Quote:
Originally Posted by ShrimpBurrito
I thought about water getting into the channel and rusting either the channel or the bolts too. I didn't think the channel would end of being a big deal because of the nice big holes the tension rods go through.
I could use a stainless or galvanized bolt, but it's my understanding that neither are as strong as a grade 5 bolt.
Dave
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S/S is made to be pretty, not strong. Also it is called "Stain
less" for a reason. S/S will still corrode and as it does, it's strength quickly degrades.
Fine thread Grade 8 bolts should be used in places where there is extreme stress (not applicable) or the possibility of shock loading, like in safety chains. Grade 8 bolts are less susceptible to corrosion too. That's one of the reasons that they are used in the suspension of your car. All suspension bolts (and some assembly bolts) on vehicles are required to be grade 8 by law (fine threaded bolts are stongest because the threads are not cut as deep). This is because of the superior strength and resistance to shock-loading. When using any steel bolts, it's always a good idea to use an anti-seizing compound (on the threads of the bolt) and lock-nuts. Double nutting is best. If you are concerned about aesthetics, you may want to use a nylon-insert lock-nut.
I'd be careful about drilling holes in the trailer frame. It should be avoided if possible. Cracks can develop from the holes due to the constant flexing and working of the trailer frame. One tip for drilling through the frame is to drill a larger hole and have a piece of pipe welded into the hole. This will avoid crushing, water intrusion and cracking. A better idea might be to weld a thick 1/2" nut on the outside of the frame and use that to bolt the chain to that nut.
Most holes that come in the frame from the factory are stamped, not drilled. It is rare to find any holes in the tongue area due to stress and flexing.
If you are concerned about the strength and corrosion of the chains, you may want to look into "high tensile" boat anchor chain. It is corrosion resistant and extremely strong. It can be purchased by the foot at most marine supply stores relatively cheaply. 3/8" Proof Coil anchor chain (which is not high tensile) has a 10600lb breaking strength and is around $2.50 per ft. High tensile chain is about 40% stronger but over double the price. I would avoid chain from hardware stores. They are mainly meant for fencing and there are no set quality standards or testing. Very dangerous stuff for this application IMO.
http://www.westmarine.com/webapp/wcs...FQ89awod3We1Fg
I would not feel comfortable with plastic coated cable. Although it is more aesthetically pleasing, water can (and most likely will) get into the plastic and you may not see the corrosion until it is too late (if it is colored coating, you
won't see the corrosion). Once the water gets in, it cannot escape. Cables also tend to corrode from the inside out. With chain, what you see is what you have. I'd
much rather have a rusty chain that I can see than a plastic coated cable that I can't see.
If you have a
clear plastic coating on the cable, inspect it regularly and replace it at the first sign of discoloration.
Bolts are graded at their "Breaking point":
http://dodgeram.org/tech/specs/bolts..._strength.html
It is true that softer bolts will stretch before breaking. However, they will ultimately break at a much lower load.
BTW, the weakest point in the safety chain system is often the attachment to the TV. If you are clipping to the attachment points on your hitch, it is probably soft cold rolled steel bar welded to the hitch. The weakest point in the entire system may well be that weld. Check that carefully for gaps and cracks.