Bad vibration may have found the problem

Sport · **Posted:** Tue Jul 07, 2009 8:51 pm

I was looking closely at the driveshaft by the TC and axle. Where the driveshaft connects to the axle I noticed some cracked seals and grease, is this area called the U-joints? Well would this be the cause of my vibration issues and if so is there a good after market option to replace these?

Jeepjeepster · **Posted:** Tue Jul 07, 2009 9:18 pm

Are you talking about the front drive shaft or the rear one?

If youre talking about the rear one I do not know of any seals that you can visually see crack but the U-joints can cause vibrations.

The front driveshaft has boots that can crack/tear and will cause the joints to go bad. It has a CV joint.

Sport · **Posted:** Tue Jul 07, 2009 9:28 pm

it is the rear and I am talking about the U joint. After a little internet searching I confirmed that is what I am talking about. the picture below shows the black rings that I am calling seals that are cracked and exposing grease..

djui5 · **Joined:** Tue Jun 17, 2008 1:38 am **Posts:** 536

What kinda vibration is it causing? Mine is vibrating around 70mph+ and I can't for the life of me figure it out.

Sport · **Posted:** Tue Jul 07, 2009 9:54 pm

I guess you can say a hum and right around the 40mph mark I get a shudder.

Sport · **Posted:** Tue Jul 07, 2009 9:56 pm

Where can I get new U joints? I found Precision on Summit but there are too many to figure out.

http://www.summitracing.com/search/Bran ... toview=SKU

Sport · **Posted:** Tue Jul 07, 2009 10:10 pm

ok, got it narrowed down to 2, does anyone know which one??

http://www.summitracing.com/search/year ... s=Rank|Asc

Sport · **Posted:** Wed Jul 08, 2009 9:16 am

Well, I bought them both. One is super and the other isn't but they are both the same style so they both will probably work.

I will let you know if the vibes go away.

djui5 · **Joined:** Tue Jun 17, 2008 1:38 am **Posts:** 536

Please do. Gonna check mine tomorrow

phxtoad · **Posted:** Fri Jul 10, 2009 12:08 pm

Randy - What you didn't inspect them when flopped?

Todd

djui5 · **Joined:** Tue Jun 17, 2008 1:38 am **Posts:** 536

phxtoad wrote:

Randy - What you didn't inspect them when flopped?

Todd

hahahaha

Found out what the problem was today. One of my CV's were clicking and Phoenix Rack told me it was where the inner axle splines meet with the CV. Sure enough, got an axle assembly from AMC4x4 and had Todd put it in today. The one in my heep was really rusted. So rusted that the splines were not meeting where they should be and were skipping, plus it had a lot of play in it, kinda like a bad ball joint. Put the new (used) one in and I hit 90 with very minimal vibration, which could be a number of things. So the major vibration is cured

Jeep didn't seal this connection from the factory, so when you drive through rivers and such it gets water in there, which starts the rust, which leads to failure. I'd recommend taking out the assembly and putting some silicone seal around where the large part of the CV meets the axle shaft. You'll see what I meant. I think the drivers side is next.

Oh I checked the rear U-joints while it was on the lift and they seem just fine. Now all my suspension bushings front and rear are a whole nother story :lol:

XJMA · **Posted:** Fri Jul 10, 2009 8:24 pm

To check the Ujoints, with it in park (parking brake for safety, yada yada) just get under there and try to rotate the shaft. Get your hand in there and feel the connection. The driveshaft should rotate just a tiny bit, a few degrees, and if there is any play at all between the driveshaft and the yoke, the Ujoint is bad. If not, just pump more grease in there and you're good. If the Ujoint seals are cracked, it wouldn't be a bad idea to replace it.

Now there are greaseable and non-greaseable Ujoints, and it's debateable as to which is better....the general thoughts are if it gets water a lot, greaseable are best because you can replenish the grease, but the thinking on the non-greaseable is that when you grease the greaseable ones, you're also introducing a little dirt that was on the zerk....so if the seals last on a non-greaseable, they should last longer....either way, they both get the job done. I usually go with greasable on the drieveshafts and non-greaseable on the axles, but whatever works.

kj-dec · **Posted:** Sat Jul 11, 2009 4:52 pm

XJMA wrote:

To check the Ujoints, with it in park (parking brake for safety, yada yada) just get under there and try to rotate the shaft. Get your hand in there and feel the connection. The driveshaft should rotate just a tiny bit, a few degrees, and if there is any play at all between the driveshaft and the yoke, the Ujoint is bad. If not, just pump more grease in there and you're good. If the Ujoint seals are cracked, it wouldn't be a bad idea to replace it.

Now there are greaseable and non-greaseable Ujoints, and it's debateable as to which is better....the general thoughts are if it gets water a lot, greaseable are best because you can replenish the grease, but the thinking on the non-greaseable is that when you grease the greaseable ones, you're also introducing a little dirt that was on the zerk....so if the seals last on a non-greaseable, they should last longer....either way, they both get the job done. I usually go with greasable on the drieveshafts and non-greaseable on the axles, but whatever works.

Greasable joints also can have a 'weak spot' where the zerk fitting is located, if its between two legs. The drilling/threading creates an area where a stress crack is more likely to form; usually only a problem with a lot of power/torque drivetrains. I doubt a stock Liberty would be affected

Zerks in a bearing cap don't have that problem, but can get banged up or broken off easier.

We had a U-joint fail at the zerk on my Dad's old truck; turned out it was a furrin' POS replacement that a shop installed and it died within a year. The Spicer brand replacement lasted the rest of the life of the truck.

Sport · **Posted:** Sat Jul 11, 2009 8:20 pm

Replaced the joint today and bada bing, no more vibration. You should have seen the condition of the caps and seals. two of the caps had literally a tablespoon worth of dried mud and another cap smelled like it had been burnt and the grease was black. Not sure what was going on there but the new one is nice and greasable.

DieselsRule · **Posted:** Sun Jul 19, 2009 9:07 pm

This discussion was most helpful to me. I checked front tires and found "cupping" on the inside. four new tires and a front end allignment took care of the noise and steering column vibration. with all this racket cleared up I could feel a vibration under load. The rear shaft ujoint at dif. was one of the worst I have ever seen! I pressed a new joint in and the ride is so smooth I have to watch the speedo to keep it legal!

Bad vibration may have found the problem

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