Thumping Noise When Turning Front Wheels All the Way R&L
 

Noticed that when I was turning in a circle both ways on my 99 PSD there was a slight thumping as though the tire was rubbing...but it is not. Jacked up the truck and do not see any obvious problems. Both wheels seem tight on the bearings. Any suggestions? How do you check the ball joints for wear? Thanks!

With the tire off the ground, get a long pry bar and put it under the tire and try to lift the tire. You will be able to tell if the ball joints are bad.

or the u-joints in the front axle.....

When I put the bar under the driver side and lift up there is play in the bottom ball joint and there is none on the other side. Would that test method show wear on the top joints as well if there were play? I do have a leaky inner seal on the differential on the passenger side so it looks like the whole front axle needs to come out and might as well replace all ball joints and seals, eh? How do you check the u-joint? Any play?

Perhaps your hubs are locked, or failed to unlock (if ESOF-type) and the u-joints are making fairly normal sounds at full deflection.

Verify that your front hubs are unlocked (or remove the hubs) and try this again. Unless your ball joints were really shot, or you were going over bumps, I wouldn't think they would clunk in a low speed sharp turn on a flat surface.

The hubs on full on "auto." I do wonder if one ball joint could cause that sort of thumping sound I hear at the full turn right and left position. The U-Joint is firm. Hmmm.

Generally speaking, if you need to replace one ball joint you should go ahead and replace both.

Does the steering wheel jerk a little when you hear the thumps? If it does, one or both of your hubs are probably locked in.

How many miles do you have on the truck?

Ball joints for the most part last only about 100k some more than others? But from what I read in your reply, if you have movement with the pry bar under the wheel then the ball joint is bad. And as stated above I'd replace them all.

Not really...only happened the other night in a parking lot when I was turning around. Then I played with it turning right and left at about 10 miles an hour. Only at the full turn of the wheel did I hear/feel slight thumping (almost like the tires where rubbing or running over little rocks). Didn't recall any noticable jerking in the wheel. I have felt that...if that is what you mean....when I have had it in 4WD on ocassions and turning. Thanks.

I bought the truck used 4 years ago with 175K and it has 218K now. I don't know if or when joints have been replaced so I might as well pull the whole axle and do it all including the inner differential seal which appears to be slightly leaking. Tempted to just let it go for awhile until I'm more inspired and/or confident. Don't want to pay for all the labor if I don't have to.

Mine had this same problem recently and it was the driver side hub stuck locked. To see if it's stuck just get under the truck and with the selector switch in 2wd and the hub in auto you should be able to grab the u joint at the end of the axle and spin it easily by hand.

I have something similar going on right now. If it is stuck locked in, how do you unstick it? I think the wind chill is about 10 degrees today... Don't really feel like wrenching too much right now!

To unstick it get some snap ring pliers and pull the hubs out ( very easy ) and take them in the house. Go to guzzle7pt3.com and look up hub" Ford auto lock hub lubrication " under the maintenance section.

Sometimes with my ESOF, on auto, the hubs unlock, but in tight turns you can still hear them locked in. Try reaching under the truck and rotating the front drive shaft. to unlock when that happens, pick the truck up, and just spin the wheels around. I am sure you know all this, but i see it a fair amount when i use the ESOF... that used to work i mean.