I have a knocking sound underneath that I think normally sounds off when I come to a stop and then begin to accelerate again. I dont believe I hear it when I'm turning or coming to a stop, just after I've stopped then hit the gas again. Is this something that's common and there is a good place I can start looking?
Also, this sounds very related, but when I'm driving and then let off the gas and start to coast, but then hit the gas again, there is a mild knock or clunk then as well. This is the same type of scenario when stopping then starting to go again......
So I'm wondering what could be loose or worn out so I can check it out without spending 45 minutes under there moving stuff around trying to get a clunk sound.

Rear sway bar bushings or links? Shock connection points?
It doesnt feel like its play in the driveshaft....

 

Okay well I think the knocking sound isn't exactly random but it's not consistent either because I can kind of get it to do it if I hit the brakes hard enough and then if I hit the gas hard enough while cruising... and it did not do it every time I came to a complete stop then hit the gas again to start moving again...

 

You description is a little too vague.

I assume you don't feel anything coming through the steering wheel so it's not the front suspension. Also, acceleration usually doesn't affect the rear suspension to the point of making a knocking sound.

Is the knocking sound immediate upon accelerating? Is it a single knock? Multiple knocks? If it's a single clunk you need to check the u joints because that's a likely culprit.

Only other thing to clarify is if the knocking sound is simultaneous with the tranny shifting. I know that's an obvious one that you would notice but just crossing all of the i's and dotting the t's.

 

Nope not the front. At least I don't think because it really sounds like it comes from underneath the back. I don't feel it, just hear it. It's 1 clunk when it happens. The clunk is immediate upon accelerating and it doesn't happen again really until I come to a stop and start going again.
I I was just wondering if something was shifting back and forth when accelerating and stopping...
I'll get out there underneath it and a little bit and try to move some stuff around with my pry bar and see what I can get to move.....
if anything I'll put it up on four jacks and have my wife get inside and put the thing in drive and hit the gas while I'm laying underneath of it. Totally just kidding......

 

With it being a single knock I'd look closely at the u joints.

 

Let's pretend it's a u-joint.... What's a good recommendation for replacements if I plan on lifting for doing some mild wheeling? Something strong & greaseable. 3" lift for now.

 

Sometimes you gotta do what you gotta do...

How do your motor and trans mounts look?

 

HA HAHAHAHAAHAH.....
if anything I might say it's the trans mount. Motor seems solid... I'll put it on my list of inspection points though

 

How much rotational play should be in the front DS? I have ZERO play in the rear, but probably almost half an inch of rotational play in my front DS....
side note.... I have hard steering when sitting still idleing, almost like I have no power steering. Also, and here may be the worst part, I have a horrible howl from the front end when I get above 60ish. So, with all this known, could I have a front axle gear problem? Too much play, loud howl at high speeds, and almost like binding when trying to turn while moving very slow.

 

But the power steering may be a separate issue and not any kind of binding in the axle...
and 4 wheel drive seems to work fine. Still howls in 4x4.
I have to assume the fluid in the front diff is fine because the PO was meticulous in maintenance. He was a retiredmretired in the military.

 

If you're not in 4WD you shouldn't have gear noises from the front.

 

Suspension bushings can make noise when stopping and starting off if they are worn.
I just replaced all front and rear bushings to cure a similar clunking on my sons 98 xj.

 

I dont think I would call it a gear noise. It seems much too low pitched and loud to be the gear. More of a roar than a whine. Its a low frequency constant loud noise at 55-60mph+. But I digress, that may be a separate issue. Or not if its related to the drive shaft play, which could be the knocking sound I hear as it takes up the slack when I hit the gas...

Does anyone know how much rotational play should be in the front drive shaft while sitting in park? Like I mentioned, I have about 1/2" of rotational movement in the front DS while sitting in park, in 2WD. I didnt think about putting it in 4WD to test the play. I can do that this evening when I get home...