Hercules Rockefeller

I've been noticing a "clunking" noise from the rear end of the car, but it's only really noticeable when driving over sharp bumps or grooves in the road a low speeds. It seems to go away at about 30+ MPH, or any time I'm accelerating. I've got a lot of mods on my car, including several that amplify any road noises, including spherical bushings (Pfadt), coilovers, racing sway bars w/ pillow blocks, and a bunch of other track oriented mods, too many to list here.

When I drive over a smooth bump or dip, even if it causes a lot of suspension travel, I don't hear anything, but if I drive on a brick road or over a road reflector, I'll hear it every time. Also, I noticed today when backing up slowly, I had a bit of clutch chatter and it was definitely rattling the same whatever it is in the back. Perhaps it is something a bit loose in the power train and not the suspension? Any ideas on what to check next would be appreciated!

msnbound

have you tried to change the differential oil??? I did that to my z and the sounds that you were describing went away....

peterpiper

I had some weird rattle noises at low speeds, but not necessarily a chatter. I tried changing diff fluid and doing the crazy figure 8 stuff, but it wasn't that. it was the end links on my sway bars. (mine are stock, for now)

You should be able to grab your sway bar and move it around--if you feel the clunk, there you go... but if you have a chatter, I second the notion-you might want to check your diff fluid--when was the last time you changed it? -pp

fisher auto

I get a low speed very light clunk (more like a knock) coming out of the garage and in and out of gear changes also pulling away from a light. It's very minimal, not really overly concerned but do notice it.

capevettes

Check your axle shaft nuts. They are notorious for becoming loose and making noise.

setxws6

I'm willing to bet it has to do with your aftermarket suspension set up in the rear. Those aftermarket poly bushing tend to pop and make noises if they're not greased well.

Turbooo2u

It worked for me. If not that, loose/worn-out sway bar endlinks.

Hercules Rockefeller

Yes... this is probably the same thing.

And I did check the axle nuts, they are definitely not loose, so it's not that. But... after reading about the diff fluid, that might be it. It does sound like the noise is actually coming from the drivetrain, and I have 30k miles on my car with over 20 track days, so maybe it's time to change the diff fluid I'll let you know how it goes! Any recommendations on which weight and brand diff oil to use?

darb11684

May need to check rear differential fluid.

Scotten

Easy to fix, too:

http://forums.corvetteforum.com/c6-z...tructions.html

NORTY

Check you rear swaybar mounting brackets. They are known to loosen, back out and disappear...

OnPoint

And while you're doing that, lubricate your axle splines as those have caused this noise as well.

MJM

uh....yeah.

Mobil 1 and the friction modifier recommended in the owner's manual.

Dirty Howie

You ever get this soved HR ??


DH

TRINIC5

The common problem with the vettes is the Exhaust bearing on the driver side. Call the dealer and order a new exhaust bearing.

Bud Meyer

Bingo...my thoughts exactly...pull the hub caps off and re-torque the axle nut to specs.

Hercules Rockefeller

I would have thought this too, especially since the noise almost sounds like it's coming from the wheels/drivetrain. But I checked the axle nuts and they are fully torqued, so that's not it. I'm going to try to change the diff oil, but I'm beginning to doubt that's the problem; from what I've read if that's the issue you will hear noise when driving in circles, but not when driving at low speeds over bumps in a straight line.

You know what it kind of sounds like (if this helps anyone diagnose)? When you put the clutch in and push the shifter back and forth between gears, e.g. 1st-2nd-1st and you get that rear end clunky noise... it kind of sounds like that, but it happens when I'm in gear under low load, driving over rough road. Big dips and bumps make no noise, and if I'm under power (accelerating), then no noise, but if I'm cruising at <20 MPH, and I'm driving over bricks or reflectors it just sounds like something's banging around loose.

Oh yeah I also checked the swaybars, that's not the issue either, they are torqued *tight* and everything feels solid.

Bud Meyer

Sorry man...don't know what to tell you, sounds like you have covered all the bases...possible u-joint failure?