Repairing the tailgate posts, replacing the tailpan and floor patching

[Blue85]

I see these "tailgate posts" available everywhere, like Sherman 89869L/R, but I think they are just skins. Does anybody sell one that truly replaces the mounting hardware sections? I emailed LMC, but haven't heard back. Then is the only way to fabricate some nut plates, weld all that in and then do the skin over it? To weld replacements in, will I be welding to the rear quarter panel sheet metal (and burning the paint off the outside?)

I'm doing the rear tail pan and replacing a bit of the floor this spring. The lower part of the tailgate post, where the truck tailgate hinges would attach is not very solid. Since those threads have never been used, they are probably not useable, either. Not only do I want everything to look nice when I lower the tailgate, I'm also looking to swap to the pickup tailgate, so I need those mounts to be solid.

EDIT: see post #18 describing that these are not "replacement" posts, they are skins to cover the old posts.

 

[Blue85]

I was thinking maybe the tailgate hinge are part of the "Tail Light Backing Plate" (#8 below) but looking at the view below, it appears they do have the latch/strap attachment nuts, but don't come down low enough to catch the tailgate hinges. (EDIT: the image of the backing plate is just scaled wrong in the LMC diagram.) Also, I'm not sure how to swap that part out without cutting up half the truck.



Here's pictures of the LMC tailgate posts, which appear to be better shaped. With those, instead of the more generic posts shown above, maybe I can just fabricate the hinge mount section, weld it in place and use these new posts over them so it all looks good. What actually bolts into that weld nut near the top?

(EDIT: that weld nut is for the upper tailgate rubber bumper. I haven't figured out the purpose of that bracket thingy on the inside).

 

[Blue85]

My next question is on floor patches. The only part that's real bad are the back corners, so it seems a shame to cut all the way up between the wheel wells to use their K5 L/R floor sections. For 1/3 the price, can I use the pickup patches (1 and 2 below)? 24" is more than enough to get up to the back of the wheel wells. Will the ribs line up? I thought about just a general piece of floor patch to do the corners, but with the new tail pan, it would be nice to set properly rolled new sheet metal all the way across.

 

[Blue85]

New pics received. Obviously this is where all the mounting features are. Anybody have experience replacing them?

 

[Blue85]

What did you do about this @Mastiff ? I see you found this same problem. I have ordered the posts and backing plates above and I'm not sure whether cutting them up to patch onto my good sheet metal will be easier than trying to remove the old posts and backing plates with a spot weld cutter.

https://ck5.com/forums/threads/looking-for-help-on-tailgate-post-replacement-pickup.136947/

 

[Blue85]

In addition to the different distance from the tailpan to the wheel wells, the pickup truck bed repair panels are flat, where the K5 panels have a rolled-under flange along the sides (you can kind of see it in the picture below). It's that flange that lets the floor panels bolt to the "walls" inside the bed rails. They also have a flat areas for the body mount bolts. I'm going to use the pickup panels and replace this flange with some angle stock.



Right now my plan for the taillight backing and tailgate posts is to cut the old stuff out into the lower taillight area, then cut the new pieces to match and weld around at that height. Taking the old pieces out entirely is a lot of hard to get to spot welds and also a lot of welding to the quarter panel. I'm hoping to keep those welds in just a few spots to avoid much repainting on the outside sheet metal.

 

[Blue85]

Am I crazy to cut my new tailgate posts and backing plates in half and weld them into the truck in the middle? It just looks like I won't be able to reach all the spot welds to get those pieces out whole, plus it will be welding to the outside sheet metal which means a lot of paint repair.

On the other hand, alignment of all the pieces should be much easier with all whole pieces, plus a lot less welding and grinding. Plus, no row of welds and pin holes for rust to set into.

I've walked out there 3 times to start cutting them and walked away each time. The idea is to leave the tailgate posts how they are now, and cut the new parts to match, based on distance from the tailgate hardware holes above.



So I have to install the taillight backing first and weld that up, then install the tailgate post and weld that up. Grinding may not be an option in some areas, so I would basically rely on the AMSOIL rustproofing spray on the inside.

