I know this an older thread but I'm about to tackle this project. Both rear arches are rusted out on my 95 F-150, shame because the rest of the truck so nice. I can't see replacing the whole bed since these patch panels are available.

The inner is rusted as well. I'm not going to put it back the way it was as far as the inner though. That seems to be the problem to begin with. Mine was full of dirt and moisture, that combo as we all know is bad. Looking at it, there's really not much chance of it getting cleaned out very well, even if you try. I'll worry about the inner portion afterwords. Seems like they use to just have that hard plastic all the way around, instead of that metal filler/splash shield.

Being a competent welder I will do the metal replacement myself. I'll get a body shop to tackle the paint. I'll probably order panels from LMC.

For those who have done it. Do you use the patch panel as it comes and cut the bed to fit? Do you cut out the bed first then cut your patch panel to match? I'm just trying to get a game plan going. Any input on the procedure would be greatly appreciated.

 

Still being new to site, I guess I can jump in on this one. I work in a bodyshop. I recently bought a 95 with the rust around the arches. I might not tackle them this year as I got the too many projects bug. I was curious about the cost of the bed patches. Our aftermarket supplier has the bed patches (which is 41 by something in size) for 30 bucks each. Of course, that's my price.

As to the question above, once you get the patch panels, yes you would cut the bed to fit. If you were to cut the patches to fit where ther's rust, you wouldn't get all rust. And then rust would push back out next to where the patches are. There is always more rust on the inside than what you see on the outside.

When I eventually do mine, I'm going to use adhesive glue that has become popular in the collision industry instead of welding. Welding causes to much warpage, which creates more use of filler, which means more work.

 

I think the ones from LMC are 16" tall and like 40" wide and are $40 each. Seem to be quite large. I kinda see your point, I don't know for sure how far up the rust goes but I don't believe it's too far from what I can tell.

Warping on that large flat bed area is a concern of mine. I've got some experience with this aspect though and think I can get it done. Kinda what I was wonder ing about making patch panel smaller, that equals less welding.

It seems like a challenging but interesting project. Hard part will be getting over the the first cutting into my truck

 

It's is usually much better to only use as much of the patch as you need to make the repair. Smaller patch means less work, less warpage, and there's less chance of distorting body shape/lines. I have replaced body panels using panel adhesive and using a MIG welder and some times a combination of both. How you decide to cut out for your patch panel depends on which method you are going to use. If welding a butt joint is best, so once you have your patch cut to size lay it on the area to be patched and scribe a line around the patch. I like to cut just inside the scribed line and then fine tune the opening to get the proper clearance. It's a lot easier to cut some more metal out rather than putting more metal on :-). If you go with the panel adhesive method you need to leave 3/8" to 1/2" flanging area to attach your patch panel. For flat areas I use a panel flanger to make the gluing surface, but if the area is curved I cut the panel to fit and I glue another piece of metal to the back side of the area to be patched that matches the profile first and once it's dry I glue in the patch panel. That's another reason to cut your patch panels smaller, because you can use the left over material from the patch to use as a glue flange, since it should match the profile or the repair area. I used this method to replace my rusted out cab corners. According to the 3M website their panel adhesive when used correctly is 11 times stronger than welding. I know the cab corners I repaired are very solid, since when we put the cab back on my frame we carried the cab using the new cab corners as a lifting point. Both techniques have there pros and cons and like I said I often use a combination of the two techniques to accomplish a good repair.

 

thanks for the good info cujo. I think I would have to go with straight forward butt weld. My experience is welding and grinding in a munufacturing setting, so I guess that's what I'm comfortable with. The adhesive method seems beyond my scope.

 

How is this even possible ?..I have used the product....(used when welding will burn the vehicle down),,, Welding makes two pieces one ...

usually ,a weld is stronger than the steel was before ...I have removed panels that were glued ,,It was nothing compared to a weld...

This is a lap 1/4 overlay ,,,after grinding ...The 1 " wide spot is the seam,,you can't even tell there is a weld there ...


welded with a mig

You could spend all day trying to butt weld this & never get there ...No one is that good a cutting the patch or holding it in place ...

