creepy_jeepy

Well, I crawled under the jeep again to look at trans mount bushings and I could not see anything out of the ordinary, but I decided to let the experts look at it and see if they could see what was going on. I took it in last night to a trans shop and they took it for a ride. They think it's the front drive shaft out of balance. I am dropping it off to them tonight so they can put it on a hoist and measure the drive shaft while spinning to see if it is true or not. I really hope this is the problem because to have the drive shaft balanced will cost around $125.00 which is not too bad compared to the other things it may be. So they will have it for a couple hours tonight and I should know what is really wrong with it. I will post tomorrow with what I find out. Thanks all!

thelaststarfighter13

I'm just getting to the jeep scene and I'll have my XJ in a week, but I might be able to help with my experience....here goes...

My POS chevy have automatic locking hubs, I'm guessing that these newer jeeps have them too cause no-one gets out to lockem anymore. If the autolock hubs go out and are in the locked position all the time then even though you are in 2wd your entire front drive train is spinning cause the hubs are locked. when you shift to 4wd then you are driving the front end in stead of the tires just turning the front end. In my old ford when the hubs were locked cause I was too lazy to get out and unlock them and I was on the highway in 2wd the front end would hum, slip it into 4wd and the hum was no where near as bad........Just throwin it out there but are your hubs locked up all the time??????

creepy_jeepy

Well, there may be something to that as well. I'm hoping the guys at the trans shop will look at that as well. I think the Dana 30 locks into the differential somewhere and the hubs are always locked in. I believe there is a sleeve that when activated slides over the axles to lock in the 4wd. I'm not quite sure about that though. The only thing is, I think the wheels would bind up when turning like in 4wd if they were locked even though the drive shaft is not engaged. But hopefully the guys can answer those questions for me tonight.

jd4x426

the thing your talking about is a vacum disconect it was only used in the cherokees for a few years in th eearly 90s not psitive on the years but the front is always engaged but it isnt under power from the motor because the transfercase isnt engaged

JuicyJuice4x4

if it roars and then sometimes stops randomly and then all of a sudden makes a LOUD clank and then starts again, its your 4 wheel drive actuator. mine did that because it kept trying to shift into 4 wheel drive so i put a manual shifter know in it instead of that crappy vacumm system

creepy_jeepy

Check this out! So, I take the jeep to 2 different trans shops. One place had it for 2 hours and could not duplicate the sound on the hoist, but could hear it on a road test no problem. After 2 hours the shop said they didn't know what the problem was and would have to start ripping the axle apart to find the issue. The other shop said it sounds to him like the drive shaft out of wack. So before I dropped a ton of cash on finding this issue, I decided to take it home myself and pull the front shaft and see if it made any changes at higher speeds. Well, sure enough, I pull the shaft and all noises are gone and vibrations are gone as well. Purrs like a kitten at 80 mph. I inspected the drive shaft and could see no dents dings or weights off. The slip yoke has a little bit of play in it up down. Not so much that I would think it would matter, but maybe thats the problem. I also put the jeep in 4wd and then drove at higher speed to see if there would be any change. I figured even though the shaft was not there it would still lock in the hubs and get everything turning in the diff. still no noises or vibes. So, is it the shaft? or when I buy a new shaft does the sound come back because something is not spinning with the shaft out? I think this rules out axle bearings, transfer case, pinion gear, but is there anything else it could be? If I had hair I'd be pulling it out!

creepy_jeepy

SUCCESS AT LAST!!!! I bought a new drive shaft today, threw it in and low and behold no more problems! I had a bad slip joint in the front drive shaft. It didn't wiggle much at all, but it was enough to cause major vibrations and a nasty humming on the highway. Who'd a thunk it. Well I really do appreciate all the help you fine folks gave me. I'm sure I'll have more questions coming soon. Lift and tires coming next. Thanks again! God bless.

RickBeer

Save your old shaft for a spare...You or another fellow wheeler may need it on the trail