Torque for Wheel Lugnuts

[lazabby]

What is the recommended torque for the wheel lugnuts?

[Jonathan]

60 ft-lb

[Chris 16409]

Avoid an impact gun if you have OEM lug-nuts. The caps have a tendency to come off.

[DMC-81]

Hi there,

According to the Workshop Manual, it is 70ft/lbs. (L:12:01)

I have had to take my wheels off enough that I have it memorized. :)

[DavidProehl]

Interesting. I always thought it was 60 ft/lbs as well. As mentioned, wheel nuts are listed on L:12:1 at 70 ft/lbs, but "wheels" are listed on A:03:01 at 60 ft/lbs. I have always used the "wheels" spec, but now it looks like that might not be right.

If "wheels" isn't the lug nuts, what is it?

[David T]

As per ST-09-7/81 which is the latest, most up to date spec, it says 60 ft/lbs. Last item under Rear Suspension at the bottom of the page. As for the lug nuts, make sure the socket is ALL THE WAY on the lug nut or you will damage and spin the shell cover. Best practice is to snug them up and then torque them in alternating order.

[Michael]

I just ring them on nice and tight with a breaker. Most everyone else does it too but they will not admit t it here.

[Drive Stainless]

I just ring them on nice and tight with a breaker. Most everyone else does it too but they will not admit t it here.

I do this now after finding loose lug nuts that were previously tightened to 60 ft*lbs.

My lug nut caps have been coming off since they were new. Epoxy helps.

[Josh]

I torque them to 80 ft-lbs. 60-70 does not seem like enough to me.

[Michael]

60 is great for sitting in the garage. Ergo 60 is great for most cars.

[David T]

60 is great for sitting in the garage. Ergo 60 is great for most cars.

Overtorqueing can have bad results. On alloy wheels it can crack the rims. You can distort the rotors. You can fatigue the studs and lugnuts. On the shell type lugnuts you will spin the covers, especially when you try to remove them. Do yourself and your car a favor and get a torque wrench. They aren't expensive and it makes you more professional. 60 is NOT "great" for most cars. Always look up the manufacturer's recommended torque and use it. It is usually listed with tire pressures in the owner's manual. The ONLY time you tighten lugnuts by feel is if you have to change a tire on the side of the road.

[Michael]

Sometimes my sarcasm is lost on those that need it most.

[David T]

Hard to convey subtle emotions like sarcasm over the Internet. Sorry if I missed it.

[DMC-81]

Interesting. I always thought it was 60 ft/lbs as well. As mentioned, wheel nuts are listed on L:12:1 at 70 ft/lbs, but "wheels" are listed on A:03:01 at 60 ft/lbs. I have always used the "wheels" spec, but now it looks like that might not be right.

If "wheels" isn't the lug nuts, what is it?

Hmm, it seems there is a discrepancy in the manual/ documentation. Who knew! I agree that 60 seems low, especially where other cars are 80-100. I think I'll still stick with 70, as it works for me.

[Jonathan]

So I really thought I had a legitimate chance of making a single, concise post in a thread and leaving it so, but alas, that's not meant to be...

I was away for a week or so and wanted to look some things up before replying.

I had thought the confusion was between 55 and 60 ft lb and not 60 and 70. I had never seen the 70 and had always thought the other reference was 55, but for the life of me I can't find where that was.

What I did find were six torque references to the "wheels." Two for 70 ft lb, two for 60 ft lb and two for 59 ft lb (which is really just four references for 60 ft lb).

Here they are:

493634936449365493664936749368

I've personally used 60 ft lb for the majority of the ten years I have had the car and not had any issues. My lug nut covers are also all in good shape coincidentally.

I would be inclined to believe the 70 ft lb reference though as it is in the Owners Manual as well as the workshop manual (the L section already mentioned). The 60 ft lb reference is in the A section of the workshop manual, but also makes a couple of appearances in the technical bulletins, specifically the one for the suspension recall.

I will likely stick with 60 ft lb until told otherwise. 70 ft lb may be correct though and I'd love to hear from a DMCX guy with their thoughts on the matter.

Interesting how a couple of you guys mentioned how 60 ft lb "seems" low compared to new cars. It does seem low, but so does putting 23 psi of air pressure in the front tires. That's what is required though and I would be inclined to trust it. I won't try and tell you that the entire car and documentation was put together without a single engineering calculation mistake, but going with what seems right for a new car in your old car isn't right to me either. Similar with the discussion on what octane for the fuel to put in. I'd rather go with what was originally intended until you know for certain you'll have problems continuing to do so.

Now that was anything but concise, but there you go... :)

[DMC5180]

Kind of an interesting topic of discussion. Just for curiosity, I looked up the wheel nut/ lug nut torque specs for our 2 current daily drivers and 2 previously owned DD's.

