Bad axle (WHICH ONE??)

[Sandy]

I have a A3 2LTR Automatic with tripode inner joints. The car has developed a shimmy under acceleration but goes away at about 80 kms. I've been told the rollers in the inner joints wear a grove in the housing and under acceleration the rollers tend to jump in and out of the groove causing the shimmy. Is it possable to determine which axle is the problem.

[the caveman]

Go to a garage who is willing to lift the car and then look underneath when it's in gear. You will probably see which shaft is bad.

[jtanguay]

maybe rule out tires/alignment for the shimmy first???  but if you can inspect the driveshafts and locate any obvious wear like caveman said then go for it.  work your way up from easiest things, because changing the driveshaft to find out that you just needed to balance the tires, or buy new ones would be hard to swallow.  driveshafts are NOT cheap!!!

[Possum79]

I agree with jtanguay. Check your alignment and tires for wear/bent rims. That makes a really bad shimmy when that stuff is bad.

I was always told when a CV style joint is going bad it clicks when taking a corner. I have no proof of that though. I do have back up on the alignment thing(been there done that).

[Sandy]

Sorry guy's, I should have started my story at the begining. I did try another set of tires / wheels that I know are good and had the alignment done. I also put the car on stands under the control arms to keep the proper angles. I didn't see or hear anything. I don't mind buying an axle to fix the problem but as you say those axles are expensive and I want to buy the right one; or the left one. " WHICH ONE "

[the caveman]

When you're checking the axles let the suspension drop and far as possible[ put the jack stands under the body or subframe, not the suspension arms]. Even turn the wheels full left and right so that the bad joint may find the bad spot and then show up in a small wobble or lateral movement. If the vibration is only when driving dead straight then you will have to find that sweet spot. Sometimes shaft problems are hard to find but mostly show up if you look carefully. You may have to remove both axles and switch joints side to side to see if that hepls to find or even cure the problem

[jtanguay]

I agree with jtanguay. Check your alignment and tires for wear/bent rims. That makes a really bad shimmy when that stuff is bad.

I was always told when a CV style joint is going bad it clicks when taking a corner. I have no proof of that though. I do have back up on the alignment thing(been there done that).

my bad side was making a clicking noise when rolling, but not exactly under acceleration... had no idea it was the cv joint until i changed the oil one day and found the boot completely ripped and it looked bone dry inside  :shock: so i packed it with some grease to keep me going, but changed it shortly after.  i'm sure the grease would have accumulated a ton of dirt in a short period  :lol:

another thing you could do is buy the boot kits if they look any bit worn.  that way you can pack it full of fresh (good) grease and inspect them closer at the same time.  i opted for a new driveshaft for $60  :lol: but mine's a mk2 jetta...

don't forget that bad struts/shocks & strut mounts can also give shimmy's.  possibly even wheel bearings?  i've only had them growl at me, but im sure if left long enough it would start to get much much worse!

[CoolAirVw]

An axle vibration will be present with acceleration and go away while coasting.  They usually are felt worse at some certain speed and are hardly felt above or below that speed, but that behaviour is irrelevant.  A "wobbly" tire or bent wheel can behave that way as well.  

A vibrating axle will always be looseness(wear) in a inner joint.   If the outer joint is worn it will always click on turns before it can vibrate.  

You can usually determine which side by grasping the shaft in one hand and the inner cv joint in the other and wiggling, similar to wiggling a U-joint.  Any perceptable movement could cause vibration.  The wiggle motion would be in direction of rotation (forward and reverse) not wiggling the shaft in the trans.  If your trying to avoid replacing both sides then replace the side with the most movement.

When you're checking the axles let the suspension drop and far as possible[ put the jack stands under the body or subframe, not the suspension arms]. Even turn the wheels full left and right so that the bad joint may find the bad spot and then show up in a small wobble or lateral movement.

I totally disagree with the above statement.  Sounds like your attempting to diagnose a clicking outer joint.  Inner joints all this is unnecessary.  Do not take the weight off the suspension to "wiggle test" the inner joint.  Do put the jackstands under the suspension arms.  Or better yet use a drive on lift.  

I've replaced literally hundreds (if not thousands) of front drive axles.  I work at a trans shop (19 years).  In other words you can take this info to the bank.

