MUpde

Trailer Tongue Bolt Sheared

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I got home from the lake Sunday afternoon and was unhooking my trailer when I noticed the tongue was loose. Come to find out the bolt that the tongue pivots on when it's swung away sheared off. This is the 3rd time this has happened. It's an extreme trailer that was built in 2004. Any thoughts on what would cause this. Each time it's broken off I've replaced it with a 5/8"X7" Grade 8 bolt and nylon lock nut. I've included a picture of another tongue that shows the location. I looked at Extreme's website, but it was not working....

Thanks for any help in advance!

Trailer Tongue

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Does the partial threading on the bolt go way up into the hinge?

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I'm not totally sure why this would happen, but if you need to get in touch with the company that bought out Extreme, follow the link below. Their customer service is very good. Good luck

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Not sure of the size of that bolt relative to the removable pin on the other side, but after breaking 3 bolts maybe you could put pins on both sides..?? A double swing-away tongue :crazy:

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I had the same thing happen to my trailer (not boatmate) when it was only a couple years old, after a long haul down to Lake Havasu. Fortunately, the replacement bolt has held up just fine ever since.

I have no idea why the first one broke. It fell out of the hole when I was parking my trailer after launching the boat, so I was able to see it. What was left of the bolt, looked like it just shattered along the edge where it broke. It didn't look like a rough edge had sawed through it., so I just assumed that it was either a defective bolt or they used the wrong grade originally.

Hope you find one that holds up.

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Does the partial threading on the bolt go way up into the hinge?

The threads go about an inch up into the hinge....

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Find a bolt that has no or minimal threading up into the hinge (you may have to buy a longer one and cut it down), the threads create a stress concentration that can cause failure.

The length of thread for standard fasteners over 6 inches is 2*diameter of bolt (nominal) + 0.5 inches.

You could also look into a shoulder bolt if there is alot of play in the assembly.

-Chris

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Go to OSH Hardware and get a grade 8 bolt and nut, it will have 5 hash marks on top and be a gold color. They make harder ones, but I doubt if a grade 8 will ever break...

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The OP stated he has already broken 3 grade 8 bolts.

-Chris

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Grade 8 bolts have a rating of 160,000 Lb's breaking streanth. Is the any slop in the bolt? It should never break with a 5/8 bolt. And I know that you are not over tightening the nylock it would strip out first.

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Grade 8 bolts have a rating of 160,000 Lb's breaking streanth. Is the any slop in the bolt? It should never break with a 5/8 bolt. And I know that you are not over tightening the nylock it would strip out first.

120,000 psi of stress (not pounds - big difference) is the minimum proof strength of a grade 8 bolt.

If you have a picture of the sheared surface of the bolt I'd be interested.

-Chris

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Find a bolt that has no or minimal threading up into the hinge (you may have to buy a longer one and cut it down), the threads create a stress concentration that can cause failure.

The length of thread for standard fasteners over 6 inches is 2*diameter of bolt (nominal) + 0.5 inches.

You could also look into a shoulder bolt if there is alot of play in the assembly.

-Chris

Is the OP stating that it broke in the threaded portion of the bolt? I'm not sure from anything he's said.

In my case, it broke up near the head of the bolt, about 1/3 of the way down from the head of the bolt.

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The threads go about an inch up into the hinge....

Buy a bolt with a longer shoulder. If the shoulder is to long you could use some washers, or cut some of the threads off. Shoulder needs to be all the way through trailer.

Edited by scout1ton

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Buy a bolt with a longer shoulder. If the shoulder is to long you could use some washers, or cut some of the threads off. Shoulder needs to be all the way through trailer.

I did this when this topic first came up a couple of years ago... I forget what length I got, but IIRC I got it at OSH...A couple washers up top and a couple under and I was fine.

Make sure the shoulder of the bolt passes ALL the way through the hinge!

On bolt hardness...

Big difference between tensile strength and SHEAR strength.

Tensile strength is the measure of what the bolt will hold before failure in a pulling motion.

Shear strength is exactly what we are talking about. The resistance to the "sissor" action.

IIRC HARDENED bolts (like gr 8s)are more brittle than a gr5 or gr2 because Hardened bolts have been heated and cooled quickly. non hardened bolts are allowed to cool slowly.

My opinion on the scientific side is purely speculation and hearsay gained on the job (commercial Carpenter) over the years... I'm not 100% sure about the actual science data.

YMMV...

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I'd like to see photos of both bolts mentioned above as well!

I'm not surprised that the one broke at the threads...

Ever cut sheetrock or tile? simply score the surface and it will (usually...) break right where you want it to... Same idea. The threads are the weakest link in a shear situation.

