W124 400E body vibration
11-16-2007, 06:20 PM
#1
Super Member
Thread Starter
W124 400E body vibration
Ok...here is one for the pro's.
This 400E generates a "thumping" vibration around 100KPH. It's almost a droning. Things that have been eliminated are tires, wheels balance, front wheel bearings, motor mounts. It happens if the engine is on or off. It's present when coasting through that speed range. Seems to be a little worse when applying power...but not that much.
After putting the car up on jacks and taking it up to 100KPH the "pounding" was most noticable at the diff. Determined by touching it.
In fact I'm pretty sure it is getting transmitted into the body via the diff. mounts, which are OK.
It sure does sound/feel like something is out of balance....but what?
My next task is to remove the driveshaft...but it looks fine when turning...no noticable misalignment.
The right rear half shaft does seem to be a little erratic as it is turning and there is a noticable clicking coming from it...so I was thinking either wheel bearing or CV....but could that transmit such a vibration to the diff? Yet, when I touch the control arm on that side it isn't as bad as at the diff....but I can feel the thumping.
Is there anything inside the diff that could be out of balance to the point of causing it...or perhaps in the transmission?
This is a real strange one....nothing obvious...no smoking gun....but there sure are symptoms of something out of balance somewhere in the drivetrain towards the rear. Any technical guys got any ideas??
This 400E generates a "thumping" vibration around 100KPH. It's almost a droning. Things that have been eliminated are tires, wheels balance, front wheel bearings, motor mounts. It happens if the engine is on or off. It's present when coasting through that speed range. Seems to be a little worse when applying power...but not that much.
After putting the car up on jacks and taking it up to 100KPH the "pounding" was most noticable at the diff. Determined by touching it.
In fact I'm pretty sure it is getting transmitted into the body via the diff. mounts, which are OK.
It sure does sound/feel like something is out of balance....but what?
My next task is to remove the driveshaft...but it looks fine when turning...no noticable misalignment.
The right rear half shaft does seem to be a little erratic as it is turning and there is a noticable clicking coming from it...so I was thinking either wheel bearing or CV....but could that transmit such a vibration to the diff? Yet, when I touch the control arm on that side it isn't as bad as at the diff....but I can feel the thumping.
Is there anything inside the diff that could be out of balance to the point of causing it...or perhaps in the transmission?
This is a real strange one....nothing obvious...no smoking gun....but there sure are symptoms of something out of balance somewhere in the drivetrain towards the rear. Any technical guys got any ideas??
11-28-2007, 01:54 AM
#2
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ML 350
Ok...here is one for the pro's.
This 400E generates a "thumping" vibration around 100KPH. It's almost a droning. Things that have been eliminated are tires, wheels balance, front wheel bearings, motor mounts. It happens if the engine is on or off. It's present when coasting through that speed range. Seems to be a little worse when applying power...but not that much.
After putting the car up on jacks and taking it up to 100KPH the "pounding" was most noticable at the diff. Determined by touching it.
In fact I'm pretty sure it is getting transmitted into the body via the diff. mounts, which are OK.
It sure does sound/feel like something is out of balance....but what?
My next task is to remove the driveshaft...but it looks fine when turning...no noticable misalignment.
The right rear half shaft does seem to be a little erratic as it is turning and there is a noticable clicking coming from it...so I was thinking either wheel bearing or CV....but could that transmit such a vibration to the diff? Yet, when I touch the control arm on that side it isn't as bad as at the diff....but I can feel the thumping.
Is there anything inside the diff that could be out of balance to the point of causing it...or perhaps in the transmission?
This is a real strange one....nothing obvious...no smoking gun....but there sure are symptoms of something out of balance somewhere in the drivetrain towards the rear. Any technical guys got any ideas??
This 400E generates a "thumping" vibration around 100KPH. It's almost a droning. Things that have been eliminated are tires, wheels balance, front wheel bearings, motor mounts. It happens if the engine is on or off. It's present when coasting through that speed range. Seems to be a little worse when applying power...but not that much.
After putting the car up on jacks and taking it up to 100KPH the "pounding" was most noticable at the diff. Determined by touching it.
In fact I'm pretty sure it is getting transmitted into the body via the diff. mounts, which are OK.
It sure does sound/feel like something is out of balance....but what?
My next task is to remove the driveshaft...but it looks fine when turning...no noticable misalignment.
The right rear half shaft does seem to be a little erratic as it is turning and there is a noticable clicking coming from it...so I was thinking either wheel bearing or CV....but could that transmit such a vibration to the diff? Yet, when I touch the control arm on that side it isn't as bad as at the diff....but I can feel the thumping.
Is there anything inside the diff that could be out of balance to the point of causing it...or perhaps in the transmission?
This is a real strange one....nothing obvious...no smoking gun....but there sure are symptoms of something out of balance somewhere in the drivetrain towards the rear. Any technical guys got any ideas??
11-28-2007, 03:57 AM
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Ok...here is one for the pro's.
This 400E generates a "thumping" vibration around 100KPH. It's almost a droning. Things that have been eliminated are tires, wheels balance, front wheel bearings, motor mounts. It happens if the engine is on or off. It's present when coasting through that speed range. Seems to be a little worse when applying power...but not that much.
After putting the car up on jacks and taking it up to 100KPH the "pounding" was most noticable at the diff. Determined by touching it.
In fact I'm pretty sure it is getting transmitted into the body via the diff. mounts, which are OK.
It sure does sound/feel like something is out of balance....but what?
My next task is to remove the driveshaft...but it looks fine when turning...no noticable misalignment.
The right rear half shaft does seem to be a little erratic as it is turning and there is a noticable clicking coming from it...so I was thinking either wheel bearing or CV....but could that transmit such a vibration to the diff? Yet, when I touch the control arm on that side it isn't as bad as at the diff....but I can feel the thumping.
Is there anything inside the diff that could be out of balance to the point of causing it...or perhaps in the transmission?
This is a real strange one....nothing obvious...no smoking gun....but there sure are symptoms of something out of balance somewhere in the drivetrain towards the rear. Any technical guys got any ideas??
This 400E generates a "thumping" vibration around 100KPH. It's almost a droning. Things that have been eliminated are tires, wheels balance, front wheel bearings, motor mounts. It happens if the engine is on or off. It's present when coasting through that speed range. Seems to be a little worse when applying power...but not that much.
After putting the car up on jacks and taking it up to 100KPH the "pounding" was most noticable at the diff. Determined by touching it.
In fact I'm pretty sure it is getting transmitted into the body via the diff. mounts, which are OK.
It sure does sound/feel like something is out of balance....but what?
My next task is to remove the driveshaft...but it looks fine when turning...no noticable misalignment.
The right rear half shaft does seem to be a little erratic as it is turning and there is a noticable clicking coming from it...so I was thinking either wheel bearing or CV....but could that transmit such a vibration to the diff? Yet, when I touch the control arm on that side it isn't as bad as at the diff....but I can feel the thumping.
Is there anything inside the diff that could be out of balance to the point of causing it...or perhaps in the transmission?
This is a real strange one....nothing obvious...no smoking gun....but there sure are symptoms of something out of balance somewhere in the drivetrain towards the rear. Any technical guys got any ideas??
+1 on the drive shaft and flex disk and haft shaft. Grab both hafts of the drive shaft were it joins in the center, push and pull, check for any abnormal movement, do the same at the transmission rear yoke, checking for a defective transmission output shaft bearing. If the haft shaft “clicking” its bad change it. Your vibration is not from the differential.
