'72 C3500 GMC flatbed project

[JJorgensen52]

Time to start a project thread!

I bought this truck, in theory at least, to use as a work horse so my K10 can get new floor pans this summer

The truck is super clean - all original, needs outer rockers and not much else. 50,800 original miles, factory flatbed and original 350/4bbl/4spd/PS/PB

The day I bought it:


First thing was to replace the rusty hood with a good spare it came with:



And some rattle can

[JJorgensen52]

Next up: New fuel lines, pump, and filter. Found this in the fuel tank:


Was a little bit distressed by how rusty the tank in general and the sending unit are. I ordered a new sending unit and stainless fuel lines from Inline Tube.

Can I swap a '67 fuel tank for this '72 no vent model? I'm going to have a clean '67 tank available to me shortly.

This is how I left off for the day

[JJorgensen52]

And now to my current status: new rear wheel seals!

I am entirely new to the heavy duty (H072 in this case) axles, so this was a bit of a learning curve:



Driver's rear drum, both shoe hold-downs were missing so replaced those and adjusted, new rear wheel seal, packed and torqued bearings, all is well


Passenger's side... not so much.



That wheel seal had completely failed. Cleaned everything up as best I could, replaced the seal, packed the bearings, but new shoes are in order for that side as soon as the budget will allow. Yikes!

Also, I've now got a line on this '67 C-30 dump truck

which is going to get parted out and donate it's dump hydraulics and PTO setup to this truck

[fxdxharley]

how do you find these local? i never see them on criags list. stop over some time. now that the snow is gone i can actually get working on my blazer.

[JJorgensen52]

Originally Posted by fxdxharley

how do you find these local? i never see them on criags list. stop over some time. now that the snow is gone i can actually get working on my blazer.

You can't find 'em because I keep buying them

I'll definitely drop by sometime soon to check out the progress

[JJorgensen52]

Not much to report this weekend, waiting on parts mostly.

1. Found out the points weren't properly bolted down inside the distributor, at the expense of the integrity of the new muffler and a cold dark hour on the side of the road

2. R&R'd the heater controls and put screws through the face to hold the bracket to the faceplate - my '69 is like this as well, nice and secure now!


3. R&R'd the cowl, cleaned out 15 lbs of leaves and twigs and rotted organic matter from the cowl vents.

4. Removed the wooden bedside boxes from the frame


Next weekend I'm picking up the '67 C30 dump to get ready for hydraulics swapping into this truck

[MrBeast]

Sweet! I think you are at the start of a great project, I remember the thread when you brought it home.

Glad to see another dually coming back to life, there is getting to be not a lot of them left.

[JJorgensen52]

More work on the dump mechanism:

You can see a bit here, there is a bend in the actual piston, which I'm working on straightening out (I loose about 4" of return travel)


Both sides of the dump subframe were rusted through on the outside where the mudflaps / center frame brackets were mounted. Cut all that out and ready to weld in some new plate tomorrow (Hopefully)
Driver's (You can see a split in the inside wall of the frame tube as well, rust growth between the bearing block and the frame caused that. I am going to weld the split and then weld a doubler plate over it before I patch up the outside)

Passenger's


Removed the uprights, working on getting the pivot bar unseized from the driver's so I can fix the rust at the end of it



And my second or third major setback of the day - the pivot bar on the hydraulic cylinder failed! This is a 1.5" diameter steel rod - I will have to weld in a replacement. 30 years with no grease will do that


Here's the broken end still stuck in the bearing block


That's all for tonight, don't like to run the grinders at night and tick off the neighbors.

[MrBeast]

I'd just take that ram to a local machine shop and have them make you a new rod for it. Shouldn't be all that expensive and will be well worth it to have it done right.

[JJorgensen52]

Originally Posted by MrBeast

I'd just take that ram to a local machine shop and have them make you a new rod for it. Shouldn't be all that expensive and will be well worth it to have it done right.

I'm getting a quote for that from my local hydraulics service place, new rod and renew the seals, etc.

Didn't make much progress today. Weather is being non-cooperative!

Driver's side of frame - split welded and fished, patch welded in place for the bottom of the frame.




I have new hardware for mounting the ram, and most of the metal needed to rebuild the uprights and the subframe.


HOWEVER - design snag!

Turns out that when they installed the dump bed on the '67, they cut 17" off the rear of the frame to make the dump angle as it should. Since I want to keep the original flatbed and frame dimensions, that's no good.

Nearest I can figure, if I shift the subframe back when I mount it to the GMC, I can still achieve a 50* dump angle with the current cylinder and geometry if I lengthen the uprights and taper the rear overhang behind the pivot. I'm going to make up a model of this later on and make sure everything works out.

[MrBeast]

You know seeing that thing a bit better, I would honestly scrap the mechanism and rebuild it, with that much rust in it, I would not trust it, and the steel to build that wouldn't be all that much.

Some box tubing and a little time, probably less time than you would spend fixing everything that is wrong with that one. I think you would be much better off, much safer too.

[JJorgensen52]

Originally Posted by MrBeast

You know seeing that thing a bit better, I would honestly scrap the mechanism and rebuild it, with that much rust in it, I would not trust it, and the steel to build that wouldn't be all that much.

Some box tubing and a little time, probably less time than you would spend fixing everything that is wrong with that one. I think you would be much better off, much safer too.

You know, I thought about it. The tubing is structurally sound (there's not even any surface pitting), with the exception of that one spot on each side which trapped moisture. I'm confident in the strength of the metal once it's been repaired.

