Replacing rivets with bolts

[bbcmudtruck]

I have removed most of the factory cross members and replaced them with aftermarket pieces. I have drilled all holes out to 7/16 and installed grade 8 hardware. Bolt, washer, frame, washer, lock washer, nut in that order. My concern is the possibility of having nuts vibrate loose. I intended on using Loctite as well as the lock washers, but I've heard of cases where the nuts still backed off. Does anyone have any experience with "top lock" nuts? I've been told that you can reuse them as opposed to nylon. I'm leaning in this direction unless there is a better alternative. Should I opt with or without flange? Thanks for the help!

Here is an example of the top lock nuts:

Grade G/8
http://www.fastenal.com/web/products...endingMachine=

Grade G/8 with flange:
http://www.fastenal.com/web/products...endingMachine=

[jocko]

I think you're fine with a lock washer between the flat washer and nut, and Loctite. But if you really want to go crazy with it, you can drill the bolt and do safety wire. Probably way beyond what you were wanting to do, and I don't blame you. Have no experience with the lock nuts you linked - but I suppose you could use one of those in lieu of the regular old nut, but personally - I'd go with the grade 8 h/w you have, then go back after a week of driving and check em - then a month, then 6 months, and then never again. Just for your peace of mind - but I think you're just fine with the lock washers and grade 8 nuts/bolts and Loctite.

[Orange Crate]

"but I've heard of cases where the nuts still backed off"

The nut may not have actually "backed off" 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). The style of lock nuts you linked to are used in aviation in high temerature aplications all the time and obviously work very well.

[mechanicalman]

Originally Posted by Orange Crate

"but I've heard of cases where the nuts still backed off"

The nut may not have actually "backed off" 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). The style of lock nuts you linked to are used in aviation in high temerature aplications all the time and obviously work very well.

Very scientific and well thought out. Thanks I'm getting a reamer.

[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.

[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

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?

[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.

[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.

[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.

[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 😊

[bbcmudtruck]

Thanks for the guidance fellas. I'm going to play it safe and order up 80 top lock nuts and use them as well as the lock washers and loctite. The hardware that came with my ece cross member and shock relocation brackets were grade 8, but they sent nylon lock nuts. I'm just not a big fan of those and don't want a catastrophic failure due to one or more of the nuts backing off.

[RodnRudy]

The front cross member on our trucks is held on with 7/16 hex bolts lock washers and hex nuts. That cross member has stayed tight for a lot of years. The lock washer grips both the frame and the nut, and when torqued to specs should hold just fine. I don't mean to sound rude but I think you're over thinking this.

[LockDoc]

-
I also think you are going overboard on this. Make sure your bolts fit snug in the holes and use these.

http://www.fastenal.com/web/products...endingMachine=

I used them with no lock washers, nor locktite, just washers and the nuts and have had zero problems.

LockDoc

[CG]

I'm sure you already did this, but if you had all the cross members out make sure you get your frame back in square before you start tightening everything up again.

Saw someone do this once and just "bolted it all back up" and it made it almost impossible to assemble the truck correctly because it was off just a little.

[Kennuck]

If you want the lock washer to be effective don't use a flat washer under it. The lock washer needs to be able to bite into the frame and nut.

[hugger6933]

The only time I've seen problems with the self locking nuts or the nylock the ones with the plastics in them is when the person either installed them or removed them with air and then tried to reuse them. That don't mix. If you zip them on or off with a airtool their effectiveness is nil. Have you thought of shake proof washers? you know the ones with the serrated edges? Think about those see what that may do. I can tell you in the course of my rebuilding of many late model trucks that I have I have on occasion replaced a spring hanger once in a while. I also have traded back for lots of those trucks because of repeat customers and whatnot and get one of my trucks back after 100 thousand miles or so off of farm abuse. On some that I have had come back to me with replaced hangers grade 8 bolts that were double nutted still were right where I put them. On one or two of the first I had done that way I placed a weld tack on the end a single nut and threads to prevent any movement. It held up wonderfully as well. Jim

[Davidf]

Originally Posted by Kennuck

If you want the lock washer to be effective don't use a flat washer under it. The lock washer needs to be able to bite into the frame and nut.

+1 and the right answer. Lock washesr do nothing when installed on top of a flat washer. The lock washer locks to the washer, but the washer can still turn and hence the nut can loosen. When I restored my '52, I would remove one rivet at a time and drill the hole the proper size for a 3/8" bolt which I installed before moving the next rivet. This insure perfect alignment/fit of all the holes and greatly reduced the chance for movement between the two pieces (shear). Worked for me.

[slowcpe]

Porterbuilt sends their kits with Grade 8 bolts and nylock nuts. Just mocking things up I don't forsee them to ever back out. Just tightening with a 3/8" ratchet and wrench takes quite a bit of effort.

[bbcmudtruck]

LocDoc, those are the nuts that I'm wanting to use, just without the flange. I'll agree that I may be going over board a bit, but I don't mind spending a little extra for insurance. CG, I'm mostly done mocking my frame up and had to do a little tweaking on the frame before I could bolt it back together, thanks for the heads up!

[bbcmudtruck]

I'll got ahead and ask this question here since it seems to be relevant. When installing the front cross member, why are the bolts installed from the bottom up? Can I put them in from the top? It looks cleaner in my opinion to install them from the top. Also, If a nut did manage to back off, the bolt might have a chance of staying in place. The factory had 7/16" bolts in those locations, but I put 1/2" bolts in. They fit in the holes perfectly without any work. Are they supposed to be a little loose in the holes?

[LockDoc]

Originally Posted by bbcmudtruck

I'll got ahead and ask this question here since it seems to be relevant. When installing the front cross member, why are the bolts installed from the bottom up? Can I put them in from the top? It looks cleaner in my opinion to install them from the top. Also, If a nut did manage to back off, the bolt might have a chance of staying in place. The factory had 7/16" bolts in those locations, but I put 1/2" bolts in. They fit in the holes perfectly without any work. Are they supposed to be a little loose in the holes?

They can be installed either way. I think that way myself sometimes. Also, in my way of thinking all of the bolts should fit the holes snug without any movement. I don't have anything scientific to back that up but I think it is just common sense..... The less movement, the less problems down the road.

Just my 2¢ worth.

LockDoc

[Keith Seymore]

Originally Posted by bbcmudtruck

I'll got ahead and ask this question here since it seems to be relevant. When installing the front cross member, why are the bolts installed from the bottom up?

Because the frame is upside down when they are installed.

Originally Posted by bbcmudtruck

Can I put them in from the top?

Sure.

A lot of times it depends on the orientation of the tool that is used to secure the bolts (particularly if it is a right angle driver with an integrated backup wrench), which could also be used for another attachment that is not obvious to us 50 years after the fact.

Also - at the factory bolts are often oriented one way vs the other to prevent the excess from sticking out and causing a clearance problem.

K