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Hi. It is possible that the clutches are shot. The best way to check is to drive in a figure 8. A tight figure 8 at slow speeds like in a parking lot. If you really feel the chatter then, then the clutches are the problem. You can try this and then let me know.
Sometimes adding friction modifier helps. It is supposed to be added to the rear end.If perhaps a service was done without it being added, then that may help.
Yeah it would be similiar. You won't feel the binding like when in four wheel drive, but you will feel chattering from the rear.
Also, what I have seen before is in the rear parking brake assembly, there is a "scissor" type actuator that moves in and out the e-brake shoes. I have seen this actuator stick and cause the brake shoes to be touching the inside of the rotor and causing this type of vibration. You can try visually looking and using a hammer if needed to try and hit back the actuator lever in the back of the backing plate. If you are still unsure if they are sticking you can remove the rotor and check them.
Alright sorry for that. I will open the question back up to the other Experts. Thank you.
The clutch packs in the rear axle for the Traction-Loc will only make a shudder on turns. It will not cause a vibration 40-45 MPH. Since you have had the tires balanced, you may want to look at having the tires load forced balanced. Also, jack up the rear axle and place it on jack stands. Then, check for run out in the driveshaft at three points. Also, see if you could have a bent axle shaft or a bent wheel. Even though you have the tires balanced, a bent wheel/rim will cause a vibration at 40-45.
And the vibration is definitely from the rear or do you feel it in the steering wheel?
And this is at 40-45 on the highway or basically straight ahead?
Can you give me the VIN#? I want to check Fords database for your concern.
Ok. Nothing in the database for a 2003 F250, 5.4L, 4x4. Below is the info I got back.
Since the driveshaft and wheels and tires have been ruled out, you may want to look into the rear differential itself. Not the clutch packs, but the ring and pinion and also the pinion flange where the driveshaft bolts to the rear axle.
I doubt it is in the front end or transfer case.