Bolts

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Bolts

Postby QueticoBill » Sun Apr 02, 2017 12:59 pm

In modifying Iront Trailer, I need a few bolts. Is it worth stricking with the metric - like comes with trailer - for 6 additional bolts, or go ahead and use imperial?

Any other comments on bolts welcomed. I believe these kit ones are plain galvanized steel grade 8.8, and if anything these added ones will be less stressed than the original. And was thinking on new 2 x 2 x 1/4 tongue - just drilling "top" and tapping as opposed to drilling and bolting through. All these thousands of little decisions - probably not 1% matter.
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Re: Bolts

Postby Glenn Butcher » Sun Apr 02, 2017 1:18 pm

I put a new tongue on my 40x48 trailer (haven't pulled with it yet, so take for what it's worth), and I just couldn't warm to attaching that heavy 2x2 member to the frame in the same way as the original. So, I went to a local muffler shop and got them to make a couple of square U-bolts, and I used angle iron to reinforce their stress on the frame:

Image

I'm NOT a mechanical engineer, so there may be all kinds of badness with this approach, but it seemed more prudent than the original attachment.
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Re: Bolts

Postby swoody126 » Sun Apr 02, 2017 4:13 pm

as long as the replacements are equal to or have greater strength it shouldn't matter

BUTT when, knot if, you have to work on the trailer in the future you will reclassify yourself for making you have to switch tools between fasteners :(

and try if at all possible to keep the head sizes the same also

just an old man's 2ยข worth

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Re: Bolts

Postby working on it » Sun Apr 02, 2017 4:14 pm

Glenn Butcher wrote:I put a new tongue on my 40x48 trailer (haven't pulled with it yet, so take for what it's worth), and I just couldn't warm to attaching that heavy 2x2 member to the frame in the same way as the original. So, I went to a local muffler shop and got them to make a couple of square U-bolts, and I used angle iron to reinforce their stress on the frame:

Image

I'm NOT a mechanical engineer, so there may be all kinds of badness with this approach, but it seemed more prudent than the original attachment.
  • A word of caution-I think I see a future problem awaiting you; your fabricated square u-bolt is not long enough for secure fastening, and the threads of the bolt-legs may pull thru the nuts, at some time. The threads should penetrate the nuts to "at least" the top of the nut, and preferably pat it. The flat washers are not helping in holding power, keeping the bolt threads from engaging the crimped top of the locking nuts (I assume that's what type the are).
  • I'm not a mechanical engineer, either, but after a lifetime of bolting just about everything together, including race-cars, multi-million dollar newspaper production & distribution equipment, metal structures, kid's toys, and my TTT (used bolts/steel brackets wherever possible; favored by me over pocket screws, biscuits, and blocking methods), I've learned about using the proper (minimum length of bolt-thru-nut thread engagement. Always use all the interior threads of the nut to get maximum holding power. In drag-racing, they inspect your wheel studs to make sure they go fully past the nut.
  • from NHRA 2007 Rule Book, Section 16 General Regs wrote: "The thread engagement on all wheel studs to the lug nut, or lug bolts to wheel hubs, must be equivalent to or greater than the diameter of the of the stud/bolt. Length of the stud/bolt does not determine permissibility. (Example: A 7/16-inch stud must be thoroughly engaged through the threads in the hex portion of the lug a minimum of 7/16-inch.)"
  • Though the rule may not be strictly enforced at all tracks or for all classes, you can bet that the higher-horsepower cars are looked over, and the fastest Sportsman classes must even increase the wheel stud size to specially-made 5/8" bolts. Part of the reason for this is the rounded-off or incomplete threads at the end of a bolt/stud, so the inspectors want to see that the nut' threads are fully engaged, for strength.
  • Here's a snip from the website Bolt-science http://www.boltscience.com/pages/shortbolting.htm, describing why short-bolting is avoided, in standard practice, though there seems to be no single standard shared among many professional associations.
  • short-bolting.PNG
    short-bolting.PNG (414.16 KiB) Viewed 327 times
  • I like the idea of having an angle bracing/holding your tongue piece, I use similar u-bolts and angle iron for clamping power on my trailer, too, but I always make sure I have extra length of threads showing past the nuts, for surety of thread engagement. I often use double-nutting, or lockwashers+nut+nylock, to ensure the bolt not stripping thru as easily. And on vital parts, like my axle u-bolts (made of tougher stuff than most u-bolts), I always torque the special nuts for the same reason-you'll never see a manufactured truck or trailer without the u-bolts showing extra thread.
  • 2013 HHRv,"squareback/simple" TTT, semi-offroad? 4x8, 2000+ lbs travel weight
  • featuring: 3500 lb Dexter axle w/brakes & HD leaf spring system > riding on General Grabber 27x8.5-14LT tires, LED lighting inside, A/C & heat, AGM battery 12vdc, 110vac from extended run generator onboard or park power, Coleman dual-fuel stove & Northstar lantern
  • 147697148333
  • 148599125895148106
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Re: Bolts

Postby Aguyfromohio » Sun Apr 02, 2017 4:36 pm

I am a mechanical engineer.
Rule of thumb is that full strength is when all threads in a standard hex nut ( or the same thickness in a tapped hole) are engaged with the screw.
The fastener looks halfway thru the hex nut, so my first guess is it's half strength.
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Re: Bolts

Postby Glenn Butcher » Sun Apr 02, 2017 5:01 pm

Ah, meant to type something about that, forgot before I posted.

The picture shows a "loose fit". When I torque them down, there's about 1/8" of thread above the nuts. I may go and get them to cut another pair for a bit more clearance. Thanks for the vigilance, though, really wouldn't want anyone to think that the situation in the picture is okay.

The whole thing's apart now, under a tarp. Work gets in the way of progress... :D
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Re: Bolts

Postby QueticoBill » Sun Apr 02, 2017 6:13 pm

Not attaching like existing, whole second tongue on Ironton 5*8. Very similar to bobhenry's photo/work on Harbor Freight - at end of this page/thread: http://tnttt.com/viewtopic.php?f=35&t=22538&start=30

Besides 4 M12 bolts at the "A" where coupler was planned to mount, one bolt on each of 3 frame pieces. And using 2*2*1/4 - which spreadsheet here says is over 400% of what's required. Damn tongue is heavy compares to rest of frame.
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