I just got my 97 wrangler 3 days ago. Last night it started making really loud knocking noises and it only happened while in motion. It feels like the front end keeps locking up then breaking loose. It still shifts fine and the engine is still running perfect. So i'm inclined to think that it's the transfer case. I've done alot of work on cars before, but never on a jeep, so I'm not really sure. Any suggestions?

i removed the front drive shaft and the problem persisted.... so must not be the transfer case. maybe the front differential is shot. again, any suggestions would be great

Pull the cover and see what u have! My buddy had the same problem and it was his ring gear but you never know. Also check your axle u-joints, and hubs you never know what it might be till you get into it. Good luck!!!

NP 231 T-case's are very simple to work on, only special tool you need is a big set of snap-ring pliers.

I gues check to outer hub assmbly too. could be a hub?? dunno much about tj's sorry.

These is not much to check on the unit hubs, they are a sealed assembly so they cannot be rebuilt or opened up. If the problem went away when you took off your front drive shaft it leads me to belive it is in the t-case. This is because even if your in 2wd the internals of your front axle will still spin while being driven down the road. This cause the front drivehsaft to spin, wich spins some of the internal parts of your t-case.

so, i realized that it's actually the rear that's locking up not the front. i had a friend drive it 10 feet down the street.... i guess i'll take the transfer case apart and go from there. it couldn't possibly be the transmission could it? the front wheels don't have the same problem as the back.

This message has been edited. Last edited by: TJChuck,

Since you now have things narrowed down to the rear axle....
(1) Check the u-joints in the rear drive shaft.
(2) Check the output shaft yoke on the t-case to see if it's loose.
(3) Check the yoke on the rear diff to see if it is loose.
(4) Pull the diff cover and check for damage to the ring and pinion as well as the spider gears(or TracLock unit).
(5) While you're in there, pull the axle shafts and check the splines for any twisting or damage.
(6) Check all the bearings

All this stuff look good? With the front and rear drive shafts removed, start the engine. With the transmission in 1st gear, run the t-case through all modes (2 & 4 Low, 4High, and Neutral) and listen for noises.

Next: Since you bought it used, is there any chance the rear diff has a locker in it? Some tend to be noisy when they engage or disengage, and can cause the tires to *chirp* when going around a corner. Quick way to check is to jack up one tire and try to spin it forward ( Don't forget to leave the brake off and the transmission in neutral for this check!) . If it won't move, chances are theres some type of locker in there.

BTW, are you running a D35 or 44? D35's are notorious for breakage! If you're running 33" tires or bigger they will seriously shorten the life af a D35.

Now that you say its the rear axle, I would seariously just pull the diff cover on it and look for damage. Chances thats your problem.

so yeah there was definitely some busted teeth in the rear differential..... any suggestions on where to go from here? i.e. a rebuild or a replacement. lowish budget, but if better parts available for not too much extra cash then will definitely consider

Well, there is only one thing to do. Rebuild the rear axle. If your housing is strait then there is no need to replace it. What size tires do you have? If they are 32" + range then it might be a good time to drop some lower gears in the axles. However you will have to do both front and rear axles if your going to change the ratio. If your on a tight budget then just replace the gears with the same ratio you have in there and that will solve your problems. However setting up gears is not something that the adverage Joe mechanic can do, take it to a shop with a good rep. on doing gear work.

hey thanx, yeah i don't really have the cash right now to change out the ratio. i think i'm just gonna get stock ones thrown in there. i do have 35" tires on there, but right now i just don't have the money to throw down on it like i'd like to. i appreciate all the helpful advice

Glad to be of help. 35" tires and D35's don't always get along very well! When you replace the gears, try Yukons. They seem to have a good reputaion. Our local hard core shop recommends and uses them on his rig.
When the budget allows, you need to swap in:
(a) Dana 44
(b) Ford 9"
(c) Ford 8.8"

My personal favorite is the 9".

one more thing.... to be honest i don't know if the ratio has already been changed. i bought the jeep from a dealer and consequently was unable to talk to the previous owner. how would i be able to figure out if it has been changed, and what has it been changed to? if that's even possible

When you take it to a shop they should be able to figure it out by counting the teeth on the pinion and the ring gear. If you want to get a rough idea of what they are this is what to do:

First sence your rear axle is blown, you going to have to do it with the front end.

So, Lift both front tires in the air.
Mark a spot on the driveshaft or the yoke.
Then turn one of the tires a FULL rotation (360*) while counting how many times the driveshaft makes a full rotation(thats what the mark is for)

For example, if you spin the tire one time and the drive shaft spins three and a half times, then your gear ratio is about 3.50 +/- get it? Then apply that to the gears avaliable for that axle and your closest guess would be 3.54 gears.

An other example, if you spin the tire one time and the drive shaft spins around a little more than 4 and 3/4 times, then your best guess would be 4.88 gears.

Here are some common gear ratio's found in Jeep axles,

Factory gear ratio's:
3.07
3.54/3.55
3.73
4.10 (4cly only, or Rubicon modles)

After market:
4.10
4.56
4.88

Hope that helps your some!

thanx a ton... i've learned alot these last 4 days(i've had my jeep for 4 days), with still alot to learn. if all goes well i can get it to a shop in the morning and be back on the road in no time.
i'll post again and let you know how it goes

If you purchased it from a dealership, take it back and tell them to check it out. That is unless you took it out a day after you bought it and jacked it up. Im sure there is no warranty, but it cant hurt to have them look at it.

yeah no warranty.... that plus the fact that the dealership is about 2hrs drive makes it a little difficult. i am calling them in the morning to see what they can do for me, but i'm not too optimistic.

You should be able to find an entire stock axle (assuming one of the stock gear ratios) for cheaper than you can get it rebuilt. Try to get in touch with the local 4x4 club and see if they can help you out. Most people swap out the rear axle ASAP, and there are generally lots of D35s in good shape floating around.

Im in the same boat bud so dont feel alone. Had mine 3 months and drove it about 3 weeks. I already blew out 2 dana 44 rears. Now im faced with the regear option!!!! Sux with no money!!