AXLE NUTS...FYI..

[hardnoks]

ARE you all aware of this emerging issue w/some vettes and the latest info on it???Torque Specs are now 140 ft lbs w/a new nut and LOCTITE 272.

If there is presence of the nut "indexing and/or looseness", do the following:

1. Remove existing nut
2. Apply Goodwrench # 12345493 (also known as Loctite 272) on threads in area where nut finally seats
3. Install new nut (p/n 10257766)
4. Torque nut to 190Nm (140 ft-lb), static
5. Allow 24 hours cure time.

Note that a NEW nut is required and the torque has been increased from 118 ft-lb to 140 ft-lb.

from the factory.Here's the only TSB # I have right now.

That is the old TSB from 2005. It does not include Loctite and the recommended torque is 118 ft-lb. Based on the information Hib obtained, I suspect that there is a new TSB in the works which includes the procedure described in the first post.

I didn't hear of the newer fix till after I had this done.

This # is right off my bill from the dealer."PERFORM REAR AXLE TORQUE""SET TORQUE AS PER BULLETIN" is what the whole thing says,then the #.
TSB 05-04-95-001.

The GM Loctite part number in the factory instructions is 12345493.
When I purchased some yesterday I was told that the Loctite now has a new
part number of 89021297 (same product). I wanted you to add a note
indicating that the GM Loctite part number can be either 12345493 or
89021297.

More info on this.Thanks.

 

[BlackZ51Vett]

 

[jbeidl]

Please Let GM Know

I posted the corrective action information above on another forum. I received the information from the assembly plant by filling out an "Owner Feedback" form. If anyone on this forum has this issue please let GM know.

GM needs to understand the extend of this issue. This is a link to the Bowling Green Assembly plant

http://www.bowlinggreenassemblyplant.com/

When that page comes up you will see a yellow button in the center of the page labeled "Owner Feedback". When you click that button it will start the process to fill out a feedback form.

I think that everyone that has this problem should report it on this form. You can indicate that you already have the corrective action procedure and that you just wanted to make GM aware that you have experienced the problem. Provide any facts you have, which nut(s) were loose, how loose they were (torque if you started low like I did to measure existing torque) and anything else that you might have noticed. You should also report it to your dealer the next time you are in for service.

Save The Wave,
John

 

[hardnoks]

GM

Well,I just filled mine out!!Told them about being charged for the TSB,TOO!!

 

[jbeidl]

Well,I just filled mine out!!Told them about being charged for the TSB,TOO!!

Thank you for sending in the form. When I was at a C5-C6 seminar in Carlisle two weeks ago, this question came up. The tech giving the seminar did not think there was a problem, he had only heard of a few incidents and thought they were caused by worked performed and the nut not torqued properly. I spoke with him after the seminar and assured him this is not a few isolated incidents and that no one had ever touched my car after I picked it up from the museum. He advised that anyone with the issue let GM know about it so corrective action can be taken. That is what prompted me to fill out the form. The information on the new procedure was the result of that submission.

We need everyone that has/had this issue let GM know about it.

Save The Wave,
John

 

[dtvet]

What are the symptoms of this problem?

What year cars does it affect?

 

[jbeidl]

What are the symptoms of this problem?

What year cars does it affect?

I don't know if anyone has been able to detect this issue while driving. If anyone has please post symptoms.

The axle shaft is free to move on the inboard CV joint. If the axle (spindle) nut is loose the axle shaft is free to move in/out on both ends. I believe the suspension components will keep the outboard CV joint and spindle shaft from coming out of the hub.

I have seen reports of this problem on 05-07. I suspect it may also appear on 08's.

Save The Wave,
John

 

[dtvet]

I don't know if anyone has been able to detect this issue while driving.

I guess I am a little confused as how people know that this is a problem, if there are no symptoms. Is it a problem?

 

[hardnoks]

symptoms

I don't know if any symptoms have been reported.Just pull the center cap of the wheel and see if they're loose.Either that or wait to see if the axle falls off or something.
I think guys were just in there checking other stuff or swapping tires or something and found out about the axle nuts.Either way,what's the difference,it's an issue now.

