Lug nut torque - Montana Owners Club

CamillaMichael · 06-05-2010, 10:16 AM

I have viewed the video on Keystone's website describing how much foot/lb of torque (120 for our fifth wheel) to apply to the lug nuts. I can safely say that easily twice that had been applied to the lug nuts on one of the tires I had to remove (picked up a nail on the way home from the dealer) from our rig. The few times we have moved our unit, each time I have checked the lug nut torque, each time applying the recommended torque...this seems incredibly light. Why would we want to attach wheels to our rig with such "light" torque?

BB_TX · 06-05-2010, 10:36 AM

The torque recommendation is based on the strength of the bolts. Tight enough to securely hold without overly stressing those bolts to the point they may fail.

CamillaMichael · 06-05-2010, 10:54 AM

Quote:

quote:Originally posted by BB_TX

The torque recommendation is based on the strength of the bolts. Tight enough to securely hold without overly stressing those bolts to the point they may fail.

Has the quality of bolts fallen in recent times? In the past I have always observed lug nuts secured so tightly that two strong men and a boy were required to remove them! Not throwing any darts...just really curious about the change in torque. THANKS for the info about possible bolt failure...last thing we want is to have one of our wheels pass us as we travel down the highway!

ols1932 · 06-05-2010, 10:59 AM

120 ft. lbs. is the recommended torque and is plenty. I don't find that light at all. I believe that there has always been torque recommendations but most of us just ignored them and tightened the lugs as tight as we could with our lug wrench. I have no idea what we torqued them to. Could have been nearing 200??

Orv

firetrucker · 06-05-2010, 01:06 PM

Correct torque is based on the strength of the stud metal, and the torque limits have been standardized for decades. The idea is to stretch the stud with the nut so that it holds the rim to the hub. If you stretch the stud too far by torquing the nut too much, you will stretch the stud beyond its elastic limit and make it much more prone to failure.

That is why it is recommended to clean the hub, rim, nut, and stud, and, at most, to lightly oil the stud (you might get away with a very light coating of antiseize). Since not too many people follow these recommendations, it is not uncommon to occasionally break a stud or two. If tight is good, REALLY tight must be better...NOT!

Bob

BB_TX · 06-05-2010, 02:23 PM

Just to add. Mine are torqued to 120. I always check the torque on mine before a trip. Checked them 4 days ago in prep for upcoming trip. First 30 were still correct. #31 needed a quarter turn. 32 was correct. That is about typical after a trip of 1000-1500 miles.

8.1al · 06-05-2010, 03:24 PM

If a car or light truck that has lug nuts so tight that it takes 2 men and a boy to loosen them then they are way too tight, 120 ft. lbs. is quite tight and sufficient.

clutch · 06-05-2010, 07:05 PM

One way to look at it is 120X 8.

I think 120 is plenty.

Art-n-Marge · 06-05-2010, 09:54 PM

Since I have aluminum wheels the recommendation is 110 to 120 ft/lbs in my user guide. Many of us split the difference and use 115#.

In the olden days the wheels were often overtorqued. I recall numerous problems with folks and friends and acquaintances when the bolts sheered off because they were too tight, or you needed a Gorilla to remove the over-torqued nuts and the metal wheel has now seized onto the brake drum, or the seize was so tight removing the nut breaks the bolt off at the hub (this happened to me on a prior SOB trailer - I was so miffed because I actually witnessed the tech air hammering the nuts back on my rig after some work was done and this was the dealer!). I could kick myself that I did not speak up. A tech can use an air hammer but just for getting the nuts on the bolts quickly or as soon as the first click is heard (hoping the air hammer torque is very low), then complete the install with a calibrated torque wrench. This procedure is much more common now (much to my relief).

Now that I know about this and with forums like this the word gets out to follow torque specifications properly.

In a somewhat related subject and while you are at it camillamichael, you should check the nuts on the U-bolts for each wheel. Many of us have found that they have severely loosened since we picked up our rigs. I recall after much discussion that the recommendation for these nuts are supposed to be about 65# for each nut (four per wheel). I found more than 50% were loose and some of those very loose. Others found theirs were about to fall off! Let us know what you find. Do not overtorque these either. Over time you'll find they will keep the torque setting.

indy roadrunner · 06-06-2010, 02:25 AM

By over torquing you are also stretching the holes of the wheel hub. Especially the aluminum wheels. This will lead to your lug nuts working loose. By over torque you not only stretch the threads in the stud but in the nut which actually weakens their ability to remain tight and possible crack or break.
They give us torque values for a reason and should be adhered to.

