CV Joints: How to tell if they are bad? Urgent.

[Cerbin]

Lately i have heard a sound coming from the rear of my car, kinda a rotational rubbing sound, you can feel it a little bit as well. The sound is not constant like krrrrrrrrrrrrrrrrrrrrrrrrrrr but rather krrr krrr krrr krrr krrr krrr. The sound speeds up proportional to the car speed (not engine speed). I think it might be one of the four CV joints, but am not sure. When i have the car jacked up though with the wheels off the ground, i rotate the wheels and no sound.

I noticed that a few of the joints wern't totally snugged up and and that some grease had been flipped onto the underside of the car.

Question is: Any ideas on the sound?? Is there a way to check the joints w/o removing the whole joint? and is there anything i can look for on the joint besides wear on the ball bearings or associated parts?


Thanks in advance. Timely repsonsed appreciated.

Patrick
PS. my car is really lowered, but this sound has not been an issue until recently

[Cerbin]

i have 901 trans. and lobro type half shafts.

Bump.

[Groesbeck Hurricane]

Patrick,

Check to see if the boots are intact. If the joints are not snugged up then you are on the way to loosing them which could cause other damage. Dirt can enter the CV Joints via damaged boots or when the joints are not snug.

Safely jack and support your vehicle and work on one side at a time. Remove the tire and then you can inspect the two boots on each half axle. If the boot is damaged or the joint is loose I would suggest removing the half axle and investigating the CV Joint. You will need new boots and new bolts if you need to remove!

This is a messy job. Inspect the balls and cages for damage or wear. Everything should be smooth and shiny with no scoring. If there is scoring or the cages are damaged then you will need to replace the CV Joints. If the joints are in good shape (post photos for opinions) then you can easily repack the bearings and replace the half shafts. Many people suggest changing the side of installation of your half shaft to even out wear.

This is not a difficult job, but is messy. If you are hearing the metallic noise from your CV Joints they may well already be bad. But no one will know until you remove them and inspect. Keep us informed!

[Superman]

David's advice is on target. Your symptoms do not sound like CV joint issues, though. So, I'd assert you have two issues. One is a rubbing problem you have not located yet. Another is the possibility of dirt in your CV joint. Dirt will kill your CV. Remove, disassemble, repack.

[nostatic]

If it is the CVs, shouldn't the noise be worse when going around corners?

[Superman]

Yep. They can make a clicking noise and they can make a rumbling/shuddering noise/vibration thing. They don't sing or growl or rattle or scrape.

Scraping noises are gong to be cause by a rotational body contacting a stationary one. "Duh" you might say. I tend to give simple advice, but then problems tend to have simple causes. Id say the tire or brake rotor is rubbing against something. Get a passenger. Roll down the windows and go to a quiet, smooth parking lot. You'll find the wheel.

[Groesbeck Hurricane]

Super,

Thank you! I had a nagging suspicion about the rubbing but did not put it together with the fact the car is "really lowered." Could this not also be caused by the rear shocks going bad or wheel contact with the oil lines?? Thanks,

[Cerbin]

Thanks for the info guys... i rechecked the boots and they are a little dated but have NO tears in them. I will try to locate any wear on stationary objects around the rotating parts indicating rubbing. (i like the idea of having someone drive the car and so i can pinpoint which side it is on)

There is no gasket b/t cv joint and hub and tranny? correct?

Patrick

[BK911]

It could also be wheel bearings. One of mine was bad and made a noise that was proportional to speed. The noise also fluctuated with steering input.

[bigchillcar]

While we're on the subject here...my car has been making a clunking sound as I step on the gas, particularly in low gears. For instance, I'm just rolling along without gas and then tap the gas pedal, I hear a clunk. Its sounds like slack somewhere in the drivetrain. What I'm wondering though...is it the cv joints (my boots are intact) or the transmission itself? Why do I suspect a tranny teardown may be in my not so distant future? Patrick, I hope I haven't stolen your thread by asking.
Ryan

[beepbeep]

There is easy way of checking for worn CV's that worked on my 930:

Just cruise at idle on flat ground in 1:st (930) or 2:nd (SC), if you hear bucking and clunking your CV's are worn.

After i replaced all CV's, i could drive at 800 RPM w/o any bucking or slack.

[bigchillcar]

beepbeep,
that's what I'm hoping for...worn cv's. If I jack the car up, put it into 4th gear so it's easy to turn the transmission by turning the tire, there's slack of maybe 5-10 degrees (guess) before the transmission is actually being turned. Sound like cv's?
Ryan

[BK911]

It only takes a couple of minutes to pull the cv’s off the car. Take them off, inspect, clean out all the grease with rags and brake cleaner and inspect again. Then if all’s good repack with grease and reinstall. Even if that’s not the problem, it certainly won’t hurt! Make sure to torque them properly. After a couple of hours of drive time, torque again.

[nostatic]

Ryan, I know when I had that problem with my '67 Bug, it ended up being loose motor mounts. That probably doesn't help much though...

[Bill Douglas]

One of my CVs was doing a big clunk just after I started moving so I pulled the shaft with CVs out, repacked them with grease, and put them back in with the inside one on the outside. This way the balls and races are working in the less worn direction. And the clunk has now gone.

At one time my handbrake cable had come loose and was rubbing against the inside of the wheel or something, I refastened it to the hub and the noise stopped. I was quite relieved it was something minor.

[bigchillcar]

Todd,
I suspected them right off, but I think they're ok...I think they are...I think they are...

Bill,
Good plan. If I remove them to do likewise and re-pack, are the bolts re-useable? I thought I read that they may not be... Anyway, I have Wayne's book, I'm sure it explains.
Ryan

[Superman]

I love this kind of stuff. Play in the drive train is probably not CV joints. Could be, but probably not. With a wheel off the ground, turning the wheel, check to see if the drive flange on the tranny is turning with the wheel. If so, then the CV joints are not sloppy. That amount of sloppiness in CV joints would cause plenty of clicking and snapping and knocking as you drive.

Heavy clunks are usually loose motor mounts. This sounds like your situation, BigChillGuy.

A single, recurring heavy clunk just AFTER takeoff can be a CV joint or U-joint on other cars. Fix this or be prepared to call a tow truck. This was your situation Bill, or so it seems.

Wheel bearings usually growl. Louder with increased wheel speed.

No on the worn shocks, yes on the rubbing oil line, David.

At least these are my guesses, guys. Now, if you're foolish enough to assume I know what I'm talking about, you should talk to JW. He knows how FOS I am.

[Cerbin]

I was snooping around on the internet... check these out
www.dunegoon.org/sandrail/cvjoints.html

They shaved 6 Pounds off!1

[bigchillcar]

Superman,
I've owned jeep cj-5's and 7's...I completely agree about the u-joint clunk...replaced a many of those.

Motor mounts, huh? Anyone got a quick check for those? I assume this means replace, not tighten? I haven't played with this component in any car before. Seems it might involve jacking the car up from underneath the engine (near the sump)?
Ryan

[Superman]

Jacking is a way to see if they're loose. All four can be replaced in a few minutes using a floor jack and a ratchet.

I think it was in the latest Excellence that I read about an early 356 race prepper who shaved about 20 lbs of weight off a 28-lb flywheel/PP/disk combination. Amazing.