Nothing Special's '71 Bronco

[Nothing Special]

Thanks for the kind words!

I looked at the project you linked. That looks great, but beyond what I want to do or what I think I need to do. Not saying it isn't a good choice for you, but when I read "modified the doors" I knew I was out! And as I've noted, tying to the frame on the driver's side isn't really possible due to the aux gas tank. Of course that doesn't mean that I couldn't on the passenger side, but it doesn't seem necessary to me for this vehicle. Again, not that it's a bad idea, just probably not for me in this case.

Filling with foam doesn't seem necessary or advisable to me. Sort of like Ford pickup cab corners. Filling metal with something that holds moisture in once it's there doesn't seem like a good way to prevent rust, even if it makes it harder for the moisture to get there in the first place. My original thought was to spray so WD-40 ("Water Displacing") in, but Gary and Jim's concerns about that evaporating out pretty soon, and Jim's suggestions of more stable stuff have me leaning toward bar oil now.

By the way, I don't think I've mentioned it yet, but my plan for mounting the rub rails includes running stand-offs all the way through the 4x4 tube so they will be welded to both the inner and outer walls of the 4x4. That won't do much to strengthen the tube against a hit on the bottom, but it will strengthen it against hits from the side.

I do, in general, like the idea of the HMWP (? maybe I have the initials wrong, but the cutting board plastic that people use on skid plates). But I don't think it will be a big issue on these rockers. In the picture below (posted several days ago) you can see how far down the radius arm mounts are below the rockers. That's what hits the rocks the hardest! And in between the radius arm mounts the transfer case hangs almost that low. The hope for next winter's project (once I finish this up which was supposed to be LAST winter's project!) is a tummy tuck to get all of that higher and get a skid plate under it. I MIGHT put plastic on that skid plate. But I don't think it'll be as needed here.

http://forum.garysgaragemahal.com/file/n65396/DSC_0475.jpg

OK Gary and Jim, you have me thinking about panel adhesive now, I've never used that stuff before. Help me think through what that process would look like.

Sorry for all the questions, but my lack of familiarity with the process gives me some concerns about whether I can do it well, which is why I'd rather go with welding. That's a process I'm familiar with and I know that I'll have all the time I need to do it right. But as Jim brought up, adhesive would do a much better job of preventing rust from starting between the pieces. So I would like to understand how challenging it might be to glue it in.

As I understand, panel adhesive is supposed to be applied to bare metal. I'm thinking with the rusty metal I'm starting with I'd still want to coat it with Ospho, but maybe after the Ospho has had its time to work I'd sand it down again?

And how long do you have after applying it before it better be assembled and clamped? I'm thinking that it could easily take me around a half hour to get it all spread on and get the tube lifted up into position. And then more time to get it clamped down well.

And clamping it. No trouble holding it up against the door sill. I can use a jack for that. But what about the inner rocker? As I understand you should use a lot of clamps to get good, even pressure on the sheetmetal (I think a single jack against the bottom of the tube will still put even pressure against the door sill). But I don't really want to buy a dozen 6" C-clamps to clamp the inner rocker to the tube (not that 12 would even be enough...). What about using 2 or 3 6" C-clamps to clamp a piece of say 1" square tubing to the inside of the rocker, sandwiching the inner rocker sheetmetal between the 1x1 and the 4x4? Would that be good enough? Or would I need to do 2 of those, one along the top of the inner rocker, one nearer the bottom?

And if I get it lifted into position (before clamping it) how much leeway do I have to move it around to get it positioned correctly? I know that as I've been test fitting it I rarely get it in the right position the first time. I at least need to tap it forward or backward to get it lined up, and then tap it inward to get it tight against the inner rocker (although the clamps will help with that). But with the adhesive on it will I have time to move it around like that or will it really try to stay where it first touches?

To maybe help picture everything a little, here's my crayon sketch of a cross section of the rocker. The blue is original metal that I'm keeping, the red is original metal that's gone (either due to rust or due to a cutoff wheel) and the black is the metal I'm adding.

If I weld I'm thinking of spot welds between the inner rocker and the 4x4, spot welds between the door sill and the 3/4 x 1 spacer, and a weld bead along the outer edge of the door sill outer step and the 4x4 (to keep that from being a sharp edge that cuts peoples calves as they get in and out).

