Torque Lug Nuts to Avoid Brake Disk Warp ?

solaraman2003

Does anyone out there TORQUE their lug nuts when they mount their wheels on the Solara ?

My super-ace mechanic brother-in-law says that you SHOULD do this (to manufacturer's specs) so that you don't warp the rotors

Mr_Shiftright

I doubt you could warp them with a hand wrench. This type of caution is meant for gorillas with air wrenches who smoke funny cigarettes during lunch.

bretfraz

I do this to avoid possibly damaging my rotors and my alloy wheels.

andre1969

I don't have a torque wrench though; I just tighten them to the point that they "feel" right. I think all rotors nowadays are pretty flimsy compared to the old days, and are just much easier to warp. On the plus side though, I think they're also cheaper and easier to just toss and get new ones, than the older styles.

How much does a torque wrench run, anyway?

0patience

andre1969,
How much does a torque wrench run, anyway?

Do you mean how much torque? Mine have 450 ft. lbs and 650 ft lbs. Enough to break all the lug nuts with ease.

Or do you mean how much do they cost?
You can buy cheap junk for about $50 or you can buy a quality Ingersoll Rand air wrench for about $129

bottgers

It's more likely you'll experience rotor warpage due to brake heat rather than overtorqued lug nuts.

swschrad

if you overtorque a couple studs, and don't adequately torque another on the other side, considering how marginal rotors are getting I would not guarantee this won't happen.

another way to get this result is to jam down lug nuts one by one. this gets to the funny result of the little centering conical section of the lug nut not going inside the wheel hole, but binding up on the outside of the hole on the rim's edge. first time you slip on pavement, you have a loose stud as the wheel reseats. good way to have lug nuts come loose and wheels fly off into the bushes, and a good way to break lugs. that kind of pressure is bound to warp hot, thin rotors.

in any event, it's something you have to watch for when tightening down a wheel. and why it's supposed to be done in a star pattern in two or three passes.

solaraman2003

Also, I'd like to point out that the owner's manual of my Toyota Solara DOES specify that you torque them. I haven't actually done this yet, since my car is brand new and I've yet to rotate the tires the first time.

I just wonder how many people are aware of this and/or ensure that this is done when going in for service (i.e. tire rotation).

rubicon52

There are at least a couple of reasons for tightening the lug nuts yourself with a torque wrench. One is avoiding warping the brake rotors. Another is avoiding cross threaded lug nuts.

Even if you're using an air wrench, you should turn the lug nut on a few turns by hand and then use the air wrench. However, a lot of the gorillas as these discount tire places do all the turning with the air wrench. If the lug nut is cross threaded, the air wrench will still drive it on fine. The problem comes when you try to remove that lug nut and discover that its cross threaded.

This happened to me once. I immediately went out and bought a floor jack and now do my own tire rotations.

Mr_Shiftright

I think this is quite over the top for the regular car owner. If you use the star-pattern for tightening, and use only reasonable force, I can't imagine how on earth you could warp a rotor unless they are making them out of frozen pizza dough.

Also, a good torque wrench isn't cheap, and a cheap one isn't good.

So just tighten your wheels firmly by hand and don't over-caffeinate prior to installation.

oldharry

Right now, I have several torque wrenches, I torque every lug on every car, and working in an alignment shop, that is lots of lugs. About once a year, I send them off to Angle Repair for recalibration and repair.

It is heat that warps rotors, but if they are not tightened evenly, they expand unevenly. Tightening by hand in several stages, you will most likely be close enough. Using a power wrench, even with "Torque Sticks" may end up with uneven tightness if one i tightened before the rest are snugged.

A 50 to 250 pound foot Central Tools "click" type wrench wholesales for about $240. I buy mine through a wharehouse company.

Harry

hank14

Should any lubricant or grease be applied to lug nuts? I certainly don't want them flying off, but they can sure make a lot of noise when going on and off.