3 are GM vehicles (Cadillac,Pontiac,Chevrolet) with Alloy wheels ALL spec'd at 100 ft lb. Tapered seat lug nuts
1 Toyota with Alloy wheels spec 76 ft lb. Flange type lug nut with integral centering bushing.

1 DMC with 2 conflicting spec listings of 60 or 70. In this case, I shoot for the middle at 65 ft lb tapered seat lug nut

[Jonathan]

Interesting discussion indeed.

Something else came to mind and that is about the conversion from ft-lb to N-m or vice versa. I have seen in other areas where the conversions aren't consistent. And this is not something exclusive to DeLoreans either. You can find it occasionally in today's products too.

The conversion as I understand it is:

1 N-m = 0.7376 ft-lb

or

1 ft-lb = 1.3558 N-m

So, with the different references we've seen in the DMC documentation, I get this for the accurate conversions:

59 ft-lb = 79.99 N-m
60 ft-lb = 81.35 N-m
70 ft-lb = 94.91 N-m

80 N-m = 59 ft-lb
100 N-m = 73.76 ft-lb

So, often when it quotes both sets of units in the spec, one of them isn't right anyway, because they are all rounded one way or another. I think the one that might have been originally intended is the 80 N-m, because you see how this is exactly 59 ft-lb. That might not have looked quite clean enough in the manuals though for someone that was doing the review and it then became the 60 ft-lb we see.

And perhaps enough problems had arose and people got nervous and made a poor decision to go on top of a previous poor decision and someone, JZD perhaps, might have called over and said, "60 ft-lb??!! That seems too low! Make it higher!" And we got the 70 ft-lb.

Just a guess of course. None of those guys back then had the Internet to look things up. Nor did many of them use the US system of measurement, so they might not have been very familiar with it. We still see inconsistencies with how many litres are in a US gallon versus an Imperial gallon. Or confusion between pounds (or ounces) of force versus pounds mass. Someone in the UK trying to figure it all out at the time might have just said the heck with all these fractions of ounces and inches and pints and picked something that ended with a zero and that was that.

[Dangermouse]

So me standing on the end of my lug nut wrench and thinking "meh, good enough" is not scientific enough?

[Jonathan]

So me standing on the end of my lug nut wrench and thinking "meh, good enough" is not scientific enough?

<SARCASM FONT>Oh, that's plenty good enough. Just make sure you do your torquing before having lunch as that excess weight might throw off the calculation.<SARCASM FONT>

[Dangermouse]

Good tip.

[Jonathan]

Good tip.

Oh, that's up to you. Depends on whether you liked your lunch or not I guess? 10% perhaps if the service was adequate.

[Michael]

So me standing on the end of my lug nut wrench and thinking "meh, good enough" is not scientific enough?
Worked for me for the past 25 years. Never had a wheel come loose or warp. Funny how 70lbs is safe but 90 will warp a wheel...WTF are these wheels made of?
I like to follow maintenance rules but I don't take it overboard. For example you will never see me asking about the torque numbers for the screws that hold the center console in place.

[Mark D]

For example you will never see me asking about the torque numbers for the screws that hold the center console in place.

47 inch-lbs for anyone who's wondering.














Just kidding, I pulled that number out of my ass. :bootyshake:

[Jonathan]

...Just kidding, I pulled that number out of my ass. :bootyshake:

Limited room to work in that kinda space. I'd suggest a crow's foot extension might help.

[David T]

Overtorquing lug nuts can cause problems. One one car the owner put alloy rims on. While we were driving on a caravan he lost some of his lug nuts. We all took one of each of our wheels to get him rolling again. Alloy wheels can distort from the pressure of the lug nut and actually get looser as the metal flows away from under the lug nut. You can crack the rim from too much pressure too. BTW that owner who lost his lug nuts was ROB GRADY on his green car! So if it can happen to him it can happen to anyone. If the factory went through the trouble of revising a torque it is worth adhering to it. When was the last time you had your torque wrench recalibrated? Just how accurate is it? Could it be off 10lbs? Could your 70 really be 80 or 60? Most torque values are + - 10% anyway.

[Bitsyncmaster]

When was the last time you had your torque wrench recalibrated?

Where did you get yours recalibrated?

[PJ Grady Inc.]

"It does seem low, but so does putting 23 psi of air pressure in the front tires." The front tire pressure spec was later ammended to 25lbs btw.

