Dealer and LSD Problem
 

I noticed that when making a tight turn (close to the steering lock) that my 2009feels as if it is going over bumps in the road. My warranty expires in April so I decided to have the dealer take a look at it. They called back and said that the differential fluid needed changing and it "would only cost about $200." I had changed to Redline about 10,000 miles ago and knew this probably wasn't the problem. I told them that I would change the fluid myself (if I had a lift this procedure would cost $20 and take 15 min.) When I picked it up they said they went ahead and changed the fluid anyway and added additives and would put it under warranty. They then confirmed that the problem still existed. Told me to drive it for 100 miles and bring it back if it doesn't clear up. I told them that I thought the LSD in the 370Z was actually a sealed unit inside the differential casing and additives probably wouldn't help. I don't think they believed me. Anyone else have this problem?

With the diff... no. With dealers... yes.

It's not unusual to get some binding when making tight turns especially in the colder conditions.

And yes the viscous diff housing is sealed. The fluid does get pretty nasty though, so changing the diff fluid every 10k or so is a good idea.

The "bumping" that you're feeling is most likely due to the tires. I'm a little clueless how turning the front wheels would have anything to do with the diff.

When you turn sharply you create a large difference in wheel speed between outside and inside. With a limited slip differential it is fighting against this as by design it is there to reduce the difference in differential wheel spin. It is part of the reason why the front wheels "skip" in the cold.

This makes sense for me. Happens in cold temps for me.

Off topic. But the other day when i went to get a alignment I almost got stuck entering there entrance being at such a angle being I have a aftermarket LSD. Pretty funny. Not sure if that can happen with the stock VLSD.

I think that rear wheel spin would solve your problem...:bowrofl:

as in.... initiate rear wheel spin

One thing I have noticed is that lately when trying to do a quick jump off the line I get a lot of tire hop. Could the two problems be related?

Wheel hop is usually a different prob. That is more related to power transfer. Rigid motor mounts and possibly other suspension upgrades might help that.

I get the rubbing/bumping sound on full lock turns only when I just start the car. Once it is at all warm I can't reproduce it.

Most of the hopping/bumping that I get is from the front wheels. Don't see where the diff has anything to do with that. I think it's a lot more basic than that. Cold tires+sharp angle=skipping. Like when you run a dry finger over a wet glass.
If the OP is getting bumping in the back, then I fully agree with you.

He has the OS Giken which acts like an open diff when one wheel is off the ground :)

My daughters car is having the same issue in the cold. Dealer just replaced the diff and it still does it. The thumping from the front is because the LSD is not slipping when cold so you have a live or solid rear axle. When you try to turn, the car pushes the front tires and they slide, grab, slide, grab which is the bumping feel. Will an additive help????

No, the viscous unit is sealed. With all-season/winter tires it shouldn't happen as much as the tires will grip better in the cold. You could always swap to an open diff from a base model :)

Is the bumping only on sharp slow speed turns? Even if not no additives are going to work. IMO its nothing to worry about.