vibration coming from the rear of the car. A wheel could still be out of balance, or if you have aftermarket wheels (or wheels off of an XC90 with larger center bores), you'll get a vibration too if they're not hubcentric to your car.

Edited by javadoc, 14 July 2010 - 03:54 AM.


#3 quiksilver

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Posted 14 July 2010 - 04:38 AM

This might not be what you're feeling, but the heat-shield on my car, by the cat, likes to make contact with my driveline and make some mysterious noises. I recently reinstalled it with new nuts (and larger washers) to try and hold it in place better. There's such a little amount of room there that the slightest deformity lets the thin tin contact the driveline. In my case, it'll start making noise around 30mph, and go away around 50-60mph, and sounds like something under there's going to come apart with a speed-variable thwacking sound. HTH!

OTOH, a vibration that can be felt in the seats, but not in the steering wheel can indicate a vibration coming from the rear of the car. A wheel could still be out of balance, or if you have aftermarket wheels (or wheels off of an XC90 with larger center bores), you'll get a vibration too if they're not hubcentric to your car.


Stock meteors are on the car.
I'll check the heat-shield tomorrow.

#4 quiksilver

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Posted 16 July 2010 - 04:54 PM

Checked the heat-shield, that's not it.
Anyone know what could be causing it?

#5 JRL

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Posted 16 July 2010 - 06:24 PM

Classic wheel balance speeds. 55 -75+
Have the balance rechecked, I'll bet they're...

(Your choice here)!
Out of balance
You have an out of round tire
A wheel may be bent

...and yes, feeling it in the seat and not in the steering wheel means your problem is definitely in the REAR

If you want to do it the easy way, first just swap the front tires to the rear and see what happens.
If you have vibration thru the wheel, you know the problem is in the rear wheels and tires (now on the front)!

#6 SKI-R

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Posted 17 July 2010 - 01:46 AM

100% agreement with Jim's assessment. Good luck.

#7 Rob

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Posted 17 July 2010 - 02:12 AM

Thanks Jim for the assessment; sounds right - I went through that many times. These cars are oh so sensitive to wheels out of balance.

Moving to wheel & tire sub-forum.

Rob

#8 quiksilver

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Posted 19 July 2010 - 03:02 PM

Okay, thanks guys.
I'll get the shop to check the wheel balance again sometime this week.
So there's no possibility of this being drive-shaft related?

#9 JRL

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Posted 19 July 2010 - 04:10 PM

Anything and everything is always possible

#10 Tzantushka

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Posted 20 July 2010 - 12:31 AM

Anything and everything is always possible

That is a classic piece of of JRL advice!

Anything that rotates can be:
- out of balance
- out of round
- out of alignment

Trent