Rear Differential Noise When turning at Low Speed

[thekurgan]

Originally Posted by mxa121

Mine makes crunching noises at low speed turns, specifically to the right. I hate it.
I am out of warranty but the fluid was replaced just 5k miles ago. I may try and have the dealer replace it withe the "fix" fluid. I need to check the service order when I get home to see what they put in it.

I would avoid that FM boosted fluid and live with the cold temp sounds as it's normal and actually keeps the diff functioning as it is supposed to: locking.

[mxa121]

Originally Posted by thekurgan

I would avoid that FM boosted fluid and live with the cold temp sounds as it's normal and actually keeps the diff functioning as it is supposed to: locking.

Just checked my Invoice from the last service (p/o)

**********
DIFFR DIFF SERVICE REAR
6 83-22-1-467-993 DIFFERENTIAL OIL:832512__________14.00___84.00
3 83-22-2-282-583 FINAL-DRIVE GEAR OIL
SAF-XF:832514____________________________________58.32 ___174.96
PARTS: 258.96
**********
So it lists the old p/n for diff oil first, with qty 6 at $14 ea
Then it lists the +FM diff oil second, with qty 3 at $58 ea
It charges parts for both.

Confusing if you ask this guy... It 'looks' like I have the modified fluid in my car, but what is the 6 qty of the old p/n for?

[Beemdog]

Originally Posted by mxa121

Just checked my Invoice from the last service (p/o)

**********
DIFFR DIFF SERVICE REAR
6 83-22-1-467-993 DIFFERENTIAL OIL:832512__________14.00___84.00
3 83-22-2-282-583 FINAL-DRIVE GEAR OIL
SAF-XF:832514____________________________________58.32 ___174.96
PARTS: 258.96
**********
So it lists the old p/n for diff oil first, with qty 6 at $14 ea
Then it lists the +FM diff oil second, with qty 3 at $58 ea
It charges parts for both.

Confusing if you ask this guy... It 'looks' like I have the modified fluid in my car, but what is the 6 qty of the old p/n for?

Looks suspicious unless they changed the diff oil 3 times! The capacity is 1.2 liters; so three 500 ml bottles of either the standard or the friction modified are needed for a drain and refill.

[330iToy]

Hi everyone, I understand this post is old. I have a 2011 E90 M3 DCT that I bought new. I had the grinding noise around 10,000 miles and they put in the new additive with new diff fluid. Symptoms went away. I am at 26,500 miles now and have a serious clunking and feels like it is rolling over speed bumps. Turning right or left. I thought wheel bearings at first. What is the chance both going out at the same time? Very slim I would imagine. It is not that kind of grinding noise as well. Something else I have notice over the past few months. I am not getting any traction. It is spinning through 1st-3rd way too easy. Even if I stomp it in 4th when it downshifts I get wheel spin. Traction control light stays on for any aggressive driving. Still have great tread on Michelin PSS's. Mainly stock, cat back, intake and slight tune. Never tracked, and yes I need to drive it more. Health problems prevent that. It is my baby and a bucket list. Any ideas? LSD going out or already out (clutches)? Thanks for any input.

[dparm]

Originally Posted by 330iToy

Hi everyone, I understand this post is old. I have a 2011 E90 M3 DCT that I bought new. I had the grinding noise around 10,000 miles and they put in the new additive with new diff fluid. Symptoms went away. I am at 26,500 miles now and have a serious clunking and feels like it is rolling over speed bumps. Turning right or left. I thought wheel bearings at first. What is the chance both going out at the same time? Very slim I would imagine. It is not that kind of grinding noise as well. Something else I have notice over the past few months. I am not getting any traction. It is spinning through 1st-3rd way too easy. Even if I stomp it in 4th when it downshifts I get wheel spin. Traction control light stays on for any aggressive driving. Still have great tread on Michelin PSS's. Mainly stock, cat back, intake and slight tune. Never tracked, and yes I need to drive it more. Health problems prevent that. It is my baby and a bucket list. Any ideas? LSD going out or already out (clutches)? Thanks for any input.

Your guess is as good as mine, but slipping clutches is definitely a possibility.

The GKN Visco Lok LSD that our cars have is a speed-sensitive unit, not torque sensitive. As the speed differential between the two rear wheels increases, it will apply more locking to keep them in-check. This would explain why the sound is only apparent when you are turning.

Here's a technical overview if you're curious:
http://www.gkn.com/driveline/about-u...coLok-engl.pdf

I would get it to the dealer as soon as you can. If the differential seizes or fails, that could be pretty dangerous.

[330iToy]

Originally Posted by dparm

Your guess is as good as mine, but slipping clutches is definitely a possibility.

The GKN Visco Lok LSD that our cars have is a speed-sensitive unit, not torque sensitive. As the speed differential between the two rear wheels increases, it will apply more locking to keep them in-check. This would explain why the sound is only apparent when you are turning.

Here's a technical overview if you're curious:
http://www.gkn.com/driveline/about-u...coLok-engl.pdf

I would get it to the dealer as soon as you can. If the differential seizes or fails, that could be pretty dangerous.

Thank you very much!!!