need some advice on diagnosing a problem

[Primer88]

My fiance's 02 Supercab XLT 4wd automatic has a strange clunk when leaving from the stop. This truck is 99% street driven and according to carfax the previous owner had it under a lease. I don't see any signs of offroading as the paint is super clean/no dents anywhere on the body or frame so I doubt he was hotrodding it on the trails.

The clunk happens when you leave a stop under in low to moderate acceleration. I can't feel it under hard acceleration.

The clunk happens once or twice leaving from a stop, you can't hear it at all. You can just feel it. There is also no humming from the rear or front. The clunk feels like it's coming from the rear. I've been under there a couple time rackin on the driveshaft back and forth as well as trying to rotate it (tires still on the ground) and there is zero movement. I also haven't noticed any unusual amount of play in the rear axle with the rear end jacked up off the ground.

Any tips for trying to diagnose the problem? My first thought is u joints but I've never had to mess those before. My last 2 rangers (lowered 2wd) never had a problem like this so I've never had to dick with it. I'm also not a 4wd guy so I wouldn't know where to start with checking the front end for possible known problems on these trucks. I'm 99& certain this clunk is in the drivetrain and not in the suspension.

again, it's a 2002 4.0 4wd automatic supercab. 1 piece drive shaft and 8.8 rear end, 4.10 gear with factory limited slip (all factory)

 

[Sasquatch_Ryda]

Pull the rear drive shaft, check both u joints. If that doesn't point you in any direction, separate the slip spline on the drive shaft, clean the splines and old grease out and re lube it and reinstall.

 

[Mark_88]

My suzuki clunks when I take off from stop lights...no noise, just that clunk...mine is the front brake pads...they move around and that may be because they do not have the anti-rattle clips and it's been doing it since I've owned the truck...it doesn't do it so much since I changed the front pads, but I can still feel it...

Yours might be drive train or something else, but I'm willing to bet (not much till I get working) that yours is probably the same thing...

 

[Primer88]

I don't think it's the pads, I had a similar problem with the front pads on my 00 ranger. This clunk can be felt through the the whole truck. Best way I can describe it is that it feels like something back there is catching up with the rest of the rotation of the driveline. I didn't mention this in my original post but the clunk happens after I begin moving. it's not a clunk, then start moving.

I will however check out the pads, it needs to be done anyway.

 

[shadetree]

I would lock the emergency brake where the truck can't move, then have someone rock the truck back and forth and watch the drivetrain, and related components and see if I could cause the noise. It could be anything, shock/spring binding/lose, worn hangers, etc. Some earlier models had a problem with one of the spring leaves binding and would make a thumping noise. There is a Ford SB on this particular problem.shady

 

[snake]

That was a common problem on 4X4 trucks, was even a TSB on it some years back. The slip joint on the driveshaft runs dry and starts to thump- the quick, temporary fix it to drop the shaft and lubricate it, but the longer permenant fix is to replace the whole damn thing. At one time Ford was helping to defray the cost of the repair, but I think that deal expired a long time ago.

 

[Primer88]

Thanks, I'll start with the slip joint and go from there.

 

[Primer88]

It was the slip yoke, thanks.

 

[snake]

Cool beans.