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  #1  
Old 01-16-2009, 02:17 PM
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Odd vibration at 37 MPH

I've got a consistent vibration in my '90 300SE that happens at exactly 37 MPH and lasts until about 50-55 MPH, diminishing as I get there. It's very noticable and feels more like a 'vibrating bed' than a wheel vibration.

Any ideas?

Thanks

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'93 300CE 38K Sold
'89 560SL 19K Sold
'91 300SE 191K Totalled 11/6/08
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  #2  
Old 01-16-2009, 02:36 PM
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Could this be a harmonic which would indicate merely that you need to get one of your wheels better in balance?
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  #3  
Old 01-16-2009, 05:06 PM
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Location: Plano, TX
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Doesn't sound like a wheel/tire imbalance, those typically start at higher speeds and get worse the faster you go.

This does sound like out-of-round tires. This typically feels like an odd shimmying at surface street speeds, as if the pavement were slightly wrinkly, but fades away at highway speeds.

If the tires are substantially worn it's probably best just to replace them. Otherwise have them tested on a Hunter roadforce balancer to evaluate the runout in addition to the balance. This will tell you whether one or all are out of round and by how much.

- JimY
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  #4  
Old 01-16-2009, 06:31 PM
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Here's a partial list of things to inspect....

1) Tire/Wheel balance or tire deformation
2) Warped rotor and/or sticky caliper
3) Motor mounts, transmission mount, differential mount
4) Ball joints
5) Steering damper
6) Idler arm bushings
7) Wheel bearing adjustment or excessive wear
8) Front shocks

All but the wheel bearings are likely to need replacement at that age anyway. If you haven't yet done your motor/trans/diff mounts yet, do them anyway as this will make a huge improvement in vibration, idle smoothness, etc.

-tp
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  #5  
Old 01-17-2009, 12:09 AM
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I didn't realize you were talking about a '90 300SE, I was going by your handle. Guess I should read more closely.

The 300SE is VERY prone to having vibration issues when the motor mounts are shot. Also, the exhaust likes to sit on the idler arm when this happens.

After I changed out the mounts on my 300SE, it felt like I had a new motor.

If your motor mounts are shot, do them along with the trans and diff mount and your issue will likely go away.

-tp
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  #6  
Old 01-17-2009, 01:11 AM
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That describes a worn driveshaft center support to a "tee". The worn support allows the driveshaft to turn in a orbit until it eventually gets enough speed where centrifugal force pulls it back to center, usually occurring and diminishing around the speeds you have listed.
Try having someone in the back seat to see if they can feel the vibration in the driveshaft tunnel area or have somebody else drive while you check.
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  #7  
Old 01-17-2009, 11:28 AM
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Man, you guys are good!
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  #8  
Old 01-18-2009, 09:24 PM
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Quote:
Originally Posted by tyl604 View Post
Man, you guys are good!
I second that!

I'll check the driveshaft support, and the tires for flat spots.

Thanks
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Marc Galassini

'93 300CE 38K Sold
'89 560SL 19K Sold
'91 300SE 191K Totalled 11/6/08
'90 300SE 90K
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  #9  
Old 01-19-2009, 08:02 PM
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I agree; driveshaft. Most likely suspect is center bearing support as stated.
the driveshaft front flex couplers can get pretty bad and still not vibrate, they just clank a lot.
You didn't state if the vibration is felt solely in the steering wheel, or in the body. If it's the latter, my vote goes up to 90% for the evil driveshaft center bearing. These are really not that hard to repair, once you drop the entire exhaust of course.
Check the U-joint just behind the center bearing also. These usually have a pretty good "detent" in them, but hang on for a long time with no bad habits.

DG
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  #10  
Old 01-19-2009, 10:33 PM
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Yknow, I haven't done my center support bearing yet and I have started to notice a vibration that feels a bit "shafty".....

-tp
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  #11  
Old 01-24-2009, 10:49 AM
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Quote:
Originally Posted by S-Class Guru View Post
I agree; driveshaft. Most likely suspect is center bearing support as stated.
the driveshaft front flex couplers can get pretty bad and still not vibrate, they just clank a lot.
You didn't state if the vibration is felt solely in the steering wheel, or in the body. If it's the latter, my vote goes up to 90% for the evil driveshaft center bearing. These are really not that hard to repair, once you drop the entire exhaust of course.
Check the U-joint just behind the center bearing also. These usually have a pretty good "detent" in them, but hang on for a long time with no bad habits.

DG
Absolutely a body only vibration...

Thanks
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Marc Galassini

'93 300CE 38K Sold
'89 560SL 19K Sold
'91 300SE 191K Totalled 11/6/08
'90 300SE 90K
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  #12  
Old 02-12-2009, 10:21 PM
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Quote:
Originally Posted by duxthe1 View Post
That describes a worn driveshaft center support to a "tee". The worn support allows the driveshaft to turn in a orbit until it eventually gets enough speed where centrifugal force pulls it back to center, usually occurring and diminishing around the speeds you have listed.
Try having someone in the back seat to see if they can feel the vibration in the driveshaft tunnel area or have somebody else drive while you check.
You were 100% right! Center support replaced... vibration gone!

Thanks All

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Marc Galassini

'93 300CE 38K Sold
'89 560SL 19K Sold
'91 300SE 191K Totalled 11/6/08
'90 300SE 90K
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