Builds 1977 FJ40 Rebuild – Focus on Custom Stainless Tub

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Rear Quarter Panel Sill Extensions

We will get to the rear sill soon, but since we introduced these quarter panel sill extensions, it seems that they come next. The overall process for these and the remaining panels / components is similar to that used to build the quarter, so we won't go into the same level of details here and going forward. That said, please ask questions, or make suggestions.

For those of you familiar with the OEM rear sill, it is basically the end cap to the rear floor, but also extends out into the quarter panels providing support and strength along the bottom rear. These panel sill extensions connect to the new rear sill and the quarter panels in a similar way the the original.

And one thing I haven't noted above. we always try to remember DAing (sand with and orbital sander) all stainless after the panel is cut and before we start to bend. This allows for a very complete and consistent surface for better primer adhesion.

Here are several pics of this rear sill extension, showing the original plasma cut panel, through formation and final weld and second DA.

 

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Unfortunately, I just noticed that several photos that I included above in Post 20 didn't remain in the post because I posted too many.
So let's try this again.

84 BJ42 Quarter Panel (79 - 84)

84 BJ42 Square Fuel Door (79 - 84)

77 FJ40 Rectangle-Shaped Fuel Door (this pic is from a 78 actually, and not the truck I'm currently working on, but they are the same - this will be a valid door for 75 - 78)

 

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Removing the Existing Quarter Panel

To remove the quarter panel, you need to remove bolts, spot welds, and cut the top of the panel free.

The primarily tools that we used are a spot weld drill bit and a die grinder. You will also need a 10mm wrench, a chisel and hammer, a 3/32 or similar sized bit, and other hand tools. The spot weld drill bit is a small hole saws. We use a kit that has multiple sizes, which is very handy - the larger bits can be used to drill out things like the pin on the headlight bezel hinge - more on that later. And we use a thin, 1/16 cutting wheel on the die grinder.

Removal Outline:

1. Remove the 10mm bolts from the rear side of the B-pillar where the quarter panel is bolted in place.
2. There will be spot welds that need to be located and removed - there are three primary areas:
   1. A row across the top of the quarter, were it is spot welded to the upper skeleton rail.
   2. Another set that connect the quarter panel to the top panel of the wheel well.
   3. Assuming that you want to preserve the floating nut attachments for the doors and the spare tire reinforcement plate, you will need to remove spot welds holding these in place.
   
   
   We marked each spot weld with a pen. We then drilled a shallow pilot with the 3/32 or similar bit. Be careful not to drill deeper than the thickness of the quarter panel. This pilot helps to hold the spot weld hole saw tip in place. If it starts to wander, you greatly increase the chance that the bit will break.​
   ​
   Carefully drill out each of the spot welds, but again only drill through the quarter panel, not the rail. After a few, you will get a good feel for the depth and watch for the color to change or for rust to appear – this will be a good indication that you are through the quarter panel and should stop. If someone has painted the tub, you might also have body filler on the panel making it more difficult to find the spot welds. If this is the case, it will likely be fairly obvious where they are located if you look on the inside, or gently, with a flat grinder, remove some filler to locate the spot weld.​
3. Draw a line or mark with tape where you will cut the entire quarter pan free from the top skeleton rail. See the pics for the rough location, especially the photos where the panel is removed. This should be roughly 1/8th of an inch above the upper row of spot welds, but the spot welds will likely be slightly inconsistent.
4. Once the panel has been removed, we ground down the remaining spot weld material.

Below, you might notice that the spot welds are not visible. This is because, the panel has additional layers of paint, so we ground it off, exposing the spot welds and starting to drill.

 

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Lower Rear Cowl Corners

This panel is relatively simple to make, but there is a fair deal or work behind the panel, not just because it is rusted, but also so we have stainless to stainless lap joints in this area, for the surfaces that the cowl panel will mate to and the mounting surfaces for the front floor.
Here is the starting point.

This is what was behind the cowl corner.

The homemade bender worked quite well for this:

And here is the new lower cowel panel.

And here we have replaced the behind the scenes supports with stainless so the new panel with be stainless to stainless lap joints, including the mounting surfaces for the front floor.

Here is the panel being welded in place.