If you know what you are doing ,you will get 0 warpage , every one that can weld 1/4 inch steel ,thinks they can weld 22 guage,,,think again..

Lap the patch , stitch the weld ,cool it with air every 5-10 seconds or so (or just wait untill cool)..very little filler ...needed ...

BTW , if you are going to glue a panel ,,you need to have a way to clamp it every 4-6 inches ..not so easy in most applications

 

When I can't get a clamp on it I use pop-rivets to hold the panel and when the glue dries I grind the rivets flush. Another guy on the site uses flush mount rivets and says this eliminates the need to grind them flush.

If you use welded lap joints you need to weld both sides or you leave a chance for water etc getting between the metal from the back side. This is especially a problem when you don't have access to the back side of the panel, because you won't be able to apply any seam-sealer. With the panel adhesive method I feel I can better protect the backside of the patch from elements, since I can clean, paint, seam-seal all the exposed surfaces before I install the patch w/o the fear of catching all the stuff I used on fire when I weld. The adhesive also protects the metal much like a seam-sealer, so I make sure to coat all the clean/sanded metal where the bond is made with plenty of adhesive, such that there will not be any exposed metal on the inside of the patch. If I have access to the backside of the patch I will use seam sealer after the glue is dry to further protect the panels. Believe it or not the person that turned me onto the use of 3M panel adhesive is a professional welder by trade. As I stated before some panel repairs are better suited for welding some might be better suited to panel adhesive. Most of my larger patches I did on my truck were a combination of the two methods.

 

Cujo, would you agree that the panel adhesives contain some form of corrision resistance in them? I believe Lord Fusor that is used at the shop I work at does. Atleast according to the product reps.

 

Yes I believe so, here's a link to the stuff I've used and have been quite happy with:

3M 08115 Panel Bonding Adhesive

Here's what 3M says about this product:

http://multimedia.3m.com/mws/mediawe...6EVs6E666666--

http://multimedia.3m.com/mws/mediawe...6EVs6E666666--

For use on outer body panels only. Not for use on structural components such as pillars, frame rails, core supports, or rocker panels (on unibody vehicles). Cures on demand with addition of heat. Glass beads work as built-in spacers for optimum bond line thickness. Product has corrosion inhibiting ability. Has excellent shelf life, either opened or unopened. Using this product eliminates most overhead welding and heat warpage of sheet metal (associated with welding). Work time is 2 hours at 70 degrees F and 1 hour at 100 degrees F. Handling time is 4 hours and cure time is 24 hours. There are two recommended applicator guns. They are the MixPac® Manual Applicator 08117 or the MixPac® Pneumatic Applicator 09930.

 

The panel in the pic will be coated from the inside & then the foam sound deadening material replaced ,(it was also welded with a weld through primer ),,

But mainly ,,it is in a spot that is not exposed to anything besides humidity .

Panel bonding has its place ,,but in a unibody vehicle ,that was designed to fold up a certain way ,I don't want to be resposible for a panel not protecting the occupants ..

As for what 3 M says about its product ,,I have heard it many times , from many companies ,untill there is a failure of a product ,, then its alway's something "you"did improperly ,,and not the fault of the product .

They guarrantee the product against defects ,,but it is up to the user to determine when to use it or not ..

As for corrosion protection ,,I agree it will help..

But keep in mind ,these vehicles are originally built under ideal conditions , & most won't go more than a few years without beginning to show rust in winter conditions ..

If you are restoring a classic,,it may never see any more water than from a garden hose .I have a few cars I built 30 years ago that have no corrosion protction at all & are the same today as they were when I built them , fair weather drivers only ,of course ..

BTW both ends of the panel in the pic are but welded .
The reason was to not have a lapped seam where it meets the door or the tail light .No filler was needed.
I elected to section the panel due to having to duplicate the look of the factory seam sealer in the trunk opening ,& I don't care for the way my glass shop is removing glass now (A saws all with a wide flat blade )
I tends to damage the paint around the entire perimiter of the window opening..(more potential for corrosion)

 

Man, you guys are talking about technical body shop stuff and have lost me LOL

Good information though.