Warning: Do Not over torque wheel lugs!

[bytehoven]

We took delivery of a new CX-9 Sport on Monday.

I made arrangements to swap out the original Bridgestone Duelers at a local tire dealer, for (4) new Michelin Latitude Tour HP tires for $170 total/installed. The dealer took the factory Duelers in trade.

I have done this many times with new vehicles at this tire dealer, always at a great price and without a hitch.

Well there was a hitch this time. The mechanic did not use a torque stick and over torqued all the wheels. As soon as I had my 1st chance to brake at highway speeds, I had serious vibration through the vehicle.

I knew exactly what happened. The rotors were warped due to the over stress.

They tried to remount the wheel with the proper lug torque, but the damage had been done.

The tire shop is replacing all (4) rotors with OEM parts from my Mazda dealer, and my service manager confirmed Mazda would still honor the break system with proof the tire dealer used Mazda parts. Proper torque is 95 ft lbs. I figure the tire shop mechanic applied in excess of 120 ft lbs.

The service manager confirmed care must be taken with the rotors on the CX-9, particularly the front rotors.

Just a heads up.

RJ
...

[bgibb68]

i hate to tell ya but that should be common knowledge.....

the best one i've seen has been a tire shop cross threaded a lug nut on my dad's car and probably put about 150lbs on it.....i had to break the lug

if any one ever touches my tires....i usually loosen all the lugs and then put my torque wrench on 'em

[CX9 SportOwner]

This brings up a common misconception about torquing lug nuts. Torque sticks are only supposed to get you close to final torque without going over, allowing the installer to still save time with an air wrench. They are not intended to tighten the nuts to final torque. If you keep driving them with an air wrench, they will tighten beyond their rated torque limit. Too many shops either don't know this, or use them to cheat anyway. Lug nuts should ALWAYS be tightened to final torque with an actual manual torque wrench.

You can not only warp the rotors, but invisibly damage the wheels, causing catastrophic failure. Make sure your shop hand torques the nuts, or go somewhere else.

[DaleNixon]

I'm pretty sure most dealers don't bother hand torquing the lugs. Be careful everyone!

[bytehoven]

The service manage said 95ft lbs lug torque. The Toyo tire/wheel guide says 80 ft lbs for the 2008.

What's the proper torque?

Regarding the torque stick, they are usually (+/-) a couple of lbs, so you can get 78 on one lug and 82 on another, with a 80ft lb stick.

I agree hand torque is the way to go.

RJ
...

[ceric]

The manual says
79.6―108.4 ft-lb

[CX9 SportOwner]

If you don't know, a good rule for alloy wheels is this:

Flat seat nuts - 90ft lbs
Conical seat nuts - 75-80ft lbs

I honestly don't know which type the CX9 has. Discount Tire rotates them free of charge.

[Rush]

I had an entire set of lug nuts destroyed by a shop that didn't watch their torque. A friend of mine literally had to DRILL OFF the lug nuts. It was ridiculous.

[not_too_shabby]

I got in the habit of loosening and retorqueing my wheels any time I had worked done on my car that would have involved removing wheels. Not only is it bad for the reasons mentioned above, but try to remove a lug nut that has been overtorqued on the side of the road with oem tools in the back of the car.

[CX9 SportOwner]

Very true. I admit that even with shops that say they hand torque, I still retorque them once I get home, just to be sure.

I had a shop argue the use of torgue sticks and how reliable they are for final torquing, even after I found half my lug nuts hand tight, and 3 so tight I had to use a cheater bar to get them off.

[CX9inMA]

Yikes! I had no idea this was so important. I have always done it the way my father showed me -- hand tighten, drop the car and then step on the tire iron and give it a couple kicks after you hear the screech. I wonder what torque that would register. ;)

After my first tire debacle (slid into a storm grate going about 15 MPH around a turn in snowy conditions with the hideous Duelers and burst a sidewall), I had to put the spare on the car at home. I had only hand tightened the lugs before lowering the jack and forgot to step on the tire iron after-the-fact. I drove to he deal to have a couple new tires put on only to discover that they had to order them. On the way home, I noticed a severe vibration and immediately pulled over. Then I remembered the lugs were only hand tightened and got out the iron and added some torque. I guess I was very lucky.

[CX9 SportOwner]

Yeah That trick is from the old days when wheels were steel. Wasn't even a good idea then.

I actually had a wheel cracked by a shop from over tightening the nut, which was a conical seat.

[fraochdha]

a month ago, I hit the dealer for basic maintenance, and they told me that I had a broken lug and that it was going to cost me about $180 to replace it. My argument with them was that I haven't taken my car to anyone but them, so if it was broken, it was something they did. The service manager argued with me, and told me that taking the lug nuts off was what did it, not on... and I called her out on it. They looked at my vehilce repair record, and finally conceded to repairing them for free.

Fortunately, I keep all of my mechanical repair receipts... and proved them wrong-- evidently, it's easy to strip or break these lugs.

be careful

P.

[CX9 SportOwner]

Good job not giving in and making them fix their mistake.

The two things that can break a stud are over tightening the nut, thus stressing the stud by literally stretching the steel.

The other is rust and corrosion seizing the nut to the stud, causing the stud to twist of.

It's not a bad idea to use a little anti-seize on the studs. Regular rotation will usually keep them from seizing, too.