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Jayem
Forums Junkie

Location:
Finland
Registered:
November 2002

Headbolts from metallurgist point of view.	Wed, 22 October 2003 18:00

What makes headbolts, flywheelbolts, conrod bolts, etc. special? What is the strenght grade for before mentioned bolts (bigger than 8.? I know that some cars (some opels for example) require "stretching bolts" for head(I hope that's correct term). Why is that so? What makes ARP bolts so renowned? Quality is obvious point. Are ARP bolts forged? What kind of metals are these bolts made of? How are these bolts hardened? surface hardened? [Report message to a moderator]

Lambolica
Forums Junkie

Location:
Northwestern Sydney
Registered:
August 2002

Re: Headbolts from metallurgist point of view.	Thu, 23 October 2003 03:15

From a structural steel point of view most buildings that contain steel work use 4.6 grade bolts for connections (4.6 being the common bolt grade for automotive use) for connections that have high tensile or shear loads 8.8 bolts are specified for their higher tensile strength (ie can be done up tighter without stretching as much) similar to the shear that would be created in flywheel bolts etc 8.8 bolts. I believe that 4.6 & 8.8 bolts are all mild steel with 8.8 having a diffrent treatment in the moulding (Hardening) I'll look up the specs and post them. [Report message to a moderator]

Mr DOHC
Forums Junkie

Location:
Brisbane
Registered:
October 2002

Re: Headbolts from metallurgist point of view.	Thu, 23 October 2003 11:29

u mean torque to yeild bolts for the stretch ones, these are the ones that must be replaced everytime a H.G is done [Report message to a moderator]

Jayem
Forums Junkie

Location:
Finland
Registered:
November 2002

Re: Headbolts from metallurgist point of view.	Thu, 23 October 2003 13:05

I know that strenght for example 8.8(X.Y) can be calculated: tensile strength=100X yield strength=10X*Y Strength grade__________4.6_4.8_5.6_5.8_6.8_8.8_9.8_10.9_12 .9___ Max tensile strength____400_400_500_500_600_800_900_1000_1200_ __ Max yield strength______240_320_300_400_480_640_720_900__108 0___ Tensile strength and yield strength in MPA's [Report message to a moderator]

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