Noises coming from under the car?

[S65 SCHNAUZER]

So there's been this constant humming/whining noise coming from under the car consistently around 35~60 mph and most recently a squeaking coming from one of the wheel areas from idle to about 15 or so mph.

I changed out the front wheel bearings yesterday but the noise is still there.

Does anyone have any info on this? Hoping this is one issue and not multiple.

Thanks.

[Bpark1977]

Originally Posted by SCHNAUZER_M

So there's been this constant humming/whining noise coming from under the car consistently around 35~60 mph and most recently a squeaking coming from one of the wheel areas from idle to about 15 or so mph.

I changed out the front wheel bearings yesterday but the noise is still there.

Does anyone have any info on this? Hoping this is one issue and not multiple.

Thanks.

Can you confirm that it occurs at those speeds regardless of gear/rpm? 35-60 is a big range.

[S65 SCHNAUZER]

Originally Posted by Bpark1977

Can you confirm that it occurs at those speeds regardless of gear/rpm? 35-60 is a big range.

The noise somewhat subsides if i let go of the accelerator. id say its more accurate towards 35~50ish or so mph

some more info would be that i changed the differential fluid with redline 75w140. could this be? since i didn't use oem fluids?

[S65 SCHNAUZER]

update:

When i hand turn the back passenger wheel, it screeches. the pads were recently replaced so either bearing is shot, or something else?

any help is much appreciated

[Ajolives]

I would take the wheel off and check the pads that were just replaced - make sure they're secure and lubed. Check both halfshaft cv boots to make sure they're not ripped or open.
Also could be a stuck handbrake.

Usually a worn bearing will be accompanied by slight vibration, especially if it's loud enough to hum, and gets exponentially louder as you drive at higher speeds and doesn't 'go away' at a certain speed. It's dependent on wheel speed and not acceleration.

[S65 SCHNAUZER]

Originally Posted by Ajolives

I would take the wheel off and check the pads that were just replaced - make sure they're secure and lubed. Check both halfshaft cv boots to make sure they're not ripped or open.
Also could be a stuck handbrake.

Usually a worn bearing will be accompanied by slight vibration, especially if it's loud enough to hum, and gets exponentially louder as you drive at higher speeds and doesn't 'go away' at a certain speed. It's dependent on wheel speed and not acceleration.

So I took apart the callipers and rotors and put it all back together after some cleaning and sure enough the squeak/screech went away. I don't think it's the bearings after gutting and moving the wheel hubs to test for any vibration in the springs.

The humming has begun to appear around 20mph now and goes to about 50. Any higher and it's more of a high pitched noise not too noticeable. A local shop thinks it's the Center bearing on the drive shaft. Probably gonna take her in tmrw

[S65 SCHNAUZER]

So a shop told me its most likely a differential issue. Possibly pinion bearings..almost 1,500 for a rebuilt diff.

However, i did just notice that the redline 75w140 gear oil i used states that it wasn't designed for manual transmissions cause of synchro issues.

75W140 GL-5 GEAR OIL

This product is not designed for use in most manual transmissions or transaxles, since the extreme slipperiness may cause synchronizer mesh issues that lead to shifting problems

Could this possibly resolve my issue? My M3 is a 6 speed

[tlrid3r]

Originally Posted by SCHNAUZER_M

So a shop told me its most likely a differential issue. Possibly pinion bearings..almost 1,500 for a rebuilt diff.

However, i did just notice that the redline 75w140 gear oil i used states that it wasn't designed for manual transmissions cause of synchro issues.

75W140 GL-5 GEAR OIL

This product is not designed for use in most manual transmissions or transaxles, since the extreme slipperiness may cause synchronizer mesh issues that lead to shifting problems

Could this possibly resolve my issue? My M3 is a 6 speed

Did you use that oil in you transmission or in your differential?

I ran that on my diff no issue, but in the transmission will cause issues.

[S65 SCHNAUZER]

Originally Posted by tlrid3r

Did you use that oil in you transmission or in your differential?

I ran that on my diff no issue, but in the transmission will cause issues.

I used it in the diff. I just flushed it and put in BMW fluid but the noise is still there.. will probably end up swapping the diff.

do you know how urgent this fix this?

[tlrid3r]

Originally Posted by SCHNAUZER_M

I used it in the diff. I just flushed it and put in BMW fluid but the noise is still there.. will probably end up swapping the diff.

do you know how urgent this fix this?

You need to confirm it's not a wheel bearing. I had that fail but not a diff. I have 121k miles with 60k of it being major track abuse.

You should be able to isolate it.

[S65 SCHNAUZER]

Originally Posted by tlrid3r

You need to confirm it's not a wheel bearing. I had that fail but not a diff. I have 121k miles with 60k of it being major track abuse.

You should be able to isolate it.

I didn't think it was the bearings because when I spun the rear bearings there was no vibration to the springs. Also, the rear lifted and tested the noise and it seemed to come from the Center rear. Steering wheel shakes at 80mph too

[tlrid3r]

Originally Posted by SCHNAUZER_M

I didn't think it was the bearings because when I spun the rear bearings there was no vibration to the springs. Also, the rear lifted and tested the noise and it seemed to come from the Center rear. Steering wheel shakes at 80mph too

Looks like you have isolated. I know Brendan at speed Garageworks does diff rebuild for less than buying new.

[S65 SCHNAUZER]

Originally Posted by tlrid3r

Looks like you have isolated. I know Brendan at speed Garageworks does diff rebuild for less than buying new.

Yes I believe so, I'm thinking of going the rebuilt route but would want to purchase one from say diffsonline and swap then send in my old one..do you know if Brendan has that option?

Also i'd assume putting in a used diff is a bad idea?

Thanks.

[tlrid3r]

Originally Posted by SCHNAUZER_M

Yes I believe so, I'm thinking of going the rebuilt route but would want to purchase one from say diffsonline and swap then send in my old one..do you know if Brendan has that option?

Also i'd assume putting in a used diff is a bad idea?

Thanks.

I rebuild my diff with Brendan to upgrade the LSD unit.
Brendan does not sell diff only rebuilds. But he offer all option for rebuild.


Thread here. Diff Rebuild-Clutch LSD https://www.m3post.com/forums/showthread.php?t=1588016