If I glue it I imagine using adhesive between the inner rocker and 4x4, between the door sill and the spacer, and also between the door sill outer step and the 4x4 (I'd probably try to feather that edge in with a flap wheel after the adhesive had cured). And probably using another 1x1 to clamp the outer door sill down to the 4x4.

[Gary Lewis]

OK Gary and Jim, you have me thinking about panel adhesive now, I've never used that stuff before. Help me think through what that process would look like.

Sorry for all the questions, but my lack of familiarity with the process gives me some concerns about whether I can do it well, which is why I'd rather go with welding. That's a process I'm familiar with and I know that I'll have all the time I need to do it right. But as Jim brought up, adhesive would do a much better job of preventing rust from starting between the pieces. So I would like to understand how challenging it might be to glue it in.

As I understand, panel adhesive is supposed to be applied to bare metal. I'm thinking with the rusty metal I'm starting with I'd still want to coat it with Ospho, but maybe after the Ospho has had its time to work I'd sand it down again?

And how long do you have after applying it before it better be assembled and clamped? I'm thinking that it could easily take me around a half hour to get it all spread on and get the tube lifted up into position. And then more time to get it clamped down well.

And clamping it. No trouble holding it up against the door sill. I can use a jack for that. But what about the inner rocker? As I understand you should use a lot of clamps to get good, even pressure on the sheetmetal (I think a single jack against the bottom of the tube will still put even pressure against the door sill). But I don't really want to buy a dozen 6" C-clamps to clamp the inner rocker to the tube (not that 12 would even be enough...). What about using 2 or 3 6" C-clamps to clamp a piece of say 1" square tubing to the inside of the rocker, sandwiching the inner rocker sheetmetal between the 1x1 and the 4x4? Would that be good enough? Or would I need to do 2 of those, one along the top of the inner rocker, one nearer the bottom?

And if I get it lifted into position (before clamping it) how much leeway do I have to move it around to get it positioned correctly? I know that as I've been test fitting it I rarely get it in the right position the first time. I at least need to tap it forward or backward to get it lined up, and then tap it inward to get it tight against the inner rocker (although the clamps will help with that). But with the adhesive on it will I have time to move it around like that or will it really try to stay where it first touches?

To maybe help picture everything a little, here's my crayon sketch of a cross section of the rocker. The blue is original metal that I'm keeping, the red is original metal that's gone (either due to rust or due to a cutoff wheel) and the black is the metal I'm adding.

If I weld I'm thinking of spot welds between the inner rocker and the 4x4, spot welds between the door sill and the 3/4 x 1 spacer, and a weld bead along the outer edge of the door sill outer step and the 4x4 (to keep that from being a sharp edge that cuts peoples calves as they get in and out).

If I glue it I imagine using adhesive between the inner rocker and 4x4, between the door sill and the spacer, and also between the door sill outer step and the 4x4 (I'd probably try to feather that edge in with a flap wheel after the adhesive had cured). And probably using another 1x1 to clamp the outer door sill down to the 4x4.

I don't think it'll take you that long to get things in position, but 3M's Panel Boding Adhesive has a handling time of 90 minutes and a curing time of 24 hours.

And I don't think you'll need more than maybe 3 C-clamps with the piece of 1" to spread the load. You don't want to squeeze all of the adhesive out.

But I used it on painted surfaces. So I don't think you have to get the treatment off.

[ArdWrknTrk]

OK Gary and Jim, you have me thinking about panel adhesive now, I've never used that stuff before. Help me think through what that process would look like.

Sorry for all the questions, but my lack of familiarity with the process gives me some concerns about whether I can do it well, which is why I'd rather go with welding. That's a process I'm familiar with and I know that I'll have all the time I need to do it right. But as Jim brought up, adhesive would do a much better job of preventing rust from starting between the pieces. So I would like to understand how challenging it might be to glue it in.

As I understand, panel adhesive is supposed to be applied to bare metal. I'm thinking with the rusty metal I'm starting with I'd still want to coat it with Ospho, but maybe after the Ospho has had its time to work I'd sand it down again?