CamillaMichael · 06-06-2010, 03:55 AM

Like most people, I have been misled in the past...even by the people selling the product, so when I saw the 120 figure (compared to what I had always done in the past...incorrectly, it would seem), the first thing that I thought was here is another piece of bad info...but thanks to all of you who shared your thoughts, I am now much more comfortable with the 120 figure. Thanks!

farmboy · 06-06-2010, 05:04 AM

Just to compare, check the torque required for the rims on your truck. I think you will find that are about the same or a little higher, maybe 10 to 15#. IIRC mine are 130# on my truck.

Art-n-Marge · 06-06-2010, 10:12 AM

Like farmboy points out, larger pickup trucks may be more. While I keep my RV at 115#, my '06 Ford F-250 specifies 150#. I dog-earred the page in the user guide since I check before each trip. Just for reference and I am at the local tire shop rotating the tires, I'll ask the tech what setting he's using. They always reply, "Fords max out our torque wrenches at 150#". I like that. It maxes my torque wrenches, too. I keep one in the RV and one in the TV.

KDS MONY · 06-07-2010, 09:58 AM

The studs are a press in fit to the hub and are held by small splines on the lug nut. Last year when we put new tires on our SOB they unfortunately over tightened one lug and stripped the splines and we had to replace the stud. Fortunately the damage was to the stud not the hub and a new stud has held tightly, but if it didn't then the whole hub would probably needed to be replaced. Best wishes, Jay and Kathy

Tom S. · 06-08-2010, 03:04 AM

Regarding the use of oil or anti-seize (or grease), on lug nuts/studs, in a word: don't.

Part of torque reading when tightening up a nut is the friction of the nut against the threads of the bolt/stud. Any lube will change this friction by lessening it, causing you to over-tighten the nut to get the correct torque figure. If you want to test this (in other words don't believe me) put a dry bolt in a vice with some washers to simulate a wheel and torque a nut down. Scribe or mark a line so you know where the nut should stop, then remove the nut and lube the threads. Now reapply the nut and torque it again. You will see the line on the nut moves past the former spot. If you have the proper equipment (micrometers) you can also measure the additional stretch.

I know someone is going to say: I've used oil/lube on lug nuts all my life without a problem. I'm happy for you. It doesn't make it right, it just makes you lucky.

royando · 06-08-2010, 05:01 AM

With 24 years in the automotive service industry and an AA degree in Automotive Technology, I always put a little grease on the threads but never on the mating surface. Never had a lug nut come loose.

priceml · 06-08-2010, 05:17 AM

I had a 1974 GMC motorhome for about11 years and the torque on them were 250 ft.lbs.Some tire shops could not remove the lug nuts with an impact gun. 120 ft.lbs seems enough for the Monty.

Native Tex · 06-08-2010, 05:36 AM

Folks, as a testiment of one who has had a wheel run off his Monty, just be sure you follow procedures and torque your wheels regularly. We were lucky that there was very minimal damage and no one was hit by the loss wheel.

skypilot · 06-08-2010, 12:41 PM

With regards to the use of lube on the lug nuts -- I have yet to see any lug nuts (to include the new ones recently released by Dexter) that take any type of lube. However, on the Fords, they have a two part lug and the manual on mine actually recommended using a small dot of lube on the top part of the lug (not on the mating surface) Since I don't have a Ford any longer I can't find the exact citation any more but I remember the techs at both Firestone and Goodyear dealerships putting some light weight oil on them to help them seat better. Several years ago though.

herewegotogether · 06-08-2010, 01:39 PM

I just had to comment, when I was driving Big Rigs the vehical Inspections for the lug nuts was to check that they were at least hand tight. I just thought I would mention that as the OP seemed concernned that 120 ftlbs was not alot. Also the tires and rims expand as they heat up and any tigher you begin to stretch the bolts, if they are already overtight the added expantion will over stretch the lugs and they could break do to the excess pressure from over torqueing when cold and the added expansion from normal heat build up while driving. Just my pennies worth

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