Topic: knocking in 4wd

[stan98tj]

New noise the jeep has been making recently. When I engage 4wd, i get some type of "thunking" or knocking from the front end. Doesn't happen in 2wd...if it does, it's too low or faint for me to feel or hear. 4wd does work, it's just that I'm not sure where this noise is from. I grabbed the front driveshaft and it didn't seem to have any play in it. Could it be a blown hub? Bad drive shaft? Would 4wd engage if it were a bad hub?

[Jeffy]

Are you turning when it knocks?

[sharpxmen]

bushings on control arms maybe (or the joints if you upgraded)

is it knocking when you engage or when you start from standstill (anyway, i mean details on when the knock occurs).

[stan98tj]

turning doesn't affect it, knocks either way. the knocking slows down as I slow down, loud at first and then sorta subsides a bit (but that could be cause I may not hear it as well while driving?)

[sharpxmen]

so is it 1 knock or repetitive (i assume that's what you mean by slowing down as you slow down). in that case i say a u-joint or R&P

one thing you can do is suspend the front and and keep it in 2wd, rotate each wheel and see if you hear something (lift 1 wheel at the time if you have an open diff or selectable so the d/s rotates) and if the knock is there try to figure out where it comes from (a buddy rotating the wheel would come in handy here).

[Bounty Hunter]

Could be a worn chain in the transfer case, they can slap the inside of the case when in 4wd.

[stan98tj]

Update:
New Years day, I'm on my way home at about 1am and I get on the highway, at about 50mph I feel a very strong and loud vibration pulsing through the entire cab. I reduce speed to about 40, seems to be ok and then gets worse until a series of loud knocks, bangs and shakes and the sound of metal scraping on metal forces me to pull over. ATF fluid is pouring from under the jeep, pieces of my transfer case are laying in the transmission skid. Time to call the first tow of the year, i'll have to wait til daylight to remove the skid....happy F*&%ING new year.

[neale_rs]

Sorry to hear that. 

[stan98tj]

Sorry to hear that. 

Just Empty Every Pocket? been my new years resolution since 2007

[Jeffy]

Well, I think the knocking was the first clue to not drive it. 

[stan98tj]

Well, I think the knocking was the first clue to not drive it. 

it was only doing it in 4wd at first...then it did it in 2wd, but i was already on the highway then 

[stan98tj]

OK, so the case is grenaded. I have pics ill put up later. I'd like to know what my options are.
Can i run any t-case out of a TJ? I have a 3spd auto, by the way.

Also, is there any way for me to run a Rubicon case? I've also heard of the terra four low kit. Any opinions? If i can't run a rubi, could i gear the stock case to have 4:1 like a rubi?

[sharpxmen]

i think the rubi would work, never measured to see if there's any difference between transmissions at the output shaft and housing (as far as clearance for the t-case input) but from what i recall the NSG and NV3550 are very similar (same depth roughly) - i have both in my garage and i can do some checking/measuring if you really considering it. The things that i think would need attention would be the driveshaft (rear) and the speed sensor (different inpulses/mile). Possibly the t-case shifter as well but that's probably easy to adapt (if there's any difference, i'm not sure).  

EDIT: i can't remember if you have a 6 cyl or a 4 cyl, if the latter forget about the rubi t-case, you need the transmission as well.

[stan98tj]

i think the rubi would work, never measured to see if there's any difference between transmissions at the output shaft and housing (as far as clearance for the t-case input) but from what i recall the NSG and NV3550 are very similar (same depth roughly) - i have both in my garage and i can do some checking/measuring if you really considering it. The things that i think would need attention would be the driveshaft (rear) and the speed sensor (different inpulses/mile). Possibly the t-case shifter as well but that's probably easy to adapt (if there's any difference, i'm not sure).  

EDIT: i can't remember if you have a 6 cyl or a 4 cyl, if the latter forget about the rubi t-case, you need the transmission as well.

I def have the venerable 4cyl + 3spd auto. So i take it the Rubi is a not an option? I thought the 3spd 4 banger trany had 23 spline like the rubi?

[Jeffy]

I think the rubi might be a possibility. Your auto and the 4.0L transmissions use a 23 spline long shaft.  Not only do you have to match the spline count but also the spline length. Early cut and late cut relate to YJ's and TJ's, IIRC. http://www.novak-adapt.com/knowledge/np_nvg_input_gears.htm

For any other NP/NVG 231 you can mix and match to get it to work.  You just need to swap your input shaft and possibly the rear housing and output shaft.  -J is for Jeep, -C is for Chevy, D- is for Dodge.  I think there's also a -HD as well that was used in the Dodge 1500.