And how long do you have after applying it before it better be assembled and clamped? I'm thinking that it could easily take me around a half hour to get it all spread on and get the tube lifted up into position. And then more time to get it clamped down well.

And clamping it. No trouble holding it up against the door sill. I can use a jack for that. But what about the inner rocker? As I understand you should use a lot of clamps to get good, even pressure on the sheetmetal (I think a single jack against the bottom of the tube will still put even pressure against the door sill). But I don't really want to buy a dozen 6" C-clamps to clamp the inner rocker to the tube (not that 12 would even be enough...). What about using 2 or 3 6" C-clamps to clamp a piece of say 1" square tubing to the inside of the rocker, sandwiching the inner rocker sheetmetal between the 1x1 and the 4x4? Would that be good enough? Or would I need to do 2 of those, one along the top of the inner rocker, one nearer the bottom?

And if I get it lifted into position (before clamping it) how much leeway do I have to move it around to get it positioned correctly? I know that as I've been test fitting it I rarely get it in the right position the first time. I at least need to tap it forward or backward to get it lined up, and then tap it inward to get it tight against the inner rocker (although the clamps will help with that). But with the adhesive on it will I have time to move it around like that or will it really try to stay where it first touches?

To maybe help picture everything a little, here's my crayon sketch of a cross section of the rocker. The blue is original metal that I'm keeping, the red is original metal that's gone (either due to rust or due to a cutoff wheel) and the black is the metal I'm adding.

If I weld I'm thinking of spot welds between the inner rocker and the 4x4, spot welds between the door sill and the 3/4 x 1 spacer, and a weld bead along the outer edge of the door sill outer step and the 4x4 (to keep that from being a sharp edge that cuts peoples calves as they get in and out).

If I glue it I imagine using adhesive between the inner rocker and 4x4, between the door sill and the spacer, and also between the door sill outer step and the 4x4 (I'd probably try to feather that edge in with a flap wheel after the adhesive had cured). And probably using another 1x1 to clamp the outer door sill down to the 4x4.

Ultra High Molecular Weight Polyethylene (UHMW) is used a lot as an inexpensive alternative to Delrin (acetal) and Teflon (polytetrafluorethelyne) PTFE.

I've used it for things as diverse at rail buttons for my rockets to lining a slice gate channel in a dam.

It would work great for a rub rail, just be sure to sink the fasteners well below the surface.

Panel adhesives have all different cure times, and you have further control by raising or lowering the ambient temperature.

Letting some dry ice cool the rails before clamping would slow the cure in summer.

Putting them on a heater would speed it in winter.

If treating with Ospho (I use KleanStrip Concrete and Metal Prep from the big box) I would just rinse with water, or a mild basic solution to make sure the acid is gone.

Panel adhesive is just a toughened epoxy, but I wouldn't apply it over paint like Gary.

In that case the paint's adhesion is the weak link. (Paint is NOT an adhesive)

Composite/materials nurd since I first played in mud......

 

[Gary Lewis]

Ultra High Molecular Weight Polyethylene (UHMW) is used a lot as an inexpensive alternative to Delrin (acetal) and Teflon (polytetrafluorethelyne) PTFE.

I've used it for things as diverse at rail buttons for my rockets to lining a slice gate channel in a dam.

It would work great for a rub rail, just be sure to sink the fasteners well below the surface.

Panel adhesives have all different cure times, and you have further control by raising or lowering the ambient temperature.

Letting some dry ice cool the rails before clamping would slow the cure in summer.

Putting them on a heater would speed it in winter.

If treating with Ospho (I use KleanStrip Concrete and Metal Prep from the big box) I would just rinse with water, or a mild basic solution to make sure the acid is gone.

Panel adhesive is just a toughened epoxy, but I wouldn't apply it over paint like Gary.

In that case the paint's adhesion is the weak link. (Paint is NOT an adhesive)

Composite/materials nurd since I first played in mud......

I agree that you wouldn't want to paint your parts and then use the panel adhesive. I was just saying it will stick to paint.

[ArdWrknTrk]

I agree that you wouldn't want to paint your parts and then use the panel adhesive. I was just saying it will stick to paint.

