Strange vibration
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Junior User
Joined: Dec 2004
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Strange vibration
Hello! I don't know exactly where to post this, so I'll put it here:
I have a 78 F150 4x4 4speed that vibrates pretty harshly when between 30-45 mph and on up higher than that too. I think it must be a bent or misbalanced driveshaft, bent axle, or something possibly in the rear end.
I can only feel the vibration when I am on the gas and in gear, if I throw it in neutral and coast, I don't feel it, so I threw out the idea of an unbalanced wheel. I don't think its a U-joint... Can someone please tell me all the possible causes and what to look for? THank you very much for your time.
I have a 78 F150 4x4 4speed that vibrates pretty harshly when between 30-45 mph and on up higher than that too. I think it must be a bent or misbalanced driveshaft, bent axle, or something possibly in the rear end.
I can only feel the vibration when I am on the gas and in gear, if I throw it in neutral and coast, I don't feel it, so I threw out the idea of an unbalanced wheel. I don't think its a U-joint... Can someone please tell me all the possible causes and what to look for? THank you very much for your time.
Posting Guru
Joined: Aug 2000
Posts: 1,984
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Highboy, my 78 Bronco with 4 sp (NP435) has vibrated since it was (almost?) new. I've done everything to fix it, nothing worked. I do notice that mine will not vibrate when the gear oil is cold, so it must be transmission related. A couple years ago, I replaced the gear oil with 85W-140, and the vibration went away. I had to change it back to the lighter 75W-90 however, because it wouldn't shift on cold mornings.......
Sometimes when at cruise speeds and vibrating, I can shift into neutral, and then reshift back into gear, and the vibrating will stop. I think it's something unique with the NP435, at least in my case.
Sometimes when at cruise speeds and vibrating, I can shift into neutral, and then reshift back into gear, and the vibrating will stop. I think it's something unique with the NP435, at least in my case.
