72 Demon now underway

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gen2hemi

gen2hemi

former ASE knuckle buster
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Mar 15, 2010
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After 2 years of disassembly, scraping undercoating, sourcing parts, and generally figuring out what its going to be when it grows up, this Demon is taking shape. It is going to be be finished in Top Banana (FY1) yellow, organasol hood black out, twin snorkle scoop, black longitudinal stripe.

Last year we finished the motor, a 360 with Scat forged 408 kit, RHS X heads, and will assemble first with an RPM Air Gap with Thunder AVS 800 cfm, maybe a 6 pack setup later on. TTI stepped headers with muffler decision still up in the air.

We have a 8 3/4 with 3.55 SureGrip still to overhaul, and an A body 833 we can't decide whether to just go through and run stock or put in Passon 5 speed guts.

Enjoy the pics and post any comments or questions.

10-07-07_1449.jpg


10-07-07_1457.jpg
 
After disassembly I started blasting the front clip with a small 100lb blast setup in my driveway. I tried a couple different media types, I liked the recycled glass #40-80 the best. I also tried a garnet sand product that was pretty efficient but didn't hold up to recycling more than once before it produced a lot of dust. The glass is good for 4-5 passes if you filter it good between sweep ups.

2 things quickly got my attention: nothing compares with a production quality blast shop's system to turn out a complete car, and don't try this at home with the standard dead-man valves that Eastwood, Northern Tool, etc include with their blast pots. They will fatigue you needlessly no matter how strong your grip and forearms are!

Note the body cart. We were going to go with a rotisserie on this project but wanted to put the $$ that would cost into the car instead, so I went through all the scrap lumber I had around and built the cart you see for nothing but the cost of the casters ($45 Harbor Freight) and some good construction galvanized lag screws (Simpson). Eastwood sells a steel cart for $500! This one is working out awesome.

Demon to blaster.jpg
 
One of the first chassis mods we wanted to do was get the front frame rails strengthened so we ordered the XV lower radiator support brace.

Good enough product but these guys have it backwards. They ship the brace "cut down" so the stock radiator lower tank won't fit (ie run a crossflow). They include two tubing sections that you have to weld on to run a stock radiator. Made me have to weld up these extensions and finish the welds; 2 hours I didn't need to spend. WHY NOT bend them up to fit stock and let me cut it down if I don't need the clearance??? I'll also note their mandrel bending is not great with a lot of distortion on the inside bend. Quality square tube bending uses an inner die that doesn't gather the metal but forces it to concave into the inside radius.

I chose to "flush" the brace to the core support, bringing it as far forward as possible. Took more cutting and fitting this way but to my eye it looks more "right" than tucking it behind the original lower rad tin.

Brace 1.jpg


Brace 2.jpg
 
Looks like a great start to the project. Will look great when done.

Please tell me that the cart is somehow attached, or somehow fixes it's position to those framerails. Otherwise if you whack the car it looks like it could slide off?

Grant
 
Hard to imagine finding a 40 year old Mopar that doesn't need a floor pan!

Auto Metal Direct has a the Demon and Duster covered with a one piece replacement. I have to report it fits AWESOME.

I am posting a few detailed photos so you can see the weld patterns around the perimeter and the crossmember and seat brackets. I stopped counting spot welds but estimate about 135 in our car's floor. (Note: Areas where it is rusted are very hard to locate the welds in.)

I used a Blair Rotobroach, mix of 7/16 and 5/16 sizes and a 3/8 low speed air drill. Don't try to use the cheaper cutters (even the basic Blair ones) on a project this big. You will get frustrated early. Only drawback to the Rotobroach over a spot weld bit is you have to grind off the pads left by the cutter. I used a combination of sanding discs (4 1/2 and 2"), and a production flap disc where I could to flatten them, and followed with weld-through primer on the shiny metal.

This car proved to be a marvel the further we got into removing the floor. It was in way better shape rust-wise than the exterior belied, and the rockers and frame rails were nearly perfect. Just a little pitting in places, no structural damage.

Floor 4.jpg


Floor 3.jpg


Floor 2.jpg


Floor 1.jpg


Floor fit 1.jpg
 
OneOfMany said:
Looks like a great start to the project. Will look great when done.

Please tell me that the cart is somehow attached, or somehow fixes it's position to those framerails. Otherwise if you whack the car it looks like it could slide off?

Grant
Click to expand...

It can't move Grant. To locate the body I used a stack of washers (8 high or about 1") .875 OD, with a 5/16 bolt through them at the dowel holes in the forward and rear frame rails. If you look close in the forward frame rail area of the first photo in the "Replacing a floor pan" post above you can see it. I measured the locators in an X to make sure the cart was square (and the body once down on the "dowels".) If you look close at the pics you can see the rear blocks are movable, the fronts are fixed (on lag screws). I used a threaded rod to attach the rear pads to the cart "clamp style".
 