It's a glue. It'll stick to just about anything (including your clothes and yourself! )

[Nothing Special]

It's a glue. It'll stick to just about anything (including your clothes and yourself! )

One more question about panel adhesive. How good is it in constant tension? It turns out that the inner rocker is a bit too long.when I get the 4x4 into position the inner rocker is bowed in, leaving a big gap between it and the 4x4. I can C-clamp a 1x1 against the back side of it and pull it tight against the 4x4, so I could hold them tight together while the adhesive cured. But the sheetmetal really wants to pull back away from the 4x4. Will the adhesive hold it there against a constant stress?

[ArdWrknTrk]

One more question about panel adhesive. How good is it in constant tension? It turns out that the inner rocker is a bit too long.when I get the 4x4 into position the inner rocker is bowed in, leaving a big gap between it and the 4x4. I can C-clamp a 1x1 against the back side of it and pull it tight against the 4x4, so I could hold them tight together while the adhesive cured. But the sheetmetal really wants to pull back away from the 4x4. Will the adhesive hold it there against a constant stress?

Tensile strength is more than adequate.

I can try to find that data.

I'd only be concerned about peel, but on sheet metal to sheet metal joints I've seen the epoxy hold and the metal tear.

This stuff is authorized by the DOT and the insurance companies.

Good body shops use it in some situations because it doesn't distort or affect the temper of panels.

I think Gary's body guy (John?) Was going to use it for attaching new bed sides.

[Gary Lewis]

One more question about panel adhesive. How good is it in constant tension? It turns out that the inner rocker is a bit too long.when I get the 4x4 into position the inner rocker is bowed in, leaving a big gap between it and the 4x4. I can C-clamp a 1x1 against the back side of it and pull it tight against the 4x4, so I could hold them tight together while the adhesive cured. But the sheetmetal really wants to pull back away from the 4x4. Will the adhesive hold it there against a constant stress?

I think it will hold that easily. But I don't have any data to back that up. Perhaps on the pages I linked to below there is info on that?

However, you could drill and tap the 4x4 to suck the inner rocker down against it. Or, do as I did, and use big pop rivets to pull them together. I used Marson 3/16" stainless rivets with a grip range of .062 to .270" to do that. And by having the adhesive already in between the parts I knew that the holes would be sealed.

The adhesive I used was SEM DUAL-MIX™ MULTI-PURPOSE PANEL ADHESIVE Part #39747. But SEM also makes DUAL-MIX™ STRUCTURAL IMPACT RESISTANT ADHESIVE

Part #39757 which might be a better fit. However, they both require use of a special gun, and you'll need to borrow one of those or buy it, and I think they may be expensive.

 

[Nothing Special]

Tensile strength is more than adequate.

I can try to find that data.

I'd only be concerned about peel, but on sheet metal to sheet metal joints I've seen the epoxy hold and the metal tear.

This stuff is authorized by the DOT and the insurance companies.

Good body shops use it in some situations because it doesn't distort or affect the temper of panels.

I think Gary's body guy (John?) Was going to use it for attaching new bed sides.

Good to know that the tensile strength is really good, but throwing a few screws in there seems like a good idea too. I think I'd drill and tap it after the adhesive cured but before I removed the clamps. It's only 3/16" wall, but that's about right for a #10-32. Or maybe I should use pop rivets. That would be easier and quicker that tapping anyway.

FWIW, I'd be a lot less concerned about mounting bed sides with the stuff than having something trying to pull it apart with probably over 100 lbs of force. But it is a lot of area, so perhaps the stress (force per unit area) isn't that high anyway.

[ArdWrknTrk]

Good to know that the tensile strength is really good, but throwing a few screws in there seems like a good idea too. I think I'd drill and tap it after the adhesive cured but before I removed the clamps. It's only 3/16" wall, but that's about right for a #10-32. Or maybe I should use pop rivets. That would be easier and quicker that tapping anyway.

FWIW, I'd be a lot less concerned about mounting bed sides with the stuff than having something trying to pull it apart with probably over 100 lbs of force. But it is a lot of area, so perhaps the stress (force per unit area) isn't that high anyway.

If you intend to add fasteners after cure, at the very least dab some epoxy on the things and in the hole before you tighten it up.

But you have a lot of area, and if you get 100% fill (as shown by squeeze out when you lay a central bead) I think there's really nothing to worry about.

4x50 is 200 sq."