Replacing rivets with bolts

[jeffahart]

For sure, lots of conflicting info on the internet, plus it's hard to get to a true authority on a subject.

I posted above for argument sake. But if it were me, I would have bolted with grade 8 & lock washers and never second guessed myself. I bolted on the ORD shackle flip mounts which replaced the original factory riveted mounts. Did not think twice about it. But I guess once shear is mentioned my ears kind of perk up. Being a contractor in Los Angeles you get a lot of talk about shear forces.

[Orange Crate]

Originally Posted by MARKDTN

For a frame bolt, you really should have the type that is not threaded all the way to the head. The smooth shank part will help keep the joint snug. They may be hard to find with exactly the right shank for what you need.

This is a really good point. If you want to come close to the rivets ability to survive shear loads with a bolt substitute you need to use this type of bolt. Without a shank, in shear, the bolt threads would compress easily allowing even more lateral movement and then you would basically have an oval bolt profile (unless that is what you are after!). You could find a bolt with the right shank length and then cut the excess threads off after installation (or just leave them, whatever...).

[Vintage Windmills]

Should not be a problem if using grade 5 or better hardware. The original factory rivets are likely 1010 steel, which has a tensile strength of only 53,000psi. Compare that to a grade 5 bolt at 120,000 psi and a grade 8 at 150,000 psi. These are tensile values but shear is about 60% of each value, respectively.

Originally Posted by Orange Crate

A riveted joint is an interference fit which helps greatly when trying to minimize the shear movement of two plates. A common bolted joint does not have this same shear prevention property. A bolted joint can easily match a riveted joint in tensile strength, but most common bolted joints are not installed as interference fit joints. But they can be, by drilling and reaming the hole to a size that is actually smaller than your bolt diameter by a few thousands and then cooling the bolt with dry ice and installing it cold. Anyway....a nut "backing off" is more likely due to the plates moving in shear allowing the bolt to also move and deform (stretch). When you have two different types of joining styles (rivets & bolts) in one system the weaker style will show up as a failure of some form (stretch in tensile or shear load).

Originally Posted by MARKDTN

For a frame bolt, you really should have the type that is not threaded all the way to the head. The smooth shank part will help keep the joint snug. They may be hard to find with exactly the right shank for what you need.

Not exactly. Most bolted applications specify clearance even in shear loads. A properly tightened bolted joint creates friction between the bolted members which prevents the shear from usually being seen by the bolt. If the force (like in an accident) exceeds the friction force, then you can get movement and the bolt takes shear. But the friction still helps to reduce the load seen by the bolt in shear. Imagine a 3/8 bolt being torqued to spec, it provides about 5000lbs clamp load! Multiply that by friction factor of steel on steel, about 0.6. That results in about 3000lbs to overcome before the bolt can see shear.

You are right about mixing bolts and rivets, avoid that in the same members. The rivets would take an unfair share of the load if the force became high enough to create sliding before the clearance in the bolted holes would be taken up.

[MARKDTN]

Originally Posted by Vintage Windmills

..Not exactly. Most bolted applications specify clearance even in shear loads. A properly tightened bolted joint creates friction between the bolted members which prevents the shear from usually being seen by the bolt. ...

I work in an industry installing equipment on heavy trucks. I can tell you that the threaded all the way vs: smooth shank does make a difference in a subframe mounting bolt. You want a smooth shank and you want it very snug. You can take it for what you paid for it, but that is definitely what I would do in this case. And I would use grade 8 fasteners.

[jeffahart]

What about using wheel studs. You could pound them in.

[mechanicalman]

Originally Posted by jeffahart

Well, coming from a construction background. We're always told that nails are better than screws for shear because they are generally more ductile than screws. Better ductility means better absorption of seismic energy. In earthquake prone regions the engineers are strict on fasteners for seismic code. The city of Los Angeles has some of the most strict seismic building code anywhere.

Just wondering if one might apply that theory to what's being talked about here. Maybe grade 8 is not over kill but possibly inappropriate for shear force. Maybe you want a bit if elasticity?

I'm not an engineer but, all things equal, you would think the same principles apply.

I'm thinking the nails bend, slide in and out, give a little and the screws might just pop and break because the threads hold them tight? For earthquakes that is IMO preferable to not pop and collapse. Better the house is just a little out of square.

I've actually dreamed of building a house with screws instead of nails (thinking the nails were only cheaper and easier), but now I might change dreams LOL.

I'm also thinking that would not be good on a car frame because it would not spring back necessarily and become loose over time and fail.

I'm not an expert on this either, just an average joe thinking aloud

[mechanicalman]

Originally Posted by MARKDTN

For a frame bolt, you really should have the type that is not threaded all the way to the head. The smooth shank part will help keep the joint snug. They may be hard to find with exactly the right shank for what you need.

