2006 purple paint code
- Thread starter flybysr1
- Start date
ASTM A574 is the designation for alloy cap screw, cap screws and bolts are different. These terms are often incorrectly used interchangeably. The variations between these fasteners are fairly significant both from a manufacturing perspective and application standpoint. Generally speaking, hex cap screws are used in precise applications like an OEM setting where tight tolerances are required. Hex bolts are often specified when the mechanical properties are more important than dimensional tolerances, like the construction industry.Thanks B dub. The broken one I just got out is a ASTM 574 which according to the old inter-web is harder than grade 8. Hmmm, it looks like the recessed area is large enough for a 7/16 head....
What size do you currently have? In post 24 you said 3/16", that can't be right, is it?
Just some info that may interest you:
Single shear strength of body of A574 cap screws by diameter
1/4" - minimum of 5,300lbs
5/16"- minimum of 8,285lbs
3/8"- minimum of 11,910lbs
These values are for each cap screw in shear connection such as fender struts. To put this into perspective, if a 175 lb man was falling onto your rear fender at 55mph, he would apply 8.85 tons, or 17,700 lbs of force to your struts. So theoretically, with four 1/4" cap screws holding your fender in place you still have reserve capacity for buddy landing on your fender at 55 mph.
I hear a lot of people say they break bolts off all the time, one potential cause may be the choice of supplier. Probably 70-80% of the structural bolts we use in our industry come from China, with all the correct QC documentation..documents that aren't even worthy of wiping your ass with. Our internal QC checks fail about 40% of the bolts we receive, so be diligent when purchasing your fasteners. Sorry for being long winded, just my
by the way..
Single shear strength of body of A574 cap screws by diameter
1/4" - minimum of 5,300lbs
5/16"- minimum of 8,285lbs
3/8"- minimum of 11,910lbs
These values are for each cap screw in shear connection such as fender struts. To put this into perspective, if a 175 lb man was falling onto your rear fender at 55mph, he would apply 8.85 tons, or 17,700 lbs of force to your struts. So theoretically, with four 1/4" cap screws holding your fender in place you still have reserve capacity for buddy landing on your fender at 55 mph.
I hear a lot of people say they break bolts off all the time, one potential cause may be the choice of supplier. Probably 70-80% of the structural bolts we use in our industry come from China, with all the correct QC documentation..documents that aren't even worthy of wiping your ass with. Our internal QC checks fail about 40% of the bolts we receive, so be diligent when purchasing your fasteners. Sorry for being long winded, just my
by the way..
flybysr1
Member
Sorry. in my haste I screwed the pooch. It's currently 3/8.
flybysr1
Member
Okay, I'm very cool with idea that this hardware could be inferior as Doug suggests. I do view the effort of drilling an re-tapping all of these holes to 7/16 as challenge that I ain't skeered of. To be straight up, I am more concerned with clamping forces, not shear forces. In my world of robots I have seen cases where vibration gets the chance to work on a bolt. It's possible with vibration to stretch the bolt rendering the clamp forces to be compromised, resulting in broken bolts. Just a thought.
Install with loctite blue and torque to spec. Any vibration of the struts would act as shear forces, and bolt fatigue is certainly something to keep in mind. Should visually inspect the condition of your fasteners once a year, off season maintenance. I pulled my strut bolts this winter, no signs of wear at all but replaced with new anyways, since they are only a couple bucks each..
Works for me..
BWG56
Guru
Good explanations Chucky, I thought I was back at work having a round table design discussion.Just some info that may interest you:
Single shear strength of body of A574 cap screws by diameter
1/4" - minimum of 5,300lbs
5/16"- minimum of 8,285lbs
3/8"- minimum of 11,910lbs
These values are for each cap screw in shear connection such as fender struts. To put this into perspective, if a 175 lb man was falling onto your rear fender at 55mph, he would apply 8.85 tons, or 17,700 lbs of force to your struts. So theoretically, with four 1/4" cap screws holding your fender in place you still have reserve capacity for buddy landing on your fender at 55 mph.
I hear a lot of people say they break bolts off all the time, one potential cause may be the choice of supplier. Probably 70-80% of the structural bolts we use in our industry come from China, with all the correct QC documentation..documents that aren't even worthy of wiping your ass with. Our internal QC checks fail about 40% of the bolts we receive, so be diligent when purchasing your fasteners. Sorry for being long winded, just my
Using the right size for your calculations, 3/8", would really be more like 24 tons(48,000lbs) instead of 10-1/2 tons with the 1/4", seeing your calculations of 8.8 tons, the 3/8 diameter hardware would give you approximately a 3:1 ratio safety margin which is what we designed to in my world when I was working.