Time to replace driveshaft?

[_rgk]

Time to replace driveshaft? (Road Noise Troubleshooting) *SOLVED*

*Please see second post for solution*

01 Protege LX (2.0)

Question: can anyone tell me whether the driver's side driveshaft (the single shaft, not the joint shaft) is supposed to be "loose" at one of the boots?

I removed the shaft a few months back to fix a leaky transmission seal, and noticed that the shaft moved quite freely at one of the boots, whereas at another boot the shaft did not move as freely. In other words, one side felt solid, and another felt free.

I have been having some crunching noise coming from that area when slowly going over bumps, and lately I have started to have a rhythmic pulsating noise that increases with vehicle speed. I am thinking it might be time to replace the driveshaft, but would like to confirm that this is, in fact, the case.

Could it be anything else? And does a "loose" shaft at the boot signal the end of the shaft's life?

Thanks!

 

[_rgk]

Road Noise Troubleshooting

I have been getting a terrible thumping sound from the front end while driving: the sound increases in speed with vehicle speed.

I have figured this out and would like to share my results.

Because of the rhythmic nature of the noise consistent with vehicle speed, I could reasonably rule out the transmission. I assumed it was either the CV axle or the wheel bearings. The sound seemed to be coming from the front left (driver's side).

First, from what I gathered after some research, the outer joint of a CV axle will be "looser" than the inner joint. This is to allow for the joint to move around as you are turning and going over bumps. This provided some relief for my anxiety (nobody wants to drop $300+ on a new axle, and nobody should bother with a $50 hunk of junk from China), but did not completely rule out the CV.

I raised the vehicle on jack stands and realized that both my stabilizer links were loose. This explained the popping and crunching sound when going over bumps, but not the rhythmic road noise.

With the vehicle still up on stands, I spun the wheels by hand. The front left wheel was making a rusty, crunchy sound. Problem solved, right? Well, I replaced the front left bearing and the sound persisted. As an aside, sethro_GT's excellent Front Wheel Bearing Service How-To aided in this process.

So now the ultimate question: do I replace the CV axle, or do I attack the front right bearing? I wisely decided to sleep on it and run some more tests (which I really should have done before replacing any part).

I rotated the tires (back to front) and took the car for a spin. The sound was still coming from the front left, so I could reasonably exclude a bad wheel or tire. I also noticed a sticking front right caliper, removed it, and spun the axle (by hand in neutral as well as with the aid of the motor in drive). I also checked the rotors and noticed nothing out of the ordinary.

I checked and double-checked the CV axles. All boots were in great condition. No leaks, no tears, no chattering or clunking in rotation. I raised the vehicle, spun the wheels, and listened carefully. Nothing. I felt like going crazy.

I then found a couple of excellent resources.

The first was a quick youtube video from a tech at Kona Car Shop: How to find a bad wheel bearing every time. In this brilliant thirty-second video, the tech explains a wonderful trick he uses to find out which wheel bearing is making the noise.

The second was this page: http://www.knowyourparts.com/technical-articles/symptoms-of-a-worn-wheel-hub-bearing/

Here I found a common-sense breakdown of road noise symptoms, from snapping, clicking, or popping (CV joint or bearing endplay), to grinding when vehicle is in motion (normally heard when turning or when there is a shift in load), to humming, rumbling or growling (If bearing-related, the noise or vibration is present when driving in a straight line, but intensifies when turning the steering wheel slightly to the left or right. Typically, the side opposite the rumbling is the defective side).

Armed with this information, I decided to replace the front right bearing, and voila: no more noise.