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Samc · 02-13-2011, 03:50 PM

Specifically, any reason not to use a 5/8 grade 8 bolt, washers, lock washer, and nut, instead of the usual pin and safety clip, to attach a tow bar? it would be harder to steal, that's for sure, and I don't see why not, but thought I'd ask (after all, if I knew everything......... )

Chuck 1935 · 02-13-2011, 04:08 PM

Quote:

Originally Posted by SAMCUDNEY

Specifically, any reason not to use a 5/8 grade 8 bolt, washers, lock washer, and nut, instead of the usual pin and safety clip, to attach a tow bar? it would be harder to steal, that's for sure, and I don't see why not, but thought I'd ask (after all, if I knew everything......... )

I've been using a nut and bolt and as a safety meassure, I drilled the nut and bolt and used the pin through that. I've towed for over 70,000 miles using a grade 6 bolt without any problems.

H. Miller · 02-14-2011, 06:07 AM

Why not just get a pin with the locking cylinder on one end? It's much easier to "uninstall" should the need arise.

Samc · 02-14-2011, 07:14 AM

Quote:

Originally Posted by H. Miller

Why not just get a pin with the locking cylinder on one end? It's much easier to "uninstall" should the need arise.

good question. A couple of reasons, actually (I have a pin with a locking cylinder), but mostly because the lock gets in the way of attaching the safety cables on my hitch. I could buy another, I suppose, but I find them awkward as all get out with my somewhat arthritic hands.

Ed-Sommers · 02-14-2011, 08:57 AM

No reason why not, I have in the past after misplacing the regular pin.

Ed

Bob86ZZ4 · 02-14-2011, 09:42 AM

Wouldn't the bolt be not as strong as a pin? If the overall diameter of both the pin and the bolt are the same, the pin should be stronger, all other things being equal. Cutting the threads into the bolt means the solid section will be smaller in diameter than the pin. Probably doesn't matter.

wa8yxm · 02-14-2011, 09:52 AM

The only question I'd have is with the bolt grade... I dn't know the grade of the locking pin.

There may be other issues too depending on where you are using it.

The Receiver/adapter main tow pin... I see no major issues there provided the grade is correct, though I use a tow pin with padlock there

Tow bar to base plate.. In some cases if yu were to over tighten the bolt you might damage things..

Samc · 02-14-2011, 02:58 PM

Grade 8 is the toughest commonly available, with a yield strength of about 130,000 psi. Hardware store bolts are a grade 5 or 6, yield strength (in smaller sizes) about 90,000 psi. For a 5/8 bolt, that's about 39,000 lbs yield for the grade 8, and about 27,000 lbs yield for the grade 5/6; both much higher than any likely load, even under severe braking (acceleration is generally not an issue with a 20,000 + lb vehicle), although the grade 8 should be strong enough to pick up the whole coach with a hefty safety margin. I don't think I'd stand under it suspended by the grade 5/6 (or for that matter, the grade 8, but that's just me). And, of course, we're ignoring potential stress risers such as the threads. Realistically, if all we were worried about were the shear strength of the bolt, a piece of raw asparagus would probably work for a tow; the load isn't much until the brakes are applied. I wasn't clear that I'm asking if there are subtleties I'm missing, and crushing the towbar/base plate connection is one of them. Good catch; although I'm only concerned with the towbar/hitch connection at the moment, it's still something to keep in mind.

The towbar/hitch connection is static, but the towbar/baseplate connection has some movement, so I'd be concerned about wear there, too. The pins appear to be surface hardened to resist wear (a file won't touch a good quality pin), so a bolt as a replacement would be a temporary fix.

Any other concerns? This is helpful.