[the caveman]

Yes Coolairvw you are right in the respect that having the suspension all the way down may actually hide the problem as the suspension isn't normally in that situation. On the other hand checking the inner joints can be deceptive as they will have some rotational play in them even new. Only the outers cannot have any play. I check them by holding the driveshaft with big vise grips and then rotate the wheel while also turning the steering to check for play in the joint. Again the outers should not have any play at any point, the inners can have some. Usually if the vibration is caused by a bad CV joint then it should also cause some noise similar to a bad wheel bearing. I also just recently replaced an axle on a 2000 Beetle which had vibation while accelerating,coasting and braking. But only between 50-65 kph.

[CoolAirVw]

Usually if the vibration is caused by a bad CV joint then it should also cause some noise similar to a bad wheel bearing.

Huh??

[the caveman]

Usually if the vibration is caused by a bad CV joint then it should also cause some noise similar to a bad wheel bearing.

Huh??

What do you mean. have you never heard one like that?  I guess you haven't worked on as many cars as i have. Most of they time it can be obvious, but wait till you have one. I and many [even better] mechanics have been fooled by a bad bearing or CV joint thinking it was the other.

[Sandy]

Can I jump in here ?  I drove this car 2000 miles with the shimmy and a noisy wheel bearing which has been since replaced . In my case I knew one had nothing to do with the other.What I do have is a bad inner cv joint causing a shimmy. I thought maybe someone might know how you could tell whether it was the left or the right .

CoolAir Vw;  The "wiggle test" you speak of doesn't seem any different from left to right.  Some people have told me that more times than not the bad axle is the longer (right side), maybe the length has something to do with it?  Since this is the easier of the two to change I think I'll do that one first.

[CoolAirVw]

  CoolAir Vw;  The "wiggle test" you speak of doesn't seem any different from left to right.  

Make sure during the "wiggle test" that the trans is in neutral on level ground.  

Some people have told me that more times than not the bad axle is the longer (right side), maybe the length has something to do with it?  

Funny you should say that, about 15 years ago I heard the same thing.  Then after years of diagnosing cars I realized that "more times than not" means about 51 percent of the time.  

Since this is the easier of the two to change I think I'll do that one first.  

Sounds good to me.

[CoolAirVw]

I and many [even better] mechanics have been fooled by a bad bearing or CV joint thinking it was the other.

I've been fooled by wheel bearings.  Which side is bad???  Even though I always "rack" the car and have an assistant run the car with the wheels up, and I listen with a mechanics stethiscope, sometimes it can be hard to tell.  Sometimes it ends up that both sides are bad.  Sometimes, but not always, the bad wheel bearing doesn't make noise when you lift the car, because you take the load off the bearing.

I've been fooled by axle vibrations or even clicking axles. Which side is bad??  Sometimes it can be hard to tell. Sometimes it ends up that both sides are bad.  

Several times, in the course of the 21 years I've worked in the automotive field (19 years in transmission field), I've changed an axle, only to find the problem didn't go away.  So I assume that I misdiagnosed the problem, and changed the wrong side.  When this happens I pull out the new axle, reinstall the old axle, and get a new axle for the other side.  In quite a few of those cases I end up changing the other side again because, both were bad.   Some of those cases it turned out that I was right and it was the first side but the new axle was defective.

For many years we had problems with "certain" sources of axles, and I've seen them cause axle seal leaks, (when there was nothing visually wrong with the seal surface), vibrations, and clicking on turns.  

I've even had shimmy problems from the aftermarket NEW (Made in China) axles that have recently hit the market.  

POINT I'M MAKING is I've been around along time and I've made all the mistakes there are to make, although I'm sure I'll make some more, because there's always new and creative ways to screw up.  

But one misdiagnosis I've never made is changing a wheel bearing when the axle was making a noise similar to a wheel bearing.  Nor have I ever changed an axle when the noise was coming from the wheel bearing.  So in answer to your question, Caveman, no, I've never heard an axle make a noise similar to a bad wheel bearing.

Diagnosing a car can be conclusive and you can say, "Here is your problem."  But sometimes, diagnosing is not so conclusive and you say, "I've eliminated this and this, so its probably that." Interpret this last statement this way, "I've changed the left axle and it didn't fix the problem so it has to be the right axle causing it.  Some aspects of diagnosing a car are more ART than SCIENCE.  

A word about quality of parts.... my shop doesn't install the poor quality parts I mentioned above.  I identified axle problems about 9 years ago from "certain" suppliers and stopped using them.  But it didn't stop my customers from using them, since they are cheap and readily available, and so when their crappy parts cause problems I end up having to diagnose and repair them.

Sorry for the thread jack, and for writing a book!

[Possum79]

Hey I like having many views of how to do things. It's more ways to think of how to fix your problem. Thanks both of you guys, even though this wasn't my thread I still liked it.