Pop Rivets
 

I've read about these and they seem like a good idea for places that I'd rather not weld. I don't have the tool, but they seem to be reasonably inexpensive. Does anyone have experience with these? Why would I rivet something instead of just using something like a self-tapping screw? Since I already have a welder, should I not bother?

I'm not a fan of pop rivets on cars. They do not seal the moisture out like welds or good fiberglass repairs. Usually the car will start rusting around the riveted area, and you'll have holes again.

A mechanic I know recommended using PL-400 adhesive along with rivets on repairs that needn't be pretty. The PL-400 will seal the moisture out.

I might be wrong but I believe riveted repairs are illegal in the UK - check to make sure that any repair you make with rivets are not going to cause you any trouble at your next inspection.

Tucker pop rivets are not strong. There are similar dowel type rivets (with many different names) used through out the aircraft industry. These are much stronger than the widely available pop rivets. However, in the aircraft industry old school thought is that you should always use a solid rivet when ever you can. Only use the dowel type rivets when you can not get to both sides of the joint you are making - a blind riveted joint.

The main benefit of a riveted joint is that you can drill out the rivet to make future repairs. However I'd advise regular checking of any riveted joint (much like in an aircraft maintenance schedule) to make sure there are no signs of movement. Obvious signs are signs of ripping and tearing - but you also get black residue (much like when you polish metal) from movement as well.

I'm only interested in blind riveting, if I can get to the back, I'd rather weld.

Is the use of adhesive only for sealing, or is it meant to add structure? I'm not sure if I trust glue, I'm having enough trouble trusting rivets.

So what about using self-tapping screws instead? I'm not sure if anyone's done this, but would there be any reason not to use them?

same rust reason as the pop rivets. Probably worse in my opinion, as the screw would almost invite corrosion. Might be really short term. At least with riveting, you can treat and paint the hole beforehand, rather than just cutting the hole as you screw.

If you can get to the back with a piece of steel, you can maybe use buck rivets which are solid and really only need something hard to crush against on the back side. All those mid size delivery trucks are almost completely constructed of buck rivets, and they are very strong. Like a UPS truck.

But if you can get to the back, you might as well weld since you have the welder as you say. What part are you talking about? I think you and I are doing almost the same repairs!

I'm most concerned with the inner rocker panel, which I think might be part of the floor pan, it's the panel that the seat belt bolts into. I also watched this video where this guy used rivets because he was afraid of warping the thin metal. You make a good point about the corrosion, I was just curious why everyone uses rivets instead of screws, there's almost definitely a good reason.

Ive got the same rust there as well. I went ahead and completely cut enough of that inner panel out that I can weld the outer rocker panel from the inside, then I will weld the inner back in and weld it to the new patch.

The stuff is thin, but I think the door panel which you have been using is almost the same thickness! Plus, if it warps a little, so what? won't hurt if the seat belt bolt is not square, just so its attached firmly

The reason is that rivets don't - well shouldn't - come loose. Where as screws are designed to come loose - albeit ideally when you want them too!

Dont use pop rivets on anything that is structural. They dont have the required strength. They do come loose under load & are a PITA.
I am concerned that mention is made of metal including a seat belt mount, that is way too important for your safety for pop rivets. You dont want the metal around the mount failing & your head going through the wind shield!
Mig or tig weld is fine. If the metal is too thin, then chances are it has corroded away too much.

Pop rivet tools were made first in the early 1960s, when MIG welding was rare and most welding was done by gas, and panels were thick. There were no adhesives like PL-400 in those days.

It's a matter of history and what was available. In those days people used flat panels coated both sides with polyseamseal, which was the first silicone, then pop riveted, esp in areas where it was difficult to reach or where appearance didn't matter, like the trunk space.

The poly was salt resistant and in an area like Detroit, that was needed. After a year, the poly wore off, you scraped it and replaced it with undercoat.

Obviously this was long before galvanized steel was used. The pop rivet tool was HYDRAULIC because the rivets were steel, not aluminum.

I wasn't sure on the warping, but I thought I'd mention it. I'm more interested in the rivets for places that are hard (if not impossible) to get to the back of.

What about welding in support for the seat belt and pop riveting the rest? I could do that.

you are talking about places where the welding would be over a closed channel and you won't be able to get to the back and paint? Like the rocker channel once you close it up?

As long as its structually repaired, I see no reason why pop rives would not be great to close up a sheet metal opening that is not providing any strength of any kind. Heck, you could even weld a piece of angle iron along the bottom of the floor for strength, and put in a removable panel in the rocker with rivets so you can paint everywhere else, then close it up, or inspect down the road.
A pop rivet should be perfectly fine for something like that, just don't depend on the rivets for structure or for weight. There are tons of fasteners on a car that are way weaker than a pop rivet that are just holding sound, or cover panels.

