posting for a friend, his Z is making a very loud knocking noise from the rear end. the sound coincides with the speed of the car. i was thinking cv joint or wheel bearing but when the brakes are applied the noise goes away. the right rear brake is rubbing a little bit but i dont think that would be the cause/issue. any input from anyone would help. thanks!

 

anyone?

 

LSD?

 

sounds like a personal problem.... Preperation H maybe?

 

if it's that loud & noticeable, he needs something better/stronger than the preparation H......
BTW, i still have that magazine in your avatar....nice car.

 

Check and make sure no bolts are missing that's where I would start. Get under the rear and shake things around and see if u can replicate the sound. Possible there's a missing tooth in the differential maybe? Just a few suggestions

 

I was going to say diff. until you mentioned it stopping with the brakes. I would check to make sure the brakes bolts on the caliper are all tight. Maybe check the ebrake drum

 

Put the car on jacks and shake the real wheels. If it's not tight and solid, make sure the axle nut on the end of the half-shaft is tight.

I had a similar problem with mine (just fixed it) and discovered there is no "castle" bolt or keeper cap on the nut. I've never had the nut off of the half-shaft, and no reason for the stealership to have it off on the two times I've had the car in to them. Nobody else has touched the car. Wonder if this is a factory assembly "oops" or a design omission? The cotter pin near the end of the half-shaft will keep the nut on, but won't nearly keep it tight.

Luckily, while I was looking for a deal on a half-shaft and considering the option of replacing just the CV joint (cheaper, but a major hassle), it dawned on me that the nut had come off too easily.

Anyway, I torqued it to 140 with some thread-locker. So far, so good.