I agree. Might be hard to find, but for sure preferable and the snugger the better.

[jeffahart]

Originally Posted by mechanicalman

I'm thinking the nails bend, slide in and out, give a little and the screws might just pop and break because the threads hold them tight? For earthquakes that is IMO preferable to not pop and collapse. Better the house is just a little out of square.

I've actually dreamed of building a house with screws instead of nails (thinking the nails were only cheaper and easier), but now I might change dreams LOL.

I'm also thinking that would not be good on a car frame because it would not spring back necessarily and become loose over time and fail.

I'm not an expert on this either, just an average joe thinking aloud

Oh for sure, screws have the clamping force for decks and such, but for shear their strength becomes their weakness.

But what do you think of my idea of knurled wheel studs. Pound them in and torque the crap out of them.

damn it now... I want credit for a good idea here!

[mechanicalman]

Originally Posted by Vintage Windmills

Should not be a problem if using grade 5 or better hardware. The original factory rivets are likely 1010 steel, which has a tensile strength of only 53,000psi. Compare that to a grade 5 bolt at 120,000 psi and a grade 8 at 150,000 psi. These are tensile values but shear is about 60% of each value, respectively.

"Because there is effectively a head on each end of an installed rivet, it can support tension loads (loads parallel to the axis of the shaft); however, it is much more capable of supporting shear loads (loads perpendicular to the axis of the shaft). Bolts and screws are better suited for tension applications".

"At a central location near the areas being riveted, a furnace was set up. Rivets were placed in the furnace and heated to a glowing hot temperature often to white heat as the hotter the temperature the more plastic and easily deformed is the rivet. The rivet warmer or heater or "cook" used tongs to individually remove rivets and throw them to a catcher stationed near the joints to be riveted. The catcher (usually) caught the rivet in a leather or wooden bucket with an ash-lined bottom, placed the glowing hot rivet into the hole to be riveted, and then quickly turned around to await the next rivet. The "holder up or holder on" would then hold a heavy rivet set or dolly or another (larger) pneumatic jack against the round head of the rivet, while the riveter (or sometimes two riveters) applied a pneumatic rivet hammer to the unformed head, making it mushroom tightly against the joint in its final domed shape. Alternatively the buck is hammered more or less flush with the structure in a counter sunk hole.[1] Before the use of pneumatic hammers, e.g. in the construction of RMS Titanic, the man who hammered the rivet was known as the "basher". Upon cooling, the rivet contracted and exerted further force, tightening the joint".

And that's how it exerts clamping force.

http://en.wikipedia.org/wiki/Rivet

There you have it, rivets better for shear forces and bolts better for tension loads.

But as I read on I was surprised to find the reason they are better for shear forces is because of the tightness between the plates as a result of cooling after installation (shrinkage), not the hardness of the rivet. And this makes me think that this, in the case of auto frames, deforms the metal of the frame and keeps the rivets tight in the frame despite the shrinkage.

Bolts are harder than rivets. But damn it seems those rivets are harder to chisel out than bolts. I was under the impression that the hammering used to install those rivets imparted a forge-like hardening of the steel but this article refutes that. Another post that made me learn.

[mechanicalman]

Originally Posted by jeffahart

Oh for sure, screws have the clamping force for decks and such, but for shear their strength becomes their weakness.

But what do you think of my idea of knurled wheel studs. Pound them in and torque the crap out of them.

damn it now... I want credit for a good idea here!

Heck yeah that's a good idea!

[Vintage Windmills]

Originally Posted by mechanicalman

"

There you have it, rivets better for shear forces and bolts better for tension loads.

Not that simple. You can't neglect area in shear and the strength of the fastener. Granted a 3/8 bolt has less cross sectional area to react shear than a 3/8 rivet but consider the strength as well. I don't know for sure but theres a good chance the original rivets are 1010, which is close to grade 2.

Originally Posted by mechanicalman

"
But as I read on I was surprised to find the reason they are better for shear forces is because of the tightness between the plates as a result of cooling after installation (shrinkage), not the hardness of the rivet. And this makes me think that this, in the case of auto frames, deforms the metal of the frame and keeps the rivets tight in the frame despite the shrinkage.

What you read about the rivets tightening down upon cooling is the clamp force I was talking about with bolts. Its helps in both instances.

Many rivets are installed cold so this doesn't always apply.

Originally Posted by mechanicalman

I was under the impression that the hammering used to install those rivets imparted a forge-like hardening of the steel but this article refutes that. Another post that made me learn.

May be the case for cold installs.

[Vintage Windmills]

Originally Posted by MARKDTN

I work in an industry installing equipment on heavy trucks. I can tell you that the threaded all the way vs: smooth shank does make a difference in a subframe mounting bolt. You want a smooth shank and you want it very snug. You can take it for what you paid for it, but that is definitely what I would do in this case. And I would use grade 8 fasteners.