 

[Blue85]

So the LMC parts are for pickup and not for K5, even though they list them for both. The mounting features are there for truck hinges, but not K5 latches and cable supports. So if you want those features, you'd have to drill holes and weld nuts in for them. I will contact them to see why they don't mention this. On the other hand, if you want to run truck gate and never go back to K5 gate, it will be cleaner overall.

 

[Blue85]

So far, the only response from LMC is

These are aftermarket pieces so there may be slight variances from the originals.

I've been cutting the spot welds to remove the Right post, but there are a few difficulties:

• The right post has a flange on the top that's on top of the "wall" sheet metal, so it either has to be cut off (which I've done) or the quarter panel has to come off.
• The tailgate post is spot welded to the backing plate behind the "wall". I may have to measure out where to drill these, probably ending up with some oversize holes.
• The tailgate post is tapered towards the top, so there will be some binding pulling it out. I don't think this will be a big issue, though.

It's obvious this is all assembled before the rear quarter panels are installed.

 

[Blue85]

About spot weld cutters. The teeth are easy to break off, so get spares. For the 3-layer stuff ("wall", tailgate post, taillight backing plate), the harbor freight version ($5) is better than the LMC version ($12) because it doesn't have built in depth limit. In fact, the square body sheet metal is thicker than that one is designed for, so you have to swivel the bit around to cut all the way through.

You must drill decent pilot holes for the center pin of the cutter.

 

[jekquistk5]

I need to do this as my the box is bent on mine. My tail gate is permanently closed right now

 

[Blue85]

After cutting chiseling and sawing about 20 welds, I finally got the right post out. The tailgate post and backing plate are welded together at the factory, then welded into the body and then the quarter panels installed. Right now I'm not sure how to re-assemble all of this. Might be possible lifting the body a couple inches. The post slips behind the wall while sitting on the tail pan.

 

[Cntymnty77]

I’ll be watching this. I need to do mine as well but I’ve got other crap higher on the priority list right now. And I think I don’t want to do it so I’m putting it off...

 

[Blue85]

Getting the original tailgate posts off is a huge pain. A lot of the joints can be air chiseled through the tail light hole, but not the top ones. So with more cutting, the pieces came off, leaving metal and welds to cut out between the panels.

That done, the job turns from demolition to building

I cut the backing plates a little long then iteratively trimmed until they matched the cut factory ones.

 

[Blue85]

A crappy welder makes all these spot welds and grinding take a long time. Only solution I found was to tack one backing plate (portion) in place, put the tail pan in place, then tack the 2nd backing plate in.



Look, the tail light holes line up:

 

[Blue85]

To get the new tailgate posts in is tricky. The flange on the forward-facing edge has to go underneath the bed wall, the top has to tuck under the top bed rail and the bottom goes on both sides of the tail pan.

I cheated by bending the lower rear fang 90 degrees outward. The I jacked the body up until the tail pan could be lower than the bedside wall. Then it's a combination of moves to get it into place. 1st side is easier than the 2nd.

I traced out the holes from the spot weld cutter onto the posts first and drilled smaller holes for plug welds. I made up a pattern on the rear flange.

 

[Blue85]

With the posts welded up and bolted to the tail pan I can start on floor repair. You'll see in the pics I'm going to a truck tailgate. The LMC posts have no K5 cable or latch features and I just left them that way. If I go back to K5 gate someday I'll have to graft those on.

For some reason the PS all dropped together square, but the DS was like 3/4" narrow at the bottom. I had to slot the post-to-tailpan holes out about that far to get the tailgate to fit.

 

[Blue85]

BTW, the "Sherman" parts I referenced in the first post fit entirely over the top of the stock or the LMC post, so it's intended to just skin over whatever problems the factory posts have, given that all the mounting hardware behind is fine. It doesn't cover the bottom trunion mounting hole, so theoretically that could mount slightly crooked if you don't shim and total width for the tailgate would be reduced a bit.

 

[Blue85]

I picked up the harbor freight flange/punch tool and based the whole floor splice on it. I would consider butt welding everything, but the difference in ribbing between the factory and LMC parts makes that seem nearly impossible.

The factory floor was flanged down at the edge so the patch panels can sit on top of everything.

 

[Blue85]

Now I have a floor to climb on to make a fuel pump door.