mfisher2112

I have a 96 grand cherokee limited 4.0 that I have put enough work in to that I don't want to give up on it now.

It has a severe road "hum" over 45 mph. The hum goes away if I accelerate, but is severe at constant speeds.

Today it developed a "knock" or "click" coming from the rear of the jeep.

It's to the point now that I am afraid to drive the thing any further than I absolutely have to.

There is no shake or vibration in the wheel at speed, or when braking.

I've been told rear wheel bearing or rear differentials.

I don't want to drop the cash on a new rear if it is just bearings, but I don't want to waste the effort putting new rear bearings in if the rear turns out being bad.

Any thoughts?

Bustedback

Cheaper and easier to swap in a used rear axle. I would pull the cover off of the one in your rig and look for signs of metal in the oil and at the bottom of the diff housing to confirm there is a problem.

mfisher2112

I'm currently searching for a used rear.

Do you think the issue is the rear?

mfisher2112

Found a rear. $250 with core was the best I could find on such short notice. Hope this solves the issue. Only have 1 day off work to get this handled.

Bustedback

You should be able to get it done in a day, it is really pretty simple. Just be careful and use jack stands, not blocks of wood or cinder blocks, jack stands.

mfisher2112

Thanks. I have a couple of sets of 3 tonners. I always use 2 sets. Used to work on mustangs all the time when I was a kid, but never done a rear swap on one of these before.

ol"blue

Welcome to CF. Just be sure the gear ratio matches the gears in the front axle if you have 4WD. If you have the V8 you probably have the D44a rear axle with 3.73 gears. With the 4.0L 6 cylinder, you have the D35 axle with 3.55 gears, or you may have 3.73's with the tow package. There should be a tag under one of the bolts holding the rear differential cover on, and it should have the gear ratio on it.

mfisher2112

I'll double check it in the morning when I get her off the gvround, but my understanding was the limited 4.0 had the spicer d35 with 3.73 gears. Is it possible it has 3.55? It does have the tow hitch.

ol"blue

Most, if not all, 4.0L ZJ's without the tow package came equipped with 3.55 geared D35 rear axles. The tow package usually added the 3.73 gears. Anything is possible when they were ordered/built, and over the years previous owners could have changed things.

mfisher2112

That's a good point. I'll double check it when I get it in the air in the morning. Thans!

ol"blue

Okay. It could also be that someone added the hitch later. Just a thought.

Good luck either way.

mfisher2112

Checked it out. Tag said 3.73, so the new rear was correct. Once I got it up in the air it was abundantly clear the differential and both wheel bearings were shot. Glad I went with my gut and just went with the rear.

Got the old rear out. Took me nearly all day to do that. New rear is stripped of extraneous parts that were still attached except for one sway bar bracket the junk yard obviously couldn't get off and just cut the bracket.

Going to have to try to get in position myself later this morning.

Replacing shocks while I'm under there. Drivers side shock had a baseball sized hole rusted through it.

I'm honestly surprised this thing hasn't killed me by now!

ol"blue

You lucked out on all accounts.

mfisher2112

Yeah, until the very end. Got the old one out, managed to muscle the new one in place by myself, everything was mating up perfectly. Went to bolt the driveshaft on to the differential and snapped one of the tiny little bolts off in the yoke. Awesomeness at its finest. So frustrating.

ol"blue

That sucks. Are you going to try and remove the broken bolt, or just swap yokes with the one from the other axle?