Rapom's Rocket - just another Duster build thread

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Seems like it but not really. Just catching you up on whats been done previously. This stuff really does take a lot of time to do... right. Or maybe I'm just old and slow?

Well we know this was an auto car and I'm converting to a 4 speed OD trans so there are some things that need changing. Here's a link to a "how to" thread for installing a manual hump that I did a while back:
It's a stick car now!
 
I continued on with the passenger floor pan replacement but failed to take any pictures as one morning I was out in the shop and just knocked it out. Turned out very nice. There are tons of threads on floor replacements so I won’t go into it. Here are a few pictures of the work I did on the driver’s side floor. It was solid but had some good surface rust going. Pic 1: A wire wheel on a drill took most of the paint and rust off. The floor had a weird discoloration in it that I thought was corrosion but that came right off with the wheel. It was in the metal not on it. Pic 2: Taped up and a heavy coat of rust converter doing it's thing. Pic 3: A good coat of POR 15 laid down. After the passenger foot well was replaced the rest of the floor was gone over with the wire wheel and a good coat of flat black primer and paint made it all look uniform.

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Since we were talking about the trans hump I'm going to show you some teaser shots. I made some modifications to the Lakewood bell that are not shown here... yet. That's a Hurst Pro Billet shifter that I got a smokin deal on at a Seattle NHRA National years ago. A distributor was using it as a display item. I'll just say "under cost". The poly bushed trans mount is from Mancini Racing. To keep things consistent I put in matching poly engine mounts also from Mancini. The pistol grip is a E body stick that I'm pretty sure I'll have to make an adapter for to angle it back some once the drive train is installed and I can sit in the seat. I know the B body stick works but I like the shorter shift throw of the E body stick. Carbon fiber grip panels were picked up from a vendor at Mopars at the Strip in Vegas (a yearly exodus for the last 6 years)
 

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Because I knew that it was going to be a while before the previously shown work was completed one of the first things I did was clean up the 8 ¾. After a coat of paint, swap out of the 4.30 chuck for the 3.55 from my Demon (both suregrip), new seals (pinion & axle), new brake shoes and hardware, resurfaced and painted (POR 15) drums she was slid into the corner of the shop to await the 4 link.

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Here is a how to on home made frame connectors. With a little organization I can knock out a pair of these in about a hour. Material is .120 wall 2x3 tube, IRC about 52” long, some plate steel for the front tube attachment to the trans cross member, or what I used here, some 2” wide cuts off a chunk of 2” x 1/8” scrap angle iron. All this can be done with a 4”- 4 ½” grinder with a metal cutting disk, a flap wheel for weld clean up and a drill.
Measure the distance from the trans cross member to the front of the rear frame tubes where it meets the floor pan. Mark this distance on top of the tube. Slice the tube down both sides of the top, using the inside of the side walls as your guide, then cut the flap off square at your mark. The opened up tube fits nice and snug over the rear frame horns. The tube has to be bent up approx 15 degrees at this point so using the grinder take a ¼” – 3/8” pie cut out of each side at the same mark as before (red arrow). With a helper or floor jack, ect. support the tube in position against the trans cross member and bend the rear of the tube up into position over the frame horn. A dead blow hammer works great. Tack weld the pie cut, one bead on each side is good, to hold it in position. Don’t get aggressive and weld it to the frame horn by mistake. Now is a good time to tack the angle iron in place on the front of the tube. Remove the tube and clamp a piece of flat copper, I made mine out of a 3” long piece of water pipe smashed flat in my vice, to the inside of the pie cut and weld it closed. The copper keeps it flat on the inside wall and won’t stick to the weld. If you don’t do this you will play hell cleaning up the weld so you can get it to fit over the frame horn again. I drill four evenly spaced ½” plug weld holes along each side but I like over kill in most things I do. Finish weld your angle brackets and your connector is ready to be welded into the car. Note: the trans cross member has a bump out on the drivers outboard side of the frame connector which makes putting a tab on that side difficult. I normally grind the tube end to fit snug and weld it home. See last pic. Some guys are going to cry foul and insist they need to be cut through the floor. Is that stronger, yes, but it’s a LOT more work. I'’ve done them many different ways but this is easily the fastest and simplest.

