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Discussion Starter · #1 ·
hello all.
my first post , and it's a doozy.
the 94 truck has a 2 piece frame. riveted together, front and rear sections , just behind the cab.
quite by accident today, when cutting up a 94 diesel, with 38" rails,
we discovered this rear cut off, with springs ,hangers and all, fits, or appears to fit inside the frame rails of a  74 crew cab.
we discovered this by storing the cutoff on the empty rails of a crew cab. planning in the future, to transfer parts from one frame to another.

meaning, we should be able to cut and glove the newer rear section to the 74 front frame rails.

questions.
is this a commonly known,done thing on dodges?
of other years/models?
 

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Why would you want to?  The rear suspension is the same basic design so you wouldn't gain anything other than a sliced frame that would be weaker than the original.
 

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Not a common swap/splice, but might be a decent option if your old frame is wasting away. The shape is a little different - flat. Good for a flatbed, might complicate mounting a pickup bed.

I ended up with the same 2ndgen frame chunk.... but instead stripped and transplanted the hangers, leafs, and axle onto my '93.

 

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I see what you are saying, But I have to wonder the feasibility of splicing frame sections for a frame that is already in questionable condition. If the back section is rotted away, the front is usually not much different.

Having migrated from the rust belt, I don't like the way the 2nd gen frames have the C shape to them. Its just a rust bed waiting to happen.
 

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SuperBurban said:
I see what you are saying, But I have to wonder the feasibility of splicing frame sections for a frame that is already in questionable condition. If the back section is rotted away, the front is usually not much different.

Having migrated from the rust belt, I don't like the way the 2nd gen frames have the C shape to them. Its just a rust bed waiting to happen.
The last 1stgen I helped part out... front frame was still very good; but all went to crap from the fuel tank back.

The 2ndgen frame is normal channel from the factory frame splice back. Its also a nice heavy gauge (~1/4" thick) unlike the forward section of those trucks.
 

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Discussion Starter · #6 ·
sorry for the delay. i work forest service and am gone from computer a lot. want to get back to you on this.

the point of splicing the rear cut-off from a later dodge is this:

newer frame / spring geometry. better ride.
and the ease of the swap. its an afternoon's work.
assuming the frame is bare like mine is.

Both frame sections ;front and back are quarter wall. both are 38 inches width.

easier and less troublesome than swapping over frame rail components. better crossmembers on the new stuff.
and my favorite: dodge figured out the spring hanger locations and geometry. i can ride on their engineering instead of guessing where to put the newer components on an old frame that has a different geometry.

shock mounts brake line routing etc. all done for me.

Strength. A one piece frame  is ideal, but not necessary. Dodge engineered this splice from the start. The billions of miles logged by dodges with this two section frame are a good enough indicator to me that the splice is plenty strong.


this old crew cab frame is getting a custom box that will look a lot like the civilian power wagons from the 50's.

i don't know what cab i will use
right now it looks like a standard cab, a 9 foot box and dual propane torpedo  tanks  stacked vertically between cab and box. thats because i have already such a tank from an RV, and it fits like factory, between the two stacks that will help to warm the tank.

will be using a new ( i mean new, 16,000 mile)  360 from a motor home,, rejiggered for propane.

gonna be a different and fun rig.
its got the big front axle that gets ford hubs. right now its got the dana 80 rear dually axle but am looking for a lighter, smaller option.  80's are pigs, and consume a lot of power. if i could get a dana 60 or a 1050 AAM axle that is wide enough i would prefer that.

thankyou for your comments.
 

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The spring geometry is moot.  It's still a leaf spring suspension with a solid axle.  The only real difference is the spring length which is easily changed on the current frame with a hell of a lot less work than a frame splice.

Ease of the swap?  Yeah, I'm going to guess you have never done this before.

As for the strength, there have been a lot of issue with the spliced frames in the BR series trucks.  You are also missing a big point with your idea that Dodge engineered the rear frame and it's strength.  Dodge engineered the complete frame, they never intended someone to splice it to an older frame which were designed to work differently.  When the older trucks were made, frame flex was a desirable thing and was engineered into the frame.  By the time the BR series came about, they were trying to get rid of the flex and make the frames rigid.  That is two completely opposite ideas you are trying to put together that is going to put all the stress on the weakest point, the splice.

I could understand this if there was more to gain.  If the rear frame had independent suspension, multiple axles, or something that would make it a huge upgrade over the original design.  But all you are getting is more of the same.  It wouldn't even be worth it to me if the rear axle was linked as a 4 link is pretty easy to do these days and could just as easily be done on the original frame.  Again, if the frame were damaged or there was a big upgrade, I could see it being worth the effort but there isn't anything to gain for the extra work.  It just seems like you stumbled on a couple pieces that would fit together and are now looking for excuses and reasons to take advantage of your discovery.
 

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Discussion Starter · #8 ·
all of ur points are accurate and valid, and true ...to a degree.
yes I stumbled on parts. a delightful surprise.
the motivation is a suspension upgrade in the easiest way.
I had installed Sulastick bushings on the 94.
the 94 rode well. the 74 did not.
why, hmmm frame and spring geometry.

this is the motivation for the swap.

just sticking later components on an old frame accomplishes nothing.
there are a number of engineers papers on the subject.
spring centerline, the line of axle travel, the slapback, and reverberation of spring leaves etc .
all play a part in attaching leaf springs to a semi rigid surface.

