dfeck
Gold Member
Does anyone have any documents that gives detailed information on how to determine the hardness of a bolt?
How to determine bolt hardness?
- Thread starter dfeck
- Start date
- Views: 15477
jrlichina
Platinum Member
Bolt grades are sometimes difficult to determine if you do not have the manufactures box. In GENERAL bolts with no markings are Grade 2, each additional mark is one more. So bolt with 6 "ticks" on the head is a Grade 8. I've attached a link the denotes the grades.
Grade Chart
Grade Chart
rancar
Veteran Member
- Joined
- Jan 26, 2002
- Messages
- 1,719
- Location
- Cambridge, New York
- Tractor
- JD425 lawn tractor; JD4710 CUT; JD JX75 Walk Behind
Grade 8 bolts have that yellowish, bronze color. In all applications regarding operation of tractors and their attachments it's recommended that Grade 8 bolts be used and at minimum grade 5 (silvery color). Under no circumstances should less than grade 5 be used.
...Bob
...Bob
You might want to go by the head more than the color. While I've yet to see a grade 2 bolt that funky bronze/yellow color, I have come across some grade 5 bolts that are. (The store had them labeled as G5 and the heads also reflected the G5 markings.)
Not real sure if you were talking about holding equipment together or not with G8, but I'd tend to agree if that's what you were referring to. Sheer pins (i.e. bolts) are a different matter though as most of the stuff I have requires Grade 2 bolts so that your PTO shaft isn't mangled when overpowering resistance is encountered. The one exception I have is an add-on slip clutch I have for my mower where it specifically said to use only Grade 5.
I suspect I'm a lot like you that if it is a non-moving-hold-it-together situation and I can't find the mfg. specs, I'd too go with the G8. If it's a PTO shaft or something else that uses the bolt as a safety thing, I'd go with a G2 if nothing is specified.
Not real sure if you were talking about holding equipment together or not with G8, but I'd tend to agree if that's what you were referring to. Sheer pins (i.e. bolts) are a different matter though as most of the stuff I have requires Grade 2 bolts so that your PTO shaft isn't mangled when overpowering resistance is encountered. The one exception I have is an add-on slip clutch I have for my mower where it specifically said to use only Grade 5.
I suspect I'm a lot like you that if it is a non-moving-hold-it-together situation and I can't find the mfg. specs, I'd too go with the G8. If it's a PTO shaft or something else that uses the bolt as a safety thing, I'd go with a G2 if nothing is specified.
JohnMiller3
Elite Member
- Joined
- Jan 15, 2001
- Messages
- 2,517
- Location
- Capital District, Upstate New York
- Tractor
- Satoh S650G, MF135, MF165, JD5205
<font color="blue">...bolts that have a reddish appearance...</font>
Sounds like they are "Metric" Grade...? What's stamped on the end caps?
Sounds like they are "Metric" Grade...? What's stamped on the end caps?
gerard
Veteran Member
I THINK the bolts at the TCS store are color coded blue and red. The red are grade 5 and the blue are grade 8. That also corresponds with the ticks on the head...........
Since I'm at work and the bolts are at home I'll have to get back to you. I'm using these for towing hooks that I'm going to use on my FEL. I picked these up from a bin at my fathers trucking business. I don't think they're metric because I used a 3/4" wrench to tighten them to a piece of angle iron so they can be welded to my FEL. I guess I can ask my father but I know him well enough that he won't know or remember. He's got a ton of hardware and him knowing why he bought these specific bolts are remote. Now that I got the chart I'll check the heads and report back.
Thanks
Thanks
RoyJackson
Rest in Peace
- Joined
- Nov 17, 2001
- Messages
- 23,144
- Location
- Bethel, Vermont
- Tractor
- John Deere 4052R Cab,, Deere 855D UTV, Z920A Zero Turn Mower and assorted implements
"Grade 8 bolts have that yellowish, bronze color."
That's Cadmium plating you're describing. You really need to go by the head markings...that's about as reliable as you can get without actually metalurgically testing the bolt. There is a flood of counterfit bolts now and then (our less then reputable friends in the Far East along with some greedy scumbags here in the USA provide them).
I've a picture of the headmarkings, but a grade 8 should have a line extending in from each corner of the hexagonal head of the bolt (total of 6 lines). A grade five should have 3 lines extending in from every other corner of the bolt head (again, hexagonal (or 6 sides for you guys that were in the USMC)). Now, those markings are per ASTM and SAE. Therefore, those markings may not be applicable for all manufacturers. I've seen a "filled triangle" on one side or the top of the bolt designating grade 8's.
If I can find the picture of the head marking chart, I'll post it.
That's Cadmium plating you're describing. You really need to go by the head markings...that's about as reliable as you can get without actually metalurgically testing the bolt. There is a flood of counterfit bolts now and then (our less then reputable friends in the Far East along with some greedy scumbags here in the USA provide them).
I've a picture of the headmarkings, but a grade 8 should have a line extending in from each corner of the hexagonal head of the bolt (total of 6 lines). A grade five should have 3 lines extending in from every other corner of the bolt head (again, hexagonal (or 6 sides for you guys that were in the USMC)). Now, those markings are per ASTM and SAE. Therefore, those markings may not be applicable for all manufacturers. I've seen a "filled triangle" on one side or the top of the bolt designating grade 8's.
If I can find the picture of the head marking chart, I'll post it.
