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Old 04-01-2011, 06:18 AM   #1
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3000 rpm Vibration

I know there has been alot of discussions on the board here about the 3k vibration and what that vibration comes from. My vibration comes at around 3k rpms and is between 69-73mph when I feel it in the steering wheel.

I had wondered if it was the wheels, shocks, tires or the engine mount.

So I decided to give a little test and I may be way off here so correct me if I am wrong. I would get up to 73mph at around 3k and feel the vibration/shake and then put my car in neutral and let the rpms drop and the vibration goes away when the rpms are down and my speed is still in that 69-73 range. This should be telling me that it is the motor mount correct?? Am I missing something here? If it was the wheels I would still feel it with the car in gear or not right??

Please help me with this. Thanks to all.

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Old 04-01-2011, 07:40 AM   #2
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I have the exact same issue... Waiting to see replies on this topic.

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Old 04-01-2011, 07:51 AM   #3
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In my car, it's independent of speed and get the vibration only when I'm slowing down throgh 3000 rpm. Whichever gear I'm in, if I'm slowing down in gear, I begin to feel the shake at ~3100, and ends as rpm passes 2900. I never get the vibration if I'm accelerating through 3000 rpm.
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Old 04-01-2011, 08:34 AM   #4
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Quote:
Originally Posted by JTP
In my car, it's independent of speed and get the vibration only when I'm slowing down throgh 3000 rpm. Whichever gear I'm in, if I'm slowing down in gear, I begin to feel the shake at ~3100, and ends as rpm passes 2900. I never get the vibration if I'm accelerating through 3000 rpm.
+1.
I think JTP's not feeling it on the way up because the time spent in that rpm range when accelerating is very small.
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Old 04-01-2011, 09:09 AM   #5
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I can even be on Cruise Control at 70 and I am getting the VIBE. To me it makes sense that its the motor mount. Thoughts??
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Old 04-01-2011, 10:04 AM   #6
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Again, if it's only at 70, then there's likely something in your wheels, alignment, etc. If you get the vibe in every gear at around 3000, then it's likely your motor mount, or your clutch, or the exhaust, or ???
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Old 04-01-2011, 10:12 AM   #7
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I had a vibe that occurred in every gear at 2300-2400 rpms. Pretty bad - shook the whole car mildly.

Gone with motor mount replacement and happened at all road speeds for the appropriate gear, so I knew it wasn't rotationally related or balancing/alignment.
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Old 04-01-2011, 10:23 AM   #8
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There seems to be two causes of this. The front motor mount and the Dual Mass Flywheel. I just changed my DMF and that solved the 3000rpm vibration. Start with the front motor mount then move to the DMF next.

If you end up changing the DMF then do the IMS bearing at the same time...shared labor...assuming it is a 986 and not a 987.

Chris

EDIT: Oops I see in your sig that it is a 97 with over 70k in mileage. Chances are high you need it all; front motor mount, DMF, clutch, IMS....might as well change the AOS while you're there.
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Old 04-01-2011, 10:32 AM   #9
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Thanks Dragon
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Old 04-01-2011, 01:10 PM   #10
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Quote:
Originally Posted by Dragonwind
There seems to be two causes of this. The front motor mount and the Dual Mass Flywheel. I just changed my DMF and that solved the 3000rpm vibration. Start with the front motor mount then move to the DMF next.

If you end up changing the DMF then do the IMS bearing at the same time...shared labor...assuming it is a 986 and not a 987.

Chris

EDIT: Oops I see in your sig that it is a 97 with over 70k in mileage. Chances are high you need it all; front motor mount, DMF, clutch, IMS....might as well change the AOS while you're there.

Thanks Dragonwind... I'm gathering a list of hardware I will need to replace the IMS bearing (LN Engineering), clutch assembly, flywheel, RMS, and motor mount. While I'm in there might as well do it all.

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Old 04-01-2011, 05:47 PM   #11
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Quote:
Originally Posted by clickman
+1.
I think JTP's not feeling it on the way up because the time spent in that rpm range when accelerating is very small.
Good point, I'll have to test accelerating at different rates and see if I notice the vibration.

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