I purchased a used 2001 F150 4x4 supercrew with a 3" suspension liftkit from an individual a few months back, anyway, I started hearing a knock noise every now and then coming from passenger rear side, whenever I make a turn(drive and reverse) on an incline or decline. Any ideas what could be making this noise?

A buddy of mine suggested I go get an alignment, and see what they think; I ended up doing that, and the people who gave me the alignment said the suspension was fine, they didn't encounter the noise, but it shouldn't be the suspension.

 

I fit coming from the rear axle, it's probably the clutches in the rear end locking up. Get a bottle of limited slip additive, & add to the rear end. That should take care of the problem.

 

Can I just top it off with the additive right now, or should I change the rear end fluids and add the mix with it?

 

Just go ahead and add the additive now. I will take a little time to quite down. Make sure the additive is Ford compatable.

 

I topped it off with the additive about a week ago, and the problem continues to persist, so I'm going to change out the oil completely and see if it helps.

Anyway, could it possibly be the leaf springs making the noise? I examine them, and noticed the leaf springs on the passenger side(same side where the noise might be coming from) was missing both clamps.

 

Okay this is an old thread, but doesn't seem to have any closure. Now I'm facing a similar situation and can't find much on this anywhere.

Ever figure this out?

 

Some things to look at towards the op. since it has a suspension lift it could be the springs my trucks done it.

It could also have a spider gear tooth missing reason for it to only pop turning one way. The tooth is jumping and reconnecting.

Personally I don't believe in the additive hoopla the first 2 times when I broke axle shafts and needed to pull out a shaft I went back with it, but the next few times when I was stranded on the side of the road it wasnt that easy to get so I just went back with a fully synthetic gear oil. 6 years later I'm still waiting for that 9.75 to go out so I can replace it with my 9"

You could have a busted shock, or it's come loose where it's bolted on.

And exhaust hanger could be hitting your exhaust.

Hell I've even had my bed bolts loose and it was making an irratating sound. These are all just expierances I've had, either being careless, dumb, or lazy and the problem excalated to other problems.

Hope this may help