Broken shank bolt

[Jim J]

I have an equalizer hitch and check the torque on the shank bolts before every trip. I also look at all the connections at every stop. On my spring trip to Virginia, I had just completed a tow from Bedford ( D Day memorial) to our campground in Natural Bridge. When I checked the hitch the nut was missing from one of the shank bolts.

I took the hitch apart and discovered the bolt had failed because of corrosion in the valley of a thread that had reduced the bolt diameter to about half of nominal. This bolt was one that came with the hitch about 15 years ago when it was new. It was marked as a grade 6.

Fortunately there was a good hardware store nearby that carried the right size of grade 8 hardware so I was able to replace both bolts and nuts and all the washers. They even loaned me a torque wrench so I could complete the replacement while at the store.

I was fortunate that there was no damage and that the Ace hardware I went to had the right parts and tools to complete the job.

I recommend annually inspecting these bolts for that type of corrosion and possibly replacing them every 5 years or so as a preventative measure. You can’t see that type of corrosion without disassembling the hitch.

[Al U. Minium]

Thanks for the useful information.

As a data point, are you a full timer with hitch in the weather all the time or something less?

I replaced shank bolts with grade 8 twice in the last 3 or 4 years. Cheap enough to do during hitch maintenance or anytime you take it apart.

I carry a spare shank bolt in my camping tool box due to they aren't that easy to find.

McMaster-Carr is a good source if you can wait a day for new ones and they normally provide documentation on their hardware.

Al

[GCinSC2]

Jim,

Glad nothing bad happened, you found it during an inspection.

Any chance for a pic of the broken bolt?

I run an Equal-I-Zer too for about 9 years and I look at folks hitches with permission and one thing I have noticed is that the bolts may be tight but the hitch head is not tight on the shank. Various brands.

Take a look between hitch head and the shank, can you slip a crisp dollar bill between them?

I've seen no gap to say that's a gap you've got there.

IMHO these bolts must clamp the hitch head to the shank. If the hitch head can move L-R, or even up-down then the bolts are being asked to be a pin and not the clamping system that a bolt is designed for.

One Equal-I-Zer was on a newbie's rig and while raising the hitch to remove bars the entire head moved on the shank up-down. This hitch was setup by a "national dealer" and they didn't tighten the angle set bolt correctly, didn't tighten the hitch head bolts and the hitch ball shank was too long and the long shank interfered with the WD bar trunions and big crunch. I replaced the hitch ball, tightened the set bolt and then the shank bolts.

I've made shims that I've fitted to a few heads, then when tightened the head is fully clamped to shank.

Good news, you caught it w/o a big oops moment.

Gary

[Jim J]

Here are pictures of the broken bolt and the one that did not break. Both were replaced.

[GCinSC2]

Jim,

First, big thanks for posting the pic.

The intact bolt all of that undercutting at the end of the threads that looks like the whole head was loose and sloppy on the shank and the bolts were getting hammered as the head was moving.

Were you able to look for a gap on the head to shank fit and is the angle set bolt tightened and the washers are nicely compressed against the shank?

Thank you.

Gary

[dznf0g]

Originally Posted by GCinSC2

Jim,

First, big thanks for posting the pic.

The intact bolt all of that undercutting at the end of the threads that looks like the whole head was loose and sloppy on the shank and the bolts were getting hammered as the head was moving.

Were you able to look for a gap on the head to shank fit and is the angle set bolt tightened and the washers are nicely compressed against the shank?

Thank you.

Gary

I agree, appears to me there was some looseness to the assembly for a relatively long period of time.

[Mollysdad]

Originally Posted by Jim J

Here are pictures of the broken bolt and the one that did not break. Both were replaced.

Are you sure those are grade 6?
Mine look brand new and have no rust. (maybe grade 8)
Every Equalizer hitch I've seen has bolts that look new.

I also fiddle with the hitch enough that I have the bolts out every year or so. No wear.

[xrvr]

Periodic maintenance....once a year.

[GCinSC2]

Just for reference bolt head markings.

https://www.boltdepot.com/fastener-i...ade-chart.aspx

Grade 8 bolt heads have 6 radial lines grade 5 has 3 radial lines.

[Jim J]

Yes the remaining shank bolt was pretty worn after the top one broke. Did that happen after the break or before? I don't know. Could be both.

I always check the torque prior to each trip and I disassemble the head every year check things. replace washers, tighten set screw, etc.

The cause of the bolt breaking is reduced diameter due to the corrosion. Bolt failed in tension.

After that type of failure, the whole system is not working the way it is designed, The part of the bolt that stayed in the upper hole prevented extreme movement of the hitch on the shank but minor pivoting around the bottom bolt was still possible and could have produced the wear.

Anyway, all the hardware got replaced plus I now have spares.

[GCinSC2]

Jim,

Can you check, is the hitch head firmly clamped to the shank? Remember the dollar bill test I mentioned? And the angle set bolt.

Gary