Builds 1977 FJ40 Rebuild – Focus on Custom Stainless Tub (3 Viewers)

[psmbfuer]

Thanks Malleus - as Rush’s Neil Peart put it, “Lady luck is golden… So get out there and rock and roll the bones. Get busy.”

 

[psmbfuer]

Now we need to take a good set of measurements, remove the rear sill and uprights, and put everything back together. While I haven't seen a factory striker mounting area in a while, here is a shot of ours and I'm pretty certain that this is not factory, not that it matters much.

And below, we have marked and then drilled pilot holes so we can start with the spot weld remover bit.

We marked and measured references across the outside of the sill. And we will carefully remove the sill in one piece with as little damage as possible, so we can use if for future reference, should that be needed. I have no additional pics of the removal process, but you didn't miss much, we just used the spot weld bit that I have shown prior in this thread, made sure the bolts holding the sill to the frame were out, and from the tools laying in the next pics, it looks like we needed a little additional cutting / convincing and out it came.

You will also see the new stainless 2" x 3" tub laying in place - this will be the cornerstone of the rear sill and everything else will mount to it.

It's also kind of amazing how clean the rear edge of the floor is.

 

[psmbfuer]

In the above pic, it is also worth pointing out that the floor has impact damage just above the cutting wheel on the die grinder and several ~ half inch holes, all of which we will need to repair later - for now we'll stay focused on shoring up the rear opening.

 

[psmbfuer]

The rear opening will be made up of four main pieces:

1. The 2” x 3” main tube – this will be bolted to the original frame holes using M10 bolts.
2. The .5” x 1.5” upper tube – this will be bolted to the main tube, via nuts that will be welded flush to the upper face of the main tube. We will also use panel adhesive to mate this to the main tube. It will also house the latch in a recess similar to factory.
3. A single piece of 16 gauge. It will also run the entire width of the rear opening and will serve as finish trim on the same vertical plane as the upper tube, and on the bed side of the upper tube. Wide head, low profile bolts will run through this, through the rear floor, and bolt into nuts on the main tube.
4. Two uprights that are made from the same .5 x 1.5" as the upper tube. These will be bolted to the end of main tube and the vertical wheel well panels.

Advanced warning, we don’t seem to have all of the pictures that I expected to have and your going to need to trust that we used panel adhesive because we can’t find a single photo of this.

Here are several shots of building the main tube. We used a die grinder with a 1/16 cutting wheel to open up the ends, several bit sizes for the holes, and the welder. Below is the fresh 2" x 3" main tube, starting to remove metal where the uprights will anchor.

Now the upright handheld in location on the main tube.

Below is the main tube after DAing with holes for the frame bolts and the row of holes along the front will slide beneath the current floor holes and connect to the 16 gauge "trim". The bolt on the nut is an approach that we use for keeping the flange nut centered while is is welded in place.

Below, you can see the nuts and how they line up to the holes in the rear of the floor. All of the other rear open parts are laying there as well, but I don't want to get ahead of myself.

Here is the end plate about to be welded into place. There is a flange nut welded to the rear of this and the bolt is used as a handled to position the end plate for welding.

The end plate mostly welded into the main tube.

Here you can see the main tube installed under the floor with the "trim" in place, and starting to install the flush nuts that will be used to mount the upper tube.

Same as above, showing perspective, zoomed out, showing 2 nuts - If you are careful selecting the bit size, you can often make the hole just large enough that the nut is snug making welding a lot easier. We are also not using flange nuts here because the nuts need to be flush with the upper surface of the main tube.

Here is one of the flush mount nuts TIGed into place. We didn't use any filler wire - this will be slightly weaker, but should be plenty strong and no clean up required.

 

[alberta mac]

Hey alberta mac, the magnet is pulling against the original and remaining carbon steel center portion of the mid-tub cross member, serving as a stop to the new panel, so it doesn't try to move foward before I get a few tacks started. With the long vice grips in place, it is likely not needed. And for clarity sake, if I were using 400 Series stainless, the magnet would pull against it as well, but everything I'm using is 304, unless a piece of 316 slipped through - I get most of my stainless from a scrap yard and most of what I buy has the alloy number stamped on it.

I also noticed your FJ45 king cab reference in your signature line - very nice. Is it still progressing? After we complete this 40 (should that ever happen), I'm hoping to build a slightly shorter extended cab than yours, on an LX450 chassis that I have. I have most of my drawing and planning complete, but Cruiser time is in short supply when compared with the rest of life.

The 45 just needs an emergency brake set up but I will be pulling the B series and dropping in a 3Bt. I'll drive it rough before bringing it back in to redo the rear tub and look at the body. The bj42 I redid in 304 stainless back in 1995 and still holding up. Nice work !

 

[psmbfuer]

Thanks for the update and good to hear that you are making some progress. No surprise that the 304 is holding up and good luck with the swap.

