Um.... Higher up in this post, Spin says this


The 160 lb ft is wrong. What am I missing?


Elmer

 

Well I just checked my 2006 Z and the threads are rusted and the nut is not,but I did check to see if they were finger loose and they were not.So I just marked them to see if they move any over the next few months.With the surface rust on the threads , I do not think the nuts are going to move much.Mind you I have had no noise or clunks coming from the back end of the car at all.

 

Thanks for the post.

 

The TSB has been updated by GM, as stated above, per the new GM bulletin and service manual, the torque spec is 160N·m which equates to 118 lb ft.

 

Checking with a TQ wrench as to the current TQ value and verifying TQ value of a nut that is still for any time will take far more TQ to get it going and this isnt a valid way of checking how tight a bolt is. You have to loosen it and keep it moving up to its desired TQ setting. This is why the loc-tite is a valid fix.

It would be best to check the nut's position with a painted mark on the nut to axle relationship. If its the same, dont touch it. If the TQ value moved and the nut is in the same position to the axles markings then if its loose its because of a different reason than the nut moving and you fix wouldnt do anything. Loc-tite is valid and checking a frozen nut with a TQ wrench is not.

When this topic came up there were others who posted pics of the axle breaks they had when they retorqued the bolt. I wasnt the only failure and back then, some of the breaks were from guys who simply retorqued to the old 118' lb GM spec as you suggest doing. They broke also at the base of the spindle and not at the center part thats thinner on the early C6's.

This thread was posted by a guy who stated that he re-torqued the nuts regularly and thinks that the one time he didnt do it was why it broke. He kept TQ'ing it to a point it broke. Has anyone ever reported a break that didnt continually TQ it?

http://forums.corvetteforum.com/c6-z...ut-torque.html

My second axle was at 160ft lbs for about 90 miles and broke. My point of sharing the info was to show what happened to some guys who keep reTQing. Some broke at 118 and others broke at 160ft lbs. The constant is they all keep reTQing.

 

Go by a marked position.

 

When the car is in use, there is far more than just that load on the shaft.

 

Your post is showing the right thinking.

You can not check a fastener that has been still and TQ without first loosening it to get a real TQ value. It takes far more TQ to get a fastener moving that has been still. This of course would be a big issue if the fastener takes only 50 or 60 ft lbs to get movong. Its TQ vaue would have been far lower.

The best way to see if it moved would be to mark its position and just look at the marks. It its loose and it didnt move something stretched or got compressed.....agree?

If something stretched or compressed further TQ'ing could be a danger.

 

Let me see if I have this straight; the axle nuts were originally torqued to 118 lb ft at the factory, but were coming loose, so a TSB was issued to increase the torque to 140 lb ft and use locktight. Then the torque was increased to 160 ft lb with locktight, and now the recommendation is to torque new nuts to 118 lb ft with locktight.

Is this the correct and final word on this issue? or maybe I should wait until GM decides to revise the TSB (again) on this???

Not trying to a smart arss, but I have new axle nuts and want to install and torque correctly the first time.

Any GM engineers out there with the definitive answer?

 

So,

for those of us who had nuts on our 2005 that were finger tight, but no noise, and used the 215Nm/160 lb ft (w/ 272 Loctite) spec just LAST week...is the conventional wisdom that we take them off and do 160Nm/118lbft?

....or leave them at 160 lb ft and just avoid the re-tourqing

 

 

 

Look on the bright side - at least we aren't talking about lug nuts any more.

 

To avoid any failures, possible injury, property damage or denied warranty coverage I'm having my dealer inspect and or repair my car IAW the current TSB.

I'm too old and my Z is too expensive to fool around with this. These threads have been very enlightening to say the least.

Cheers

Tom

 

Spring is coming time to bring this post up again.

 

Spinmonster, this is an excellent post and I'm sorry I missed it the first time around. The spindle nuts are not intended to be re-torqued because they have a concave surface on the bottom that flattens at torque to mate intimately with the face. This is intended to really be a one shot deal.

The loose spindle nut has been identified to be at least partly caused by a slight tolerance stack-up between the thread peak and pitch of the nut vs. the spindle. The new torque spec is intended to be used with in conjunction with the TSB and new spindle nut which has a new part number because it is designed to be a better match to the tolerances of the spindle and eliminate this slop that was thought to be contributing to the nuts relaxing over time.

You are exactly correct in your thought that over torque can contribute to damage because once the nut has been torqued and flattened, additional attempts at torquing the nut can actually start to pull the spindle forward and all sorts of interesting things can begin to happen at greater power levels.

 

I don't know how you could torque to 160lbs without breaking the nut.

 

So Paul,

if i have not checked the nuts on my 07 (4,500mi) i should just check the TQ and tighten if loose. OR, if loose should i just purchase two new nuts and install them with Locktite to 118? this is getting confusing. maybe i'm just dumb :o.

 

jimmie jam, the only dumb question is the one not asked.

Don't try to torque them from the state that they are in.

You should check to see if your spindle nuts are loose. Check by hand or by just using a wrench. Don't specifically try to tighten or loosen, just see if they are loose.

If you find them to be obviously loose, my recommendation would be to purchase two new spindle nuts of the correct part (new part) number and get the locktite and apply the locktite and torque the new nuts and allow it to sit for 24 hours before driving the car.

If you don't find them to be obviously loose, I wouldn't necessarily do anything. Don't attempt to torque them up, that is certain. Having the nuts loose is not a particularly dangerous situation unless you have a lot of horse power. The axle isn't going to fall off or out of the car. Having the nuts loose can contribute to some rear end noise but that is for the most part the extent of the risk. The hub is still attached to the control arm. Over torquing is more dangerous than too loose as you can damage the spindle.

The new torque information is specific to the new spindle nut part number included. Do not attempt to torque the old nut to the new spec and don't just apply locktite to the old nut and re-torque.


The last TSB information I could find was 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.

Update 9/13/2007

Part Number 12345493. has been superceded by 89021297.

 

was the torque # changed at all by gm since 2010?