There is weld through primer to cover the back of the weld as well, and other treatments for this type of scenario.

Here is a thread about my driver side rust situation, kinda similar to the rot you are dealing with, except you have that floor pan under the pedals issue as well. http://www.superturbodiesel.com/std/emergency-rust-repairs-t-1276.html

It's painting as well as cleaning. Like the front seat supports, the spot welds on the DS tunnel would be nearly impossible to get to to clean and paint. I can get to bare metal with sandpaper and my hand when it's just paint, but theres undercoating down there too and I can't get my angle grinder down there.

A heat gun should make that unbelievable undercoating more pliable, and able to tear it back. Honestly, I got so tired of dealing with the undercoating, that in several areas where I had immediate access to the back side I just welded the one side and put the undercoating fire out with a sopping towel every 30 seconds or so. Not all that safe, but it sure saved a lot of time.

If you want all the room in the world though, you should pull the drive shaft. (depending on the condition of the bolts)

It's more than just the drive shaft. If you look under, you will see an odd plate/bracket looking thing that is below the drive shaft and welded onto the floor pan. Then look above the drive shaft and you will see the tunnel roof. What you will also notice is that the roof is also welded to the floor pan, which goes over that. So that's two layers of metal between you and the drive shaft. And with all those spot welds, things can get sticky. Eventually, I'd like to take that off and properly replace all the spot welds, but I really can't do that now.

So back to the rivets, McMaster has some non-pop brand high strength (also called structural) zinc coated blind steel rivets that I think would be good to use. My question is: what tool would I use to install those? And if I'm replacing spot welds (which I drill out with a 1/4" bit), I'd need 1/4" diameter rivets, but a lot of the standard tools do not come with (or use, from what I can see), 1/4" attachments.

An air powered rivet gun will set most 1/4" pop rivets.

That sounds like a buck rivet like I was saying before. Is the top of the rivet a dome shape? Does it look like a mushroom in profile?

If its a steel rivet, It may have to be done hot, like red hot so the steel is soft and crushable. Not sure though.
If its an aluminum buck rivet, you put a special end piece into an air hammer that cups the dome shape, and you hold a piece of steel to the back side, something that the rivet will crush against.

Then you hit the dome with the air hammer and it will crush the backside against the steel plate (which someone has to be holding).

I used to work on those cube trucks like UPS trucks, and this was something we were doing all the time. Its pretty amazingly strong if done right, but it would require you to get to the back side.

Why don't you just simply use bolts, nuts, and lockwashers instead? You can always drill the hole for a bolt, put it in and tackweld it from the outside, then just run the nut in on the opposite side. Can you post some pictures of exactly where the hole is so we can get an idea of what you are dealing with?

Pop rivets are illegal for body repairs that are considered structural. Any patches must be seam-welded and not buried under tons of undercoating so the MOT chap can see them. Then you can bury them.

heres a few pics- shows the difference between pop and buck rivets. I think the same safety laws are also in effect here for the pop rivets. Pop rivets are way weaker than buck rivets.

Versions of heavy steel buck rivets are used on frames of lots of vehicles. I just replaced some cross members on a 98 F150 the other day, which was riveted together with heavy steel buck rivets.

Solid rivets are indeed way stronger.

I wouldn't however recommend trying to set a steel rivet unless you have some serious air tools. You might get away with a 3mm diameter steel rivet and a standard air chissel type gun (obviously fitted with a rivet head) but you'll need a heavy reaction block on the other side to get it to form properly.

If you don't have the air tools then you'll need space to swing a heavy hammer and the accuracy to hit the rivet and not your fingers or anything else you don't want broken!

Aluminium solids are way way easier to set - mostly they are formed when cold. Some do need heat treatment for preparation and then they have to be used within a specified time frame before they work harden.

What ever you choose to try I'd recommend setting a few test pieces before you do your main job.

Here's what I was talking about:

http://www.mcmaster.com/#blind-rivets-and-steel-rivets/=6th7sy

They are still blind rivets, but steel. I wouldn't bother with the buck rivets. At that point, it'd be easier to weld. I'm trying to find an easier way, not a harder way;).

Here's what I'm looking to replicate, more or less.

http://www.youtube.com/watch?v=wefP9BgPpgY&feature=related
http://www.youtube.com/watch?v=BeT4Qz_ugK4&feature=related

Well I'd opt for the rivet nuts - I used to install similar things on the back of Phantoms - they were bloody tough to get out again!

that guy is doing a nice job, but it looks like it will take him forever. I like the holes along the bottom of the rockers, good idea to keep the things ventilated. What level of quality are you shooting for?

I say go for the rivet nuts as well. That guy is restoring that car vs keeping it in daily service while working on it like you appear to be doing.

