Hi, This is my first post here in FTE. Absoutly Wonderful Site. My truck is a 1997 F-150, 5.4L V8, Super Cab, 8 Foot Bed, Lariat, 4x2. Rare Truck I have read in some posts... Well, down to my question. at low speeds up to 25 MPH usually when slowing down with my foot off the accelerator, i can her a *whap whap whap* sound coming from what i think is one of the four tires. (Im glad i could narrow it down for you) It dosn't stop when I press the brake pedal, and dosn't happen all the time. Temperature has no effect on it, happend through winter and still now in the 50's. It dosn't effect anything, braking is fine, all else is fine. Could it be a warped front rotor or rear drum, or possibly a u-joint, or the drive shaft... I have no clue. I know this truck like the back of my hand, do all my own work, but can't figure this one out. Any advice would help. Thanks!

 

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U joint. Go back and forth between drive and reverse and listen for the clank. MY 2 cents.

 

I doubt if it is a warped rotor or drum. You would feel this as a pulsation with the brake applied, and your problem happens whether or not the brake is applied. I would agree, the first thing to look at are U-joints.

 

A warped rotor can sometimes cause a noise like that as it forces the caliper back and forth, even when you're not braking. You would have a pulsation when you press the brakes though.
I would also start with checking the U-joints. You may have to remove the driveshaft to tell for sure if they are good. Sometimes they will feel ok but are actually binding.
If they are ok I would swap the tires in an X pattern and try it. I've been fooled by tires a few times lately.

 

That Was It, The U-Joint In The Driveshaft. Thanks So much.

 

Thanks for letting us know what you found

 

Amen and Happy motoring!