IM not sure what it is. The real axle nuts are tight. Ive had the torque tube and everything out of the car so Im sure its something I did. Basically if i were to go from 1st, move forward a few inches id get the clunk. If i then stop and go into reverse i get the same clunk. It seems to do it a majority of the time just going from reverse to first as soon as i start to move. It wont do it if in im 1st, move forward, stop, then move forward again. Ditto with reverse. It is duplicated only the first time you change directions (IE move forward in 1st about a foot, stop, put it in reverse and go back.). The thunk happens the second you start to move. I feel it ever so slightly in the shifter and i can hear its somewhere under the center of the car (maybe rear) Anyone have any idea what could be going on here?
Thanks
dave

 

I have a simular issue and received a reply to my question when I posted it. Hope it helps. I need to go to dealer and see what they can do.

"This is what I recommend. Chock the front and rear wheels! Make sure that the car will not go forward or rearward!! SET THE PARKING BRAKE! Crawl under the car and inspect the rear drive shafts. Push, pull and yank on each one of the drive shafts. There should be ZERO slop in any dierction.

Have some one get in the car and while Keeping the brake applied shift into 1st gear and have someone (that knows how to operate a clutch!!) let the clutch out far enough to preload the drive train then, shift into reverse and do the same thing. Again, look for any slop in the drive train components and drive shafts. Look for any lost motion in the drive shafts, wheel bearings and suspension components.

Listen for abnormal noises. My guess is that your going to find your propellor shaft inside the torque tube to have a bad rear rubber insulator. You will not be able to see that problem but, diong all of this other stuff will eliminate a WHOLE lot of other drive line components.

Jack up the rear of the car and check the rear wheel bearings for abnormal clearance. Grab the wheel at zero degrees and 180 degrees and push and pull inward and outward. Do the same at 90 degrees and 270 degrees. There should be very little if any deflection in the wheel bearings.

If you have any questions on my explanitions on how to do all of this inspecting, PLEASE let me know. It comes natural to me and explaining how to di it is difficult."

 

i had my torque tube out and inspected the bushings and checked the runout of the prop shaft and all was well. Any idea if there should be any play when the rear is in the air and the wheels are rotated left to right w/ the car in gear? I have a bit when i try to rotate the tire either way.

Dave

 

Just a guess on this but it may have nothing to do with the torque tube.
Leave the car in park or first gear. Grab each rear tire and rock it back and forth as hard as you can. If you hear a distinctive clunk coming from the center of the wheel you have a good possibility of having a lose axle nut which allows corrosion into the spline. Loosen the 34mm axle nut and spray some lubricant into the spline area. Tighten the nut to 118 ft. lbs. recheck in a couple of days after some hard driving.

 

I did have a wheel nut loose earler today but i retightened and it didnt help. I put the car in gear and i car rock the wheels forward/back w/ the tires in the air a little bit and hear a clunk but im guessing thats just gear clearances in the trans.

dave

 

I don't think we are talking about the same nut. What I am referring to is the 34mm (wrench size) axle nut in the center of the rear hub:

 

yep thats the nut I was referring to. The more I think about this it isnt a clunk so much as a click that you can feel. It isnt a loud thud or anything.
Dave

 

i can duplicate teh problem by putting the ebrake on and loading the drivetrain in forward or reverse.

Dave

 

Sounds like a spider gear in the diff or a worn out clutch pack.

 

I really drove the car for the first time today. The clunk is easily duplicate by putting the Ebrake on and loading the drivetrain. It will happen in first or reverse at any time now. It doesnt happen every time but it isnt limited to just initial take off or reverse.

Dave

 

I have the same dam noise on my Z.....

 

ever figure it out? Can you feel it in the shifter? Does it sound like a pop?

Dave

 

Here are a few things to check.

Complete empty your car’s storage compartment, glove box and console to ensure something like a lug nut lock is not rolling around one of these area’s.

Drive the car, if the clunk is still there, do the following.

Back the car up on some ramps and inspect the following for security. Note, use wrenches and socket to see if you have any loose nuts or bolts.

Rear Trans cradle to frame
Rear diff mount to cradle and rear diff mount to diff
Shake the left and right muffles, listen for same tone of “clunk” check and make sure the mufflers are positioned correctly in the hangers.
Inspect the “hard” rear brake lines by the diff, make sure they are not banging on the diff.
Inspect the rear stabilizer bar at the cradle and at the A arms to include stab bar end links.

Since the TQ was removed the tunnel cover can cause the same symptoms refereed to as “oil canning” sound,
If you installed the tunnel cover bolts 1 by 1 and tightened them. If you did this, then loosen all the tunnel bolts (do not remove them), so that the tunnel cover relaxes, then tighten all the bolts.

If after all this the clunk is still there then do the following

Place the rear of the car on jack stands (note jack stands should be placed under the rear A arms so the suspension is still loaded by the weight of the car. After removing the rear wheel, install the wheel lug nuts to hold the rotors in place. Start the car and see if you can simulate the clunk. If the clunk is still there than inspect the half shafts for proper installation into the diff. It will also be helpful if someone was to “drive the car as you did and you try to listen for the clunk and it’s location. WARNING the rotors will be spinning and you do not want to be close to them.

If none of the above actions produce the “smoking gun” then you will have to drop the exhaust and tunnel cover to inspect the shifter linkage and the fuel and brake lines that run along the left side of the TQ tube for contact.

Good luck.
Kevin

 

ive done all of the following except get the car in the air. im farily confident its something in the drivetrain causing this problem as i can feel it in the shifter as well. Its not a rattle because it can happen just when starting off but not always. I need to get it in the air, lock the ebrake and have someone load the drivetrain while im under there so i can try to pinpoint where the n oise is coming from. I uust gotta find someone I trust to be up there. I have checked all brake lines and sway bars, anything that bolts to the frame and or can move/pivot for binding, looseness or clearance issues.

dave

 

little more info I noticed that when i downshift and let off the clutch it'll sometimes make this single pop that i can hear and feel in the shifter. It seems like when the drivetrain torques its occuring, but its not a trans or body mount to be certain.

Dave

 

Take that nut off and spray some grease in the opening, coating the splines. I have a can of white lithium grease I bought at some auto parts store. When the splines get rusty, they will creak and pop.

 

how can that creak and pop/ If that nut is tight that hub shouldnt move on the splines at all.

Dave

 

I can just tell you from experience that it does. Maybe the rust creates gaps.

 

did you remove the spindle to clean the rust off or just shoot something in there and that dispersed all the rust?

Dave

 

I started with anti rust spray and ended with aresol white petroleum. Never removed the spindle. Just spun the nut out of the way. Maybe somebody else can be more definitive. It has been about 4 years since I did mine.

I remeber it's around 120 ft lbs to tighten the 34mm (wrench size) nut. I had to borrow the socket and then bought one. So of course the problem has never come back!