[hyhoo0]

I had a wavetrac lsd installed and ever since I have noticed a soft humming sound when engine breaking from 40-30mph. It only happens in gear with no power when the car is engine breaking.

It doesn’t seem like standard gear whine to me as the sound level is the same for all gears and it only happens between 30-40mph and only when not accelerating.

I’m bringing my car back to the shop Monday but I wanted to see if anyone had any ideas on what it could be. Could it be the limited slip itself or possibly how it was installed? My lsd came pre-installed in the rear end casing.

[sneaks]

The shop should be able to sort it out and now it is documented in case of catastrophic failure down the road.
Let us know what the shop finds!

[Bimmer This]

Soulds like they didn't set backlash properly. You hear it mostly on de-celeration right?

[shifterboy45]

Originally Posted by Bimmer This

Soulds like they didn't set backlash properly. You hear it mostly on de-celeration right?

good possibility ...

[Jeff@TopGearSolutions]

Originally Posted by Bimmer This

Soulds like they didn't set backlash properly. You hear it mostly on de-celeration right?

More then likely, someone else had this same problem.

Have the shop that did the work contact wavetrac to determine correct backlash, this seems to happen a lot with shops doing an incorrect backlash.

The answer should be stickied so they can tell people....

[dzenno]

Just had the same problem fixed...backlash is too loose in your case, should be between 0.0035 and 0.0045, yours us most likely 0.008 - 0.0012

[BrianMN]

Backlash is super important! I'm surprised they let it leave the shop without driving/testing it.

[hyhoo0]

Ok I'll definitely have them look at the backlash first.

I had the welded ring gear so I bought the LSD pre-installed in a rear end casing. If it ends up being the backlash setting would the backlash have been set by the company that installed the LSD into the rear end casing? Or would the shop who transferred out the rear end's have had anything to do with the backlash settings?

[Bimmer This]

Originally Posted by hyhoo0

Ok I'll definitely have them look at the backlash first.

I had the welded ring gear so I bought the LSD pre-installed in a rear end casing. If it ends up being the backlash setting would the backlash have been set by the company that installed the LSD into the rear end casing? Or would the shop who transferred out the rear end's have had anything to do with the backlash settings?

The company that installed the LSD into the differential would be resposible for setting backlash.

[Yankees 2010]

Originally Posted by hyhoo0

Ok I'll definitely have them look at the backlash first.

I had the welded ring gear so I bought the LSD pre-installed in a rear end casing. If it ends up being the backlash setting would the backlash have been set by the company that installed the LSD into the rear end casing? Or would the shop who transferred out the rear end's have had anything to do with the backlash settings?

You are right. If you bought the LSD pre-installed in the BMW housing, then you would need to go back to the company who sold it to you.

[Papajim]

What is backlash?... Because translation doesn't help much...
What should be watching for?

[packinDSS]

Originally Posted by Bimmer This

Soulds like they didn't set backlash properly. You hear it mostly on de-celeration right?

Ditto. I had this problem on a mustang after having the limited slip differential replaced. I had to bring it to another shop to adjust. I would only trust a shop that specializes in rears in the future. It takes an experienced tech to install this properly

[dzenno]

Any updates, resolved?