Diff whine on overrun

A

Adamski

Lifer
 Edinburgh
Had the zed out for a long run today. First run in around 3 weeks. Did a variety of roads, including some motorway and A/B roads.

My zed has always had a slight diff whine on the overrun. Not an issue said Eastern BMW at my last visit. It's only noticable at around 65mph and 45mph. No other speeds. It is present when in gear, but much quieter when in neutral. No noise on acceleration, no noise when driving at a steady speed. Only a slight whine when on the overrun, at the speeds mentioned.

Now, my car has a warranty. And I have OCD. I hate noises, regardless of whether they're ok or not.

The problem I have is this:

a) Eastern BMW have already said there is no issue - I fixed all issues on the car's health check when I bought it, and gave the tech a good grilling at the time
b) I'd like Eastern to take the diff apart and confirm without any doubt, that the diff is ok
c) Any investigation work is not covered under warranty
d) I don't really want another wallet raping to be told categorically that there's nothing wrong with the diff

There are a few threads about this on zroadster.net and also various threads on M5 forum etc. BMWZ4MC HERE and srhutch HERE have both confirmed that they have similar noises as mine, which makes me think it could be a common noise on zeds with a limited slip diff. A characteristic of the car like the tappety engine, clunking diff, notchy 1st to 2nd gear shift etc etc. My gut feel is that there's no issue, and I'm being daft.

So.... I'll throw this question out to the floor: Does your diff make any noise on the overrun?

Responses welcome from everyone, but please bear in mind that I'm asking about a limited slip diff. Most zeds have an open diff.
 
Funny you should bring this up today as I wondered if a fluid change in the diff would make a difference. Mines due an inspection 2 in a few K. I will certainly ask about it when due.
 
Mine didn't change after having the diff seal and fluid changed. No issues found in the diff when the seal was changed....

Maybe I'm being paranoid
 
I have heard quite a few times that a different diff oil can be used to quieten the noisy diff. I think it's a common problem. My Indy asked if my car has standard BMW Diff oil or the uprated oil when it went in for it's insp II last month. My diff doesn't make any noises at all and it's still using standard BMW diff oil. However, I don't believe it's uncommon to hear some whines etc from the diff.
 
I've had this same issue since I got my ///M and am similar with OCD to you and also have BMW extended warranty. I've usually always had my own way when claiming for stuff. But for this they pushed back. I didn't have the time to push them then. But my argument would be "it didn't leave the factory like this and others cars dont do it". However - BMW are being arsey as they said they wouldn't investigate until I am back on oem rims and tires as they think it's related - whe we all know it isn't!!! I'm running oem csls.

Have you got some 224s to retest with?
 
No. Don't have 224s. Good to know at least 3 others with the same noise. Mine has had the diff seal changed, which involved opening up the diff. No issue found at the time, so I can take comfort from that.


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My car also makes this overrun whine, was going to ask about it when I get my RTAB limiters fitted. Good to see it's not just me!
 
Tbh, I thought that was the norm on the diffs, I have a similar thing, although it's very slight and only when coasting, I.e. Not present when under accelerator pedal pressure but when the car decelerating under in gear coasting, and like you only at about 60mph. I've recently had my rear diff pinion replaced (no diff oil change) but I do recollect the same whine being present prior to change.

I can't comment on any other cars but would be interesting if other grades of diff oil would help.
But as long as there isn't anything causing internal damage don't mind the diff whine.
 
Great. Another weird noise to try and hear, and to get paranoid about. Thanks Adam - I think I am going to turn into the Andysat of M owners...

I can't recall ever hearing this sound on my car, though I'll keep an ear out. I assume from what you and others have said that it's really only noticeable when you lift off and coast at 45/65 mph ?

Is this a noise that becomes more likely/audible the more mileage the car has done, or is that not something that's known ?
 
You really have to listen for it I would say. You never noticed it when you rode shot gun did you.

If you have the radio on or were talking you'd never hear it.
 
Nope, didn't hear it... Though the big noises were all I could hear at the time :lol:
 
No it's certainly not an obvious noise, and not something that will drive you mad, in fact I think it would only bother dogs as it's low audible volume but high pitched... Awooo :D
 
Old thread dragged up.
Ive only had my 3.0 4 days from a dealer.
Noticed first day a whine on back on over run only.
Very loud its going into garage in morning .
To investigate will report back.
2010 e89 3.0l manual 52k.
Glad dealer been brill though.
 
It's strange. I've started using my zed (non M) again recently and noticed this diff whine in certain situations...I just put it down to old age etc and because I'd fallen out of love with the car it was one more excuse to start scouring autotrader for something different....but now I realise it could be a characteristic of the car then....
 
Every Z4 Coupe I've been in have had that whine.
Both 3.0Si and M's actually.

Not strange as EVERY diff regardless supplier makes noises, it's a matter of noise insulation thru bushes and carpets basically. I suppose the Z4 Coupe body stiffness and/or stiffer bushes and/or lack of sound deadening makes for our aural experiences... :)
 
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