bambamshere Posted May 26, 2019 Report Share Posted May 26, 2019 Does anyone know the Grade of bolt that is for the timing gear. Buddy says it is Grade 8 and I was saying I think grade 5. I snapped one today and it only was going to to 15 foot pounds. Pretty soft bolt. They are black bolt. Oh yeah it is the 3 bolts on upper gear for timing chain. Quote Link to comment Share on other sites More sharing options...
Radarsonwheels Posted May 26, 2019 Report Share Posted May 26, 2019 I think the grade is measured in tension not in shear? I thought grade 5 was less brittle and better for some applications since it will bend before breaking but I’m not any kind of expert. Sounds like you might have had a pot metal bolt in there! Hope it extracted easily and didn’t add a day to your thrash. Quote Link to comment Share on other sites More sharing options...
kencombs Posted May 26, 2019 Report Share Posted May 26, 2019 What are the markings on the bolt head? In most cases that will indicate the grade. But, on older stuff it may not be marked. 3 dashes are gr5, 5 dashes are gr8. As far as tension, not shear: torque is tension. The chain load when running would be shear. Most important, there is no way to tell how many times it has been removed, replaced, retorqued or even changed in its' life. 1 Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted May 26, 2019 Report Share Posted May 26, 2019 Your shopping cart is empty. Subtotal: $0.00 Quick AddCart / Checkout Fastener Info General Fastener Info Measuring Fasteners Materials and Grades Printable Fastener Tools Type-specific information Wood Screws Sheet Metal Screws Bolts Flange Bolts Machine Screws Nuts and Washers Anchoring Products Eye Bolts and Eye Lags Hanger Bolts U-Bolts and J-Bolts Shoulder Bolts Sex Bolts Blind Rivets Driver Bits Unit Conversion Tap and Drill Sizes Other Useful Information Bolt Grade Markings and Strength Chart Print this page US Bolts Head Marking Grade and Material Nominal Size Range(inches) Mechanical Properties Proof Load(psi) Min. Yield Strength(psi) Min. Tensile Strength(psi) No Markings Grade 2 Low or medium carbon steel 1/4" thru 3/4" 55,000 57,000 74,000 Over 3/4" thru 1-1/2" 33,000 36,000 60,000 3 Radial Lines Grade 5 Medium carbon steel, quenched and tempered 1/4" thru 1" 85,000 92,000 120,000 Over 1" thru 1-1/2" 74,000 81,000 105,000 6 Radial Lines Grade 8 Medium carbon alloy steel, quenched and tempered 1/4" thru 1-1/2" 120,000 130,000 150,000 Grade A325 Carbon or Alloy Steel with or without Boron 1/2" thru 1-1/2" 85,000 92,000 120,000 Stainless markings vary. Most stainless is non-magnetic 18-8 Stainless Steel alloy with 17-19% Chromium and 8-13% Nickel All Sizes thru 1" 20,000 Min. 65,000 Typical 65,000 Min. 100,000 – 150,000 Typical Metric Bolts Head Marking Class and Material Nominal Size Range(mm) Mechanical Properties Proof Load(MPa) Min. Yield Strength(MPa) Min. Tensile Strength(MPa) Class 8.8 Medium carbon steel, quenched and tempered All Sizes below 16mm 580 640 800 16mm - 72mm 600 660 830 Class 10.9 Alloy steel, quenched and tempered 5mm - 100mm 830 940 1040 Class 12.9 Alloy steel, quenched and tempered 1.6mm - 100mm 970 1100 1220 Stainless markings vary. Most stainless is non-magnetic. Usually stamped A-2. A-2 Stainless Steel alloy with 17- 19% chromium and 8-13% nickel All Sizes thru 20mm 210 Min. 450 Typical 500 Min. 700 Typical Tensile Strength: The maximum load in tension (pulling apart) which a material can withstand before breaking or fracturing. Yield Strength: The maximum load at which a material exhibits a specific permanent deformation Proof Load: An axial tensile load which the product must withstand without evidence of any permanent set. 1MPa = 1N/mm2 = 145 pounds/inch2 Shop for US Bolts Shop for Metric Bolts C Quote Link to comment Share on other sites More sharing options...
bambamshere Posted May 26, 2019 Author Report Share Posted May 26, 2019 It is Black with a F on the head. I bought a bunch of Grade 5 bolts last night. But I will see if I can get Grade 8. Oh and the only marking on the top of head is that F Quote Link to comment Share on other sites More sharing options...
DJ194950 Posted May 26, 2019 Report Share Posted May 26, 2019 That " F" stands for the Chinese word - cheap trash! Just my guess.? I would never use anything less than a marked grade 5 on my vehicles. Grade eights are made for high stress- pull wise, not shear were primary to the job. Some jobs really require that bolt to stretch, bend, etc. resisting outright breaking. Just one opinion! DJ Quote Link to comment Share on other sites More sharing options...
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