I do appreciate the input, though. I guess it's just the yankee in me, hard to scrap things

[JJorgensen52]

Finished patching up the subframe today and got it separated from the original chassis



With all holes drilled and primed

[JJorgensen52]

Spent most of today out and about, so not much work got done:

1. Got the seized rear pivot shaft free - had to cut a relief in the housing and spread it a bit, this pic was taken after I'd finished welding it back together.


2. Just a shot of the poor PTO pump - the slip joint in the shaft seized up and caused the u-joint to chew into the packing retaining screws.


3. The herd at rest!

[JJorgensen52]

Had today off so I made some great progress today:

Uprights are completely repaired and I've extended both sides so they're now 110" in length to match the original flatbed. I tapered the tubing from 4" tall down to 2" tall behind the pivot point, in order to be able to maintain approximately a 55 degree max mechanical dump angle without cutting off the rear of the truck's frame.






You may note I have not yet added the reinforcement plates to my extensions - I ran out of flat stock so I'm going to finish that off in the AM

Got the ol' John Deere involved to lift the flatbed off - this assembly is extremely rigid by itself, I was quite surprised!




Truck chassis with just the wooden carry blocks and brackets remaining - those come off tomorrow for subframe fit-up. Turns out the wood spacer blocks have some dry rot at the bottoms near the frame, so I will be using them as a template to cut new ones from PT lumber.

[JJorgensen52]

Progress update!

Hydraulic ram is rebuilt, pump moved to frame and replumbed:



Bed lowered:


Bed lifted (not under power yet, no PTO driveshaft)


PTO installed


And an unexpected hangup:


The rear brake line on this truck was fitted to a standard 1/4" brake tee - which cracked and started spraying fluid everywhere. Come to find out, the reason it cracked is because the factory line is not a 1/4" brake thread at the axle, after all. Unable to find the right parts, this '92 S10 Blazer rear line and 3/16" - 1/4" adapters worked out just like GM meant it to.

As soon as I get a PTO driveshaft installed I need to run the control cables, then redeck the bed

[JJorgensen52]

Driveshaft fabricated (at least a temporary home made for now)



Unfortunately, the driveshaft is rubbing on the parking brake cable arrangement, so I am going to have to rearrange that linkage to make everything work.

[JJorgensen52]

Today's update:

PTO Controls installed. I used bezels from factory switches so they *kinda* look like they belong, but the lead on the cables is such that they won't quite sit square to the cluster... oh well.


Stripped out all the old hardware


Trimmed and routed some planks to fit


Did some test fitting


And got it all decked out



I still haven't installed any of the middle hardware, and the ends are only on finger tight, but I ran out of time and daylight. Project for another day.

[JJorgensen52]

Better shots. It's starting to look like a real truck again!

[JJorgensen52]

Update time!

My rear view mirror has fallen off repeatedly, so I went to the '71 style


Manufactured new PT frame spacer blocks



And I didn't like the open rear frame look, so I threw together a quick frame cap / bumper this afternoon



And I got loaded up for the local truck show tomorrow

[builtbyKane]

That's an awesome flatbed. Don't let it sit, it needs to be worked everyday!
Posted via Mobile Device

[JJorgensen52]

Originally Posted by builtbyKane

That's an awesome flatbed. Don't let it sit, it needs to be worked everyday!
Posted via Mobile Device

Thank you! I intend to put it to work very soon.

Just one crummy shot of my junk from the show today


In other news, I finished shortening the rear wiring harness and re-taped it... not much to show, but that was the idea

[storm9c1]

Like!

Nice job. Nothing beats an old dually -- back for 4 more decades of work. And then it will still be askin' "more please"!

I made a set of wooden "stake bed" sides for my rollback so it can do more than haul cars as well. Makes for a rather large tilt-bed dump.

Cool to see you restore the SM465 PTO setup. I ended up using a Muncie dual belt-drive for mine. Electric clutch. But prevents me from easily adding A/C. Also made for some interesting fab work to get the correct clutch fan spacing.

[JJorgensen52]

Originally Posted by storm9c1

Like!

Nice job. Nothing beats an old dually -- back for 4 more decades of work. And then it will still be askin' "more please"!

I made a set of wooden "stake bed" sides for my rollback so it can do more than haul cars as well. Makes for a rather large tilt-bed dump.

Cool to see you restore the SM465 PTO setup. I ended up using a Muncie dual belt-drive for mine. Electric clutch. But prevents me from easily adding A/C. Also made for some interesting fab work to get the correct clutch fan spacing.

Well thank you! Somehow, in my mind, an old truck has to have a PTO. It was a tough call, the '67 I pulled the parts from had floor mounted levers to control the PTO, but I just couldn't bring myself to hack into a perfect factory floorpan.

I've never seen a Muncie belt driven hydraulic unit for a bed before, that's interesting! It's fairly common to see that sort of set-up on period snowplows, but they're basically just a second power steering pump. Is the Muncie set-up some kind of heavier duty pump?

[storm9c1]

Originally Posted by JJorgensen52

I've never seen a Muncie belt driven hydraulic unit for a bed before, that's interesting! It's fairly common to see that sort of set-up on period snowplows, but they're basically just a second power steering pump. Is the Muncie set-up some kind of heavier duty pump?

At one time, I never saw a HD belt-drive PTO either, but here it is:

http://www.munciepower.com/products/...&back=Products

Mine is an older 4-5 GPM PH series unit. Works great to operate the bed. I have a large hydraulic recovery tank, so there is plenty of extra fluid for the large rams on my setup. The bed setup is fairly new, but the 40 year-old hydraulic winch (possible original) is SOOOOO slow. I can't bring myself to replace it because it can pull a house.