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post #1 of (permalink) Old 03-07-2008, 06:12 PM Thread Starter
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Question What grade bolts to use

Are grade 8 bolts suitable to attach a tow bar to the front of my jeep?
It will be used for both long and short distance tows.
Thanks in advance,
JD

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post #2 of (permalink) Old 03-07-2008, 06:40 PM
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Grade 8 should be fine... as long as you're not using just one...
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post #3 of (permalink) Old 03-07-2008, 09:28 PM Thread Starter
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Quote:
Originally Posted by LEVE View Post
Grade 8 should be fine... as long as you're not using just one...
Yeah... but what do you know bout jeeps.
JD

73 CJ5 And 2 Ranchers.
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post #4 of (permalink) Old 03-07-2008, 10:01 PM
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Quote:
Yeah... but what do you know bout jeeps.
That's been debated on this board for over 12 years now. Somehow... there's never been a consensus and I'm too darned ignorant to know any better!
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post #5 of (permalink) Old 03-08-2008, 12:13 AM
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Quote:
Originally Posted by newguyJD View Post
Are grade 8 bolts suitable to attach a tow bar to the front of my jeep?
It will be used for both long and short distance tows.
Thanks in advance,
JD
I use grade 8 for everything.

88 YJ SOA2.5" 2"BDY Locked F/R Chevy 4.3 NVG241OR 4.56's 36x12.50
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post #6 of (permalink) Old 03-08-2008, 06:02 AM
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In part, it depends on the way the joint is designed. A lot of guys will attach a tow bar using a bolt as a pivot pin. Instead of being tightened down, it's double-nutted or a Nyloc nut is used just to keep it from falling out. That's a bad design, using a bolt in a way it's not designed for. A clevis or hitch pin should be used there, but if you do use a bolt that way, a softer grade 3 is a better choice.

If you're doing it right, where the bolt gets torqued down and only provides a clamping force, grade 8 is OK, but probably overkill, and grade 5 might actually be better.

With cyclic loads, if the bolt can see some beam load, softer bolts can actually last longer because they're more fatigue resistant.

EVERYTHING's easy for the guy who doesn't have to do it.
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post #7 of (permalink) Old 03-08-2008, 06:23 AM Thread Starter
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So if I'm using it to attatch the tow bar the to the front of the jeep, one on each side, where it will pivot up and down, I should use a hitch pin or a clevis?

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post #8 of (permalink) Old 03-08-2008, 08:22 AM
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Quote:
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So if I'm using it to attatch the tow bar the to the front of the jeep, one on each side, where it will pivot up and down, I should use a hitch pin or a clevis?
Yes. Hitch pins are made for that application, bolts are made for squeezing things together.

But hitch pins should always be used in shear, never in beam. That means that the joint should have two fixed members and a movable member between them or vice versa, with the pin passing through all three.

If you can't do that, you need a top-hat bushing that goes through the tow bar and then is clamped down hard by a bolt.

It's hard to explain but easy to draw. If you're not following this I'll do up a sketch. You don't want to get this wrong.

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post #9 of (permalink) Old 03-08-2008, 10:00 AM
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...and when you're done with that sketch, please post it....
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post #10 of (permalink) Old 03-08-2008, 01:08 PM Thread Starter
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I just went and bought 2- 3/4 X 4 inch hitch pins. they will be easier to remove if needed and the bolts made the tow bar too tight to swing up and down freely. thanks for the input. It might be a good idea to post that sketch just ion case.
JD

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