"Clunk" While Accelerating and Braking
 

So my '99 F350 4x4 is making a clunking sound and there is a distinct jolt in the truck while this is occurring.

Symptoms:
From a stop while accelerating, there is a distinct jolt and clunk. The best way I can describe the feeling is like something isn't tightened down all the way so there is a split second while inertia is generated and the "looseness" catches up to the acceleration.

When stopping, the clunk and jolt is generated when the truck comes to a complete stop. When the truck rebounds backwards a bit because of the suspension pulls it backwards after stopping, you will hear the clunk again.

I replaced the ball joints a week ago an a wheel hub bearing on the right side. I don't recall this before these repairs, but it may have been making this noise. I was more focused on the grinding from the wheel bearing so I may not have noticed the clunk and jolt then.

Any thoughts on where I should start looking for the problem?

Drive shaft skip joint needs grease.

X2 on the slip joint.

Yep slip joint needs grease. Mine is doing that same thing but I just need to find the time to do it. I would post the link on how to do it but im on my phone. Maybe someone can post it for ya.

I have had bad U-Joints behave that way too. Once I had a U-Joint that only had one of the four bearings go out so you couldn't feel it by hand but the truck's torque caused it to move enough to make it clunk on acceleration and deceleration.

Good Luck!

Slip joint needs Teflon grease.

I hate to mention it could be the crush sleeve at the pinion gear also.
I hope it's just a grease issue. Mine wasn't !!

mine has the same issue. i have been under there tightening everything and searching to find the answer.. guess i need to greese mine to.. can anyone post pics of how ans where and what type to use..

If you're still having issues, I've had the same issue before. Started after doing work on the hubs.

Go back under the truck and retighten the caliper bolts. It seems I have to do this about 50 miles after I get the truck back on the road every time I pull the brakes.

That is why you are hearing it as the weight shifts back too, it is rotating the caliper just a hair around the hub, and it produces a thunk that you can hear and feel.

Try that, couldnt hurt to check it anyways, it takes about 2 minutes to do all 4 corners.

Still having trouble? Check out the motor and transmission mounts, the rubbers might needing repolacement.

Heres the thread:

https://www.ford-trucks.com/forums/11...=droldsmorland

Some other bits of useful info here too. Scroll down to the bottom of page 1. Then the grease PN is on page 2. Yes only use the FOMOCO grease! I learned this the hard way.

link
 

I could not get on the page you listed Bad link?

I had an issue almost like this.. when stopping hard and keeping the brakes held, once I let off the diff would unbind and you could hear and feel a clang..greasing the splines on the drive shaft going into the transmission was the fix..

try this link or do a search under my name or "mysterious-thump....Some other bits of useful info here too. Scroll down to the bottom of page 1. Then the grease PN is on page 2. Yes only use the FOMOCO grease! I learned this the hard way.

https://www.ford-trucks.com/forums/1...=droldsmorland

Got it thanks, I am going to do this with ujoints this weekend