S3 Rear Diff noise

[Brookie-S3]

Hey all

since i got the car ive heard a bit of rear diff noise and i think its getting worse.
took it down to leeds audi where i used to work and went out with a tech who also heard it.

if you do 75mph, and back off the throttle then on very lightly there is a whine there, rather annoying as this is mostly my crusing speed on the motorway

its booked in on wed for them to check

anyone else noticed this ?

 

[Deleted member 21388]

Not noticed this but I would be very suprised if its the rear diff as I would have thought at 75mph its would be mostly fwd (unless hard accleration say through a bend) on a motorway.
My money would either be on the exhaust moving on its mounts and causing a whine / rattle worse when taking left bends on its mounts (which mine had to recently go in for) or a rear bearing ?
Would be interested to know the outcome

Richard

 

[Splathead]

Yep, I've noticed a whine at exactly 75mph on a constant throttle in mine as well. Any faster or slower and it disappears. I noticed it the day that I picked it up. I just turn the stereo up or change speed.

I'll be interested to know what you find out.

 

[Amchlolor]

Not noticed this but I would be very suprised if its the rear diff as I would have thought at 75mph its would be mostly fwd (unless hard accleration say through a bend) on a motorway.

I'm confused by this statement.
Surely the diff still works (i.e.its internal rotate), even if no drive is getting to it?
The rear-wheel driveshafts must still rotate with the wheels, which means the differntial gears must rotate in the differential housing?
Okay, they are just 'freewheeling', but they're still moving?
So there is still a chance of noise?

 

[Louay]

I recently had an S3 and too noticed a rattle type noise at certain speeds, especially in 5th and 6th gear, between 4k rpm and 5 rpm, found out that it was the plastic nut that secures the spare wheel in place! could it be that?

 

[Khufu]

I'm confused by this statement.
Surely the diff still works (i.e.its internal rotate), even if no drive is getting to it?
The rear-wheel driveshafts must still rotate with the wheels, which means the differntial gears must rotate in the differential housing?
Okay, they are just 'freewheeling', but they're still moving?
So there is still a chance of noise?

I agree, unless wheel spin, the front and back should rotate at the same speed. Maybe he means the noise only come on under load?

 

[Deleted member 21388]

I'm confused by this statement.
Surely the diff still works (i.e.its internal rotate), even if no drive is getting to it?
The rear-wheel driveshafts must still rotate with the wheels, which means the differntial gears must rotate in the differential housing?
Okay, they are just 'freewheeling', but they're still moving?
So there is still a chance of noise?

D'oh me been stupid - of course they are still rotating
- If its doing it at a certain speed would suggest something out of balance much like wheels / tyres out of balance vibrating a certain speeds.
Richard

 

[Brookie-S3]

i used to be a tech at leeds audi
its nothing rattling round in car or the boot
its not a wheel bearing as it does not increase with load around corners.
the rear diff rotates the same speed as the front, its 4 wheel drive !

its defo the rear diff at 75mph, only on very light throttle i can get it to play a tune if lift of throttle then back on lightly........

not tyres out of balance

 

[JohnS3]

Mine does this too, would like to hear how you get on though.

 

[JohnS3]

Bump. Any news??

 

[SiT]

I get this also.

For a little comparison, i used to get this on my MkV R32 which is a similar setup to the S3. I did find it more pronounced in the R to my current S3... but it is there all the same.

 

[S3OPES]

I have this same problem but it does when i'm coming off the throttle from high revs. did you get it sorted. Or has anyone discovered the cause yet?

 

[SiT]

Its still happening on mine too, although looking at my post from Sept last year, it IS now more pronounced then my R32..! It's been to the dealers a few times now, the last with Audi replacing my Propshaft.

In Toby C's thread though looks like he has had Audi to replace his rear diff. My car needs a service imminently; I’ll push again when it's in as the propshaft hasn't cured it, in fact i now get it at around 70mph.

 

[tobycruse]

Just had my diff replaced, the noise has gone. Have a look at this thread:

http://www.audi-sport.net/vb/showthread.php?t=70200

 

[kinson]

Glad that I found this thread...
I notice the clinging noise coming from the rear left recently. The noise appears when the gear is engaged and foot off the throttle. Noise disappeared gear is moved to "Neutral" (disengaged). I suspect this is something to do with the differential, instead of the wheel bearing, and after reading this thread, I'm more confident it is not the wheel bearing. The only thing is whether the rear differential refers to the Haldex unit? Is the whole Haldex unit required to be replaced?

BTW, I'm driving a MY 2009 S3 Sportback (8PA).