BEZ06

It's been really cold here lately - it's gotten down into the 50's at night, and only in the mid 70's during the day!!!

With the colder weather I noticed my cold tire pressures on the DIC were down a couple psi, and the RR was down about 4 or 5 psi from the 30 psi cold I maintain. I'm running the stock PS2 ZP tires.

I aired them all up to 30 psi (using my accurate hand held gauge, of course!) and then checked the DIC display when driving the other day. Everything looked good except the RR was down was about 3 psi lower than all the others. While taking my wife around shopping and out to dinner, I checked the tire twice at two different stops we made - at least the tread I could see from a quick look and feel, and couldn't find anything.

When I got home I jacked the right side and took a good look at the RR and found a screw you can see in the pictures below - in the first picture, the screw is on the right side of that wide smooth rib:







Yesterday I took the wheel off and took it to my local Discount Tire - they've mounted up a bunch of tires on my Z06 track wheels, and fixed a couple punctures in runflats in the past. They do a great job and take care of my wheels with very professional and careful service.

And they FIX PUNCTURES FOR FREE!!!!!

To repair a runflat the puncture must meet requirements such as not too big, not too far out toward the edge of the tread area, only one repair can be done (at least to maintain the speed rating).

The tire must be removed from the wheel, the liner has to be prepared, and a proper plug/patch must be used. Then they remount the tire, and balance it - FOR FREE!!

That kind of service will make sure they continue to get my wheel/tire work in the future.
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NOW FOR THE REAR AXLE SPINDLE NUT PART!!

I got it home and was ready to put it back on the car, but saw the axle nut and thought I'd check it to see if it was torqued properly.

I've read a bunch of threads with a progression of SB's that have changed the axle nut torque spec over the years.

If you haven't had another C6 you might not be aware that it's a widespread problem that the nut will losen over time.

I thought they had fixed it a couple years ago - they have changed the torque spec over the years from an original 118 lb-ft to as much as 160 lb-ft (see the SB in the link at the bottom of the page where that spec is used). My 2006 Service Manual has the 118 lb-ft spec, and the 2009 manual has a 151 lb-ft spec. I thought they had done something on the production line starting a couple years ago that was supposed to make sure the nut wouldn't back off.

I have read that the ZR1 axle nuts are put on at the factory with Nord-locks, but other models aren't. I looked at mine, but I can't see any Nord-locks on my late '09 ZR1 - but I couldn't see back behind the nut back in the hub, and I didn't take the nut off.

However.....I just thought I'd check mine while I had the wheel off. I cranked my torque wrench up to 130 lb-ft just because that's as high as it would go. I've got a 2009, ans as I mentioned, I believe the most recent spec is 151 lb-ft.

I put the wrench set to 130 lb-ft on it and pushed and the nut turned about 1/8th of a turn before the wrench clicked!!!

I mounted up the wheel, and was ready to lower the car, but I had the whole rear off the ground, so I decided to take the left rear off and check the nut as well. If you can get the center cap off your socket may fit in there onto the nut without taking the wheel off, but on the stock ZR1 wheels I needed to take the wheel off to pop the center cap, so I just removed the wheel and checked the left axle nut, and it was exactly the same as the right side - it turned about 1/8th turn before reaching the 130 lb-ft my wrench was set to.

If they were torqued at the factory to the old 118 lb-ft spec, I don't think they were even close to that!!!

So.....like I did on my other C6s, the axle nuts are now added to something I'll check on a fairly regular basis!!! I'm definitely going to get me a new torque wrench so I can torque accurately to 151 lb-ft, and I may do the Loctite thingy sometime in the future.

I you have your rear wheels off, you might want to check to see how the axle nuts on your car are doing!!

Here's a link to a thread discussing the problem on other C6 models. It has an intermediate SB in it with the 160 lb-ft torque spec, but to my knowledge it is now 151 lb-ft in all current documents. It also discusses using Loctite:

http://forums.corvetteforum.com/c6-c...a-warning.html



Bob

ufso

Just a heads up...you're not supposed to torque the axle nut if it's loose. You're supposed to buy new axle nuts. Take off the old ones, blue Loktite the threads, put on the new axle nuts w/the correct torque and let dry 24 hrs. before you drive.

