Trailer hitch bolts
- Thread starter Bonnewagon
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Steve I will use gobs of anti-seize no matter what. The zinc may help a bit but in the end it doesn't really matter what they are if they are not stainless. It's hard to get a good picture of a single bolt but you would not believe the wasting. The only threads left were the ones in the actual nuts. The rest were just lumps of crud. Here is a pic of the rusty hitch I sent Steve. The bolts were worse!
Yes The high strength stainless is pricey.last time i installed a hitch it came with silver zinc grade five.it's the same that all aftermarket rear bumpers come with.there's something to be said if that's what's coming with new parts.i'd wait and see what shows up with your new one and go from there.
Mark, did you see this, didn't your daughter just buy a Liberty?
https://www.foxbusiness.com/markets/jeep-recalls-older-suvs-for-suspension-flaw
https://www.foxbusiness.com/markets/jeep-recalls-older-suvs-for-suspension-flaw
maybe annual inspection and reapplication of a thread lubricant? also ensures you are verifying they are to proper torque
Mark, I found this on a Jeep forum talking about trailer hitches.....
"Nothing wrong with grade 8, but 5 should be fine; grade 5 bolts have a shear strength of about 90,000 lb/sq in, grade 8 is about 130,000. For a half inch bolt, that's a shear of 17,600 lbs each for grade 5, vs 25,000 each for the grade 8. Even if you're planning to pick up the vehicle by the hitch, one grade 5 in shear is more than strong enough. Their tensile strength is slightly higher than the shear, so that'll work too, but now you're putting all the load on the threads.
Moreover, the bolts are only in shear from vertical loads on the hitch; the pulling load on the hitch goes right to the crossmember. I'd worry more about how the Curt hitch isn't welded all the way across at the front of the channel that goes around the crossmember. And anybody notice that the factory rear hook uses three bolts?
Hardware store stainless steel is not only softer and weaker than carbon steel, you can get funny corrosion problems as well; plus which, it'll round off and bugger no end. Bad idea.
Not to say don't use grade 8; just no need to get hysterical about it. Four grade 5's have about the same shear strength as three grade 8's"
"Nothing wrong with grade 8, but 5 should be fine; grade 5 bolts have a shear strength of about 90,000 lb/sq in, grade 8 is about 130,000. For a half inch bolt, that's a shear of 17,600 lbs each for grade 5, vs 25,000 each for the grade 8. Even if you're planning to pick up the vehicle by the hitch, one grade 5 in shear is more than strong enough. Their tensile strength is slightly higher than the shear, so that'll work too, but now you're putting all the load on the threads.
Moreover, the bolts are only in shear from vertical loads on the hitch; the pulling load on the hitch goes right to the crossmember. I'd worry more about how the Curt hitch isn't welded all the way across at the front of the channel that goes around the crossmember. And anybody notice that the factory rear hook uses three bolts?
Hardware store stainless steel is not only softer and weaker than carbon steel, you can get funny corrosion problems as well; plus which, it'll round off and bugger no end. Bad idea.
Not to say don't use grade 8; just no need to get hysterical about it. Four grade 5's have about the same shear strength as three grade 8's"
The CURT hitch arrived today. Nice item! There are 3 possible mounting scenarios and the CURT company included the hardware for all 3. Not only that but all the bolts for my usage are 10.9. So there it is. They want the strong stuff and if I want stainless I will need to figure a way to get some ARP Stainless 300 bolts which are the only ones even stronger than those.
When I put a hitch on the GP I drilled and tapped the nut on the L bracket at the end of the bumper shock so I could use a larger diameter SAE bolt. The SAE bolts are a lot cheaper than the metric bolts so if I were you I would see if the anchors or nuts they use could be drilled and tapped
Yeah Steve I considered that. But while chasing the m12 threads I noticed that whatever strip of steel the weld nuts are welded to is pretty shabby. It was all I could do to carefully clean what was there. It seemed they would break off if I over did it. And if one breaks off inside the frame rail I'm totally screwed. I'm guessing the weld nut strip is in as bad a shape as the bolts were.
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