(I see what you are talking about with the double body panel underneath. If it were me, Id just drill a hole through both, pull the driveshaft out of the way, spot weld a bunch of nuts on the inside of the tunnel, then bolt my new panel down and compress the two stock panels together so I have a sandwich of three panels.)

How would I install rivet nuts? What's the advantage of a rivet nut over a standard rivet?

Sometimes a special spanner...
 

Rivet nuts are usually installed by using a special spanner. One bit attaches to the base of the rivet - the bit that will stay on the structure you are riveting - and another integrated spanner / socket fits on the top bit that is designed to shear off at a pre-determined force. You just wind them up until they go "dink".

The benefit of these rivets is that they are very strong. With this design much harder metals can be used as you are effectively utilising a screw thread and nut that deforms when broken - it is a bit like getting a very tight bolt and nut that has been peened (or staked) into place all in one go. Other rivet designs rely on softer metals that are deformed during the process of riveting so they are not as inherently hard or strong.

Certain heat treating processes and designs have been thought up to get around this problem (of having the necessity of a soft metal to enable formation) such as systems that need to use big forces (i.e. hydraulically actuated tools) and alloys that harden over time after heat treatment.

Is that too much information?

Alright, if I still want to use rivets, it seems like rivet nuts is the way to go. Found two different tools online:

http://www.skygeek.com/ats-rnt01.html

http://www.jcwhitney.com/assorted-mandrels-for-thread-sert-tool-kits/p2008058.jcwx?skuId=221749&TID=8014524F&utm_source=Google_Product_Search&utm_medium=CSE&utm_content= product-815291&zmam=15972153&zmas=21&zmac=141&zmap=815291#

Those look good?

I liked the idea of the steel structural rivets, but those are expensive and look like they require expensive tools to install the size I need, as well and possibly not even being good enough.

Looks good to me!
 

Well if they work they work - looks good to me. Only I'd check with the supplier of the rivet nuts to make sure that you've got the best option for the rivet nuts you are buying. (These tools look slightly different to the ones I've used before) But for an "investment" of 10 to 30 USD for a special tool that seems to me to be a small outlay compared with the MB spring compressor I've just bought, or even the W123 rear wheel bearing socket I've also just got on order...

Take the advice of the supplier / manufacturer

I use hard Aluminum pop rivets on all panel repairs on my 84 123 and 84 126
I have an inverter stick welder that will do nice welds on 20 ga (.035) metal with 3/32 rod at 25 amp reverse. But I prefer rivets. There are solid rivets on the market that are blind. They are have a powder filled filled lower stem that will expand when it explodes and are set off by heat on the head from a 300 watt soldering iron. Only problem is the $1.20 each price.
I have used pop rivets for 10 years now and the replaced fender skirts on the 123 are still holding. I will try to post some pics and instructions here.

Pop rivet rust repair
 

I have used these rivets with great success. From new floor pans in a 74 240D to fender skirts, rocker jack points and any other rust repair on my 300D and 300SD
In the pic below I have cutaway the rust back to good metal.
Did some grinding and wire brush work. Then a good soaking with a rust killer. The green lines are a reference to where the
hole will be cut for the side panel to install
http://i1011.photobucket.com/albums/...awayrust-1.jpg

To get a flat patch I indent the metal.
http://i1011.photobucket.com/albums/...oto/Indent.jpg

I make the patch from soft body metal I get from a custom car supply place. it is easy to form. I align the patch and transfer the marks for drilling. yes I have Clicos
http://i1011.photobucket.com/albums/...henewmetal.jpg

Before placing the pop rivets use a relief drill to let the rivet heads settle back into the patch metal. I got my drill from the rivet supplier. A little grinding and you will have flush patch. Remember we hammered the body metal back a little.
http://i1011.photobucket.com/albums/...vetinplace.jpg

Do some Bondo work over the patch. This area is covered by the SD Side Panel so absolute perfection is not required here.
http://i1011.photobucket.com/albums/.../SomeBondo.jpg

Finish with a good sanding primer and a sealer if your paint system requires it.
http://i1011.photobucket.com/albums/...dingprimer.jpg

The same job was done at the front fender. All panel fastener slots were rusted out and up about two inches into the fender at each slot. All this work because some body shop dummy could not take the time to figure out how to remove the side panels.
http://i1011.photobucket.com/albums/...atthefront.jpg

So, you don't need a welder to fix your car. The help from the local body shop supply store will get you started and steer you to a good indi painter that doesn't insist on the whole job. Have fun.

how did you handle the back side of the metal? Looks like lots of exposed metal inside the patch. Did you coat the metal, or back of the patch before you installed it for good?

