roadster unibody and related construction

in 2010 or so i got this 1961 Rambler American from a friend moving out of town. it was rough, a half century of daily driver use wore it out. it sat in the yard for years, somehow i decided i needed a roadster. i'd been driving a 1963 Rambler American 440 Twin Stick, but i foolishly drove it on the Bonneville salt, which tipped it past the edge of maintainability. i swapped that driveline into the roadster initially.

i went the hot rod route because i was tired of trying to maintain an old stock car in reliable road trim. too many squeaky doors, cranky windows, hard to work with seats and wiring and rusty chassis. so i removed everything that annoyed me on the car and this is what's left.

this chassis was the new AMC's hold-over small car, the 1956 Nash Rambler restyled, three times through 1963 (1961 the first year of the final fender and grille style). quality construction wasn't the problem (the malaise era some 25 years in the future). it was just very stodgy and old-fashioned. it's a unibody, a true monococoque car. there is no "frame" at all. it's light and stiff, a single welded unit. this presented some challenges later regarding transmission and rear suspension, covered elsewhere.

the first phase was of course chopping and cutting and cleaning. followed by hammering sheet metal, welding and "painting" (Eastwood Chassis Black). i'd originally intended to have the unibody sent out to be acid dipped primered and painted some truck/tractor primer or black, but (1) i couldn't afford the three grand it would take (shipping, etc) and after angle grinder/wire wheel to the thing, the patina was just too good to paint over.

this thing is basically under constant revision, some of it substantial, but the chassis is more or less unchanging.

below is a 2014 version of rolling-chassis "done".

when i lopped the roof off the A pillar tops had to have it's layers peeled back and reshaped. this was one of the places that underwent a lot of revision in the Nash to AMC restyles, so there were a lot of layers. the top of the windshield from is a separate piece, seems likely to accommodate the convertiable windshield frame.

cleaning was major work. it took about a month to chisel and scrape off the soundproofing and undercoating and sound deadening. much of it was this stuff here, what i think is asphalt mixed with clay and possibly a fibrous binder. heavy, sometimes sticky, dense, and very heavy. i bet i removed 100 lbs of stuff like this. and ouf course 50 years of dirt and oil. i had the stripped unibody up on four by fours on jackstands, and got the entire undercarriage completely clean. huge PITA. it all got painted with Eastwood Chassis Black.

before the roof came off i jacked the unibody square and added the DOM tubing sub-frame tying the A pillars to the B pillars, and then cross-tied the B pillars together separately.

i did a section at a time. there was essentially no rust in the car, except the passenger side floor. all coatings and paint came off, but i left well-adhered factory primer in place. i figured if it was going to be that hard to remove it deserved to stay there. (the small rust-through on the lower passenger side was fixed when i did the rusty floor inside.)

the original firewall had a decade's worth of factory doodads and add ons, big holes and tacked-on bulges for all the junk added over the years. i removed the whole thing and replaced it was a double-wall, 18-guage flat firewall. i also pushed it in (back) to clear the cylinder head of the later engine, the new-in-1964 199/232/258. it also makes the short 195.6 OHV very easy to work on.

the cockpit area was the second major construction area. the steering column location (stock) determined everything. that odd tripod supports the column but it's shape makes it stay close to the firewall.

the front valance is essentially made from scratch. i retained the horizintal strip that fastens to the nose parts above and only part of the corner curves. the rest was hammered from 20 guage steel. a major restyling feetch is not really clear here... the valance was narrowed about five inches, pulling the lower front corners of each front fender in. this largely eliminated the teetering-rambler-nash look, where the front wheels are tucked too far under the car. in the orginal 1941 Nash unibody car this was necessary for chassis reasons, then they got stuck on it, styling-wise. if you compare the roadster front-on pics to that of stock Ramblers, it's quite noticable. the complete bumper-delete also deleted a lot of accumulated styling detail knick-knackery, little shelfs and slots and holes and things. CLEAN.

below shows after, then before; closeups of the 1963 American and then the 1961 American here, showing how this was arranged from the factory.

this was one of those foolish aeasthetic decisions that kinda define the car. once i pulled out the instrument panel -- too hard to work behind -- and the firewall, there was no place to hang the pedals. so i made my own and put them in the floor. they're a bit overkill, a bit too close together but it's worked out fine. i have 2 PSI check valves in each line since the master cylinder is a couple inches below each caliper to prevent flow back. not sure if they're needed but no harm done if not.

this was the only rust on the car. this is a very common pattern for Ramblers especially those with rubber mats instead of carpeting, like this car. the heater intake in front of the windshield rusts and leaks water down the inside firewall under the mat and rots the floor. the damage was quite minimal, the floor skin only.