Mr_Shiftright

Lubrication may throw your torque readings off quite a bit, so be careful about that. I guess a little "never-seize" would be okay, but not a grease or anything like that as it will heat up and drool.

Never seize is great stuff. Me myself and I prefer to install lugnuts dry.

hank14

Thanks Shiftright. I'll go with that.

intransit

Warped rotors are common in todays vehicles. I've seen it occur after a panic stop. Also i've experienced warped rotors in my repair shop when lug nuts are installed incorrectly in sequence and over tightened with an air gun. I do not perform state inspections. When I brought my car in for an inspection, I asked the shop to torque the wheel they removed to proper spec with a torque wrench. They gave me an argument and said. "This was unheard of" I insisted and they complied with my wishes. The car manufacturers are reducing the weight of vehicles including rotors. In ending, if your rotor is slightly warped and you decide to replace the brake pads without cutting the rotors. a great deal of pronouced brake pulsation will result. If you don't agree that torqueing lugnuts is important, ask Mr. Goodwrench see what he says.

oldharry

If you live in a state that uses road salt, a wire brush on your electric drill will clean off the rust when you have the wheels off, and you should not have problems. The wheel manufacturers also recommend cleaning the rust from the surfaces of the wheel and hub that meet. A build up of corosion may prevent the wheels from properly seating, resulting in vibrations and/or wheels that loosen in service.

Harry

div2

Cars fitted with hub-centric wheels also need special care. The mating surfaces of the wheel and hub should be free of all dirt and corrosion. A thin coating of anti-sieze should also be applied to the mating surfaces. Failing to follow the above suggestions will likely result in a wheel that is well and truly stuck onto the hub-and that's the LAST thing you want when you are trying to change a flat on a dark rainy night. And yes, I hand torque the lug nuts/bolts on all my vehicles.

irishalchemist

If you use that (the little 'L' shapped wrench) and tighten the lug nuts in a star pattern, you will not wrap the rotors, unless you are the Hulk. If you think about it, the thing is probably 1/2 foot long, so even if you weigh 200 pounds and you lean most of your body weight on the wrench, you'll apply less than 100 ft/pound. Most lug nuts are around 80 to 120 ft/lb (I'm not talking about an 18-wheeler, but you common passanger car), so it should be fine. I even undo and redo my lug nuts that way if I see/hear them using an air gun during service.

Plus, if you have a flat in the middle of nowhere, and the previous time you had work done in your wheels the guy pounded the lug nuts with thee air wrench, you won't be able to get them off.

Do them with the provided wrench, and you should be fine...

My $0.02. G.

swschrad

at the side of the road in never-never-land in the rain at midnight, you will appreciate having had the foresight to put a two foot chunk of iron gas pipe in the trunk to use as a "cheater", or handle extender, to get those nuts off. hand-tighten with determination on mounting the spare, don't use the "cheater" again here.

warning, danger, beware of possibility of personal injury when overstressing tools, never be put in a position where the tool could trap you against a firm object or could snap back and hit you, etc. and so on, voids lifetime tool warranties, support your local lawyer, and so it goes.

cutehumor

so let me get this straight, there's no way a person torquing their lug nuts can warp their rotors. only air guns can? yes, I'm no hulk. lol I do tighten them as much as possible though. I have had the unfortunate experience of changing a flat where an air gun was used. my hand was hurting for awhile.

Mr_Shiftright

I really don't think you can bend rotors by hand, no. I've never seen anyone do this although I suppose with a long cheater bar it might be possible. Rotors aren't pizza crusts, they are pretty sturdy just sitting there.

0patience

One thing that you may want to understand about the rotors.
As they heat up and cool down, they expand and contract. If the lug nuts are not torqued the same, over time the expanding and contracting can cause the rotors to contract differently on portions of the rotor.