 

[psmbfuer]

Finishing the Rear Opening & Sill

As you could likely tell from the pics already shared, rebuilding the rear sill is pretty straight-forward, once we had a plan / design. As you likely noticed in the fifth pic In post #84. all of the parts are already there. The two uprights are just pieces of the .5" x 1.5" with the ends welded closed and several holes drilled for mounting. The "Trim" piece is a piece is stainless that was bent into a ninety, with a somewhat soft bend. We then cut the one leg off so we could use it as seen in the pics.

What I called the upper tube needs a handful of holes used to mount it to the main tube and the recessed, which is where the ambulance door latch will be bolted back in place.

Below are several pics of the uprights.

And here are several shots of the "trim" as it progresses. You will also notice that the upper tube has holes, but no nuts have yet been installed in the Main Tube.

And the holes in the upper tube will be covered with the black plastic cap that is shown below.

 

[Malleus]

Just curious, why aren't you using weldnuts with projecting bosses? I always spec'd these when I designed fabricated steel with nuts; they make locating and welding nuts very easy, especially in structural sections.

The projecting bosses fit into common drill size holes, so no special tooling is needed.

Some of the designers swore by the square nuts with the teeth on them, but the shop guys swore at them. In theory, the teeth create a weld gap that should fill with the correct amount of weld, so that the welder can tell if he's using too much or too little. In practice, they skate around too much.

The tab kind are for 18ga and thinner sheetmetal only.

I'm not criticizing, you're doing a great job. Just curious.

 

[psmbfuer]

And now several pics of the upper tube and the latch recess.

Although we don't have a pic of the final nut plate, the ends on it have been bend upward, so it still floats and allows for adjustment of the striker latch, but if the striker latch were not installed the nut plate would remain in approximate position.

Below is the floating nut plate that will reside in the tube and will float roughly 1/2 inch in all direction, so the latch can be adjusted. Unfortunately, I don't have any pics of how this was welded i

The next two pics show the caps sitting in place, but not pushed in, but more importantly, this is the first revision of the rear opening and keeping the vertical wheel well panel, with a connecting panel. In the end, we didn't like this, and we wound up removing the vertical wheel well and replaced it with stainless with a fairly seamless attachment to the upright.

Below, we removed the caps and also mounted the tire receiver and and latch.

 

[psmbfuer]

Hello again Malleus, good point and thanks for bringing it up.

To be certain that I was clear above, there are two rows of nuts on the main tube, one set that needs to be flush with the top, and another that must sit on top of the main sill.

None of the weld nuts would have been beneficial for the nuts that need to be flush.

For the row of nuts that sit on top on the main tube, I could have used either of the first two self-centering weld nuts that you referenced, if they were the correct height, but I didn't have any in inventory (I do have an assortment of the tabbed and even t-slot nuts that I use a weld nuts at times, but the dimensions were not correct and I've been out of the round-style weld nuts for a while. I have never tried the square ones), so I used the flange nuts.

For what it is worth, I like the flange nuts in that even through I need to center them with a bolt, the bolt adds enough weight that if I tap the nut with the weld wire before the surface, the nut will almost always stay in place. I also try my best to weld them at the outer edge of the flange, which also allows me to weld downward, rather than toward the nut / threads, helping to further keep the nut in place and heat out of the threads. I realize that the self-centering weld nuts attempt do this as well, by design, but you need to point your weld toward the nut, and as you pointed out, the wire can sometime move the nut before you have started a puddle if your aim is off. The other issue with the flange nut and bolt is that my centering will not be as precise as the self-centering weld nuts. Possibly as I gain more experience, I might change my views.

And one new point - for any of you that have not worked with stainless nuts and bolts, be careful to avoid galling, otherwise called cold welding - it can be a huge pain, and welding on stainless nuts of any kind can increase the chance of galling. This can be an issue with the approach that I used above, with the bolt already inserted in the nut while you weld the nut on. To avoid galling, I use a very small amount of anti-seize on the bolt before starting to weld, but if you aim the weld at the outer portion of the flange and have your heat controlled, you should be okay. Also, I recommend removing the bolt manually with a wrench or socket, and not an impact, or other high speed tools.

Sorry, that was a lot of words for what felt like a simple question.

 

[Malleus]

Well done, I think. This isn't as simple as it seems like it would be. Just another example of a proper foundation, which is too often taken for granted, being harder than it looks.

 

[Malleus]

Well done, I think. This isn't as simple as it seems like it would be. Just another example of a proper foundation, which is too often taken for granted, being harder than it looks.

 

[ceylonfj40nut]

How are you going to manage galvanic action between stainless bits and non stainless? Are you creating a internal corrosion oven?

 

[psmbfuer]

Hello @ceylonfj40nut, good question. Although I didn’t directly mention galvanic reaction, I discuss the return of rust and how I hope to avoid its return in post #11 in the “Our Plan to Achieve These Goals” section.

