OK, need some help - I have close to 90K miles on my truck. Just recently, I have noticed a "thunk" towards the rear of the truck whenever I make a turn. Does not matter which way I turn or how fast I am going, just a quick "thunk" and that's it. I got under the truck the other day to look for anything that might be loose, but was unable to find anything. Anyone had this problem or might know what it could be??

 

My neighbors 99 f150 super cab had a similar problem. He tightened up on the leaf spring clamps and it went away. Seems that the thunk came from the leafs shifting during a turn.

 

It might be the infamous mystery tranny thunk.

 

Are you sure it is from the rear? Sometimes it is hard to tell. Is ithe noise only when you turn or can you get it when going straight?

 

I have only noticed it when turning. Don't think it is the tranny thunk because I have noticed it when keeping the same speed and the tranny did not shift gears.

Leaf springs might be a idea - I was wondering if it was my suspension going out. Again, I have 90K on the truck and have not replaced the original factory shocks. I do not take the truck off-road, but I do drive it pretty hard on the road and like to see how fast I can take turns.

How long should these shocks last?? I do have the factory tow package - of course there is still some question whether different shocks were put on with this package.

 

Possibly the rear end, try adding a tube of friction modifier or change your fluid.

 

Norm has a good point - do you feel some momentary vibration? One test, is while the truck is loaded with something heavy turn slowly, preferrably up a hill. If you feel some rear end vibration it could be the rear diff. - either low on fluid or a broken rear clutch (assuming you have a limited slip rear).