 

[c4c5specialist]

HI there,
The axles or wheels will NOT fall off.
Its more of a noise created concern.
So, with that, give feedback as listed above.
It will NOT hurt and will only speed GMs action.
Alllthebest, c4c5

 

[Chrisr]

Is this affecting ALL C6's or just certain years????

 

[jbeidl]

Is this affecting ALL C6's or just certain years????

See Post #7 above.

Save The Wave,
John

 

[Hib Halverson]

I don't know if any symptoms have been reported.Just pull the center cap of the wheel and see if they're loose.Either that or wait to see if the axle falls off or something.
I think guys were just in there checking other stuff or swapping tires or something and found out about the axle nuts.Either way,what's the difference,it's an issue now.

I agree with C4/c5 Spec.

In fact, I'll go farther. The first post is more alarmist speculation than it is good information. I think, had I been the person writing it that, I'd have researched the issue a bit more before I'd have posted to the CAC.

Even at 118 lbs/ft an axle nut is NOT going to be loose nor is any part of the car going to "fall off".

Likely, what's happened here is GM has probably been getting reports from dealers of "noise", probably a clicking, or maybe a slight "creaking" or "squeaking" from the rear. Further investigation has probably found either 1) at 118 ft.lbs there still can be slight movement of the mating surfaces--sort of like the "fretting" once sees on the backs of rod bearing shells when you take them out of a higher mileage engine"--and that movement (a matter of fractions of thousandths of an inch) causes a click or a squeak, or 2) when axle nuts are removed and replaced the reused axle nut's threads have deformed enough that 118 lbs/ft is not delivering enough clamping force to eliminate the noise.

The solution was to require new nuts and increase the tightening specification to 140 ft/lbs. I will surmise that the nut, also, now might be of a different material.

I'm away from my source for TSBs right now but I wonder if this bulletin also affects C5?

Bottom line, you all don't need to go running to your dealers fearing that the rear wheels are going to come off your cars.

If you hear a slight clicking or subdued squeaking as the care slowly rolls or if you drive in reverse, stop then hear a slight noise from the rear as you start forward, take the car into the dealer, ask them to inspect the tightness of the axle nuts and advise them you're aware of a TSB on axle nuts.

All that said, if you do pull your rear wheels off and actually find the axle nut(s) loose, you can bet that it's not because of anything to do with that bulletin....it will be because either 1) the factory "forgot" to torque the nuts which is pretty unlikely or 2) if the rear axle nuts had been recently removed by a service facility, they forgot to tighten them.

 

[NORTY]

It seems like most of the problems (or the most loose) are on the passengerside. BTW. I use a beam type torque wrench and mine "came loose" at 40ft.lbs. (driverside) and 22lbs (passengerside.) Retorqued (wet) to 118 ft.lbs. I have rechecked them (often) over the past year and a half and they have stayed in spec. I did not use locktite but I did use brick grease as a "locking agent."

 

[Hib Halverson]

Brick grease is not a locking compound. In fact, it's a grease which never hardens.

If the TSB or the Factory Service Manual calls for a thread locker on that nut, I'd remove them. Clean the brick grease off and reinstall them using the thread locker called for in the bulletin or the manual.

Note that the factory info says Loctite 272 which is a high-strength thread locker. This means that brick grease would be totally inadequate. I'd use either Loctite 272 or Valco Cincinatti High-Strength thread locker.

 

[jbeidl]

Right Side Loose again, not as bad as last time

I received 3 spindle (axle) nuts yesterday. I measured them and found that the threads have a taper like I was told.

I checked my spindle nuts this morning at 5360 miles.

Started with torque wrench set at 20 ft-lb and tested at 10 ft-lb increments. Left never moved up to and including 120 ft-lb. Right side started to move at about 100 ft-lb. The same torque wrench was used in June to torque right side to 120 ft-lb. The right side was not as loose as the first time I checked it (30 - 50 ft-lb), but it was not were I set it in June at 2424 miles.

