| [GMCnet] Lug nut / Wheel nut Torque [message #249294] |
Fri, 09 May 2014 22:37  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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G'day,
For clarity I will refer to the nuts that hold the wheels onto the hubs as LUG NUTS; they are 9/16 inches diameter and 18 threads
per inch (TPI).
The GMC Maintenance Manuals X-7425, X-7525, X-7625, and X-7725 all specify to tighten the lug nuts to 250 ft lb and NOT to lubricate
the nuts or studs. I checked the Service Bulletins and cannot find any information noting to lower the torque. It has been noted on
the GMCnet that torquing the lug nuts repeatedly to 250 ft lb torque can stretch the wheel studs and cause them to break. It has
been noted to lower the torque to 150 ft lb and lubricate the threads.
I suggest we discuss this and come up with recommendations based on our discussion.
Alcoa wheel lug nuts are a done deal as the lug nuts have 140 ft lb stamped into them.
Regards,
Rob M.
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Lug nut / Wheel nut Torque [message #249381 is a reply to message #249359] |
Sun, 11 May 2014 05:03  |
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Loffen
Messages: 1087
Registered: August 2013
Location: Norway
Karma: 1
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Senior Member |
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I just had all the wheels of Dobbelt trøbbel, at the front for changing the ball joints and at the rear for cleaning up the drums since it had been standing still for years.
The front studs where good but at the rear several had been changed, the first sign of trouble was when one stud broke when I was taking off the wheel, not a large problem as I all ready had orderd a couple of studs from Golby since I like to have some on the shelf.
So of with the drum and then the hub, no problem to drive out the broken stud and replace it, then I use a 3M pad to clean all mating surfaces, I prefer to do this by hand, with a power/air tool it is easy to remove any material from the mating surface and make it uneven.( I clean the hub, drum and rim including the surface for the lug nut ) then I give the stud treads a couple of drops of engine oil and wipe them so the just have a very thin coat of oil.
When I install the wheels I first us my battery powered lug wrench, it is not very strong, just around 80 ft lb but it will give me an equal starting point to torque down the lug nuts, I allways do this in sequence (1-5, 2-6, 3-7, 4-8, 5-1 ) then I do the same with my large rachet wrench and a extender trying to use a slow even force.
Now if I have done this right I can actually feel and see when I come to the point where I start to strech the studs, It looks like the lug nut "stops" and there is a increse in the force needed to turn the wrench, I did use my electronic torque adapter to see how much force I had at this "point" and at all the lug nuts it was in the 140 to 150 ft lb range.
I even broke an old stud at 120 ft lb, oh well it was the last drum I was working on so I had some experience to replace it..
Then I take a short drive, maybe 4-5 miles and retorque all the wheel nuts, I had no difference, I did also have a 100 miles trip a couple of days ago and rechencked them again, same same.
So torque the lug nuts to 250 ft lb will only strech the studs and put unnecessary strain on them in my eyes, 140-150 ft lb did the job for me but just to make sure I will recheck the nuts after 1000 miles or so.
1973 23' # 1848 Sky Blue Glacier called Baby Blue and a 1973 26'-3 # 1460 Parrot green Seqouia Known as the Big Green,
And sold my 1973 26'-2 # 581 White Canyon lands under the name Dobbelt trøbbel
in Norway
[Updated on: Sun, 11 May 2014 13:26] Report message to a moderator |
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| Re: [GMCnet] Lug nut / Wheel nut Torque [message #249391 is a reply to message #249355] |
Sun, 11 May 2014 08:26 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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USAussie wrote on Sat, 10 May 2014 20:55Mr ERFisher
I have never, never heard of a lug nut coming off
or loose
i would do 140 and forget it.....
but, this new bunch, have to rehash it again
good work
erf
Yes, Let's do that.
Some years ago, I bought a whole new set of tires. The Firestone shop only had torque bars up to 175#. So, they used one of those. I did check the first side and got about an extra flat on each of those, but missed doing the left side. At the first stop of the excursion (a plan of over 3K miles), I just got this feeling. I dug out the breaker bar and pipe that I carry for such purpose and checked the left front. (I had seen the guy hit them with is air wrench and torque bar.) Two were loose - like the weight of the wrench loose. Four were well low of 150 and only two were even close to 150.
I got at lease one flat on the other sixteen. The right side was still good.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Lug nut / Wheel nut Torque [message #249395 is a reply to message #249294] |
Sun, 11 May 2014 09:42 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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USAussie wrote on Fri, 09 May 2014 21:37G'day,
For clarity I will refer to the nuts that hold the wheels onto the hubs as LUG NUTS; they are 9/16 inches diameter and 18 threads
per inch (TPI).
The GMC Maintenance Manuals X-7425, X-7525, X-7625, and X-7725 all specify to tighten the lug nuts to 250 ft lb and NOT to lubricate
the nuts or studs. I checked the Service Bulletins and cannot find any information noting to lower the torque. It has been noted on
the GMCnet that torquing the lug nuts repeatedly to 250 ft lb torque can stretch the wheel studs and cause them to break. It has
been noted to lower the torque to 150 ft lb and lubricate the threads.
I suggest we discuss this and come up with recommendations based on our discussion.
Alcoa wheel lug nuts are a done deal as the lug nuts have 140 ft lb stamped into them.
Regards,
Rob M.
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
You have to decide if you are going to lube the threads and lug nut or if you are going to tighten them dry. The torque values will differ dramatically because of how much friction you need to overcome. There are some conversion values available and I'll check what we do. However, if you look at the Alcoas with free spinning washers vs the steel wheels with "binding" lug nuts, you start to get an idea of the difference. After all, the studs are the same.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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