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Here's a link to some info I posted on how to eliminate the crash bumper fill panels and pull the bumpers in approx an inch and a half on each end. Still not happy with the ends protruding out past the body lines though. The cure for this is to narrow the bumpers an inch on each side. My bumpers are in great shape and the chrome is in VG Driver condition. To do this means stripping the chrome, cutting an inch out of each side, rewelding and finishing the splice then rechroming. A bunch of work and expense. Painted bumpers won't go with my paint plans. Another option is replacing the rear bumper with a '70-'72 which I have on hand. But the '73 & up have a pointed front end. I'm currently researching if an earlier front bumper could be made to look right.

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Next up is the “Big Dog” Mod I'’m making to the car, the triangulated 4 link rear. I apologize as I didn'’t take any pics of the kit before I started piecing it together. These are the bars, bushings and rod ends assembled right after I drilled and threaded the rod ends for zerk fittings. Rod ends are RH thread on one end and LH thread on the other so an adjustment can be made by breaking loose the jam nuts and turning the tube. No need to have to disconnect one end of the link so that it can be adjusted. Just have to keep an eye on the jamb nuts so they don’t work loose.

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The lower link bars are bolted to boxes welded into openings cut in the frame exactly like any spring into frame relocation. The first step is to clean the frame of undercoating and 40 years of road spooge. Next is to lay out cut lines. Cuts were made with a 4.5” grinder with metal cutting disks. Because of the narrowed axle’s width I did this install a little different than I'’ve done in the past and kept the outside skin of the frame intact.

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Due to the mondo sized tubing and bushed rod ends my homemade boxes are 4.125” wide inside vs 3” for a standard spring relocation. I went down to my steel supplier and had 3/16” plate sheared to build the boxes from. I tacked 3 pieces together using a ¼” steel plate and welding magnets to keep everything square. The partial boxes were clamped into the holes and the frames curve traced onto the side plates. Prior to this the front spring hangers and bolts were used as guides to mark and drill the first of three adjustment holes in the outer frame skins. This was also transferred onto the side plates.

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I disassembled the boxes by cutting the tack welds and used my trusty grinder to rough cut all four side plates to shape. I tack welded the four plates together and laid out the other two adjustment holes one above and one below the stock spring eye location. The spacing on the holes center to center is 1.25” IIRC. They were then drilled on my drill press, rather than by hand, to ensure everything was kept as square as possible. I then finish ground the plates to shape as one so all four were identical. In the process most of the tack welds were ground away and they came apart easily. All the pieces finished and ready for assembly:

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I then tacked together the boxes as before, clamped them into place and drilled the upper and lower holes through the outer skin from the inside for ease of access. Using several spring eye bolts to hold everything in the proper position the inner plates and rod ends, with bushings installed, were assembled with a thin washer on each side to provide clearance for ease of assembly latter. Then the inner side plates were tacked into position, the rod ends removed, and the boxes removed and finish welded. Then they were tacked into position in the frame pockets. Needless to say everything is measured off the reference lines laid out on the garage floor from the stock suspension’s pickup points and axle position. All work was checked many times for square and plumb before being tacked into position. Nothing was finish welded until the entire rear suspension was assembled for ease of making any necessary adjustments.

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The rear axle was placed under the rear of the car on jack stands and set at ride height. Pinion angle was set and braced off the floor to keep it in position. Extreme care was taken to ensure the axle was true to the guide lines made on the floor and verified off the body. I set the axle 1" to the rear of stock to center the wheels in the wheel wells. This was planned for and the link tubes were ordered 1" longer so there would be sufficient rod end adjustment remaining. I didn't take but a few in progress pictures of building the upper link/shock bar and positioning the link and shock brackets on the axle because it was extremely time consuming and involved with lots and lots of measuring before tacking anything in place. Here are a few pics of the upper link/shock bar being fabricated. Because the shocks and upper links would be loading the bar back and forth I figured a little extra bracing wouldn't hurt so I removed the pinion snubber reinforcement from the floor pan and made up a plate and stub to give additional rigidity to the center of the bar. I also removed the exhaust hanger on the driver's side as it was in the way.

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Lower and upper link brackets on the axle were the first to be positioned. Again washers were placed between the rod ends and bracket plates to provide a bit of spacing for ease of future removal/installation.