I guess I will put a new nut, Loctite 272 and increase torque to 140 ft-lb on the right side. Since the left side has not changed, I will leave it alone for now. I plan to check them as part of regular maintenance, probably at each oil change.

Save The Wave,
John

 

[KGjevre]

Thanks for the update on the loose axle nut issue.

In May 07 I picked up 33 mm axle nut socket (the Pep Boys $12.99 one) and set torque wrench to 118 ft-lbs.
Passenger side was tight, drivers side was slightly loose (1/6 turn to get click).
No track or autox yet at the time, just some quick accelerations with no wheel spin, and two small slides.
This is on a January built 07 Z06 with about 1K miles at the time, and the car is stock with no dealer visits.

Since then I did one autox and are planning to do another this weekend, so I am overdue on checking them again.

I will also do the Bowling Green Assembly Plant owner feedback.

-kg

 

[jbeidl]

I will also do the Bowling Green Assembly Plant owner feedback.

-kg

Thanks kg, the more data points that GM gets on this problem, the better.

Save The Wave,
John

 

[dtvet]

I am taking delivery of an 08 this week. Should I purchase the new nuts and loctite and replace the nuts when I get home?

 

[Hib Halverson]

Forum members-

I said earlier in this thread that I would look into this issue and get some facts. In the last day or so I've had an private email exchange with Tom Wallace, the VLE for Sports Cars at GM along with one of Tom's staff members in the Corvette Brand Quality team.

Now, at this point, official GM is not ready to comment, but the reason for that is they: 1) want to wait until the Service Bulletin distribution process had taken its course and all dealers have the TSB and 2) know SPO has enough parts (the new nut) in stock to supply all dealers.

For now, I can tell you that if the nuts on your car loosen, partially or completely, or even separate from the axle shaft, the rear wheels WILL NOT "fall off". In this instance of axle nuts coming off, the wheel/tire assembly falling off is a virtual impossibliilty.

Why?

Becasue the brake rotor will still be held laterally by the brake caliper. Because of that, the rotor/hub cannot move any where near far enough outward such that it would clear the end of the axle shaft. Obviously, for a wheel to fall off, that would have to happen, first.

What happens, if the nut drops off, is you will hear a pronounced scraping, grinding noise caused by the brake rotor rubbing heavily on the brake pads or the brake caliper body. This happens because the rotor is no longer perpindicular to the axle shaft centerline. You may, also, feel the back of the car seeming to track a little inaccurately...a slght side-to-side "swaying" if you will. The swaying happens because, with the axle nut off, the rotor can move side-to-side in the brake caliper a few fractions of an inch.

So...let's go over this again.

Even if the axle nuts loosen fully and drop off the axle shaft, the wheel/tire assembly will not even come close to falling off.

So, what can DIYs with existing C6es do?

1) Check the tightness of your rear axle nuts using a *known good* torque wrench with a range of 0-150 ft/lbs. The best torque wrenches are the dial type. The next best are the old fashioned beam-type. The worst are the click type because of their tendancy to become inaccurate and their need for periodic calibration.

2) Tighten old style nuts to 120 ft/lbs.

3) After that and after you have verified your car has the old nuts, go to your dealer and see if it has stock of or can order two of PN 10257766 along. You also need either a small bottle of Loctite 272 or the aforementioned GM thread locker.

4) When the new nuts arrive, follow the factory service manual as to the axle nut removal/replacement process. Remove the old nuts and discard them.

5) Apply the thead locker per instructions, install the new nuts and tighten to 140 ft/lbs.

6) Allow the thread locker to set at least 12hrs and perferably 24.

Keep in mind that if you ever have to remove those nuts again, you will need a lot more than 140 ft/lbs of torque and probably will need to use heat.

Non DIYs should visit their dealer. Tell the Service Writer you're believe there might be a TSB relating to rear axle nuts and that you believe yours might have a problem and you'd like the TSB performed on your car under warranty.

Once I get some of the GM engineers to go on-the-record with me concerning this issue, I'll be back here to report.