Proper fastener selection is critical to a successful project. 18-8 stainless steel fasteners have a tensile strength of 100,000 p.s.i. (pounds per square inch). They are of moderate strength and are adequate for holding on fenders, running boards, valve covers, and intake manifolds (without super-chargers). Stainless is superior to Grade 5 and Grade 8 on most applications where there is heat, i.e. exhaust manifolds, headers, etc. and they have the obvious advantage of being corrosion resistant. ARP 300 stainless is heat-treated and superior to normal stainless steel in every way. It has a tensile strength of 170,000 p.s.i., which is superior to standard Grade 8 products. Where strength is required as well as the other attributes of stainless steel, ARP is the best choice. They’re pretty too! To prevent seizing and galling of stainless steel nuts and bolts, always use antiseize. Use antiseize or ARP lubricant with ARP stainless as well.

Plated Grade 5, which has a tensile strength of 120,000 p.s.i., is also excellent for bolting on fenders, running boards, valve covers, and intake manifolds (without super-chargers), or any other general application where Grade 8 is not required. Some of our customers use Grade 5 when fabricating projects, and convert to stainless or ARP for final assembly.

Grade 8 should be used on suspension or anything else that spins, slides or thrashes about in any way. This includes alternators, power steering pumps, smog pumps, air conditioning pumps, and bolts that hold the fan blades. Keep in mind that whenever a fastener is used in a moving or shaking or rotating application its life is reduced by 92% compared to a static application.

Grade 9 (F-911) bolts have a tensile strength minimum of 180,000 p.s.i. This product is used by heavy trucking, earth-moving equipment maintenance shops, and off-road racers. We recommend using extra thick heavy-duty washers and Grade C lock nuts for a strong assembly.

Washers are the most misunderstood fastener there is, and their importance is almost always understated or ignored. Grade 5 and Stainless Steel washers are for moderate use only -- fenders, valve covers, or any area where sheet metal or some other soft material is being used. On all heavy-duty installations, as noted above, use Grade 8 flat washers.

Always use either lock washers or lock nuts without fail. We have two kinds of lock nuts. The first and most common is the nylon insert lock nut (Nylok). This nut is best used in applications where moderate strength is required. The effectiveness of the nylon locking material will degrade under high temperatures. In larger sizes, Nyloks will perform adequately on suspension as long as the bolt is in shear, but we recommend Grade C lock nuts because of their superior strength. Grade C lock nuts can withstand moderate heat(under 300°F) for long periods of time without degradation. Grade C lock nuts are sometimes called stover nuts, oval locks, crimp nuts, and top lock nuts, and should always be used with a Grade 8 flat washer.