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Then the lower shock brackets were tacked to the axle and upper shock brackets fabbed to position the shocks vertically in the fore/aft and side to side planes. The blue tape on the shock’s shaft is to mark ½ the range of travel. The mounts were positioned so that when the weight of the car was on the suspension the car would sit at ride height and the shock would be at mid stroke.

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The suspension was constructed with the rod ends set with 1” of thread showing and the lower link bars and shock mounts were set at the center hole of the 3 available. This will give me adjustment leeway in any direction needed. A few overall shots. Sorry the gas tank was in the way. I was screwing around with moving it back and up but ultimately decided in favor of a fuel cell.

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Shock info: Strange single adj coil over shocks w/ QA1 12” 150# springs, Summit Part Number CMB-15-0059. These came with bearings at each end and I presumed they would transmit a huge amount of noise into the body. Not really the hot ticket for a dual use (track & street) car. These were replaced w/ poly bushings, sourced from Strange, for $43 for a set (both shocks). I was warned by Strange that they probably wouldn't last terribly long in this type of application but then neither would the bearings.
 
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That rear suspension is incredible i can only imagine how many hours you have into that part of your build. amazing build and thanks for all the tips, (frame connectors and bumpers). keep up the good work!
 
Thanks guys, it was one of the most time consuming projects I have ever done to a car.
Once everything was finalized the finish welding was completed. Plates were added to provide additional lateral support to all the tabs and everything was brush coated in chassis black POR 15. The link bars were spray painted chassis black and the zerks installed then wrapped up and placed out of the way on a shelf until final assembly.

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Todays installment is all about fuel cells. I think I mentioned before that I ditched the stock tank and went with a fuel cell. This time around instead of mounting it on the trunk floor I wanted the cell mounted below the floor, but, I did not want it visible below the lower body line of the quarter panels from the side. That was going to take a pretty shallow cell. After some searching online I found an aluminum Jazz 17 gal cell only 7 inches deep. Although it does not have a sump, which I wish it did, I figured I could make it work. I found an Ebay auction and picked up a new one for quite a bit under retail + free shipping. Can you tell yet that I like to pinch pennies? It came with pickup fitting, return fitting, roll over valve/vent, fuel sender and a 12 bolt filler neck. The filler neck did not have a flapper valve to prevent fuel from draining back through the fill pipe in the event of a roll over, which I deem a necessity, but the 12 bolt neck is easily replaced with one that is so equipped.

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So in order to mount this thing flush with the floor it was going to need some sort of cage to hold it. Using 1.25” square tubing, which I had left over from another project, I got started. First was tacking in two cross braces between the rear frame rails. I tied the front tube into the sheet metal stamping which makes up the upper shock mount and the rear tube into two little brackets which support the floor pan at the tail light panel (arrows). Then using the cell as a template I made a tight fitting cage for it but left enough wiggle room for some thin padding material to be inserted where the cage supports the cell. This was tacked into position between the cross braces. All these tubes were set at the same level as the top of the frame rails so when the floor is re-skinned everything would be level.

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Well after admiring my work for a few minutes it became painfully aware that I had just screwed this up. The reason I decided to replace the stock gas tank was that it constricted the space I needed to get an over the axle exhaust installed. And I had just put the cell right back in almost the same spot, DOH!!! After a beer (or two) to sooth my ego I figured out that it would be a fairly easy task to do a small design change. I added stubs to the front of the cage, cut the rear cross brace out between the two floor support brackets and welded this piece into the cage itself. This moved the cage back 3” providing enough room to make the turns in the exhaust to route it over the axle and around the front of the cage. Sorry for the crappy pics, my flash made everything orange and the beer made my hand unsteady! I will probably have to skin this in sheet metal to comply with track rules but this is how it sits for now.

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Had to figure a way to reconnect the parking brake system since the brackets were cut off the frame when the link boxes were installed. After some whittling with the grinder I tacked them on the side of the link boxes where they wouldn'’t interfere with the three bolt holes and the cables wouldn'’t rub the lower link bars through the rear suspension range of motion. Last pic you can see the sub frame connectors are welded in and painted, passenger floor pan and 4 speed hump installed but not finished and my missing wrench!

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