'99 F250 Super Duty rythmic wheel thump - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

mystic mustang · 05-19-2009, 12:40

The problem is on the front passanger side of the truck. The problem was noticed at first when I pressed on the brakes and got what felt like warped rotor. Later, a light thump- thump-thump that would increase in pace the faster I would go developed. The problem is getting worse. I've noticed some light cupping on the tire, but no blisters. Is this the wheel bearing? Another guy that I know that works on cars said it is the shock absorber, but I have a problem thinking that would cause a rythmic thumping sound and make the truck vibrate when braking. Is it obvious to identify a bad bearing when you pull it?

Thanks in advance for the help.

**360ci** · 05-20-2009, 17:45

Cupping can be caused by many things, everything from an unbalanced tire to worn front end components such as a tie rod.

No need to pull it to check for bad bearing. I use the 'idiot' method: lift the wheel in question off the ground a few inches. Then, place one hand under and the other on top of the tire. If you can shake the tire towards you, then the bearing is pooched. A little bit of play might be enough to make the sound you mentioned. HD trucks can be harder to diagnose as the components are made stronger - and heavier.

If you can't see a difference by the 'idiot' method, then try a tire rotation to see if that makes a difference. Badly worn tires can cause some havoc. I would be cautious as you don't want to leave the rotated tire on that wheel too long, as it too will cup. If you are running original shocks on your '99 - replace them irregardless if they seem 'OK'. HD trucks are a lot harder to notice bad shocks, unless they're broken, bent, or leaking fluid (no fluid in gas shocks of course, hydraulic only).

mystic mustang · 05-21-2009, 04:56

Thanks 360ci. I'll try finding play in the wheel this weekend. Nice tip. If not, I'll rotate the tires as you suggest for a short while. This should give me enough feed back to figure out what the problem likely is. I bought the truck used, so I guess I have to assume the shocks are original. If rotating the tire doesn't transfer the problem over to the other side of the vehicle and there is no play that I can find in the wheel, I'll get some new shocks on it. After 10 years it's probably due anyway. Thanks again. I'll holler back either way.

**360ci** · 05-21-2009, 12:14

I would replace the shocks every 100K, irregardless of years, even if they look OK. Let us know how it turns out!

mystic mustang · 05-24-2009, 15:38

Hey 360ci. Here's how the story ends. I jacked up the truck and tried moving the wheel towards me. It was sound so I swapped front and back passenger side wheels. The problem followed the wheel. I took the truck to a shop, had them balance the wheel which needed 10 oz to achieve. ( that is a lot of weight!) They think the wheel may be slightly warped so they suggested flipping the tire on the rim to counter wear of the cupping which it may and they did at no charge. (The wheel is not directional) I installed new shocks and the rythmic thump is 95% cleared up. It's now in the back and is only barely audible. You cant feel it when driving except at braking sometimes. I still get some vibration but it is much less than before and since it is in the back, control is much better because as you know most of the braking happens in the front and steering is no longer effected. Thanks again for your help. I know how to manage the problem. Get a new wheel if the problem persists after allowing the tire to wear.

**360ci** · 05-24-2009, 16:26

Awesome! At least it's a low cost fix!