Bad front CV? Any experience?

I have been dealing with a driveline "grumble" for the past week and I have been trying to chase down where it's coming from. I THINK that I have it narrowed down to the drivers side inner CV joint, but I wanted to see what others, who have had that CV go out, have experienced.

First off, my inner CV boot is torn, and has been for the past few months. This grumbling noise started after spending three or four hours driving around on a dusty, bumpy dirt road last weekend. (now that I write this I have a feeling that I'm right in my diagnosis). The noise can be felt and heard only at highway speeds and usually only under load (when I have my foot in it or trying to maintain highway speed).

I have checked all of the usual issues: transmission mounting bolts (A-O.K.), engine mounts (just fine), transfer case fluid (little low, but had it topped off and noise is still there).

One of the mechanics at the shop that I take the VX to when it's beyond my abilities thinks that it might be the transmission and that it might need a re-build or might need a new one all together. That just doesn't feel right to me because the transmission pulls strong, doesn't slip, hasn't thrown a code and just generally feels solid, plus the noise only happens at higher speeds. I haven't heard any of the tell tale "click-click-click" noises from a bad CV, but my thinking is that since the inner CV is at the center diff, which is hard mounted to the frame, and any noise/ grinding that it makes would be transfered back through the frame and torsion bars and end up as a noise/ vibration that feels like it's coming from right beneath the seats.

This diagnosis is also backed up by the fact that if I put the VX in 4 low the noise gets worse and if I really get on the skinny pedal I DO hear the click-click-click from the front of the VX. One of the other mechanics in the shop took a drive with me this morning and he agrees that it is definitely drive line related and probably not transmission related.

For any of you that have had the front inner CV go out; have you experience a grinding/grumbling noise that you can almost feel more in the seat of your pants then you could actually hear?

CV's and half shafts are expensive enough, but a transmission would be PAINFUL (on my wallet) to replace right now.

Sorry for the long winded explanation, but I needed to get the symptoms across.

Thanks y'all.:thumbup:

Mine 'clicked' during decel. I didn't notice any vibration at highway speed. If it was there, it was probably hidden by the road noise of my Wrangler MTs.

If you've been driving with a torn boot, the CV is the most likely culpret. Stick your finger inside the boot & see how gritty the grease is.

I personally don't think you are looking at CV issues, normally they are either fine or blow in half. What you have sounds like driveline noise to me. Here is the issue discussed in our Isuzu manual:

http://www.vehicross.info/forums/sho...4&postcount=20

Hope that helps. I know some people on here that have run the VX for over a year with NO boots on the CV's at all. This could be your front driveshaft, have you checked the CV that is on there?

Usually a CV will be more evident going around street corners, not so much on the highway.

Your noise could be similar to what Lisa and a few others have experienced...was blamed on either the driveshaft slip joint or U-joints. Frankly, that seems more likely to me than a CV.

Noises can be tricky...I just thought I had a bad CV, but now it looks like the problem is actually in the diff itself.

Haven't heard from the mechanics yet, but I will definitely forward the information in the other thread LittleBeast.

Couldn't a CV go out without completely grenading itself? I would think that if you got enough sand and dust in the CV due to a split boot it would have to make some noise. The grease in the CV with the split boot is black and goopy.

I crawled under the VX while it was in neutral and tried to twist the drive shaft and banged on the U-joints. Everything seemed to be in order. No slop and I re-greased everything, but the noise was still there.

Hopefull it's nothing rediculously expensive.

Keep the opinions/ experiences coming.

I agree with BigSwede...check your ujoints and drive shaft. Is there any vibration with the noise....maybe something knocked your shaft out of balance?

how'bout a simple transfer case oil change?

Billy, I've been under the VX and looked at the drive shaft, although admittedly not THAT closely. It's still round, but I suppose one of the balancing weights could have fallen off of it. I didn't hit it on anything so I can't see how it would be bent. With the VX in neutral there is no slop in the u-joints, and they have been recently greased. Yes there is a vibration that you can feel in the floor and the seat of your pants when the noise happens. The noise and vibration only happen in third, forth and over drive and only at highway speeds (55 mph and above). I would think a drive shaft imbalance would show up at lower speeds too.:_confused

Luna-X, the transmission, front and rear diffs and the transfer case fluid was all changed about 30k miles ago with Amsoil fluids, so the should (I stress "should") be good to go. The Amsoil is supposed to be some kind of crazy milage fluid.

Thanks guys, I'll keep plugging away at it.

I think its your CV. Both of my boots ripped before Moab and destroyed the inner cups. I even replaced the CV joints but there is enough wear inside the cup to still cause clicking and vibration. I'm waiting on the RCV order to finalize (hopefully) before getting new inner cups.

Try putting the VX in 4lo and accelerating hard for a moment, if you hear the clicking sound then your CV is probably the issue. Also I would grease the driveshaft zerks to see if that fixes anything.

Let me know if you need any help pulling the CV, I just did all that work about a month ago.

Quote:

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Originally Posted by BigSwede

Usually a CV will be more evident going around street corners ...

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Yes, if it were an outer CV that had the torn boot.

The inners don't articulate on turns, only with suspension travel.

& yes, a CV usually makes noise before it explodes. Once a boot is torn & grit gets in there, the balls will wear pockets into the races. The clicking noise is the sound of the balls dropping into & out of those wear points.

Thanks guys. I keep thinking that it's the CV too. I've been under the VX and everything drive shaft related seems fine. No slop in the U-joints, the drive shaft doesn't move when I try to rotate it, and I've lubed up all three of the zerk fittings on the rear shaft.

Under normal driving conditions the CV doesn't make a clicking sound, BUT I did put it in 4 low and goosed the throttle a little and did get the tell tale clicking. The mechanics explanation for the noise at highway speed is that maybe the inner CV is shot and has been wallowed out by all of the yuck that has gotten into it, so that the CV "locks" into place out of round and the vibration/noise we are hearing is the front half shaft spinning out of round.

Still haven't heard back from the mechanics yet (they're getting a call RIGHT NOW) so I'll let you know what I hear in case this happens to somebody else.

For those reading this thread: If you notice the CV boots torn before any noise, then get them replaced ASAP. It's way cheaper to replace them, then to have to replace them and the CV joints.

I didn't hesitate to change both inner and outer boots a couple weeks ago when I seen grease splatter all in my wheel well.

Good luck Mark.


On a side note. I obtained all the info about products and how to with changing the CV Boots from this site. I love it here.