bowtie4.gif (2065 bytes) 1931 Chevrolet - Torque Settings
 

Updated: 12/08/2007

Using the right nut and bolt when restoring your car can make a big difference.  Everybody knows that stainless steel is much less likely to rust when used on a car.  But it's just as important to know when to use a Grade 5 bolt in certain areas.  One of these might be when you are mounting the body to the frame.

Grade 2 bolts are the most common used material and they work just fine as long as you paint them with primer and cover with a color coat.  This simple preparation will go a long ways towards preventing them from rusting.  And THAT might be something that you're thankful for a few years down the road when you have to remove them again.  ha!

 

Bolt Grade Markings and Strength Chart

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
Stainless markings vary. Most stainless is non-magnetic

18-8 Stainless

Steel alloy with 17-19% Chromium and 8-13% Nickel

1/4 thru 5/8   40,000 Min. 80,000 – 90,000 Typical 100,000 – 125,000 Typical
3/4 thru 1   40,000 Min. 45,000 – 70,000 Typical 100,000 Typical
Above 1   80,000 – 90,000 Typical

Hosted by:  Bill Barker
Bellevue, WA, USA