I'm a bit skeptical about the longevity of that repair. Bare metal behind patch doesn't appear to be protected, bondo over riveted seams will crack allow enty of water and therefore rust. Welding with proper panel preparation and protection is really the only long term solution to rust problems.

The back of the patch is coated with a blast mastic material called Black Knight Gutter Repair. This material has fibers that make it tough and the stuff will stick to anything. Cover all exposed metal and the rust won't come back. Makes the patch water tight so moisture from the back won't come through to the front. Any that squeezes out must be really cleaned up or body filler won't adhere to the job.

The fender skirts on my 1984 300D were built up with new metal riveted in place using the same method. That was in 1999 and still look new to this day.

Interesting repair. Actually both of you are right. "The Gears," you've probably have gotten away with this because BC isn't the harshest of environments for car bodies. "Dseretakis," you are right, you would never get away with that repair in Boston. It would pop through the front, esp. if you used Bondo. That filler absorbs too much moisture for our environments.

Don't be shocked on the effectiveness of Tar Coatings like Black Knight Gutter Repair. I have used them with great success on the undersides of cars in this environment. It would probably provide excellent protection when applied on the backside. I have one question: how did you get it in there? It would be hard to apply once the repair is finished.

Vancouver BC is one of the wettest places in North America. All body repairs must consider water flying up from the wheels at high speed and with great force. If I am unable to apply a coat of Black Knight then I will fill the area with construction foam. I also fill the fender flares with a good buildup of Black Knight as this material will grow a strong skin and be a little soft at the base. If the under coat is damaged, build up several layers to the same thickness as the factory material then stipple the last coat to look like the factory applied stuff.
On a repair like this, once the rust is cut out look inside with a flash light and small mirror. The metal is well covered with a hard coating. rust at this ares starts on the outside and spreads along the metal surface under the paint.

There is a lot of moisture in BC, no doubt. I've been to Vancouver many times--used to hire Forintek to do labwork for me. What is missing is excessive road salt and thermocycling. Auto rusting is actually the worst along this part of the Great Lakes: they use a lot of road salt, and the temperature is constantly going above and below freezing. Both of these greatly increase rust when compared to BC. Boston is quite bad also.

You are the first person I've found to use tar coatings in this way besides myself. Most are amazed on the effectiveness of this material on car bodies.

Im about to buy a rust free 84 MB, and will be using it this winter. I am very intrigued by this tar idea, as it stands to reason it works great. At least my imagination shows me super sticky gooey stuff impervious to anything but time. :D

Question, how does it hold up, and I imagine it will absorb dirt and dust until it cracks off, is this what happens? I want to preemptively coat my new car with the stuff underside before I get into the ice and snow months

We may have different philosophies regarding welding vs riveting but we do share some habits. I also stipple the last coat of undercoating to mimic factory coatings. I too use the mirror and flashlight technique for inspecting the backsides of panels for rust.

I think it will probably be good for a season or two so long as it was applied in dry conditions and moisture doesn't find its way underneath. In my opinion these coatings are great whilst the muck and the wet stays on the right side - just look at the rust you can get under MB undercoat on a W123...

There are really two camps of rust provention, and using both is valid.

There is the extremely good, but the impossible to renew. Namely galvanizing and electrocoating. Unless you have an incredible shop and are willing to totally dissasemble the car, they are OEM only procedures.

Then there are tar coatings and oils. With religious reapplication to problem areas, these are quite effective. I have a friend who had a '56 Olds that spent most of its time in this climate. His family bought it new in '56 and ran it as a daily runner until the late '80's, when he sold it to a collector. the car had only one rust hole in it. By washing the undercarrage religously every year, renewing the undercoating with tar coatings, and oiling strategic points, the car passed PA inspection up until he stopped driving it.

One other tip he taught me was to fit a piece of woven fiberglass mat to an area needing undercoating renewal, coat both sides with the tar coating, and affix it to the affected area. It increased the durablity of the tar coating, and made it easier to blend it in with the factory coatings.

Thats the part that I actually find most appealing, the fact that it eventually will fall off. The permanent factory undercoating as we all know just hides the problems until they are out of control. By yearly coating things, maybe I can do what happened with this 56 olds.

There are undercoating specials advertised around here, ill get some quotes and start another thread since this is off topic of pop rivets! :D

I am encouraged by the oldsmobile story, I know Ohio around the lakes to be an especially rusty area, similar to CNY in many ways.

Be careful about shops. I've seen undercoating jobs that increase rust. Primarily two ways:

1) they drill holes into the body which compromises the electrocoat. There is nothing you can apply that will be better than the factory coating. You do not want the original coatings compromised.

2) They apply it in a manner that plugs the drainholes in the car.

You are absolutely right on the material falling off when it loses it's effectiveness. That does happen. When that happens, reapply.