That said, I’m no expert in galvanic reaction, but I am aware of it, have had firsthand experience with it, and researched it further before we decided to do what we have done in this build.

Here are my thoughts regarding your question, but please correct / comment, if needed.

• For galvanic reaction to occur, we still need a corrosive environment, but if the carbon steel is treated / coated, the corrosive environment will be held at bay as long as this coating endures. So I’m counting on the panel adhesive to do its job well, in the cases where I used it.
• Carbon Steel and 304 Stainless are not that far apart on the galvanic chart, so the reaction is not as aggressive, as it would be, for example, between zinc/galvanized and stainless, or aluminum and stainless, although it still a concern.
• In the build, carbon and stainless are mostly joined via butt welds and will be painted. If a carbon to stainless lap remained, we have used panel adhesive to isolate the two as much as possible, but in most cases laps are now stainless to stainless.
• As you have seen in the last post, we did not replace the rear lip of the original carbon floor, which I regret, and although I do not show it in pics (it appears that I don't have any), before final assembly, the two have a complete layer of panel adhesive on both sides before being joined.
• And although we have gotten to this part of the build yet, the right and left outer edges of the rear floor have been removed and replaced with stainless, using butt welds. This butts reside on the horizontal floor and are painted, while the floor to vertical wheel well laps are stainless to stainless. And even in this stainless to stainless lap, we use panel adhesive, more as a caulk than a concern for galvanic reaction, since there is little to no change of this in between 304 and 304.
• Similar to the above, with the exception of the floor, we have replaced most carbon in the lower areas of the tub, moving the materials / galvanic process away from or concealed from the corrosive environment.
• This is also not the first time I have joined carbon with stainless in an automotive setting, and in the past have had excellent results.

Again, let us know if you see any issues with the above – always learning and still making more mistakes than I would like.

 

[psmbfuer]

And thanks @Malleus, agreed, almost nothing is as simple as it might first seem. Using galling as an example, I learned about it after I installed a bunch of M10 stainless bolts in a custom bumper several decades ago. I was young, and am pretty certain I had never heard about galling. To tighten the bolt / nuts, I got out my buddy's the large pneumatic impact and zipped everything together, nice a quick, and not even that tight.

I then needed to remove the finished and polished bumper to adjust something, and virtually none of the nuts would budge, even with the largest breaker bar. We had to carefully cut the bolts with a thin cutting disk on a die grinder. The good news was that this protracted removal process was a great teacher, and I started to understand galling, but not well enough to avoid it 100% since. Even one bolt / nut on this build burnt us with yet another case of galling - duh - how long will it take.

 

[psmbfuer]

Now that we have a good foundation in the rear opening, we can continue building the rear of the 40, so let’s move onto the wheel wells.

Before we started work on the 77 FJ40, we had been making progress on the BJ42 and built a complete wheel well prototype out of a single piece of carbon steel. After cutting the entire panel in one piece, we bent it into shape using the manual bender that we shared back on post #34. We also needed to fall back to manual bending with angle iron, c-channel, clamps, wood, and hammers - and came up with the following.

The three long bends at the rear, middle, and lower front were coaxed into shape with the manual bender, but we needed a help from the mallet to reach a full 90 degree bends.

We then used our larger work table to clamp it down to and manually make the rest of the bends. As you can see below, we needed to turn the assembly upside down to make the first bend.

We needed a shorter piece of channel so we could get two clamps on it to keep the bend crisp. As noted above, this is made out of 18 gauge carbon steel, and I'm not certain that we would be able to bend this out of 18 gauge stainless, and if we were to build this again, we likely would not bend the leg on the lower inside.

 

[psmbfuer]

But again, since we decided to originally replace only the top wheel well panel, we build the following. I believe this is the only full panel on the 40 that we didn't first build a carbon prototype.

And here we bolted all of the panels on the passenger side together (no welds at this point) and then installed the ambulance doors to check square, level, fitment, etc.

@ceylonfj40nut, you might see the color of the bolts that mount the roll bar supports in this pic - they are galvanized. Keeping these would be a bad idea in that they would corrode quickly with the bare stainless panel, especially with a little water and increased temps. We didn't have any stainless bolts when we wanted to test fitment, so we temporarily used what we had, but these will definitely be replaced with stainless.

 

[Malleus]

Those are really good looking home-brew parts. Probably as good as the prototypes for the originals.

Have you thought about hydroforming? You can do it with a garden hose and municipal water pressure - you just need the molds, which can be wood if you're only going to use them once.

 

[psmbfuer]

No, but interesting. I have seen some expensive bike frames that wee hydroformed, but have not thought about applying it to a 40. What area of the tub or otherwise would you use it?

 

[psmbfuer]

And thanks for the comments about the home-brewed parts, they are enjoyable to plan and figure out how to build.