Help me diagnose this noise

This noise has been confounding me and my mechanic for nearly 2 months now. I first noticed it driving home from an autocross - I had a few understeer plows and some wheel hop at the event, but didn't spin off the track or hit the backside of any curbs or anything.

It comes from the front-right, in front of the pedals somewhere. From inside it sounds like frame creak, but with the window down you can hear that it's actually a quick series of high-frequency clicks, like a many lug nuts being overtightened simultaneously.

Things that cause the noise:

Moving off from a stop (unless I come to a stop very slowly and gently), violent action with the throttle at less than 20kph (I get the noise on accel but not decel - and I'm running an open diff), parking lot turns with the clutch disengaged.

Things that don't cause it:

Violent action with the throttle at over 20kph, any kind of sharp turns at higher speeds, braking to a stop, hard or gently.

Things we have done to try to fix it:

Checked tightness on everything on the coilovers and front subframe, replaced 2 damaged engine mounts.

If this is a suspension or chassis problem, the only thing I can imagine is that it's some weakening of the frame around the rear of the right front LCA, there's some rust there but it's not that bad. Could a CV joint or axle problem cause this? PLZ HALP I have an autocross next weekend and want to get this fixed in time.

What kind of car? I'm thinking front sub-frame mounting points?

Same 'rolla you see in my avatar.

Could very well be the CV's, but I would be inclined to think the diff might be at fault too with a broken spider gear.

Doesn't a damaged spider gear cause a horribly loud snap and sudden "power miss" that changes frequency with speed? I should mention that the frequency of the sound is pretty much the same between "barely moving" and close to 20kph.

bad bushings? The poly bushings in my Ti Creak on acceleration from a stop, but that is it. I think it is the movement from being completely stationary to moving that makes mine creak

Road conditions make a difference? I know it's a pain, but it it possible that you've had one of the clutch or flywheel bolts start to back out?

A lot of rapid clicks in a turn under power, that about right? Does it do it both directions? If so, I vote CV. If it doesn't, I lean toward wheel bearing. If you have retorqued everything, did that include the CV axle nut? The reason I ask: FWD Chryslers used to do something similar, but it was a single click. The fix was to replace the washers under the nuts and bump the torque up. Some techs would also put anti seize under the washer and the nut, too.

Except for the part about the frequency not changing with vehicle speed. If it's in the final drive (axles etc) then the frequency should change with the wheel speed. If it doesn't, that generally points elsewhere. I'd still check the axle nuts carefully first, but the next diagnostic question to ask yourself: what could cause the noise but not change speed with the car? That almost sounds like something not even engine related, maybe a cooling fan motor?

I drove a 8V VW Jetta with a spider gear problem once (cracked), that one was a rapid clicking which was most noticeable roughly in the center of the car during a 'lane change' maneuver at about 35 MPH up. It did it both directions and didn't do it in tighter turns or at low speeds. We didn't wind it up and dump the clutch or anything like that so I can't speak to what that would have acted like.

mad_machine:

All front LCA bushings were replaced last year, along with PS rack bushings, and coilovers with camber plates replaced the struts. In that time I did about 5 events (the sound started after the last one in late March) and I've been DD'ing the car over the last few weeks, which has really angered the gremlins (but most are taken care of).

Derick Freese:

Road conditions don't make a difference. The powertrain is basically stock and I've never touched the clutch or flywheel. Also I can get the noise with the clutch engaged in neutral.

Curmudgeon:

It's a few clicks while turning but not necessarily under power, I can get the noise in neutral or with the clutch disengaged as well. And yes, in both directions. The CV axle nuts haven't been checked so that's a possibility.

I've heard the noise while turning with the fans off in glassy-smooth parking lots so it can't be the fans.

Maybe try this: drive the car in a circle so that it makes the noise. Have someone stand in the center of the circle and listen for the noise. Sometimes that will tip you off as to where it's coming from.

There's also 'chassis ears'. You attach microphones to different parts in the area, then with someone else driving you listen to each microphone in turn and narrow the source down that way.

Maybe someone down there owns a set and will loan/rent them to you. If not, maybe you can get a small microphone, attach it to a clip then use a small amplifier to a set of headphones. The problem with this is to check different parts you have to stop, get out, then move the mic. But it's a possibility.

I too lean towards wheel bearings. Since everything else has been mentioned.

I just actually read your post. I'm suspecting CV joint(s) as well.

iceracer and DrBoost + Curmudgeon ....

go to an empty parking lot .... drive slowly in circles / figure eights

if the noise is there while turning ( even with the power off ... i.e. coasting ) and ceases in the "straights'' ( of the figure eights ) I'd vote for C joint(s)

CV joints click.

Wheel bearings growl or rumble.

I can get the noise driving in a straight line, but when I'm making parking lot turns with the clutch disengaged I can get it while turning and it shuts up when rolling in a straight line.

So in a straight line under load it clicks but disappears when the load is removed? But it comes back in a turn under no load?

I swear I keep thinking wheel bearing. iceracer is correct that wheel bearings generally growl or rumble but a cracked race will click. CV's generally can be just about to disassemble themselves and won't make noise in a straight line but man will they go bonkers in a turn.

Curmudgeon wrote: So in a straight line under load it clicks but disappears when the load is removed? But it comes back in a turn under no load? I swear I keep thinking wheel bearing. iceracer is correct that wheel bearings generally growl or rumble but a cracked race will click. CV's generally can be just about to disassemble themselves and won't make noise in a straight line but man will they go bonkers in a turn.

I've never heard a wheel bearing click, but I don't doubt they can. I'll say this (to back up Curmudgeon). I've removed axles and had the CV fall apart right there in the boot. Grease balls rattling around. The joint didn't make any noise that I heard! I was amazed at how that joint looked when I opened it up.

Can you post a youtube video of yourself, making the noise?

So we can help with the diagnosis...

Well maybe I'll take a vid tomorrow.

Trans_Maro wrote: ...of yourself, making the noise

^Lol!

Just had the first proper drive on the Star Specs. The road noise is much less which allowed me to hear this noise some more. I was able to hear traces of it when going on and off the gas at up to 40kph. I also tried dropping into neutral and going on the brakes at close to 40kph and it made the exact same noise. I think that means a CV/axle-related problem is less likely, if it were related to the CV or axle it should be quieter in neutral.

Now here's the one speed-dependent factor: When moving off, it's a long, horrible creak, but when I'm violent with the throttle at close to 40kph it's barely audible, and just above that there's no noise at all. If it was a chassis/suspension problem you'd figure I should get the same creak or worse as speed increases, but instead the noise fades off. That suggests a (most likely) wheel bearing or possibly CV-related problem to me, am I right?

The noise not going away in neutral does indicate a wheel bearing type thing. You mentioned it does it when braking; the parts which get loaded during braking and accelerating are where I would look. Make sure the caliper bolts, ball joint nuts, strut bolts etc are all tight.

I have had two techs who mentioned being able to 'see' noises. Don't laugh; what they were referring to is to inspect bolts very carefully. If there was rust powder (which sometimes looks black!) around a bolt head or from under a nut/washer then very likely the part they clamp is able to move slightly under load, causing a noise.

If you can hear the noise with the clutch disengaged and the car in neutral I would suggest cecng the trams fluid for metal shavings, my dd had. No fluid in it and metal shavings throughout when I bought it and it add a weird sound like you described, turns out it was a bearing spinning onthe bore,

Fluid was changed just last week, nothing unusual.

Get both front tires off the ground.

Put it in gear at 1000 rpm or so, and turn the wheels slowly left and right.

Click, click, click?

CV. That noise is the bearings hopping in and out of a pocket.