Sharp clicking from passenger rear half shaft area.

[Ls7/Ls9 Test Engineer]

Hey all, it’s been a while.

I just started driving my 94’ Z last week after sitting for a while and I’m starting to notice a sharp clicking sound when I slowly let out the clutch and the car begins to move...
I’ve checked the lugs and cannot seem to find any play in the half shafts

There is no vibration at any speed and the noise is only present during stop start in either direction..

Are there any known issues that could be causing this noise?

Thanks for any assistance...

[Flyman 27]

Sounds like a universal joint to me.

[Ls7/Ls9 Test Engineer]

I forgot to mention that the car has 35k miles.

I also thought the same thing, but everything seems to be very tight and in good shape.
The sound is very sharp and crisp, almost like a “snapping” sound...

[DRM500RUBYZR-1]

See if the sound changes with:
1 -mild application of brake pedal before moving
2- partial application of Safety Brake before moving


While certainly not out of the question, 35 k miles seems low for drivetrain issues, low but not impossible.
Service or safety brake provide lots of opportunity for sound on initial movement, so let's rule that out.
Let us know what you find.
Marty

[lfalzarano]

I’m with Marty on the suspicion of the rear breaks, since it occurs upon braking and then take off.


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[billschroeder5842]

Marty and Lou are headed down the right path.

I had a similar situation when I first got my 91 from the original owner. Inspection showed that the rear calipers were not seated correctly (!) and the pin holes were worn "oblong." and was "floating" as the brakes were applied. I put on a new set of calipers and the noise went away.

[Hib Halverson]

Can you be a little more specific on when the noise comes?

You say "stop-start" in either direction. Do you hear the noise only when accelerating from at rest, either in forward or revers gears but NOT under braking? Or do you hear it on acceleration, on braking and either forward or backward?

Since this seems to occur at slow speeds, have an assistant with good hearing, squat down and listen as you accelerate to see if the noise is coming from under the car behind the front wheels or from the rear of the car.

Also, is the noise just a single click each time or is it a chattering noise?

Finally, does the noise occur only after clutch release or does it happen during clutch release?

[Marc Haibeck]

Is it a crunch sound that is most likely to occur when going from reverse to forward?

A common cause is loose rear spindles in the rear wheel bearings. The splines are a loose fit. The clamping action from the nut keeps the spindle from rocking in the bearing splines. It's easy to eliminate this possibility. Just remove the rear tires and tighten the nuts. The torque specification is 164 lb. ft. I like to tighten them about 10% tighter to 180 lb. ft.

[Ls7/Ls9 Test Engineer]

Good morning guys.

So to be more specific, the noise happens when the car moves either forward and backward from a full stop. The noise is more prevalent when the car/brakes are cold.
I tried the suggestion of engaging the parking brake and then gently trying to move for & aft. The noise did not occur at. The issue appears to happen only when the rotor moves, which has now moved my focus to the caliper and pads.

I’ll keep everyone posted on the progress in locating the issue, but it may be a while as I don’t use the car very often.

Thanks again for all of the suggestions and responses.

[RichS]

I've seen others say that the Teflon washer between the spindle and bearing could cause that noise also. I usually put a trace of anti seize on the ones in my GS whenever I had it apart.

[Ls7/Ls9 Test Engineer]

Hello all,
The root cause was found to be a loose axle nut on the passenger side. Bought a new nut and re torqued +10% and the issue is now gone. Thanks to everyone for all of the help. It’s greatly appreciated.

[Paul Workman]

Hello all,
The root cause was found to be a loose axle nut on the passenger side. Bought a new nut and re torqued +10% and the issue is now gone. Thanks to everyone for all of the help. It’s greatly appreciated.

Thanks for getting back to us on the fix. GOOD TO KNOW.:thumbsup:

And, Cliff, Marc's tip sounds like a good one for the SOLUTIONS collection, no?

[Dynomite]

Cliff, Marc's tip sounds like a good one for the SOLUTIONS collection, no?

Yes......Done :thumbsup:
Always keep me posted :handshak:
See.......ZR-1 Drive Train (Drive Shafts).

Sharp Clicking Rear Axle (http://zr1.net/forum/showthread.php?p=297202#post297202)

Marc has over 40 Posts on this Forum many of which are -Solutions- :thumbsup:

That is not counting Solutions he has text me :cheers:

[Ls7/Ls9 Test Engineer]

Just so everyone knows, The noise that was heard was the EXACT same noise you hear when you crack a lug nut loose. That really sharp creak sound happened each and every time I changed from forward to reverse.
Not to sure whether it was the splines moving in the hub, or the friction slip on the back seating area of the big nut, but after being tightened, the noise disappeared 100%.

