Frame Question

[Misled]

Hello,
I am working on a 1978 C10 swb stepside and have it down to the bare frame.

My question relates to the famed Chevy rivets. Is there any reasons why I can't remove these rivets and replace them with either grade 5 or grade 8 stainless bolts? I am going to have the frame blasted so I can paint it with PPG paint. I know that if I can disassemble the pieces by removing the rivets, I can get a better blast and paint of the individual pieces and then reassemble the whole thing.

This isn't going to be a show truck, but I am trying to be as meticulous as possible.

I figure Chevy put them in for a reason......I'm assuming it was cost, but maybe is was a strength issue!!!

Thanks in advance!!!

Misled

[vin63]

I know a few people who have removed the rivets for the very same purpose. Just a word of caution is that sometimes the frames will have some tension to them, so when you remove a lot of the cross members, etc., the frame will sometimes twist suddenly. Good luck.

[71Farmtruck]

I work for a fastener company, there is no grade 5 or 8 stainless bolts. Stainless fasteners are graded by their alloy content, the two most common types are 18-8, and 316. Both types have the same tensile strength, 100K-150K psi for fasteners up to 5/8", and 85K-140K psi for 3/4" to 1 1/2" diameters. The main difference between 18-8 and 316 is that 316 has a higher nickel content, therefore more corrosion resistance, it is also wayyy more expensive than 18-8. As a point of reference, G5 bolts have a 120K psi tensile strength from 1/4" to 1" diameters, and 105K psi tensile strength 1 1/8" to 1 1/2" diameters, while all grade 8 fasteners have 150K minimum psi tensile strength for all diameters.
To make sense of this rant, always use G8 fasteners for critical bolting applications, because it is 150K psi minimum, it is a safer bet than the others since its tensile strength does not lie in a range like stainless and G5. In other words, go over show, bro.

There is nothing wrong with removing the rivets and replacing them with bolts, as long as they are strong enough to hold the joint. I would recommend a powder coat over a basecoat/clearcoat of the frame, it does not shine like clear coat does, but it will stay a hell of alot cleaner.

The reason chevy used rivets is for time savings over threaded fasteners, and easier removal for repair in case of collision over a weld. The pecking order of strength of a tightly held joint from weakest to strongest is bolt and nut, structural rivet, and a weld, put in a very simplified way.

Hope that helps,

[Shane]

I have seen/hear/read somewhere that rivets were also used in some instances because they allow more torsional "twist" of the frame than bolts do. If the frame is too rigid it will develop stress cracks over time.

[Misled]

....see, I did learn some new things.......I guess I just assumed that stainless was graded like the others. I was considering using the stainless only from a corrosion standpoint.

I am probably going overboard on all of this since this truck will only see the light of day on warm sunny days. 71Farmtruck, since you know about fasteners, is there such an animal as a grade 8 bolt that has a black coating?

Shane, that is one of the things I have heard......

Thanks for the help guys!

Misled

[Kayotic]

You can still however knock out the front suspension x-member, the trans x-member and the trailing arm x-member (if equiped).

The only one that conserns me is the rear upper shock mount crossmember right over where the coils are. I suppose you could remove the lower half on both sided since it is 3 pieces. again if equiped.


I retract my statement due to your question being about a 1978..... Yeah what they said.

[jlaird]

Originally Posted by Misled

71Farmtruck, since you know about fasteners, is there such an animal as a grade 8 bolt that has a black coating?

I wonder if you can black anodize grade 8 bolts?

[Kayotic]

I think anodizing metal; weakens it slightly. Atleast the way the guy's did it at the shop I used to work at.

I believe they would give it a chemical bath thus turning them black.

Keeping in mind there are many different metals and chemicals...

I remember seeing a few websites about this topic (anodizing), but I can't recall where.

[71Farmtruck]

Originally Posted by Misled

.... 71Farmtruck, since you know about fasteners, is there such an animal as a grade 8 bolt that has a black coating?Misled

There are black coated bolts, they are known as "plain finish" but it is actually a black phosphate coat which offers little protection. They can be had with any carbon steel fastener standard or metric. These types of bolts are commonly used to rebuild 18 wheeler frames, and I am talking every stinking rivet replaced. I do not see having rigidity issues replacing the rivets with fasteners since the rivet is the more rigid, or stronger. I could see that issue happening if everything was welded.

Use a yellow zinc G8 bolt, they are so common on G8 fasteners that many people think yellow zinc means G8, which is not true. Yellow zinc offers more protection than the silver.

If you want the bolts black and to not rust you will have to coat them in paint or powder coat, I have always rebuilt the frame and added as many fasteners as feasible and powder coated with the bare frame. I really don't know anything about anodizing.

[Misled]

....how well does the black phosphate accept paint or powder coating?

[71Farmtruck]

I've had good results, but I also blasted them when I was powder coating a frame that was going to be super clean. Hell, on my old '84 I just painted over the yellow zinc and installed the new bolts in the frame and they looked good, for a driver.

[Skirkpat]

I would not, simply for the fact that bolts loosen up after time, May not be an issue, but I can't count how many times I have gone to loosen a bolt and been suprised that it is loose. If you sand blast it and use a good paint, I use (POR 15) it will be pretty nice.