this was the 1961 steering wheel. i figured i'd clean it up, JB Weld the cracks and reuse it, but all of the plastic just fell off. at first i only intended to use it for mockup, like here, then i decided it was just fine as it was, cleaned up the rough edges and it's still in use today. the plastic is still disintegrating, it gets your hands dirty as you drive. i need to deal with this someday i suppose.

the original doors, some 40 lbs each, were stripped down to the outer skin only, and mount to the unibody with sheet metal screws, hiding the sub-frame. here you can see my foolish attempt at preserviing the original bench seat. i thought it would be cool. it was not. it was a piece of junk, weighed a ton, half the springs were no good (i spent hours rearranging the springs so that the bad ones were not under assbones). right before i got it on the road i got a pair of 2005 Honda seats for fifty bucks that weighed nothing (i carried both seats plus my toolbox in my arms out of the yard) and are more comfortable than any Rambler seat i've sat in.

here the cockpit is coming together. the pedal system hasn't been mounted yet (maybe not designed yet). the drivers floor is removable.

the four quarter panels got massive restyling. eliminated the teardrop swoop wheel cutouts, going with modern-looking (sic) semicircles. they're offset a bit rearward so it *sort of* looks like the swoop is still there. don't look at the drivers side rear quarter. that's where i learned how to do this.

the rear deck lid was for me major construction. it's "ten foot" quality sheet metal work. it's held up fine, no problems, just finish is lousy. it was very tricky to align and have it look like it belongs there. the lid is a spare hood. the section connecting the C pillars was made from scratch, sheet curved in two planes, and constructed as a box from "Z" shaped sections. all of the shaping was done with a maple top bench, 2 lb ball peen hammer, a 1 x 2" bar of steel i call "the sheet metal shop", a vise and hand tools. oh and a plasma cutter. the slit-bend-tab method works great, it's just tedious as hell. any shape is possible.

rear quarter and trunk were fairly straightforward, no rust, and other than the wheel cutout restyle not much change required. these cars have a spare tire well that is hilariously useless, only the old 15 x 4" wheels and tires fit. i chopped that out, greatly increasing both trunk space and room behind the differential that would eventually where the panhard rod system lived.

of course 50 years as a daily driver means a lot of fender-benders. there was a lot of bondo on the car, much of it very well done. the better work it was used correctly, for very shallow dimples. i left that stuff in place. a couple times i discovered it with the plasma cutter. very strange feel to hit bondo with a plasma cutter. doesn't work well, turns out. who could have known!

some shots of it close to final shape, engine in the car, load on the springs, all of the major components more or less hanging together as planned. when i started this work i was on the dirt out back. halfway through the project we built this rear deck (and refinished my lab building behind me). a much nicer way to work!

i think these were taken with the car in drivable form. this shows the first pass instrument panel (there were five!) with traditional guages to get the thing on the road. the computer at this time controls only lighting.

this is one of the reasons i decided to not paint the car. i scrubbed the enxterior with a wire wheel on my angle grinder, washed it all off to look, and that was that. everything functional was painted with Eastwood Chassis Black, but the topside was sealed in "Sculpt Nouveau" (awful name) clear lacquer. this stuff kicks ass -- bought it from Industrial Metal Supply, it's water clear, goes on with a brush, dries in minutes rock hard, and after three years zero yellowing, peeling, etc. hardly even stinks. low VOC too. not even expensive. it sometimes lifts Eastwood Chassis Black, sometimes it doesn't not sure why.

the battery was relocated a couple times but finally settled on behind the seat. this battery box holds it on the sloped floor pan. a nice afternoon project.

this is the gas tank from the 1963 American. it was a ruin when i got it. i had to chop two large holes to get access to the interior to clean it. patched the holes with screws and JB Weld but then sealed with Caswell's Phenol Novolac sealer so that no gas was in contact with the patch. seven years later i had to replace the sender, and it still looked great inside. good stuff. of course since this is a rambler few replacement parts are available. i fabricated a filler neck assembly and connected it with generic fuel filler hose. and of course the Rambler tank senders are all expensive NOS and i don't like the design anyway so i adapted this thing i got from Summit Racing that works reasonably well.

random pics with nowhere else to go. the front marker lights are aircraft surplus mechanical fuel tank level lenses with big fat one-watt white LEDs behind them. the silver instrument panel was the most complex i've installed. somewhere there's a video of it, it's got very many RGB LEDs, a radio with remote instrument panel box, and other things i decided i did nto want to trust on long distance road trips.

not just a headlamp bucket, Nash's clever design has made it structural. seriously, this modest thing, held in with six screws (that's the hint) is made of 18 guage steel and severely stiffens the front fender. poor Nash, post-war they couldn't keep up with the marketing end, but quality engineering wasn't a problem.



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