So I am about to the mounting stage of my Hitchhiker side car. The top two bracket are factory from some place that I bought from the previous owner (I am at least the 3rd owner). The top brackets don't worry me as they are grade 8 hardware and mount directly to the frame tube. As for the bottom brackets I am going to modify them/make my own kind of a think. The attachment point to the sidecar arms is still grade 8 hardware. Wear that mounts to the bike is what I have to change. I am copying one of the brackets that I got with the sidecar but the holes drilled in it were too wide for my 1997 Sportster. So I bought some of the same stock mettal (1 inch square with another piece welded on it that I got 1.5 inch square that I will drill a hole for the grade 8 bolt to mount the sidecar side on). My question is this. I can't find grade 8 U bolts to attach to the frame of my bike. I will reuse the two U-bolts that came with the first factory bracket but I bought 2 stainless steel U-bolts for the other two. I was thinking using the original U bolts closest to the side car and putting the stainless ones on the opposite side. I have read that the stainless is a grade 5. Is that correct? I also have heard of gualing of the threads happens a lot on stainless. I just want to make sure I am using a safe mounting U-bolts so if someone can tell me where to get the grade 8 or something better then the stainless I will get them. I couldn't get a cable clamp in the size I needed nor does any leaf spring suspension place make them that small for me online and even those are mostly grade 5 with a few being grade 8. I don't want to kill myself of my family because of this hardware issue. Maybe I am over doing it. The mounts are all 1/2 grade 8 bolts and the U bolts are 3/8 inch diameter. Also, any good paint that I should use on the square stock when I am done welding and drilling? I don't really have access to powder coating.
Four grade 5 U-clamps will work. If using square tube stock I prefer 1/4" mounting tabs or if space is an issue with that method, I weld insert spacers into the tube to eliminate crushing and later loosening of the bracket.
Thanks, I will look into the mounting tabs. I didn't even think of the tub crush and the loosening factor. I was going to add spacers just like what was on the factory one but that would have still crushed the frame tube.
On my lower front bracket it took two U bolts and I didn't have any hard U bolts so. I have built horses carriages in the past, so I used 1 1/4" spring hanger strapes and harden bolts to connect to the bracket. doubled nut the bolts so for no problems ( hanger strap is a 3/8" strap steel with 5/16"holes at 1"&1/4 " apart)Rudyr
Stainless screws always need lubrication BEFORE screwing them in....
I ate more then one wrench when I forgot to lubricate the screws assembling SS-valves at GEA-Tuchenhagen. The moustache helps to cover the scars.
No hope to ever loosen that screw again. You break it, or you break it.
Junk metric screws (like the Japs used until 1988 on their bikes) grade 4.8 (=grade 2 or 3 ANSI) have 400N/mm2 tensile strength and 8% elongation before it breaks
Stainless is in a few applications way too soft. (metric grade 7 = 700N/mm2 tensile strength) Elongation is not even mentioned
Standard metric screws are 8.8 equivalent to grade 5 ANSI (3 marks) = 800N/mm2 tensile strength and 8% elongation before it breaks
Metric grade 10.6 are equivalent to grade 8 ANSI. (6 marks) = 1000N/mm2 tensile strength and 6 % elongation before it breaks.
Metric grade 12.4 (like in high strength bolts (grade 10 ANSI ?)) = 1200N/mm2 tensile strength and 4 % elongation before it breaks.
This short list might explain why for certain applications you better keep your hands off stainless screw or even worse cheap screws.
Good Luck
Here I jump to the fridge and leave for the rig with a couple of beers into the warm night...
Happy Valentine.
Sven
