Required Bolt Grade

[1984RESTOMOD]

Are grade 10 bolts with lock washers and lock tight sufficient for brackets to the chassis (ie cab mounts, leaf spring/radius arm brackets)?

 

[Shran]

I assume you mean metric grade 10.9...? Those would be perfect.

Grade 10 SAE does not exist, those are most commonly available in grade 2, 5 or 8. I would be comfortable using grade 8 on suspension parts, grade 5 or 8 on anything else. You could get away with grade 2 on cab mounts and stuff... I wouldn't though.

FWIW Caterpillar sells Grade 9 bolts at Cat dealers... they are pretty cool, they have the little Cat logo on the bolt head. Spendy but if you need odd sizes or really good bolts, that's your source.

 

[1984RESTOMOD]

I assume you mean metric grade 10.9...? Those would be perfect.

Grade 10 SAE does not exist, those are most commonly available in grade 2, 5 or 8. I would be comfortable using grade 8 on suspension parts, grade 5 or 8 on anything else. You could get away with grade 2 on cab mounts and stuff... I wouldn't though.

FWIW Caterpillar sells Grade 9 bolts at Cat dealers... they are pretty cool, they have the little Cat logo on the bolt head. Spendy but if you need odd sizes or really good bolts, that's your source.

Correct metric grade 10.9

 

[Snoranger]

Metric bolts are usually measured by property class, whereas standard bolts are usually measured in grades.

You would say class 10.9 bolt, not grade 10.9.

 

[Curious Hound]

Metric bolts are usually measured by property class, whereas standard bolts are usually measured in grades.

You would say class 10.9 bolt, not grade 10.9.

Yeah, yeah, yeah. You're right.

Heard a funny story yesterday. A co-worker overheard some tech scholars (think interns. They work part time and go to school part time) working on a project. One asked the other to get a wrench. The government asked what size. The requester said " 10.9mm".

 

[pjtoledo]

ditch the lock washers and use flanged nuts & bolts.
the bolts are far stronger than the sheet metal, flanges spread the load out.

 

[rubydist]

Please disregard everything that JoshT said above, it is virtually all wrong.

Instead, please review the attached specs.

There is, in fact, no situation where a grade 2 bolt will "bend and hold" while a grade 8 bolt would break. A grade 2 bolt would break around 74kpsi while a grade 8 bolt won't even yield (suffer permanent deflection) until at least 130kpsi.

Please also note that the junk you buy at HD with no head markings is grade 1. A few years back, the government started requiring a manufacturer or supplier marking on the heads of all bolts, due to all the imported junk that was marked as grade 5 or 8 but was not really, and the failures were, in some cases, pretty spectacular.

 

[JoshT]

I'm not going to argue. Like I said, it's been a long time since I was in tech. I'll delete the post.

Still, there are places where a 2 or 5 can be better choice than a grade 8. Also still a good idea to do some studying and figure out which is going to work best for you.

Few years back? Head markings were already required when I was in tech school 20+ years ago.

 

[Snoranger]

I'm not going to argue.

Don’t… he’s right.

 

[Curious Hound]

The very few places where a lower grade bolt is preferred are usually cases where the bolt is being used as a shear pin and is calculated to shear with a certain amount of force in order to protect more expensive parts of a rotating machine assembly.

 

[lil_Blue_Ford]

The very few places where a lower grade bolt is preferred are usually cases where the bolt is being used as a shear pin and is calculated to shear with a certain amount of force in order to protect more expensive parts of a rotating machine assembly.

Yup, we have an old walk behind rototiller and if memory serves correctly, the owners manual tells you to use “ungraded” (grade 1 or 2) bolts as shear pins for the tines. I’ve had to replace them after hitting a rock (there’s lots of those here to find). BrrrrBANG. Time for a new bolt…

 

[85_Ranger4x4]

Up until you are bouncing on a breaker bar wishing the stupid bolt would just break already so you can move on with life...

Also, if there is a decent chance i will have to drill them out later, grade 5 all the way. Ran into that with my water pump a year ago, the surviving grade 8 went into a can and grade 5 went back in. Pick your battles...

My shackle/spring bolts are grade 8 with holes in them and grease zerks... so they probably are not really grade 8 anymore. Don't remember what the shackle hardware was that came with the hangers. I want to say it was 8.8 which is a tad harder than grade 5.

 

[JoshT]

The very few places where a lower grade bolt is preferred are usually cases where the bolt is being used as a shear pin and is calculated to shear with a certain amount of force in order to protect more expensive parts of a rotating machine assembly.

And that may be what I'm remembering. Like I said, tech was 20+ years ago. It's not something I've needed to be very concerned about since. It is important for the overall field I trained for (Aviation Maintenance), but not so much for the industry I entered (Federal Aviation Maintenance). Here you don't need to think about bolt grades, you need to look up and use the hardware specified in the parts manual and install it per the technical data. Failure of hardware could cost lives and multi million dollar assets. If hardware specified in parts manual (or an approved in writing by engineer alternative) is used, your ass is covered if it fails. If unapproved alternative hardware is used and it fails, costing lives or equipment, your ass is on the line. Expect to loose your job at a minimum, you could potentially be facing charges, federal charges.

 

[sgtsandman]

Up until you are bouncing on a breaker bar wishing the stupid bolt would just break already so you can move on with life...

Also, if there is a decent chance i will have to drill them out later, grade 5 all the way. Ran into that with my water pump a year ago, the surviving grade 8 went into a can and grade 5 went back in. Pick your battles...

My shackle/spring bolts are grade 8 with holes in them and grease zerks... so they probably are not really grade 8 anymore. Don't remember what the shackle hardware was that came with the hangers. I want to say it was 8.8 which is a tad harder than grade 5.

I know the OEM shackle bolts trashed the metal cutoff blades on my sawzall. I had to resort to cut off wheels in order to get the old ones out. So, they are pretty hard.

 

[85_Ranger4x4]

I know the OEM shackle bolts trashed the metal cutoff blades on my sawzall. I had to resort to cut off wheels in order to get the old ones out. So, they are pretty hard.

I think they are just strong in the dark side. All that hate makes them that way.