FWIW I decided early on that 65lb's when done by hand just felt much more secure without going overboard. After torqueing several thousand lug nuts this way I discovered the "torque stick" which allowed my to use a impact gun and still maintain the desired torque setting. It changed my life.....saving me countless extra hours to devote to higher pursuits! I carried over my preferred setting by using the 65lb stick and have never lost a wheel or damaged a lug nut in all the years.
Guess what torque spec I recommend?
Rob

[SS Spoiler]

Coming back from I think Kens first DCS in Cinncinaty? at 11:30 at night
the car suddenly started rattling and clunking badly. Yelling " Mayday Mayday"
in the CB [remember those?] we all pulled over to see what happened. Walking
around the car we couldn't find anything until we heard "aha". My right rear
wheel had only one lug nut showing. Three studs had broken off and the last
one was bent. Flat bedded to the next dinky town to a motel. Next morning
I managed get the brake disk off and pound the old studs out with a rock!
The town of 450 had a NAPA, picked up some studs and we were on the road
by ten. I have always used a torque wrench at 65 lbs. Go figure.....

[Jonathan]

"It does seem low, but so does putting 23 psi of air pressure in the front tires." The front tire pressure spec was later ammended to 25lbs btw.

Hadn't realized that got amended. Did that make it into any of the literature, like a technical bulletin or something similar?

[DMC5180]

Coming back from I think Kens first DCS in Cinncinaty? at 11:30 at night
the car suddenly started rattling and clunking badly. Yelling " Mayday Mayday"
in the CB [remember those?] we all pulled over to see what happened. Walking
around the car we couldn't find anything until we heard "aha". My right rear
wheel had only one lug nut showing. Three studs had broken off and the last
one was bent. Flat bedded to the next dinky town to a motel. Next morning
I managed get the brake disk off and pound the old studs out with a rock!
The town of 450 had a NAPA, picked up some studs and we were on the road
by ten. I have always used a torque wrench at 65 lbs. Go figure.....

Many tire shops recommend you come back a few days later if possible to the lug nuts checked.

It's also possible that human error occurs. I was standing at the service desk of a local tire and brake shop. The shop owner had been working on finishing up truck that he had installed new tires on the rims when I walked in. He left what he was doing to help me. Meanwhile the owner of the truck comes in to to get his vehicle. The truck owner settles his bill and hops in the truck and backs out of the shop and leaves the premises. About 2 minutes went by and the phone rings at the service desk. It was the guy who
had just left. He made it 3/4 mi down the street and both passenger side tires were clunking severely. The shop owner was mortified when he realized he forgot to check the torque on all the wheels. I saw him put all wheels and nuts on by hand . Then I remembered seeing him torque the drivers side. At that point he stopped what he was doing to assist me and never went back and did the other side.

Human error caused by distraction.


I'm glad Rob Grady agrees with me by using 65 ft lbs.


Sent from my iPhone using Tapatalk

[DMC-81]

Wow....thorough discussion! Duly noted... 65 ft/lbs sounds good to me. :wrenchin:

[David T]

Most large shops now have a procedure that one person torques the wheels and another, different person checks their work. Same with changing oil. Before starting the motor another person eyeballs the empty bottles, makes rue there is a filter on, and checks the level. Very common occurrence for a wheel to fall off of a car after leaving a shop or driving out with no oil in the motor. In most shops that kind of routine work is usually delegated to the newest, least experienced person. It makes sense to have the work checked. Even an experienced person can overlook things as shown in the previous post. A distraction is all it can take. As for the torque stick, they are much harder to keep calibrated, it depends on the air tool, the air pressure, how long you hold it on, etc. It is faster but less accurate. I don't see many shops still using them anymore. One reason, they are not adjustable so you need to have many of them. Most cars today all have different specs.

[PJ Grady Inc.]

Most large shops now have a procedure that one person torques the wheels and another, different person checks their work. Same with changing oil. Before starting the motor another person eyeballs the empty bottles, makes rue there is a filter on, and checks the level. Very common occurrence for a wheel to fall off of a car after leaving a shop or driving out with no oil in the motor. In most shops that kind of routine work is usually delegated to the newest, least experienced person. It makes sense to have the work checked. Even an experienced person can overlook things as shown in the previous post. A distraction is all it can take. As for the torque stick, they are much harder to keep calibrated, it depends on the air tool, the air pressure, how long you hold it on, etc. It is faster but less accurate. I don't see many shops still using them anymore. One reason, they are not adjustable so you need to have many of them. Most cars today all have different specs.
I think the only reason you may see them less often is they are expensive if you need more than one or two which I don't. Just how many shops do you hang out in to notice trends anyway? I totally disagree with your accuracy statement. I've found mine to be very accurate and consistent and the quickness with which they work makes them safer. You are less likely to be distracted by the phone or a person in the short span of time it takes to compete the torque procedure. The tool is a tube of steel that flexs at a specified torque and never needs an adjustment (It CAN'T be adjusted or miscalibrated) compared to torque wrenchs which fall out of adjustment from normal use. I've used them for over twenty years a few hundred times a year and they are remarkably consistent due to their simplicity. I think you're giving your opinion based not on experience but on a hypotheseis and I think it is wrong in this case.
Rob