[71Farmtruck]

Originally Posted by Skirkpat

I would not, simply for the fact that bolts loosen up after time, May not be an issue, but I can't count how many times I have gone to loosen a bolt and been suprised that it is loose. If you sand blast it and use a good paint, I use (POR 15) it will be pretty nice.

I would say that would be a problem only if you do not prep correctly. If it is a G8 nut and bolt with high alloy structural washers and a thread locker I'd go with that over a rivet anyday.

I love POR 15 on undercarriages, floor boards, but on a frame it looks like someone base coated/clear coated while they were high. Powder coat the frame and the suspension components, you'll thank me later. Also, POR-15 does not mix well with fasteners, coating a fastener after it has been installed makes it damn near impossible to remove, and coating before installation is not a good idea because if it is on the threads it could cause galling because of how thick it is. Zinc and cadmium to a lesser extent are common coatings for bolts because of how thinly they can be applied and not affect the fitment of engaged threads. Take hot dipped galvanized fasteners for example, galvanized coatings are very thick and the manufacturing process takes into account the extra added thickness. That's why you cannot use non galvanized with galvanized, especially in a structural application.

[Misled]

Originally Posted by 71Farmtruck

Take hot dipped galvanized fasteners for example, galvanized coatings are very thick and the manufacturing process takes into account the extra added thickness. That's why you cannot use non galvanized with galvanized, especially in a structural application.

...see, I never thought of that, but it makes perfect sense!!!!

[71Farmtruck]

If anyone on the board wants some kitted fasteners for and engine or whatever let me know. I can get stainless stud kits for carbs, just about any cover on your motor, as well as exhaust, intake bolts, ect. I rebuilt my small block and used a bunch of stainless so I have it down pat.

[Kayotic]

So what's the verdict..

Should the frame be taken apart for powder coating, then reassembled with G8 fasteners?

Are high strength button head or carrage bolts available?

Talk about getting a nice powder job.

If the frame looks good and dry I would guess it's not necessary.

But if there are problem areas anyway!

You ever try to square a riveted frame on saw horses - a lot of back and forth.

[71Farmtruck]

Originally Posted by Kayotic

So what's the verdict..

Should the frame be taken apart for powder coating, then reassembled with G8 fasteners?

Are high strength button head or carrage bolts available?

Talk about getting a nice powder job.

If the frame looks good and dry I would guess it's not necessary.

But if there are problem areas anyway!

You ever try to square a riveted frame on saw horses - a lot of back and forth.

I would say that it is not necessary to completely disassemble a frame, for a resto. Sure, there might be a little crud between the joints of the braces and frame rails that are riveted in place, but who cares? If the frame is square and holds its integrity, I would just blast and coat the frame, minus all bolted on items, and leave all the riveted items on and coat it.

Button heads are available, and they, along with socket heads, and flatheads, are actually stronger than G8 hex cap screws in non stainless form, because they are made of B7 material which is greater strength than G8 due to its different heat treatment process. Carriage bolts are not a good choice for our trucks, since the hole must be square to retain the head and keep it from spinning. I think the only carriage bolts on chevy trucks of our years are the bed bolts. I particularly like the design of step side bed bolts, which utilizes an off center square hole washer to put bind on the bolt and keep it from spinning on top of the wood. But it sucks when the wood has rotted away and the bolts have rusted up.

You use saw horses? I always anchor mine securely to the floor. I use a jig made from steel beams welded together, and bolted to the floor using concrete anchors. from there it is easy to use a port a power, or a chain hoist rigged to the receiver of my truck to repair bent, out of square frames.

[Spray-Bomb]

Some say that rivets are the strongest way to fasten things together, as they fill up any voids in the hole they go in & bolts do not, therefore there is room for slop with bolts & not with rivets

Just IMO, I would not take out the rivets

[XXL]

Originally Posted by jlaird

I wonder if you can black anodize grade 8 bolts?

[SCOTI]

Originally Posted by XXL

Uhmmm . . .... That's not black anodizing. That's obviously 'semi-flat' black powder-coating in a can form .

[Shane]

the ONLY materials that can be anodized are aluminum & titanium ... and i'm pretty confident stating you aren't gonna find Grade 8 fasteners in either material.

[71Farmtruck]

Originally Posted by Shane

the ONLY materials that can be anodized are aluminum & titanium

I did not know that.

[Shane]

well, technically one can also anodize zinc, magnesium and niobium ... but those materials are very un-common in automotive applications

[71Farmtruck]

I know there are no anodized bolts in carbon or stainless steel. Besides galvanization, cadmium is the most corrosion resistant for carbon steel fasteners, however it is almost totally phased out due to it being poisonous, that is why you see "ROHS Compliant" stickers on a lot of hardware bags. Zinc should be more than adequate for our trucks.

[phipp13]

Riveting is the preferred method over welding when possible. When riviting, there are no adversly affected areas/joints due to heat annealing from the welding process. it is just stronger and tougher than any welding process. I'm a Govt Aircraft certifyied welder too...

you guys don't sound like old truck builders... You sound like engineers and metalurlogists. LOL. in my line of work Naval Aviation Prototype Structual R&D i have to deal with the subjects mentioned above all the time. NO B.S. I'm impressed
Respectfully Phipp