Question: Letters on bolt head?
- Thread starter WanaDmaxsub
- Start date
Anyone know what the letters on this bolt head mean?
It's a .5"X1.5" grade 5 rib neck carriage bolt.
I need to replace all 8 of them...with grade 8 and no ribs (to strip) this time!
Looks like them bolts are in a hitch. They look to already be grade 8 bolts
Thanks
Good question.
The bolts holding the hitch to the frame are Grade 8.
does that explain why a grade 5 might have been a better choice for a balancer bolt on my old motor. i used a grade 8 to seat the balancer. sheared it off within 2 mos...... appearantly to brittle??
does that explain why a grade 5 might have been a better choice for a balancer bolt on my old motor. i used a grade 8 to seat the balancer. sheared it off within 2 mos...... appearantly to brittle??
No, Grade 8 is stronger/tougher than Grade 5 across the board. You probably would have popped the grade 5 on install with the same torque.
These grades are standards. Specialty bolts and fasteners are another creature all together. Head bolts, Flywheel bolts, and connecting rod/main bolts are some ones that come to mind with "special" properties for their application. IIRC, the darn balancer bolt is too, but I would have to look again.
so a grade 8 wasn't even the right bolt for this application?? drilling a grade 8 bolt to tap and back out of the crank is one of my least favorite things to do.....i found that out the hard way.
Thats a grade 5 it has three marks forming a Y. Grade 8 will have six marks. Grade 8 bolts are better in every aspect. They are not "brittle" the hardness is greater meaning that they are tougher(less brittle). Typically you need to be in the 180 ksi range to be considered brittle. Grade 5 signifies 120 ksi material where as grade 8 is 150 ksi material. Nearly all fasteners you run across are considered "ductile".
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so a grade 8 wasn't even the right bolt for this application?? drilling a grade 8 bolt to tap and back out of the crank is one of my least favorite things to do.....i found that out the hard way.
Wasn't an aftermarket dampner was it?
nope. factory dampner, but it was new. rubber on the old dampner had pulled apart so i had to replace it.
Certainly no expert, but IIRC:
Grade 8 is alloy steel. This means the steel itself is stronger regardless of heat treat, but they are heat treated for extra strength. This mean if the bolt get really hot, it will hold it's strength better than carbon steel. Most jet engine stuff is grade 8 if it's not a special bolt.
Grade 8's are also known as 10.9's which is a metric class.
Grade 5 is good quality carbon steel that has been heat treated. Metric is 8.8.
IIRC, there are a few head marks that are high strength ASME markings, they start with the letter B. Don't remember what's what.
Grade 8 is alloy steel. This means the steel itself is stronger regardless of heat treat, but they are heat treated for extra strength. This mean if the bolt get really hot, it will hold it's strength better than carbon steel. Most jet engine stuff is grade 8 if it's not a special bolt.
Grade 8's are also known as 10.9's which is a metric class.
Grade 5 is good quality carbon steel that has been heat treated. Metric is 8.8.
IIRC, there are a few head marks that are high strength ASME markings, they start with the letter B. Don't remember what's what.
a little more info
A bolt graded by the ANSI standard is identified by the number of lines arranged around the head of the bolt. The minimum value of tensile strength is defined as 2. A bolt of this value has no lines on its on its head.
0 lines = Grade 2 tensile strength
3 lines = Grade 5
5 lines = Grade 7
6 lines = Grade 8
The ISO standard uses two numbers on the head of the bolt. The first number indicates the tensile strength; the second number signifies the yield strength.
If a bolt is marked 8.8, it has a tensile strength of 800 MegaPascals (MPa) and a yield strength value of 640 MPa, 80% of its tensile strength. A marking of 10.9 indicates a tensile value of 1000 MPa with a yield strength of 900 MPa, 90% of its tensile strength.
4 = 400 MPa
5 = 500 MPa
8 = 800 MPa
10 = 1000 MPa
.5 = 50%
.6 = 60%
.7 = 70%, etc.
The suitability of a bolt for an application is determined by its tensile strength and its yield strength. The tensile strength is defined as the maximum stretching stress a bolt can withstand without breaking. The yield strength is the maximum stress a bolt can withstand and still return to its original form.
A bolt graded by the ANSI standard is identified by the number of lines arranged around the head of the bolt. The minimum value of tensile strength is defined as 2. A bolt of this value has no lines on its on its head.
0 lines = Grade 2 tensile strength
3 lines = Grade 5
5 lines = Grade 7
6 lines = Grade 8
The ISO standard uses two numbers on the head of the bolt. The first number indicates the tensile strength; the second number signifies the yield strength.
If a bolt is marked 8.8, it has a tensile strength of 800 MegaPascals (MPa) and a yield strength value of 640 MPa, 80% of its tensile strength. A marking of 10.9 indicates a tensile value of 1000 MPa with a yield strength of 900 MPa, 90% of its tensile strength.
4 = 400 MPa
5 = 500 MPa
8 = 800 MPa
10 = 1000 MPa
.5 = 50%
.6 = 60%
.7 = 70%, etc.
The suitability of a bolt for an application is determined by its tensile strength and its yield strength. The tensile strength is defined as the maximum stretching stress a bolt can withstand without breaking. The yield strength is the maximum stress a bolt can withstand and still return to its original form.