Yeh, its nice and strong, LOL ..I didn't exactly have any twig lumber lying around. Other than the casters it can support house construction kind of loads. I sleep better too, because my son and I spent so many hours under that thing scraping and wire wheeling the undercoating the last thought I needed was one of us getting pancaked by an old Mopar.
 
Before we took the car to the blaster I thought it would be a good idea to open up as much frame rail area as possible so they could shoot media "where the sun don't shine".

I'm putting up some pics of the trunk pan under way, ultimately the car will get trunk floor, trunk extensions, lower quarter partials, and taillight panel - all available AMD pieces. The taillight panel fit (good) is attested elsewhere on this forum.

This is time consuming, tedious work busting spot welds. Nothing to be afraid of, just a lot of reps. My suggestion - cut out the spare tire well so you can stand in there and work more comfortably.

Trunk 1.jpg


Trunk 2.jpg


Trunk 3.jpg


Trunk 4.jpg
 
Cool. Look forward to your progress. I've got a 72 Demon project with a 408 and a Passion built all aluminium 833 close ratio 4-speed and 3:55 gears. Mine is not completed yet, but should ready sometime this year. Check out my profile/old posts for more info.
 
gen2hemi,

I'm glad you said the AMD floor fit well. Looking forward to getting started doing the same on my Duster. I hope once the old floor comes out the remains look as solid as picture in your project. I'm going to connect up the front to back as well. Are you making your own or going with the laser cut units?
 
66340SEDAN said:
Nice project and nice work, keep the pics comming!
Click to expand...

Demon 408 said:
Cool. Look forward to your progress. I've got a 72 Demon project with a 408 and a Passion built all aluminium 833 close ratio 4-speed and 3:55 gears. Mine is not completed yet, but should ready sometime this year. Check out my profile/old posts for more info.
Click to expand...

Thanks for pointing me to your prior post; nice job on that electrical thread. My Chall above has much the same configuration, only difference is I used a Painless battery disconnect relay at trunk mounted battery and another master disconnect (a 200 amp Marinco manual disconnect) under the dash, effectively isolating the 1/0 power run at either the battery or prior to fuse block and forward harness.

The ammeter elimination is critical to all old Mopars, glad you put on the spotlight. Even in a car with a reworked amp gauge and new harness like my Chall I wouldn't risk it. Besides breaking the two sides of the ammeter circuit and adding a second fusible link to the old alternator branch effectively gives you another safety valve.

I'll look forward to following your project too. These 408s (ours is .040 over and almost a "413") are going to rock. We put in the COMP Mutha Thumpr 287TH7 which with 833 and RHS heads, even 1x4bbl should get it out of the hole..dayathink?

crank 1.jpg
 
Joe Mc said:
gen2hemi,

I'm glad you said the AMD floor fit well. Looking forward to getting started doing the same on my Duster. I hope once the old floor comes out the remains look as solid as picture in your project. I'm going to connect up the front to back as well. Are you making your own or going with the laser cut units?
Click to expand...

Joe, I actually bought the subframe connectors as a package with torque boxes front and rear from Auto Rust Technicians. They are pretty basic square tube design like old super stock Dart factory racer note, but they are heavy wall and have nice slot for ebrake cable, sculpted end to meet rear frame rail, and drain holes on bottom. I don't like their install directions which say to just butt them up to crossmember and weld, so I am cutting a gusset plate and attaching to the connector tube first, then putting a plug and perimeter weld to the crossmember. Working on that part of the build now, I'll get some pics when done. I wasn't crazy about the laser cut style because of all the floor pan weld bead work to such thin metal. Yeh you end up with a boxed structure but nothing like a stout square tube. BTW, I also like Magnum Force's design which I have on my convertible Chall using twin DOM tubes siamesed together.
 
gen2hemi said:
Joe, I actually bought the subframe connectors as a package with torque boxes front and rear from Auto Rust Technicians.
Click to expand...

Thanks for reply. Just checked ARTs site nice. Sounds like you went with their Performance Pack..A-Body Mopar. I'll probably get this as well good price for the kit.
 
Before I could put the floor pan in permanently I wanted to fit check and install the subframe connectors. I'm using some pretty generic one's from Auto Rust Technicians that they package as a kit with their torque boxes.

Because of the beating the leading edge of the rear frame rail area has received on most Mopars, getting the sculpted end of the subframe connector to fit was a lot of work for such a simple addition as a couple pieces of "square steel tubing". The actual connectors are generic as well and need to be cut to length for the Demon (108" wheelbase). This left some spare stock that would come in handy. I completely rebuilt the end of one frame rail with some 14 gauge sheet. To fit the shape of the subframe connector to the frame rail, I mocked up the position with blocks to get the connector parallel to bottom of rocker box and fore-aft rocker alignment, and fitted shims cut from the square tube scraps. You can see one before welding in the pics.

SF 1.jpg


SF 2.jpg


SF 3.jpg


SF 4.jpg


SF 5.jpg
 
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