Mr_Shiftright

Well I was assuming that the one same owner/installer would quite naturally torque the nuts more or less the same with a lug wrench--by tightening them "as tight as you can". I bet with that dinky wrench the torque readings would be approximately close to one another.

swschrad

you are NOT going to be tightening the nuts down to a consistent pressure against the rotor. you will put a similar FORCE against all the studs, but you will have differing thread resistance on thread sets that are not clean, dry, and non-lubricated than on thread sets that are.

and if you do them one at a time, I guarantee you will NOT have one or more of the lug nuts centered in the hole of the wheel... where the taper at the end of the nut will not have entered the wheel to make a final centering adjustment... and those will loosen in just a few hours of driving. possibly even spin off into the weeds.

just two more ways to have uneven force against the rotor... and when it gets hot, it will expand wherever it can. if there are gaps between the wheel and the rotor... and there WILL BE sooner or later if all the nuts aren't snugged up the same... the rotor will be encouraged to distort.

0patience

I'll agree that normally tightening them by hand is not going to create much problems.
It is when impacts are used when the most problems are caused.

Mr_Shiftright

I think the owner's manual gives you proper directions for how to tighten the studs by hand anyway.

In my opinion, if they install a rotor that can actually be bent by changing a spare tire with a lug wrench, then they are REALLY cutting the corners too thin in making the car. Reminds me of when GM expected Corvair owners to put just the right amount of air in front and rear tires (different pressures), accurate to within a pound or two, or face dire consequences--well, guess what?

just4fun2

are saying, but, I can't imagine how a rotor can be warped by over tightened nuts. On my van the wheel studs are in the wheel hub. Now the rotor slips over the studs and the tire/rim goes on next. You are basically sandwiching the rotor between the hub and rim. Now with the thickness of the hub/rotor/rim, how can that much metal be twisted by over tightening the bolts?

I would think that the tire/rim going around a corner in the road at 45 mph would put more pressure on the studs than over tightening the wheel nuts would. Where am I going wrong here?

swschrad

in fact, it might act as a collar to cushion the uneven force away from the stud pressfits in the wheel or hub. but as the rotor heats up and cools down while you drive and brake, it expands and contracts unevenly due to the big old gap where you have a loose bolt. guess what happens when you hit a puddle with a hot brake rotor when it's unevenly expanded? -- it gets stressed. apparently these parts aren't tempered enough to stress-crack, but they will warp at that point from the sudden quenching. the warp will be high on one brake pad, causing uneven heating from then on... and it pulls the warp.

you don't have to warp 3/4-inch to make a shudderingly obvious difference, just a few thousandths of an inch (probably 10+ thousandths, but I don't gage rotors for flatness, but that seems a reasonable out-of-flatness to cause issues.)

0patience

Some of the vehicles, the rotors are stamped metal and not cast.
Stamped metal is extremely succepptable to warpage, which is why some aftermarket replacements for vehicles like the Lumina are cast, machined rotors.

Understant that the hub of the rotor affects the braking surface. If you pull a bolt down, the face of the rotor flexes. As it heats and cools, it will set in a position.
Most often, this only happens when air wrenches are used. It can be corrected by having the rotors turned on the vehicle, but then again, if they are stamped rotors, then replacing them is the best option.

bcarter3

I've been in aviation maintenance for 43 years. Virtually all fasteners have a designated torque and some of them are considered mandatory. While a car or truck may not require the same degree of care, I use a service manual for my vehicle and always use a torque wrench if torque is mentioned. If anyone in my family has to change a tire on the road they can do it with the tools provided with their vehicle. We do not carry "cheater bars". My torque wrenches are never used by anyone other than myself and are kept in a protected case. A damaged torque wrench is no better than a breaker bar. Having said all that I will admit that a good mechanic can recognize when a nut or bolt is tight without stripping the threads.

Mr_Shiftright

I've worked on small aircraft and the standards are considerably higher for mechanics and what they are supposed to do and not do. Also, everything on a plane is light AND strong. It's the "AND" part that makes the parts expensive, not the "light" part. Some automakers get the light part right but not the strong part.

