Need Help... CV/axle question

[VXorado]

If I understand the design correctly, the CV axles drive the front wheels thru those bearing-to-groove slots in the joints. IOW, they act just like a gear, interlocking to move the axle.

While I understand how the design allows for 360-degree articulation of the wheel, there's one thing I'm not sure of....

In my past experience with a failing CV joint, I know exactly what a popping joint sounds like during a turn. I know how to tell when a FWD unit sounds when it's failing. My question is whether it's the same for 4WD.

Is it possible for failing CV joints/axles to make noise similar to a wheel bearing noise WITHOUT having the classic popping sounds while turning?

I notice some mild vibration around 55mph. In a thread about 1yr ago, I proposed it might be engine noise. But, I've yet to confirm that. Many talk about the noisy hwy performance of the VX, but I'm still not willing to give up on any possibility.

Any opinions on the possibility of CV joints making noise running in a straight line?

The CVs can cause vibrations if they're going bad.

First, I would check the u joints on the drive shaft as they will definitely cause vibrations if you don't grease them regularly.

..and put the VX in 4lo on an appropriate surface & make some circles. If you have CV problems, you'll hear them click/pop.

[MSHardeman]

Ditto what VXorado said.

When my inner CV boot ripped, and I didn't catch it until it was too late, I was getting some vibrations at various speeds that I thought was a drive shaft issue or a transmission mount issue. Got under the VX, greased the U-joints, and slip joint in the drive shaft, checked the transmission mount bolts and still had the vibrations. Checked the CV joints on the front axle and realized that the boot was torn, and gunk had gotten in there and effed up the joint. Had to have the green cup removed and re-machined.

Since the front axle is hard mounted to the frame, I was feeling the vibrations from the bad drivers side inner CV joint in the floor boards below my feet.

Also, check the transmission mounting bolts. Others have had some vibrations, or clunks, due to the bolts backing themselves out allowing the transmission to move around.

One more shot in the dark; check your engine mounts. If one is bad/broken it would allow things to move around and possibly cause a vibration.

[89Vette]

Had to have the green cup removed and re-machined.

How does that work? I picture it as the inside of a half-sphere with grooves for the opposite "knuckle". If the boot rips and it's contaminated, doesn't that cause scarring/pitting? How would you "machine" that out?

[Ldub]

How does that work? I picture it as the inside of a half-sphere with grooves for the opposite "knuckle". If the boot rips and it's contaminated, doesn't that cause scarring/pitting? How would you "machine" that out?

Try picturing it as a cylinder, with machined grooves, where the balls transfer energy, & are able to move in & out (mmmmmm...horizontal...)...then picture having BIGGER balls...after machining...

[MSHardeman]

How does that work? I picture it as the inside of a half-sphere with grooves for the opposite "knuckle". If the boot rips and it's contaminated, doesn't that cause scarring/pitting? How would you "machine" that out?

Sorry, must have totally missed this earlier.

You are right. When my boot tore and I didn't replace it relatively quickly, junk got into the green cup and as things moved around without grease the green cup got pitted and scarred. The green cup is just that; it's a straight walled "cup" that has grooves in the walls. Can't think of the best way to put this, but the grooves run from the bottom of the cup up to the lip of the cup. When everything is together in the VX the cup lays on it's side so the grooves run horizontal (parallel to the ground). The balls of the CV joint them seat into the grooves so that they can move in and out (parallel to the ground), but can't go anywhere else. As the cup rotates the balls must rotate with it because they are in the grooves, and that is what transfers power to the wheels. Does that may any sense?

Bart has a great write-up with pictures, and as "they" say; picture are worth a.....you get it:
http://www.vehicross.info/forums/showthread.php?t=21040

Like Billy (Triathlete) said, the front axle was removed and sent to a machine shop where they welded up/ filled in any of the pits or scars and then re-machined everything back into spec.

[89Vette]

Like Billy (Triathlete) said, the front axle was removed and sent to a machine shop where they welded up/ filled in any of the pits or scars and then re-machined everything back into spec.

I had looked at the forum's reference on the subject...which were good enough (great enough) for me to visual the units. I just couldn't figure how they go in and "de-scar" the cups.

Interesting...