At low speed, I have a steady knocking sound coming from my driver side front wheel well. It is rhythmic -- one knock per wheel revolution. Everything I've read points to a bad CV joint. I looked underneath, and didn't see any problems with the boots. Is it still possible that I have a bad CV, even though I can't see any damage?

Assuming this is the problem, I know it's better to just replace the half axle. How difficult is this to do. I'm reasonably handy, having done intake, Y, suspension, brakes, etc. on my own. Is the half axle in that territory, or is it much more difficult? If I'm going to do one, should I just do them both? What else should I replace while I'm at it?

TIA for any help.

 

Does it make the noise when you are driving in a straight line or only when making a sharp turn?

 

Only in a straight line. The noise will go away when I turn a little, or when I apply the brakes slightly. Sorry, I should have specified.

 

Usually, but not always, a cv joint will make noise on a sharp turn because that is when it's under the most stress. Often times it is due to a torn boot that has caused the grease to leak out. Does the sound change pitch as you turn the wheel while driving? Does it make noise only at low speed or does it get really high pitched the faster you go?

 

No pitch change when turning, it really just goes away. I believe that the knocking is present at higher speeds, but sounds more like road noise at that point. Like I said, the boots are fine, and no grease to be seen. Weird, huh?

Anyone know other possible causes of this knocking?

 

If the noise goes away when you turn the wheel while driving and sounds like road noise at higher speeds, my guess would be wheel bearing. It 's really hard to diagnose without hearing or seeing it.

 

Ok, thanks for info, mbandi.

Now I'll show my ignorance: I don't know what a wheel bearing is, where it is, or what it looks like. How can I tell if it's bad, is it something I can replace myself, and how much would this cost?

 

It looks like this.

It's pressed into the steering knuckle (between the brake rotor & the cv shaft. The end of the cv shaft actually goes through the wheel bearing. It is kind of involved without the proper tools. The part is about $40 (aftermarket), and $9 a piece for the 2 seals (inner and outer) that usually need to be replaced at the same time. I would recommend having a technician you trust take a ride with you to listen to the noise and verify your complaint. This is just an educated guess!!!!

 

Thanks again for the info!

After doing some ghetto searches of the org, I'm wondering if it might have something to do with my aftermarket suspension. I have KYB GR2s with Maxspeed springs. Now that I think about it, I think this noise appeared after I had an alignment done. I'm wondering if one of the springs got cocked. This can apparently cause these types of noises.

I'll check it out and report back if I find that to be the case. If it's not, I'll take your advice and go for a ride with a technician. Thanks again!

 

I agree w/ mbandi about the problem most likely being the wheel bearing. I had the EXACT same problem you've mentioned (knocking under floorboad when driving straight) a month ago & it turned out to be the wheel bearing. You can jack the car up & grab the tire at the top & bottom while pushing in/pulling out to see if there's any play in the wheel...if there is play (looseness), it's definitely the bearing. The wheel should not move if the bearing is good.

 

sorry to hi-jack this thread, but i have the same noise issues but its when turning shaprly and not on a straight line. its fine with a straight line. so it seems to be the cv joint. and it seems to have happened after i lowered my car. and changing the half axle?? i should consider this or no? or can i just replace the boot that caused the grease to leak out? but agai, i didn't see any grease leak out.

SORRY AGAIN TO HI-JACK THIS THREAD!

 

Good diagnostic with the wheel bearing, but from what i understand, if the wheel bearing is bad you get a humming noise. I think it could be the wheel spindle gone bad. That usually causes the knocking, but its hell to diagnose till the mechanic takes the bearing out to change it. Hope you figure it out man

 

did you recently replace the wheel, or take it off? could be that the lug nuts are very loose...my car did this when i put on my 17" rims and the tuner lugs came loose.