And done with this for now.

 

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The passenger cowl corner had minor rust, so we build this custom patch. We were trying to get the truck ready for our trip to Moab, and it gnaws on me that we didn't do a full inner support replacement and a complete outer panel replacement, analogous to the driver's side. Also, in our moving quickly, there are very few pics of this side. You'll get a chance to see it as part of the passenger rocker panel replacement that will be coming soon.

 

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Rockers

Pics of the rockers have been shared several times above, so I'll just show some of the work on the passenger side, where the carbon floor remained. This means that there is a lap joint between the new stainless rocker and the old floor, which I'm not fond of. This is another one of these areas that I might rework prior to final painting, but time will tell.

For any of you that have not fabricated / welded much, it is worth mentioning that fitment is very important - it serves as the foundation for your weld, and with good fitment and a consistent gap, you greatly improve the likelihood of laying down a consistent bead without burn through. Also, take your time - on a weld the length of the rocker it is easy to get too much heat into the nice fresh, clean, straight panel, and wind up with a warped, puckered mess.

This pic shows the final panel fitment before starting to weld.

We also needle-scaled, wire brushed, use a wire wheel were possible, sanded, and painted inside the channel behind the rocker. The rear portion of the floor that touches the rocker was quite rusted, so it was replaced with stainless before welding on the rocker. We also drilled holes in the carbon steel lap that will allow us to plug weld from the inside of the rocker. We also painted all of the carbon steel with multiple coats of SEM Rust Trap, getting as close a reasonable to the plug weld hole to provide as much protection as possible.

At this point, we tack welded the rocker in place and then clamped on the 5/16 aluminum heat sink that we cut and started to weld.

We then took our time final-welded the rocker. And you can see the small rocker patch panel that I mentioned above, partially at least.

We then neatly ground everything down and moved on to the next part.

 

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I just noticed a rocker removal pic that might be helpful to anyone tackling this for the first time. Pretty much spot weld drilling and cutting with the die grinder.

 

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Above, I have made several references to a spot weld removal tool. It is basically a small hole saw with a retractile centering tip. Below is a shot of a smaller cheaper version, on the left, and a more expensive one that is part of a kit with multiple sizes. I recommend the kit with stronger bits with multiple sizes.

 

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Mid-Tub Cross Member
I'm not sure if there is a proper name for this, but moving back from the rockers is what I call the Mid-tub Cross Member. This is the channel immediately behind the front floor and provides the transition to the rear floor. The center of our channel is very solid, while there is a good deal of rust on both ends. This channel also is the one area in the FJ40 tub design that results in three layers of steel. Our new panel will eliminate these layers (sorry purists). We also designed the new panel so a single bent piece of stainless that will include the lower portion of the wheel well front and the rear and side portion of the floor.

We don't have a shot before we started work, but the following two pics should get you grounded.

Once the main section is removed, we needed to removed the nut plate for reuse. It had no rust and seemed worth reusing rather than replacing.

 

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We actually cut and bend the replacement panel prior to removing the original steel, and used it as a template to trace the cut marks on the original steel.

 

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Below we reinstall the mounting nut plate on this outer mid-tub cross member patch. Then we cleaned up the all surfaces, wire brush the inside of the channel, paint the channel and the nut plate prior to welding it back on.

The below might be a little hard to decipher, it is a shot from the underside of the passenger wheel well, looking toward the back side of the mid tub cross member.

Here you can see that the remainder of the channel is in good shape, so we thoroughly wirebrushed it and painted it with 4 coats of SEM Rust trap. As a reminder, if you are laying multiple coats of this, it needs to be done before the last coat is fully dry, or you will need to scuff the surface before the next coat.

Here is the roller that we used to paint the inside of the channel.

And here it is after painting.

 

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Next we final-fit the new panel, used a magnet and clamps to hold it in place and butt welded it all back together.

Here are some shots from the bottom side.

Now the top side, with the welds complete.

And the following is more a shot of the passenger floor, but it appears to the the only shot of the new passenger mid-tub cross member after final grinding.

And we should have posted these first I suppose, but here is the unbent panel being cut on the CNC table.

