Vibration one more time
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Senior User
Joined: Jun 2007
Posts: 111
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Vibration one more time
I appreciate the patience to those of you that have answered and offered suggestions in the past to this problem so I want to try one more time and see if I can explain or clarify the problem.
I have an f150 1997 4.6 4x4 three door automatic transmission. I have a vibration beginning at 40mph and it continues until about 60 mph. It seems to improve the faster I go. You can barely feel it at 75 mph. If I am driving at 30 mph about 1500 rpm there isn't a vibration. When I am driving at 40 and 1500 rpm I have the vibration. I have taken it to a transmission shop and they said it wasn't transmission. I took it to a differential shop and they said it was not the differential. The uv joints are new and the fluid has been replaced in the transmission as well as the fluid in the torque converter. Could an engine mount or the harmonic balancer cause a problem like this? Could an out of balance drive shaft cause this problem? The vibration is sudden not gradual. Thanks again for any help.
I have an f150 1997 4.6 4x4 three door automatic transmission. I have a vibration beginning at 40mph and it continues until about 60 mph. It seems to improve the faster I go. You can barely feel it at 75 mph. If I am driving at 30 mph about 1500 rpm there isn't a vibration. When I am driving at 40 and 1500 rpm I have the vibration. I have taken it to a transmission shop and they said it wasn't transmission. I took it to a differential shop and they said it was not the differential. The uv joints are new and the fluid has been replaced in the transmission as well as the fluid in the torque converter. Could an engine mount or the harmonic balancer cause a problem like this? Could an out of balance drive shaft cause this problem? The vibration is sudden not gradual. Thanks again for any help.
Hotshot
Joined: Jul 2005
Posts: 11,932
Likes: 181
if it was a harmonic balancer it would vibrate setting in the driveway when you hit the throttle. you said it does it at 40 MPH. what if you leave it in 2nd gear at 40 MPH, or pop into neutral and set at 800 RPM at 40 MPH--- see if it is rpm or MPH related.
Fleet Mechanic
Joined: May 2005
Posts: 1,739
Likes: 14
From: Vale, NC
Seems like it wouldn't be engine if you are getting vibration with the same rpms just different speeds. Have you tried downshifting out of OD at say 50 mph? If it still vibrates with the higher rpms at that speed, then it would seem to rule out engine balancer or tranny. I think you posted before you had ruled out wheels, but that seems like the natural choice especially because it smooths out as you go faster, which is how I recall an unbalanced wheel acting.