My personal opinion is that rotor thickness plays a large part in rotor life. That thickness can be achieved a number of different ways (design-wise) but I have seen some pathetic rotors on certain new cars. They seem more interested in making them look nice than in giving them durability.

q45man

The aftermarket is quick sand! We can pay anywhere between $27 and $106 for what to the layman looks like the same rotor.....Weight of rotor [same style can vary by 2.25 pounds] and the ratio of metal to air space to metal is the clue in vented units.

swschrad

after all, you can cast a lot of voids into a rotor that will crack or shatter if you don't give a (hoot). a reputable parts house won't continue to stock creepy crud in which half of the product sold comes back as DOA the same week.

0patience

bcarter3,
Comparing aviation to automotive is like comparing apples to oranges.
There are alot of requirements in aviation.
Those requirements are not there in automotive.
Not everyone carries torque wrenches, but EVERY tire shop should have them. If nothing else for liability concerns.
I have torque wrenches that range from $150-$650 (1/4" dial to 3/4" 600 ft/lb.) and all of them are sent in every 6 months for re-cal.
If I pull a tire, I may use a torque wrench or a torque stick, but all lug nuts get torqued.

7937

Funny thing this, I had my wheels rotated and some months later my car started to pulsate when braking lightly at low speeds. The car a Cavalier which, by the way, has given me good service for 4 years, has discs up front and drums at the rear.

Now I would have thought that the discs had been warped. Not so - the rear drums were the culprits. I proved this by lightly pulling on the parking brake while rolling to a stop.

A new set of drums solved the problem. I also noticed that the cheaper drums were pressed out and were manufactured in a South American country. The story I got was that these countries buy the stamping dies cheaply from manufacturers after they go out of specification after so many operations.

So either the drums had become out-of-round or the mounting surface had become warped. Anyway, it beats the heck out me as to why it happened. For sure, the lugnuts were over tightened but I still can't fathom out the mechanics of the process taking place when nuts are over torqued.

swschrad

big monstrous chunks of steel, forklift weight, I have never seen a die set that wasn't two feet square, unless you are talking about electrical connector forming dies. and those were the size of boxer's fists. they are treated like crystallized dynamite. worn dies are filled with new metal by one of several welding methods and reground. tooling is expensive and kept in shape.

I doubt they are selling production dies overseas. rather, we have some folks doing reverse engineering overseas from a sample, and their products are at best three stages removed from US production.

BTW, drums and rotors are cast metal in the case of every car I have ever bought. check 'em out for balance holes drilled in various odd places, a hallmark of casting parts that need to be balanced.

the parts you had malfunction were cheap cheat jobs.

7937

Well, that's the story the counter man gave me about the dies and who am I to argue? Anyway, he also showed me the cheaper drums and it was pretty obvious that they were stamped out.

After stamping out the drums are machined and you could clearly see where the the chuck of the lathe had gripped the outside of the drum. It's possible that at this point where the mounting for machining is critical, that any offset will be reflected in a wobbly or egg shaped drum.

No - there were no balance holes drilled in the stamped out drums.

No - the drums that got warped on my car were factory fitted drums and not cheap cheat jobs. There were balance holes and weights fitted to them - a sign that they were cast. I bought the car new in 1999.

swschrad

might as well offer a paper-mache set.

good to see you weren't taken in by the scam.

7937

It was pretty clear that they were stamped out because the 5 mounting holes had sharp edges where the the punches had exited and the counter man told me that they were indeed stamped out.

Which brings to mind another thought. Any stamped out drum or brake disc must of necessity be softer than a casting. If you are going to stamp out a part the material has to be malleable hence softer.

A casting can be made of high carbon steel and a good brake drum or disc can crack if given a hard enough blow. You cannot stamp out a form made of high carbon steel. I suppose stamped discs and drums will just dent if given the same blow. Maybe that's why discs and drums don't last so long any more. They're too soft. I'm no expert on the subject so please correct me if I am wrong.

swschrad

absolutely, it will happen... when heated, steel tries to return (poorly, but it tries) to its original shape, following the grain. cast metal is more resistant.