Hi all,

I'd like to call upon you for advice.

Last summer i had a quaife LSD installed on my 2010 c63 sedan. It really helped the car !

However I soon after noticed a vibration that is troubling me. It only happens above about 75mph (110kph).

The vibration feels like rolling on the vibrators on the highway emergency lane but very subtle and muffled. I hear it from the back and feel it in the seats and steering...This is unchanged for about 6 months.

It is pretty constant and seems more pronounced during acceleration. It does not change relative to gear. Only speed. I know it's not my wheels/tires or allignement because they are freshly balanced and alligned and also had the same vibration with winter tires.

At this point, I don't know what it could be.

My theories are:
Driveshaft screws (loose or missing)
Unbalanced Diff (factory defect)
Bearings ?
Something got damaged during installation or improperly re installed.
Wrong oil ?

I'm reluctant to tell the MB dealer because I don't want to risk them messing up my warranty...

Ps never hit anything, ever.

Any ideas (hope its not the diff...)

Up ! Really need advice here...

Thanks

I would go back to whoever installed your LSD to get them to take a look...

I would have went back to them as soon as I felt the vibrations.

Ao I called them and he thinks it may be the center drive shaft bearing or possibly the bushings. They may not have survived the torque increase (diff+tune)

Mmm...I dunno about that. Plenty of folks on this board have LSDs and tunes.

You are right but he says that what I describe is not what an lsd does if it has a problem. Maybe my bearings failed due to a combination of defect and lets call this (abuse)...

I need to go get them to check it out. Will post results here soon...

Tell the installer that he's full of shyt! A tune increase hp, but does not increase max torque at all. Sounds like he didn't properly install the lsd. It might not be properly aligned to the correct specifications.

I think he meant the lsd increases the stress on the driveshaft and bearings and bushings due to increased traction.

Anyhow i need to take the car to them ASAP to get a straight diagnosis...

Will post results

Even though you've had them balanced it might still be wheels. With the right placement of weights, it's possible to balance a bent wheel. However, they could still cause vibration.

How do I detect a bent wheel if not by balancing it ? Or cant see anything visually?

I never hit any big holes but I'd like to investigate the wheel suggestion (seems valid).

You can have someone spin each wheel by hand on the balancer and check the runout.

Edit...

Please, do yourself a favor and don't let the installer off the hook. You might have a good relationship, but if the issue started with or is in conjunction with the LSD install, don't let him divert the issue otherwise.

Since I do not know your car, history, or issue I'm not saying it couldn't be something else. Just please don't let him off with a diversion to some other aspect of the car. I'd insist on him going back in and double checking his work and LSD install.

I am also speaking from experience from a botched LSD install.

Wack, what was the outcome? I'll be swapping out one LSD for another soon plus it'll one more thing for the knowledge base here. Hope it worked out...

Balance all wheels this happen to me and if the wheels bend you will notes at low speed also

I had a similar issue and thought it was my diff or drivetrain. had my wheels rebalanced 3 times from different places and still had the same issue starting at about 70 mph and getting worse as speed went up. I found a place that had a Hunter Road Force Balancer and the problem went away the car is smooth as silk up to 170 + ! The road force balancer puts load on the wheel as it electronically measures it as if the weight of the car was on it and moving at highway speeds and tells the installer where to put weight by shooting a laser in the spots its dumby proof. They also can put the tires on differently that can also affect balance and fix alignment issues if the car pulls left or right just by the balance of the wheel and placement of the tire on the wheel. Its a bit more coin but well worth it give it a shot

I would bring the vehicle back to whoever installed the LSD, seeing as the vibrations began after that work was done.