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BOLT ISSUE #1 I have a 2005 Extereme Trailer for my 2005 Malibu LSV and had the bolt also shear off a year ago. I replaced the sheared bold and the pin (thinking it would be weaker) with two Grade 8 bolts. It appears most in this e-mail trail beleive this is the right thing to do but the one person below stated that maybe Grade 8 might be not a good choice based on how it is used. Does anyone else know? Should I be using Grade 5?

BOLT ISSUE #2 Now I had my second scare with the trailer....the two bolts holding the one side of the front axle have sheared off. I have no idea how I saw before the other two on the other side did the same and I had a free axle putting risk to my family and property. I am in the process of replace all 8 bolts (2 on each side for each of two axiles = 8) with grade 8 bolts. SHould I be doing this??

Now I am wondering what else is going to break on this Extreme trailer. I am concerned. Any other known issues that impact safety??

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Reviving an old thread to see what the verdict was on the best bolt to use.  I just noticed my hinge bolt was broken about mid way thru the threads which sits about 1/4-1/2" above the lower hinge point.  Not exactly sure how long the bolt has been broken since the last 2-3 times I used it I did not swing the tongue.  I noticed it when storing it for winterization, and thankfully the top part of the bolt was enough to keep the tongue straight and not slam the back of my truck this last time I towed the boat.

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I am seeing the same thing on mine. I don't trailer 50 miles in a year, but when I brake and the brakes engage the boat weight transfering to the tongue has caused the tongue holes where the pin is inserted to enlarge and the bolt is starting to rattle around as well. I bet when I pull it this winter it will be toast and the holes will be wallowed out. If I could adjust the brake bias it would probably help, but they ain't happening. The problem is the 3/8 mild steel plate with holes in it that will continue to wear out. When I rebuild and clean up the tongue mechanism this winter I am going to enlarge to the next bigger bolt size for both the pin and the bolt. The retention sleeves that are welded on the trailer that the bolts and pin go through are large enough so as to not need enlarging which a big part of the problem on the swing away tongues!

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10 hours ago, wdr said:

I am seeing the same thing on mine. I don't trailer 50 miles in a year, but when I brake and the brakes engage the boat weight transfering to the tongue has caused the tongue holes where the pin is inserted to enlarge and the bolt is starting to rattle around as well. I bet when I pull it this winter it will be toast and the holes will be wallowed out. If I could adjust the brake bias it would probably help, but they ain't happening. The problem is the 3/8 mild steel plate with holes in it that will continue to wear out. When I rebuild and clean up the tongue mechanism this winter I am going to enlarge to the next bigger bolt size for both the pin and the bolt. The retention sleeves that are welded on the trailer that the bolts and pin go through are large enough so as to not need enlarging which a big part of the problem on the swing away tongues!

 

I ran a google search and it seems to be a pretty common problem, some manufacturers (saw Ranger and few others) even send out new bolts, etc to replace them.  I emailed Magnum yesterday so I will see what they say or suggest then probably just go buy me a new bolt.  I think this is the first one to shear, since it is painted black matching the trailer.  I know it is the first since I had the boat 2 years now.

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19 hours ago, jwl019 said:

Reviving an old thread to see what the verdict was on the best bolt to use.  I just noticed my hinge bolt was broken about mid way thru the threads which sits about 1/4-1/2" above the lower hinge point.  Not exactly sure how long the bolt has been broken since the last 2-3 times I used it I did not swing the tongue.  I noticed it when storing it for winterization, and thankfully the top part of the bolt was enough to keep the tongue straight and not slam the back of my truck this last time I towed the boat.

Got a photo of the broken bolt and where it is mounted?  I am curious.

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2 minutes ago, MadMan said:

Got a photo of the broken bolt and where it is mounted?  I am curious.

Madman, attached is where the bolt is mounted, except it is on the other side.  The pull pin for the swing tongue is on this side.  I will take a pic of the bolt and where it is broken soon.  Basically the bolt is broken on the threaded portion which is right above the 2 bottom ears of where the pin/bolt slides thru.

20150717_181508.jpg

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20161031_130128.jpg

20161031_130150.jpg

Edited by jwl019
Add more pics

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If it were mine, I would replace that bolt with a longer one such that all the threads extend beyond the trailer (use washers to space the nut).  This is common practice on fasteners used on race car suspension.  You never want the threads taking the shear load, the thread area is much weaker.

Edited by MadMan
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48 minutes ago, MadMan said:

If it were mine, I would replace that bolt with a longer one such that all the threads extend beyond the trailer (use washers to space the nut).  This is common practice on fasteners used on race car suspension.  You never want the threads taking the shear load, the thread area is much weaker.

Thank you sir, I will look for a longer bolt, guessing a grade 8 bolt with about a 6" shank before the threads will be fine to use, then use a washer or two above the top ear and possibly below the bottom ear.

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