I have been experiencing a strange vibration, dont even know where to start to look. It comes on about 50mph, then goes away around 55mph? Almost feels as though it is in the drive line, but i cant tell. Anyone have any insight on this? I know I am due for a tire rotation, but I would think that it would do it all of the time if it were tires, right?

 

Do you feel the vibration in the steering wheel, seat of your pants, or somewhere else. This can give you a clue as to where the trouble is located. Steering=front, Seat=back, other=?... most often floorboard which=tranny.

Tires can be the culprit. An out-of-balance condition can show up in some strange ways.

 

it is tough to really isolate it, but if i had to choose one, i would say the seat. so that would tell me that something is amiss in the rear end/drive train? I dread taking it to the dealer, the last truck i took into the dealer just created a monster of problems once they started "diagnosing" things, of course that was a chevy truck too, so ........

 

i'll second out of balance tires as the culprit.

 

Could it possible be a U-Joint going bad?

2000 F350SD,RC,5spd man,V10, Front Leveling Kit,4.30 gears

 

If your truck has a center bearing it could be that.Grab hold of the drive shaft and try to move it up and down or left to right.Good luck.

 

This maybe or maybe not be of some help. I know that I have a driveshaft vibration from 38mph to 43 mph and then it goes away on my 02, V-10, SD with 4,000 miles on it. Ford says that re-positioning the driveshaft and other things with the rear diff. It is not there with a full tank and starts vibrating at about a half a tank and gets worse until it is almost empty. (Yoke and drive line angle problems have been around for a long time) I have to get into the dealership for this and a bump stop. I will follow up at a later date.

 

Dan, the vibration starts at 50 and goes away at 55? Usually when this happens it's an unbalanced tire. It works like this: a point of imbalance can only go around once per revolution, giving it a difinitive frequency 1 X RPM of the tire. At a given speed the unbalance (centrifugal force) at 1 X RPM equal the net natural frequency of a system of parts, usually the front end steering system. The source force of the imbalance excites a system at it's net natural frequency, resonance then multiplies the force 10 to 50 times. Speed up or slow down the vibration ususlly goes away because you are changing the input frequency away from the natural frequency, usually plus or minus 20% will do. Ever shut down a light weight high speed machine and listen to the coast down and the the peak vibrations as it coast down? Those peaks are natural frequencies. The possible solutions, stiffing the systems parts and raise the first natural frequency of the part or lower the input force. Usually lowering the input, balancing the tire or shaft, is more practicable than stiffining the front end or drive train. When this phenonomenom is noted the natural frequency of the system can be changed by load which can be carried bed load of fuel status. That can change the speed at which the problem is noted but the basic cause is the same.
First, check all points of potential loosness as had been suggested above. Loosness can also act as a force multiplier of sorts. Then rotate and balance your tires, if you are like me that is always over due. If the vibration remains it is most likely the drive shaft. That is the short list, the rare but possible list is much longer and involved.

 

thanks for all of the info guys. I will check out the driveshaft and go from there..

 

My 2002 SD 500mi had a vibration that started at 60 mph but wasn't constant. It turned out to be the tires. The RO stated that 2 tires required 4oz of weight to correct the imbalnce which 2 I'm not sure but the vibration was felt in the steering wheel seat and floor basicly the whole truck was shaking. Apparently the tires were not correctly balanced at the factory.

Chuck

 

If tire balance is good the next thing I would have checked out is drive shaft imbalance.