Guess drivetrain noise?

[VictorH]

In the past few days have noted a driveline noise that is getting louder by the day. It's not that loud so wouldn't be heard on audio or video recording. The characteristics as follows:
1) It's a muted tapping noise coming from the back, my guess is driver's side
2) Tapping frequency goes up with speed and less when slowing down.
3) Will make tapping noise in gear or coasting in neutral.
4) slightly louder under driving load compared to coasting
5) I can't reproduce any noise with the car up on lift, in neutral and spinning the tires (either side) by hand.
6) The drive axles don't have any tears or rips in the boots and the "slop" in the axles from side to side is about the same on right and left (I am most suspicious of a CV joint but don't know how to prove it)

I tell you what it's not:
1) Brakes, calipers are tight, pads are new and no odd wear patterns
2) Pretty sure it's not a suspension component particularly given the characteristics above
3) Tires/wheels, new less then 300 miles, new rims too, don't see any obvious damage and the car does NOT vibrate at speed

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[Bulldog9]

Rock in a tread, screw or nail in a tire that is not deep enough to leak air?

 

[cerbomark]

if it just started with the new tires/wheels then it is probably heels/tire related.

Loose tag on driveshaft flapping around?

 

[PC_GUARD]

Muffler/pipe hitting swabar?

 

[VictorH]

Never said it started with new wheels/tires. Tires are new no screws, rocks or nails and that's not the type of noise anyway.
Probably wasn't very clear about the character of the noise. It's perhaps more of a deep, rumble type of tapping., NOT a soft clicking like you get from a nail.

 

[PC_GUARD]

Never said it started with new wheels/tires. Tires are new no screws, rocks or nails and that's not the type of noise anyway.
Probably wasn't very clear about the character of the noise. It's perhaps more of a deep, rumble type of tapping., NOT a soft clicking like you get from a nail.

Perhaps differential bushing, allowing pinion angle to change?

 

[TopJimmyCooks]

Broken muffler hanger? After everyone else's suggestions there's not much left.

 

[PC_GUARD]

Broken muffler hanger? After everyone else's suggestions there's not much left.

Thats my personal initial guess.

 

[VictorH]

Thats my personal initial guess.

Why? It's a new car, 7,000 miles and the underside still looks like new, no hanging muffler(s).

Anyone have experience with a bad CV joint? What do those sound like?

The wheel bearings, I checked again tonight, they are nice and tight, no play whatsoever and rolls smoothly.

 

[S550VIN54]

Sounds like a trip to the dealership considering it is under warranty. Keep us posted!

 

[PC_GUARD]

Why? It's a new car, 7,000 miles and the underside still looks like new, no hanging muffler(s).

Anyone have experience with a bad CV joint? What do those sound like?

The wheel bearings, I checked again tonight, they are nice and tight, no play whatsoever and rolls smoothly.

Because they're mounted in rubber and can move around or a hanger can be bent slightly and not be noticed unloaded (on lift)

Being a 7k car, it's a dealership trip.

 

[VictorH]

Well, put it on the lift (at home not dealership [yet]). Ran the car in first and second gear, just at idle and then with the brakes dragging just a bit. The whole driveline is completely noiseless.
No clunking, no tapping noises. Looked underneath while running and don't see anything wobbling or out of round.
The muffler hangers looks good, everything on the exhaust looks to be tight and as it should be.
Going to take my neighbor who is retired mechanic and has helped me sort out a few issues that were tough to figure out, for a little ride tomorrow. If not luck, then might just have to go to the dealer.

 

[VictorH]

PROBLEM IDENTIFIED- It's the right front hub wheel bearing! There's no slop whatsoever, it's completely tight but when you spin the wheel it makes a muted popping noise. All the other wheels are completely quiet.

 

[S550VIN54]

Oh wow! I thought that had been ruled out. Good to hear! Glad you were able to resolve this matter.

 

[cerbomark]

Are s550 know for weak wheel bearings ? Or is this a one off?

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