Got a bit of a weird one- It's not detrimental to driving the car, not really, but it bothers me- so here I am. 2016 F type, Base, Non-locking diff.
It's not a thud or a thunk, but it's not a scraping sound- It really sounds like a brake rotor dragging or something like that. That kind of noise. It does maybe make a vibration at 70-80, but you can hear it most noticeably at 45(mph) and 10-15mph when turning right.
Things I've done:
New rear tires
New rear brake rotors
Balanced both wheels twice
Crawled underneath the car, shook everything- CV joints look good, driveshaft looks good, nothing looks like its touching or rubbing.
Checked for play in wheel bearings, even with the parking brake in service mode.
Put the car on the lift, and slowly put it into gear, let the rear tires spin and checked- No noise that I can tell.
Checked rear diff fluid, It looks the same as 25k miles ago, still fairly clear. I don't think the Base models had the rear issues that the R's did.

Thoughts on what I'm missing?
Thanks!

 

Could still be the wheel bearings, even if there's no play in them? And are you definitely sure it's from the rear - some noises seem to propagate in very weird ways ....

 

These work really well to isolate a sound. It is a pain to run all the wires to the passenger compartment. Once you do, just drive and have someone listen to the different channels:


just keep the wiring from touching anything that is rotating.

They do make a more expensive wireless version, but there is still some wiring involved.

 

Could be a slightly bent rim. It can still be balanced but be 'out of round' and it causes the slightest of wobble and you get the sound and the slight vibration. Not always easy to tell which rim without analyzing each one on a machine with the tire unmounted.

 

When I bought my 2021 from a BMW dealer, lol, I had the same type of issue. They said they checked it out "thoroughly" and "All Was Good". Well, it wasn't. The car drove just fine, but the noise bothered me. I took it to the dealer and it took 3 technicians to drive it, talk and they finally said it was in the differential. They got permission from the factory to remove the differential and that is what the problem was. The "factory" said the issue was rare but not unheard of. It was NOT repairable and they replaced it. Price? Over $10,000 per them. Luckey for me it was under warrantee.
is not to say that this is your issue, but just sharing my experience. GOOD LUCK!

 

Check the splash shield that is inboard of the rear brake. Some road debris could have bent it.

Compare the shield's distance to the rotor, on the other side.




Over the years, we have had this happen on various cars, both front & rear...

 

Very well could be- It's hard to find information on rear wheel bearings for these cars- There's a set on Amazon, but I'd really prefer a SKF/Timken or "better" bearing if I'm going through the trouble. I hear the dealer just replaces the entire hub. Having a hard time finding good information on rear bearing replacement, honestly- I'd do the hub if it's a bolt-on style like the front is, but I'm not sure. I have to do front brake pads soon, while the car is on the lift I might take a look.

I'm fairly confident it's rear- but like you said, I can't be sure. There's nothing through the steering wheel AT ALL, and everything my ear says is coming from behind- If I remove the cargo panel cover, slightly louder as well. It absolutely changes speed with vehicle speed.

When I replaced tires, I did notice sliiiightly odd wear on one of the rears- there was probably 2/32 of difference in tread depth on the circumference- I had originally chalked this up to my noise, however there was no change whatsoever with the new tires.
With the risk of getting lost in the weeds, I might put a dial test indicator on one of the rears and give it a spin, see what happens. I frankly don't really know what "in spec" would be in that situation, but I have a feeling my 50 millionths indicator is overkill.

This is a worst case, but looking around it seems the 3.0 Diffs are $3-500 for a decent used one. I'll stick the stethescope on mine, but an afternoon to toss in a diff with half the miles mine has is kinda worth it.

Will double check, but I've replaced rotors on the rear recently and checked for any spots that might be rubbing. no dice unfortunately. Will check the fronts.

Car has 76k on her, so wheel bearings and wear parts aren't out of the question. Anyone done CV shafts on F types yet? Attaching an audio clip of the noise, tried to isolate it as much as possible but this is as loud as it gets at about 45mph.

 

Did some tests, set up a dial indicator on a few spots as shown. The drivers side rear, has about 2mm of wobble- unclear if that’s axial or radial. All the other ones have about .5mm- I did this mounted on the car, and spinning them by hand, so I’m going to say that the .5mm is a margin of error.

I also lifted the car back up in the rear, and put the car in gear (following safe practices of course) and listened with a stethoscope to the hubs and the diff, no odd sounds that I could hear, so I’m thinking it’s tire/wheel related.

Might go see if the local tire shop has a tire machine that can measure runout and dial it in a bit better.