Also, I don't think Discount Tire is an official facility that Goodyear recommends to patch and plug a run-flat.

GOLD72

The ZR1 has Michelin PS2s instead of Goodyear.

As a side note, in the Houston area, there are only one or two GY stores that will even service a corvette EMT tire. It's a real joke. Discount does an excellent job of selling, mounting and repairing GY EMT tires. You won't catch me dead in a GY store.

BEZ06

Thanks for the heads up, but do you think I haven't read the link I posted???

I've read a couple of SBs about this issue - the one in that link being the most recent one I know of.

If you had a Z06 you tracked, did you swap to track pads regularly? If so, did you ever pull the calipers, or did you just remove the pad pin bolts?

If you removed the calipers, the Service Manual says to use new caliper bolts every time you reinstall the caliper - YEAH, RIGHT!!! At something like 8 bucks per bolt times 8 bolts, that would be awful expensive for all the pad swapping I've done to track pads and back to street pads. Nobody replaces the bolts every time they swap pads!!!

Considering that the ZR1 is reported to have Nord-locks to keep the nut from backing off, there's something the matter with the system, and I'm not going to buy a new nut every time I check the torque.

Like I said in my post, I may remove it and reinstall with Loctite, and I may consider putting on new nuts if I do that, but probably not.


Did your ZR1 come with Goodyears???

I tried taking a stock tire off my 2005 to a Goodyear dealer when I had a puncture - they said a puncture in a runflat couldn't be repaired!!! They didn't know what the hell they were talking about!!!

Unlike yours, my ZR1 came with Michelin PS2 ZP tires - and I won't take them anywhere but my local Discount Tire to get them worked on.

If your local Goodyear dealer is any good, go ahead and take your business there. BTW, the Goodyear place I went to about 4 years ago with my 2005 isn't even there anymore - tells you something about how good they were/weren't!

Bob

GarryZR1

So are the rear axle nuts an issue for 2011's?

ufso

Bob,

My sincerest apologies... I posted in the wrong section. I thought I was in the C-6 General Section. What I said applies to the base C-6, and I have no idea if it applies to the ZR1.

Sparky

BEZ06

I dunno?? But I suspect it probably is!!

I thought the ZR1 was supposed to keep the problem from happening - like the reports of Nord-locks being used to keep the nuts from loosening, but I don think that's the case. My 2009 still has has the problem so I bet even the 2011s may have it.

Anyway.....that's why I was posting up my experience with loose axle nuts - just so everybody can be aware that it appears to still be an issue.

Bob

Mr. Gizmo

its important to get your nuts checked and torqued on an annual basis. I make sure to get proper maintenance on my nuts.

Shurshot

I would suggest at least 2-3 times a week

Torched

That's my procedure check the rear axle nuts and all wheel lug nuts on a regular basis.

xcutter

I had this issue on my 2005 C6 and 2008 Z06. Loose Axle nut issue has been around from the begining of the C6.

911/Q45

How many miles on the car?

BEZ06

11,000 on my '09.

But - I think on the base C6 and Z06 some owners have found loose nuts on very low mile cars.

Bob

Randy_medion

How many miles can you drive with the ZR1 when tire is flat? Only 50 or more?

Ranger

I've worked the loose axle nuts issue since we discovered it on 2006 Z06s that were running at the drag strip.

Every Corvette that attends our track rentals has its rear axle nuts checked for correct torque. Almost all are loose the first time checked. That includes C5s, C6s, Z06s (either generation) and C6ZR1. May have found one or two that weren't loose but they were the exceptions.

The good news is that once the axle nuts are tightened to the GM torque spec (was 160; most recently 151), none of them we checked on repeat track visits have come loose again.

I loctited my axle nuts to the then-current 118-spec in 2006 and they've not come loose through about 200 additional passes down the 1320' since.

So torquing them to spec is a job you'll probably only going to need to do once. After that, they bear periodic checking, just in case.

Ranger