Yes all things being equal smooth is better than fully threaded but a higher shear strength fully threaded bolt can react more than smooth fastener of lower grade. For what its worth, the crossmember bolts in a modern 2500hd are fully threaded. Diesel engine flywheel bolts are fully threaded and that is purely a shear application but again, the bolts don't see hardly any or any of that shear.

[mechanicalman]

Originally Posted by Vintage Windmills

Not that simple. You can't neglect area in shear and the strength of the fastener. Granted a 3/8 bolt has less cross sectional area to react shear than a 3/8 rivet but consider the strength as well. I don't know for sure but theres a good chance the original rivets are 1010, which is close to grade 2.


What you read about the rivets tightening down upon cooling is the clamp force I was talking about with bolts. Its helps in both instances.

Many rivets are installed cold so this doesn't always apply.



May be the case for cold installs.

I wasn't talking about cold rivets, that's a new conversation piece; I can't be wrong about cold rivets if I wasn't talking about cold rivets.

The statement about rivets being stronger than bolts for shear forces and bolts being stronger for tension loads IS CORRECT, all things being equal, SURE if you use an aluminum rivet it will be weaker than a steel bolt.

If you don't know what the rivets are made of, then it's just supposition.

I appreciate your input but I'll defer to Wikipedia and the broad input of the many minds that bring that together. After all, it's not what "I say", it's what "they said" and I have the right to choose what I believe.

[mechanicalman]

Originally Posted by Vintage Windmills

Yes all things being equal smooth is better than fully threaded but a higher shear strength fully threaded bolt can react more than smooth fastener of lower grade. For what its worth, the crossmember bolts in a modern 2500hd are fully threaded. Diesel engine flywheel bolts are fully threaded and that is purely a shear application but again, the bolts don't see hardly any or any of that shear.

Do those diesel flywheels have sheer pins?

[Keith Seymore]

Rivets were cold headed in the vehicle assembly plant (not heated).

K

[bbcmudtruck]

This certainly turned into a bigger debate than expected! After reading through all of the input, I'm ok with using the Grade 8 bolts and top lock nuts. I picked up some 1/2" grade 8 flanged and coated bolts for the cross member yesterday, with matching top lock nuts. The bolts have a smooth collar rather then threads where they will be seated in the frame. Thanks for all of the help!

[mechanicalman]

Originally Posted by Keith Seymore

Rivets were cold headed in the vehicle assembly plant (not heated) K

The force required to smash those rivets in causes lots of heat, and the resultant contraction causes high clamping force retention. Any way you cut it, rivets rule on shear resistance. The factory knew what it was doing, and I never, ever heard of the rivets failing in any way. I've seen a ton of shock absorber bolts wallow out though.

[mechanicalman]

Originally Posted by Keith Seymore

Rivets were cold headed in the vehicle assembly plant (not heated).

K

The force required to smash those rivets into those frames/cross-members causes lots of heat, and the resultant contraction causes lots of clamping retention. Any way you cut it, rivets rule on shear resistance. The factory did not use them because they were not the best. I've never, ever seen one of those rivets on a chevy truck frame/crossmember fail ever. I have seem lots of shock absorber mount bolts wallow out though.

[oldertruckfan]

i'll go with a grade 5 or 8 shoulder bolt. i'm getting ready to take the old girl apart this spring and summer. after looking at what's in it from the factory, drilling it out and installing a shoulder bolt seems like a good idea.

[Vintage Windmills]

Originally Posted by Keith Seymore

Rivets were cold headed in the vehicle assembly plant (not heated).K

Keith, good to know. Any chance you know the steel grade? That is a big factor in the equation.

Originally Posted by mechanicalman

Do those diesel flywheels have sheer pins?

Not the cummins I am currently working on.

[Willowrun]

Originally Posted by Vintage Windmills

A properly tightened bolted joint creates friction between the bolted members which prevents the shear from usually being seen by the bolt.

Agree. With the clamp load and surface area the bolts don't see a lot of the shear because of the friction created between the two parts. Put your manufacturing hats on...rivets are cheap and fast to assemble which are two of the most important things when manufacturers process an operation. Only things more important are auto worker safety and quality 😊

[Keith Seymore]

Originally Posted by Vintage Windmills

Keith, good to know. Any chance you know the steel grade? That is a big factor in the equation.

Rivets are shown as SAE J430 Grade 0 (SAE 1008-1010).

Originally Posted by mechanicalman

The force required to smash those rivets into those frames/cross-members causes lots of heat

Not that I recall.

I suspect you are imagining a violent, sudden action against the rivet head, which was not the case. It was more of a slow, steady, squeezing compression which required probably a full second or more per rivet. No appreciable resultant heat to speak of.

K