[billschroeder5842]

Hello all,
The root cause was found to be a loose axle nut on the passenger side. Bought a new nut and re torqued +10% and the issue is now gone. Thanks to everyone for all of the help. It’s greatly appreciated.

Hey all- I'm going to get after this one tomorrow as I also have a sharp, click on the driver side.

I'm kind of a geek and do consult the FSM prior to project while I watch college football and read the manual. (Roll Tide and Geaux Tigers!)

For the life of me I CAN'T find the section of the FSM that covers this procedure?

Section 4B is about the rear axle, but no mention of the axle nut?

[Dynomite]

You can do exactly as Marc suggests or go a bit further........Left Click on the Link Below. (Both involve tightening the Axle Nut) :cheers:

Is it a crunch sound that is most likely to occur when going from reverse to forward?

A common cause is loose rear spindles in the rear wheel bearings. The splines are a loose fit. The clamping action from the nut keeps the spindle from rocking in the bearing splines. It's easy to eliminate this possibility. Just remove the rear tires and tighten the nuts. The torque specification is 164 lb. ft. I like to tighten them about 10% tighter to 180 lb. ft.

This Link has some Photos :thumbsup:
Clicking from rear under initial load (http://zr1.net/forum/showthread.php?p=229825)

[billschroeder5842]

Thanks Dynomite- this is exactly what I need to do.

I must have missed it.... what size socket do I need for the nut?

Looks like I'll remove the nut, repack with axle grease and torque to 190.

Thanks!

[Dynomite]

36mm Axle Nut.....If you want to go a bit further......:D

Post 240 - New Rear Wheel Bearings and Half Shaft U-Joints (https://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-12.html#post1591920876)

All tested recently on a 4,000 mile road trip :-D

[billschroeder5842]

Thanks! You rock!

[billschroeder5842]

I did the "repair" today, removing the nuts "trying" to put a bit of grease in the spindle (I used a hypodermic syringe) but the tolerances would have nothing with it.

I used the torque wrench to get the nut to 190lb.

I took it for a ride and did not hear the sharp "snap" as in the past. I did hear a very, very soft *pop* occasionally as I transitioned from forward to back. I admit I was "looking" for a sound so I could have imagined normal car noises. If the radio was on at any volume I probably would not notice anything-- again I was listening hard.

So, would you leave things alone for go back in and put an additional 10lbs on the nut?

[Dynomite]

Leave it alone..........next time if it becomes a nuisance.......put some anti-sieze on the axle spline.....that worked for me :cheers:

[billschroeder5842]

Leave it alone..........

Thanks! Will do!

[billschroeder5842]

Hello all,
The root cause was found to be a loose axle nut on the passenger side. Bought a new nut and re torqued +10% and the issue is now gone. Thanks to everyone for all of the help. It’s greatly appreciated.

Where did you find the nut? I called all the "big" parts houses and they don't have anything (back ordered) for 45 days.

Is this/could this be a hardware store item? If so, do you have size specs?

Thanks!

[billschroeder5842]

I (Finally) found a set. Davies Corvette (corvetteparts.com)in Davies Florida. They have them in stock #646030 for about $25 I got both sides for new washers, nuts, star and cotter pins, delivered on Thursday.

I swapped them this morning before all the college football begins. I torqued to 190ish. I went for a quick ride on a route that typically gets my rear axle sounding like a Rice Krispy treat. So far all quiet but I'll take it out for an extended ride this afternoon.

So, other than new, what makes the new set quieter than the original set that appears to be in good condition?

[Jagdpanzer]

Look for Dorman Spindle Lock Nut Kit 5101 at your local auto parts store.
They run around 8 bucks each

[mrand]

I wonder if the loose nut caused my right rear bearing / hub assembly to go bad... didn't notice noises until this summer - less than 75k miles. Put it up on stands and found the right rear wheel would move quite a bit.

Finally pulled the rotor off last weekend and found the nut was just more than FINGER TIGHT!

There is a huge amount of play in the hub assembly on that side compared to the other, and have a replacement in hand... hopefully next weekend I can get it off!

[lfalzarano]

I agree that the loose nut contributed the failure.


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[mrand]

I agree that the loose nut contributed the failure.
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After thinking about it more, I'm not so sure. The nut simply retains the half-shaft, keeping it engaged in the splines. The hub (and bearings) are held in place with the three bolts to the suspension system.