Iant333

Ok, well ive been having a thumping sound coming from my front end for about the past 2 monthes, and after having replaced my balljoints, u-joints, wheel bearings and checked my brake rotors to see if they were warped, I havent solved the problem. It clunks around 20 mph in both 2wd and 4wd and louder when turning.

Well today I decided to one more time to jack all 4 wheels up and see what it might be, it had me stumped again until I decided to hold one wheel and let the other one spin while I had it in drive. I was fairly confused by what happens. Unlike in the back where if you hold one wheel the other one spins faster and the one you are holding has a little bit of resistance due to the other wheel having drag. What happens is while the un-held wheel begins to spin faster the force on the wheel you hold isnt smooth, it goes BANG BANG BANG, the twist of the wheel you are holding goes on and off, like its hopping, as if something is skipping in the pumpkin.

I have a pretty decent knowledge of differentials but ive never heard of this happening before, and cant imagine what it could be besides perhaps a spider gear having broken or something, but also I dont understand how 4wd could work fine and me drive on it for 2 months like this without any problems. Basically everything works just fine but the noise is driving me crazy and the front diff shouldnt hop like that.

I'm about to go open up the pumpkin but i'm just wondering if anyone has any ideas in the meantime.

89eliminator

take of the cover and look around

89cherokeelimited

Ya it sounds like your spider gears. spider gears or or your bearings. It sux having to tear the diff apart but sounds like it's going to need it

Iant333

Ok well tore the pumpkin open and, nothing is broken, it all looks fine. I still cant figure out whats wrong but the source of the noise is the fact that the transfer case hops up and down, it has nothing to do with the axle it seems. I got it all on video since I didn't think i'd be able to explain it well enough. I dont see though how this noise tranlates into what im getting on the road as well, i makes a clunking sound at about 20-30mph with the wheel straight and about 5-30 with it turned, but above that speed it just goes away and everything is fine.


It seems like the transfer case is the actual problem here but I dont know crap about them besides they have a chain and some gears in them, so if anyone has any idea's go right ahead. I doesnt make sense to me that something like that would go bad after being only 70kmi old though.

I hopefully wont need a whole new transfer case after all the money i've been putting into everything else on it lately, but I guess we'll see. If I cant figure out what it is I guess ill bring it top the shop at school, they only charge like 20 bucks plus parts to work on stuff but I feel like that might be a big parts expense if the t-case is going bad.

UserID6095

This might be a stretch but what about the control arms? Are the bushings bad?

RENIXBEAST

X2 on the control arms mine was doin the same thing and it was the lower control arm bushings (axle side). I would also check transfer case chain, possibly stretched? Also check transmission mount and motor mounts because that transfer case shouldn't move that much.

WAD357

What do your u joints in the drive shaft look like? I know you said you replaced U joints but in the axle or in the driveshaft?

Iant333

I replaced the axle u-joints but not the driveshaft ones, and the front driveshaft has a little bit of play in 2wd but its all in the transfer case. The bushings are almost brand new, I replaced those back in July also, Ill see about what I can do with tightening the mounts, maybe its something that simple, I guess we will see. Thanks for the help.

Skreed

Take the front drive shaft off and see if it does the same thing.

93jeepthing

i am thinking driveshaft u-joints as well... maybe in the CV part, and it being so close to the transfer case maybe it is causing the case to "hop"? maybe try removing the front driveshaft altogether, drive it around, and see if it stops. At least that might give you a clearer idea of where to look. If it still happens, then you might want to start tearing into the case.

-Brian

93jeepthing

you beat me to it :-)

-Brian

xjod

Sounds to me like your chain is stretched in your t-case and slipping. Too much slack in the chain will cause it to slap the bottom of the t-case and slip.

Iant333

Ok, I took the front driveshaft off and the noise has now stopped. So what does this mean, do I need to get a t-case chain or can you re-tension the old one or is that not evenj the problem do you think? Also when I was taking it off the extension seemed a bit worn out, you could push the driveshaft up and down and it pivoted at the extension a little bit, or is that supposed to happen?

89cherokeelimited

Have to made sure your front driveshaft isn't out of balance. My front driveshaft was bent just a little bit and when I hit the road it shook the front of my jeep bad. You can get the shaft looked at or get a custom built one. I got a custom built for rear and front best investment i made... Well except I swapped to a NP231 also which was a lot better then the 242 i had. AND in my 242 my chain was stretched where it wzs rubbing the t-case I took the chain off and it still wobbled

So I dont think the stretched out chain will make it stop wobbling but it will save your t-case housing from getting scratched up badly and help you from snapping your chain while wheeling. While you have the front shaft out hold it straight up and down and look to see if you see any bends... wouldn't be a bad idea to get a pro to take his scale and make sure it's perfectly balanced.

Iant333

Ok well, got a driveshaft out of a 2000 at a junkyard for 70 bucks and put it in and everything now seems to be working fine, no more thumping so I guess thats good. Thanks alot for the help.