I've noticed the past month that there is a non-rhythmic knocking that happens underneath the vehicle. I only notice it at about 35 mph or under either under load or coasting, and braking makes no difference. The knocking does get faster with speed, but is not consistent and does not regular. It can be knock, knock, knockknockknock, lull, knock, etc. I'm wondering if I need to look at the rear diff or something. When I get over those speeds, I don't know if the knock is there due to exhaust and road noise.

G37Xs Seadan >150k.

Thanks

 

Can you be more specific? (does it happen when you're driving straight or when turning?) o you have stock sways? any other aftermarket suspension components?or post a sound clip

Just generally though the usual suspects are the sway bars, maybe you need to grease/replace the bushings on them, its a pretty easy/cheap thing to do

could also be broken endlink...will be a lot to easier to narrow down with more info

 

Is the knock metallic in nature or almost as if you're rolling around on a flat tire? Can you feel any vibrations at all in the steering wheel? Does it get worse when loading up the right or left side; or turning the wheel left and right while performing a slalom maneuver?

 

It happens regardless of direction. It's a dull knock that doesn't necessarily sound like metal on metal. It's not very loud, but I'll see if I can get a sound clip going. I know the description is a bit general. I'll see if I can get it to pickup on a recording.

 

My bet is your CV axle has gone bad.

 

I had that thought as well.

 

What your describing sounds a lot like what I just dealt with and that's what I needed replaced.

 

I need to get the wheels off of the ground and see if I can duplicate.

 

I have the EXACT same sound. I noticed it a year ago when it was very very faint. Over the last year it has gotten much louder and I'm getting bad scalloping so I have to do something about it very soon since I'm getting new tires. I've ruled out a lot of things and pretty sure it the may be the cv ball joint. Hoping I'll be able to get it up in the air this weekend to get it looked at. If I do I'll let you all know what they say.

 

Could just be a bad bearing. I'd start there and work to CV related issues. Price rises significantly once the word 'axle' starts getting thrown around.

 

Didn't get to check last week. Knocking is a bit louder and have a whump whump at speeds under 30. I can do a wheel bearing, but I haven't done and R&R on a half-shaft since my 83 Ford Escort back in 87. What's the 1-10 rating on difficulty if I need to tackle this? I'll probably eat the $70-$100 to diagnose, but if I can fix it myself, I might.

Thanks,

 

assuming your talking about the rears on the AWD, RR on a half shaft is probably a 4-5/10 on these cars, not difficult at all, its mostly just time consuming getting things like parts of the exhaust out of the way and and getting the bolts off the short shafts on the diff (having to rotate, apply parking brake and repeat)... from my experience, on my AWD sedan I found there there was very little clearance there...a slim headed breaker bar to get the nuts connecting the shaft to the short shafts going into the diff was necessary....I used the same breaker bar I use for getting to my serpentine belt and it barely fit...


If you're talking about the fronts, maybe someone else can chime in, I've never pulled mine out except at the bearing side...good luck and let us know how it goes...

 

I was in no mood (after rebuilding my other car's) and had no time to replace it so I bit the bullet to have it done. Local shop did if for $400, including alignment and removing my mid pipe (bolts welded on).

 

I finally got it up in the air yesterday. I didn't mention it before now, but technically I had two noises. One while driving and one while in park or neutral. I hopefully have found the problems that have been driving me insane and all the mass confusion will soon come to an end.


While in the air, I Scoped the front driver wheel bearing and there is definitely noise it shouldn't make. So when not in the air and back on the road driving under load, it's definitely one of the culprits helping make all the racket coming from under the car. It will be getting replaced very soon.


And I found the other culprit! The bearing was colluding against me with the driver side catalytic converter! It sounds kind of like some of the honeycomb has broken loose inside and loves to vibrate and dance around inside there between 1000-1800rpm. I want to replace, but not causing any issues yet and spent too much last week when I ordered new rotors, pads, and tires.


So that solved, here's my real big question. Could the one bad wheel bearing cause scalloping on all four tires? It's much worse on the driver side. Honestly since I bought the car, I've only rotated the tires every other oil change out of old habit. This car gets Mobil1 every 5k compared to previously changing syn/mix every 3k. I've also been told the Infiniti's are typically prone to scalloping/cupping. Thoughts?

 

Don't think one bad bearing will scallop all four tires. That sounds more like bushings or worn dampers.

Scalloping is not often reported on the board. No trace on my car in 50k miles.