The pic below is of several components that we were working, but the larger panel in the lower right is what would become the passenger side mid-tub cross member replacement.

 

[ceylonfj40nut]

Awesome work here. Care to share more details on your bender?

 

[psmbfuer]

Thanks very much ceylonfj40nut. I have placed several pics of the bender below that I hope helps. It is a very simple, homemade bender, made maybe 20 years ago and it just keeps doing its job, although it has its limits. From memory [Edit] I have now measure the bender and have updated the previous number below. Based on additional questions, I have also provided additional pics in post #70.

• The C Channel base is 6” x 1.75” x 48.75"
• The flat bar stock is 1” x .75” is what moves and swings upwards to bend the material.
• The handle is .75" x 27" rebar
• There is a stainless hinge running the entire length of the primary body. It is welded to both the body and the solid stock.
• We then, generally, use a ~1/2 thick piece of angle to hold the material in place, but many times we will cut a custom tube or angle for the job at hand.
• There are also two alignment pins, one in each end of the C Channel base and 1/2" angle. See the stubby Phillips scewdriver on the right-hand side of the first image.
• I should also note that you need good clamps - we have bent some of these larger clamps trying to hold everything in place. As you can imagine, when you start to bend, the piece of captive material to be bent first tries to slide backwards.
• You will need a good table to clamp it down to.
• And if we bend a piece of 40", 18 gauge stainless, for example, we may still need to gently and carefully coax the bend to a full 90 degrees if that was the target, and likely more so toward the end without the handle.

Let me know if you have questions or need any additional pics or details.

The below is the start of a door that we built for Tinman, a trailer that we built to take out west back in 2013, but is helpful to show the bender in use.

 

[EWheeler]

Awesome vision, talent, and execution!

 

[psmbfuer]

Much appreciated EWheeler. The vision is still well-ahead of our talent and execution, but we keep learning and moving forward. More soon.

 

[psmbfuer]

Regarding the mid-tub cross member above, I suppose I it is worth mentioning:

• While the original panel overlapped the center main channel (refer back to the first pic in post #29), the replacement panel was designed to eliminate this, and uses butt joints here, in the back where it connects to the wheel well, and along the front, curved, inside radius (refer back to post #32).
• A lap joint is still used when connecting to the new stainless rocker, so there shouldn't be any rust issue there.
• The only decision that we regret about this area is keeping the inner rocker in carbon steel, resulting in a carbon to stainless lap - we were very much trying to hold to a schedule to make our spring Moab run and the inner carbon rocker is is very good condition, so at the time, it was a good decision, but in retrospect, it would have been worth the additional time to replace the inner carbon steel rocker, rather than just the rear and rusted portion.
• By bending this area in one complete panel, several of the multi-layer laps are eliminated.
• With all the bends, this is a very strong panel, but we also made this one out of 16 gauge for added strength.

And the following provides a perspective that would have been worth sharing above - you can see that this panel fits in behind and flush with the back side of the B-pillar.

 

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Mid-Tub Cross Member - Driver's Side
The work on the driver's side outer mid-tub cross member is similar to the work on the passenger side, but there are several changes, and additional work, some of which is to accommodate the new driver's floor pan.

Below, you will see a better series of pics of the panel removal process. To remove this in one piece, as shown below, you will need to have removed at least the lower front corner of the quarter panel, allowing it will slide out.

After removal of the outer panel, we needed to cut and replace the mating surfaces of the channel, so we wind up with stainless to stainless lap joints when the floor is installed. You will also notice that remaining channel gets much cleaner as you move toward the center. We then cleaned the remaining steel with a needle scaler, wire wheel and brush, sand paper, repeat.

We then butt welded the patch from above as shown below. The washers on the left are a simple way to close the holes from the spot weld removal bit. They were slightly enlarged to fit the OD of these stainless washers and then TIG'd in place. The center holes were then welded shut with the MIG.

We then removed the nut plate and reinstalled it on the new panel. Even though the panel was not rusted through for the most part, you can see when viewing it from the back/inside that the years had taken a toll and the piece was weakened and is thin.

 

[Airdale]

Very impressive. I have similar work coming up and am enjoying your detailed explanations .

 

[Mike Shull]

Outstanding work!!!