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You're 100% going to have to weld that tube into the center section. The plug welds you're cutting away are the only thing holding the axle tube into the center section.

Subscribed. Been a while since I've seen a cruiser 4bt swap posted up.
 

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Discussion Starter · #22 ·
Yep, once I got the section off I realized I’d only have a couple plugs holding driver side on.
I cut two full inches off that side to give me some room for the bead between the mild tube and ductile housing because there isn’t much/any real estate on DS to begin with.
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I hope to get these sand blasted in the next couple days and was wondering if anyone had used Steel-it before or if you have a different product you’d recommend? I’m inclined to only rattle paint things except the tub, frame, engine, and trans.
 

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I've used steel-it. I like it, but it's expensive. The big advantage is that you can weld through it.

Weld-through primer and any enamel topcoat is just as good as steel-it from a protective standpoint, but you have to remove the top coat to weld. All depends what you want.
 

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Discussion Starter · #25 · (Edited)
You read my post right. I’m mostly interested in weld-thru coatings and would top coat later if needed. Steel-It saves that step so the cost is worth it to me. I’ll pick up a can or two of Steel-It. Thanks!!

Got my bell housing, some bolts, and shift fork from Goat. Thanks a ton!! (Be aware that shipping can take an interesting path during these times. My parts disappeared for a week because they were bundled on a pallet bound for the west coast and they didn’t explicitly track any one particular package in there?!? But a little prodding of the shipping company from myself and Goat got things settled quickly.)

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Discussion Starter · #26 ·
Been busy with other stuff, but managed to get both axles stripped and prepped for sandblasting tomorrow. Got a couple cans of Steel It in black so I can paint to avoid flash rust.
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These axles are a tad rough. This is a lot of work!

AA also sent me my NV4500 and the Atlas is due in a couple months. Should all be good timing. I want to get the axles done so I can move to prepping the frame. I have to strip and clean up all the old Chevy mounting locations and do some extreme de-uglification thanks to the PO. Then I can hang the engine and drivetrain to match up with the new axles. All that with body on. After that I’ll tack it all and pull it apart for the finish paint and 4BT rebuild. Then back together. I’m thinking it could take two years.
 

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Discussion Starter · #28 ·
Wellll… I remember sandblasting taking less time. But then these are also quite intricate and caked in flakey rust.
After nearly five hours to get to about 80% on the front, I decided to just blast the flakes and wire wheel the rest. Or pay a local shop. The purpose was to be able to disassemble without all the rust so I’m pretty much there.
I’m going to retire the portable blaster. So many things I’d rather be doing with my life. I still have the blast cabinet. It doesn’t take an hour to clean up after that thing…
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Discussion Starter · #29 ·
Got a bit more done today. I am also remodeling my house and that is taking up most of the cruiser time but shipping is taking forever so I’ve got some weekends to spare.

I ordered some new softer poly body mounts so I can pop the body back on the frame. To get there I have to clean up a ton of unfortunate mess on the frame.
For example, the power steering mod was done by Hulk with an oxy torch. Never before have I seen anyone cut away so much of the core support on a PS upgrade.
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I cut out the shock mounts and all the leaf-suspension mounts.
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Discussion Starter · #30 · (Edited)
I’ve also come to realize that if I want to pop a fresh engine into the rig then I’ll have to do it myself. Apparently no one in the Seattle area rebuilds 4BTs..? Whatever. It’ll be a good dark-weather project. And, with half the cylinders I’m used to, in the immortal words of Mr. Clarkson, “How hard can it be?”
 

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A 4bt is a very simple engine. Basic rebuild procedures apply very well. If you are going to go through it, take the time and do it right. You'll need to replace all the gaskets, seals, main and rod bearings, rod bolts, and probably head bolts. Head studs in place of the bolts are not a super expensive mod and highly recommended. Factory rod bolts are OK or you can upgrade to ARP. Main crank bolts don't need replacing. The camshaft only has one bearing and you can replace that. In the tear down, keep the cam tappets labeled as to their location. Otherwise you'll have to replace them or have the reground. They are not an expensive part. When you get into the rebuild you can decide whether to use aftermarket or OEM Cummins gaskets. In general the aftermarket ones are fine but the head gaskets from some companies are junk. Here is the #1 or a video series on you tube rebuilding a 6bt. Pretty much the same as a 4bt. This video series is 10 years old but very good.
You could also possibly get a Cummins shop manual that could help. The engine he was working with was a P pump unit but all other parts are basically the same for any B series engine.
 

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Discussion Starter · #32 ·
Thanks a ton for the insight!I am looking at it the very same way.

I’ll be reading the Cummins manual, buying the right parts, taking my time and doing it right. I’ve nothing to lose and really want it done well. I may send my pump away for a rebuild and will have a shop pop test the injectors, touch up the valves, and boil/inspect the heavy bits. All else will be on me. Super excited. I’m looking into rebuild kits now and reading up on other rebuilds on the forum.

(was there a link you tried to share? I don’t see it)
 

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Discussion Starter · #36 · (Edited)
I’m into the front axle now. Have to strip it to weld the tube to the cast and fix up some of the grinder bites.
Tool Bicycle part Hand tool Metalworking hand tool Motor vehicle

While I’m in there, as every long project begins, I will replace seals and bearings. I did have one very big question for the community:
What if I leave the 3.55s in there for now?
Justification: I will be running 38s, an NV4500, and the 4BT should sit around 1600 RPM at highway speed. I don’t want to go too fast, but if I leave the 3.55s in for now I don’t spend the time regearing.
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I’m not into crazy off road anymore so I don’t mind losing some low end. But I love the engineering and fabrication. Thoughts?
 

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Discussion Starter · #37 · (Edited)
Well I did a “something” search and subsequent research leads me to believe it’s best to stick with the 3.55s for now and change them if I want more whatever later on. On to welding the nodular iron.
 

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Discussion Starter · #38 ·
The 05+ Ford Super Duty Dana 60 axle housing was cast to form D4512 ferritic ductile iron. Its carbon content and other material properties require welding of or to the material to follow welding process for typical cast iron over that of mild steel. As such I will be experimenting before I weld the axle with some bits I cut off against some mild steel I have in my scrap pile. Here are my current notes and assumptions:
1. D4512 has a lower melting temp and resistivity and a higher CTE when compared to mild steel. Heat will therefore more greatly affect the D4512 and I will attempt to maintain a process that allows the system to maintain as much equilibrium as possible from start to finish while biasing heat to the mild steel where required.
2. I’ll be welding with solid wire MIG (which is, for my post and beyond, always DCEP/reverse polarity) 0.30 Superarc L-56 wire shielded with Stargon.
3. The axle will be laid horizontally such that the mild steel will always be the lower material in the joint. Rotating the piece such that welding occurs on the top. (Known as Pipe rotating vertical horizontal PB position.)
4. Preheat work piece with a propane weed torch to a temp of ~600F (about half of D4512 melting temp).
5. Beginning MIG settings for 3/8 mild steel with ~25cfh gas.
6. Welding ~1.5in and rotate until complete.
7. Cooling controlled by equalizing temperatures across the two parent metals with torch until T~300F then covering with welding blanket.

Given all this extra attention I Have considered ordering a truss kit so that I do all the D4512 welding at the same time.

I’ll let you know how it turns out.
 

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1600 rpm on the highway is too low. You want to be around 1800-2000rpm.
 
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