I let dodge figure that out. and they did. my 94 rode tolerably. even with that dopey huge axle back there.

frames were never designed with flex foremost in mind in the days b4 computer modeling.
they were a by-guess-and-by-god, affair.
engineers were content if the frames just held together for testing.
proof of this is all of the mfgrs. had frame cracking.
this was the principle effort of frame shops in the day. eliminate cracking. flex was a byproduct.


yes, an afternoon and done.
Dodge allowed possibly 15 minutes per frame for assembly. they made it easy.
we have a full fab shop and ton of experience...
if it takes longer I will publicly admit this here on this forum in front of everyone.

the later frames may have had issues in their design, but I never experienced this near the splice neither have any of my companions with dodges. most of whom are engaged in the logging or ag. business.
a tough market for pickups.
so, we see.
a diesel adds an entire dimension to frame stress that , thankfully I don't have to deal with.
I am past my enamoration with diesel power.
300 hp from a 360 is adequate 4 me.

I believe it to be a legitimate swap and if no one else is doing it or has hesitated, then I. step into the breach and give it a go.
I assure all that it will turn out rather well.

 

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All the early trucks ride rough, it is the nature of the beast. They used heavier springs back then, which is also why the majority of the '72-'75 truck sit higher than the later models. I kept the springs off my '74 W200 to swap under my '88 Ramcharger to give it some lift and handle better off road. It's not suspension geometry as much as it is spring rate.

And you are wrong about frame flex. It was a known and in some cases, desirable part of using a ladder frame. They could have boxed the frames years ago if they wanted. Look under a early '60s Jeep J series pickup or M715 military truck. They have a hybrid frame just like a BR series with the front half boxed. A modification for trucks back in the day was to add a swivel in the frame between the bed and the cab to allow more twist to keep the axles planted on the ground.


As for frame issues, a little extreme but it was a perfectly good frame:


All I can say is good luck with it and I think you are wasting your time. A suspension swap would be a lot easier and quicker and you can copy all that "Dodge engineering" straight over to the old frame without compromising the value of the truck. Or, if you were really serious about a better riding truck, swap to the longer GM springs. As for it only taking a day, wager it will take you longer than a day just to get the driveshaft and fuel system straightened out.
 

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Discussion Starter · #10 ·
frame designs
there have been many different attempts to build the perfect frame.
none have worked.
with hydroforming we now have a shot at it.
see what happens.
flex built into frame hoping to prevent cracks.
they still cracked
didn't box frames-too expensive, dodge especially didn't have that kind of cash. add deeper channels, hope for the best

driveline , wheelbase, e brake cables, all remain the same.
driveline and u joints are getting an overhaul anyhoo because of the nv 4500, and going to a 1 piece 5 inch drive shaft in rear, with a jointed front shaft. unmarried 205.

fuel is propane , gas  tanks have been Mia for 15 yrs.

cut frame
slide rear section inside front,
grind shape and form to fit cleanly, plug weld in rivet holes. add zinc galv spray on coating to mating surfaces,
add stitch weld in appropriate locations, brake lines, wiring and out the door.

this rig is amalgamation of 4 , soon to be 5 different dodges ,no 6 I fergot the motorhome.
there is little original value left in this truck.
thank u for ur well wishing.
I'll start the clock when we roll the chassis in and announce exactly how long it took.
 

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Discussion Starter · #11 ·
and gm springs are but 3 inches longer than the dodge spring, and are 2.5 inch wide.
further I would not be able to use my sulastic bushings on gm springs.
ever glance at how gm laid out their heavy springs?
I have a cut off from an 06 gmc 3500 diesel used as a trailer.
the hanger positioning is flat out counterintuitive.
 

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Ok, I am just going to stop replying to this thread as it's painfully obvious that you have an idea and you are going to make up whatever excuses and nonsense to justify you trying it and ignore any other ideas.  A few examples of how wrong, or seriously mistaken, you are with just about everything you posted.

You talk of a perfect frame and it is now possible due to hydroforming.  Hydroforming was patented by the Schaible Company in 1950.  Exactly when is "now"?

Also, Dodge did not have the cash to box their frames?  And AMC did?  At a time when Dodge was at it's peak popularity with stock car and drag racing?

The driveline will obviously not remain "the same" especially when you admit in your next sentence that you are changing the driveline.  The parking brake cables may remain the same on the rear half, but at some point you have to splice it to the front cables.  The wheelbase remaining the same is entirely dependent on where you cut and splice it.

An "unmarried" transfer case is called a divorced transfer case.

Just sliding the frame inside the other and welding it is more than likely going to create a huge stress riser.  You would be better off overlapping the frames about 20" and bolting them together with a staggered pattern.

The common 56" GM springs are 4" longer than the common D/W rear springs.  Both are 2.5" wide.

So Dodge has no money, but you trust their suspension engineering but don't trust GMs...  Ok.
 

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I mounted the 2ndgen hangers and leafs on my 1stgen frame. I flipped the shackles at the same time.

https://ramchargercentral.com/axle-tech-discussion/dana-80-swap-westcoast-style/

It wasn't terribly difficult, mainly labour intensive. It rides really well IMO.

The Dana 60 and 70 from 2ndgens are the same width... if there's a benefit over the 80, its that either are likely cheaper to acquire.
 
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