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Roger Frazee

Torquing Trailer Lug Nuts

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Ever since I nearly lost a wheel due to loose lug nuts, I re-torque the nuts on my 24' car hauler at each and every fuel stop.  The nuts on the front axle wheels are always tight.  However, one or two nuts on the rear axle wheels invariably need to be re-tightened every hundred miles or so.  They are still snug, but they are not at the original 80 ft lbs of torque.

 

Is it normal that the rear axle wheels lug nuts need to be re-torqued more frequently than the front axle wheels?  Could I have an alignment issue? 

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That’s not normal. Replace the studs and nuts with new ones, not expensive and easy to do. If it continues I would check axle alignment and suspension parts for looseness. 

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I’m a 30+ year class A license holder and have hauled pretty much every type of trailer. On the smaller trailers, 20k and down all the way to simple 6-8k bumper pull trailers, I have actually seen that problem quite often. Usually it’s because there’s more stress on the rear axle during the turns causing more sideways pressure on the rear wheels. Most often a trailer is not really level but slightly front high. This always transfers more weight and stress to the rear axle. Years back, sprung trailers had equalizers between the two spring sets of each axle to do just as the name suggests, equalize the load and it lessened the unevenness on the axles relative to the trailers attitude. Today, most 12k and down trailers use torsion axles hung separately with no such equalizing. With torsion axles, the force on the axle is less with less compression of the torsion rubbers, more with more compression. If the front of the trailer has a high attitude, the front axle has less stress and the rear more. It’s the nature of the beast.

      The front axle of any dual axle trailer is called the lead axle for two reasons. It’s in front, leading, and the lead always tracks the easiest (the term goes back to horse and carriage days where your lead horses were the easiest to control on a multi horse hitch). So being up front it goes through any sort of turn the easiest.  The second axle will almost always wear tires faster because of the same above reasons. Some even call the second axle the drag axle, again because it’s last, picking up the “drag” and because it does exactly that during any sort of turning. If you tow trailers a lot you’ll find you get more flats and blowouts on that rear axle. A good test is to put an infrared heat gun on your tires during a good long trip. The rear axle tires and even the bearing hubs are almost always hotter. Yes, the front axle can also drag some in tight maneuvers but the rear axle always does more. I’ve seen the lug issues happen  with steel wheels and aluminum wheels but more often steel wheels. Have to admit though, more trailers had steel wheels so not really a fair comparison.

     Mis-aligned axles almost always show by causing your trailer to crab or tow slightly sideways. You will also wear tires unevenly. Misaligned axles show wear, extreme heat, and blowouts on tires before slightly loosened lugs. If you’re not seeing abnormal wear, try to run your trailer level. Position you load slightly forward more for tongue weight if you can. Moving your load position even by 6” often makes a big difference.

Edited by chistech (see edit history)
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46 minutes ago, chistech said:

I’m a 30+ year class A license holder and have hauled pretty much every type of trailer. On the smaller trailers, 20k and down all the way to simple 6-8k bumper pull trailers, I have actually seen that problem quite often. Usually it’s because there’s more stress on the rear axle during the turns causing more sideways pressure on the rear wheels. Most often a trailer is not really level but slightly front high. This always transfers more weight and stress to the rear axle. Years back, sprung trailers had equalizers between the two spring sets of each axle to do just as the name suggests, equalize the load and it lessened the unevenness on the axles relative to the trailers attitude. Today, most 12k and down trailers use torsion axles hung separately with no such equalizing. With torsion axles, the force on the axle is less with less compression of the torsion rubbers, more with more compression. If the front of the trailer has a high attitude, the front axle has less stress and the rear more. It’s the nature of the beast.

      The front axle of any dual axle trailer is called the lead axle for two reasons. It’s in front, leading, and the lead always tracks the easiest (the term goes back to horse and carriage days where your lead horses were the easiest to control on a multi horse hitch). So being up front it goes through any sort of turn the easiest.  The second axle will almost always wear tires faster because of the same above reasons. Some even call the second axle the drag axle, again because it’s last, picking up the “drag” and because it does exactly that during any sort of turning. If you tow trailers a lot you’ll find you get more flats and blowouts on that rear axle. A good test is to put an infrared heat gun on your tires during a good long trip. The rear axle tires and even the bearing hubs are almost always hotter. Yes, the front axle can also drag some in tight maneuvers but the rear axle always does more. I’ve seen the lug issues happen  with steel wheels and aluminum wheels but more often steel wheels. Have to admit though, more trailers had steel wheels so not really a fair comparison.

     Mis-aligned axles almost always show by causing your trailer to crab or tow slightly sideways. You will also wear tires unevenly. Misaligned axles show wear, extreme heat, and blowouts on tires before slightly loosened lugs. If you’re not seeing abnormal wear, try to run your trailer level. Position you load slightly forward more for tongue weight if you can. Moving your load position even by 6” often makes a big difference.

 

Thank you Christech.  This is the best explanation of trailer physics I have read yet.  You are correct that the front of my trailer typically sets a little high.  I'll work on getting it more level and see if that helps.

 

A poster on another forum suggested balancing the trailer wheels, but I have read elsewhere that balancing is ineffective on trailers.  What are your thoughts?

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Never balanced trailer tires and unless they were way out of balance, find it hard to think it would cause the lug problems. Small trailer hubs are not as precision made as a hub on a car or truck. It’s very common to see, if you look close at a trailer hub, that it has been bored and turned off center of the casting a fair amount. Manufacturers just don’t put the accuracy in machining on a trailer hub because of the lack of need for balancing.

     Like what was mentioned about replacement of studs and lugs, I’d also recommend the wheels but this is if they’ve been on and off a lot or ever run with loose lugs (loose meaning finger loose). Worn wheels, lugs, and studs will cause your problem but I’ve seen it happen on virtually new trailers as I explained in my previous post. Unless you’ve been towing this trailer for years, replaced wheels on and off, or had some severe rusting of the studs/lugs, I’d look first at the trailer attitude and weight distribution over the axles.

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You can't diagnose a trailer problem on the internet.

 

Find a good trailer repair shop in your area & take it there.

 

 

Jim

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Roger, you say you torque your 24' trailer lugs at 80 foot-pounds. My old 24’ Haulmark which had 55,000 plus tow miles on and my new 24’ Car Mate trailer both say the correct lug torque is 140 foot-pounds. Recheck your manual for correct torque recommendations.  Below is what I found on the internet regarding correct torque: 

 

 

Lug Size

FT/LBS Torque

1/2"

90-120

9/16"

120-140

5/8"

140-160

 

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Thanks Ron.  I understand now that I need about 120 ft/lbs of torque for my 1/2" lugs.  I have also learned, by reading posts on a trailer forum, that the rear wheels are subjected to more sideways stress than the front wheels when cornering, which can be a factor in the lug nuts loosening.

 

Adding to that, I was also advised that towing with the tongue high distributes a disproportionate amount of weight on the rear wheels.  

 

I'm learning a lot on these forums.

 

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