This will be my 2nd hot rod build. Though I've built other types of project cars, I love hot rods the most, I grew up around them (late grandfather was a big street rodder in Nor Cal), and really enjoyed building the "Rice Rod" '31 Ford with Toyota power (link to that one here). That turned out nice, but… maybe too nice. I robbed myself of the “rat rod” experience I was originally going for, and it was never very fast, even though I did 90% of the work to turbocharge it without actually doing so. I loved the style of my '31, so no regrets, but I told myself the next one would be different. So when a friend was cleaning out this hillbilly creation from a Florida backyard, I couldn’t p*** up the chance to build another hot rod out of the rotten shell that vaguely resembled a 1934 Chevy. At least, we're pretty sure it's a '34 based on what's left of it. My ‘31 Ford started out almost this bad, right? $100 later it was sitting in my own backyard for almost 2 years. Of course I took my 90 year old Chevy home with my 50 year old Chevy Since then I did a few other projects, including a detached shop built in the very spot that Chevy carc*** had been sitting. I had to look at it and move it around while building my shop, and that really got the gears turning, and looking forward to working on it. Goals? It will be a true all-Chevy rat rod (to start off, at least). It will be fast. It will be turbocharged. It will be cheap. Perhaps...even cheap enough to run the Gr***roots Motorsports $2000 Challenge. At least until I decide to make it nice again. The plan: Fix up the body shell, chop the top, set it on a Colorado frame, and boost the Atlas inline motor.
First let’s take a look at that body... Bondo everywhere, even the uncured, still-gooey kind. Galvanized panels just riveted in wherever needed Some remaining structural wood pieces. Yes, structural… Oh and a RV window as a sun roof. The execution was actually not bad, but…yeah. That probably has to go. So far I’ve blown apart the body and removed all the structural wood. This is not news to many of you, but it seems these were built more like carriages back in the 30’s, with an internal wooden frame that the metal body panels are nailed and screwed to. The A- and B- pillars are not attached directly to the outer skin, but are carriage-bolted to the wooden pillars. Ah so that’s why they’re called carriage bolts! The idea here is to remove all the wood and rust on the interior and weld in some metal structure for the body. I am literally un-nailing(!) the pillar panels from the body, cleaning them up, then welding them back in properly. Despite how stripped this body shell is, there is still plenty more to cut out…
Reasons for the Colorado pickup donor: Powertrain: GMT355 is the platform that underpins the 04-12 1st-gen Chevy Colorado, GMC Canyon, and Hummer H3. It’s closely related to the GMT360 which is Trailblazer, Envoy, etc. And they all come with GM Atlas Vortec engines, in flavors ranging from 2.8L or 2.9L 4-cylinder to 3.5L or 3.7L 5-cylinder (Colorado, Canyon, H3 only) up to 4.2L 6-cylinder (Trailblazer, Envoy). These are becoming popular for swaps because they’re built strong like LS bottom ends but with light aluminum blocks and good flowing DOHC heads, and they’re just as cheap and abundant. They can be tuned with HPTuners just like any LS, even with turbo. And unique to the 4 and 5 cylinder, they can be had with a factory 5-speed manual, the venerable Aisin AR5. The 4.2L 6-cylinder has a unique crank bolt pattern, with no OEM flywheel/clutch option, so staying with the 4 or 5 cylinder has a unique $2000 Challenge budget advantage. Ch***is: The Colorado isn’t just a powertrain donor for this project though. They are lightweight yet body-on-frame, which is a great combination for a hot rod. Especially the regular cab 4-cylinder which only has a 3,100 lb curb weight. The wheelbases are a pretty close match and the rear axle is the right width. Front is a very compact double wishbone (think Mustang II). I’m optimistic that this ch***is will be a good foundation for a hot rod build. I’m going to use everything I can from the truck and recoup the rest, which has been my go-to Challenge budget strategy. So I bought a 2005 Chevy Colorado 2.8L 5-speed on Copart. It runs, it drives, it has a quarter million miles, but no weird noises or engine lights. I would have preferred the 5-cylinder because more is better plus inline-5 noises, but got impatient in my search for the unicorn 5-cylinder, 5-speed, regular cab, running driving truck under $1000…yeah it just doesn’t exist. I can always swap out the motor for the 5-cylinder, 4.2L 6-cylinder, or even an LS with an adapter. I think the benefits of starting with the correct sized Colorado ch***is and factory manual trans hardware will outweigh a bigger motor, at least for now. The interior smelled of Montegos and the bed was full of at least 185 ****s, plus some debris from the wreck. Clutch tool behind the seat implies that job was done at some point. Basest of base models doesn't even have the Oh **** handles. No rust, but plenty of that red Georgia clay. Also shown is the 10-bolt 8.0" rear end and one of the front drag wheels. If you squint, that looks like sports car suspension. There she is, the venerable 2.8L LK5 4-cylinder. 175hp at 5,600 RPM. I bet we can spin it faster and with more boost.
Pillars are cleaned up and tacked into the body now, with weld instead of wood! Had to make this upper door frame panel since I only had one side. Just tacked for now until I can box these panels in after setting the door gaps. Next step rockers. Probably square tubing for that. But first let's see how it compares to the donor car. I think it's going to work out well. Wheelbase looks right and engine will have to set back. Speaking of engine, here's my pieced-together sub-$300 turbo kit, all of it used parts. Holset HE351 off a ***mins 5.9, random intercoolers, 80lb Siemens Deka injectors, and a AEM wideband.
Health check on the donor car. Overall just getting acquainted with the Atlas and taking measurements too. Compression check on the motor looks good. 150+-5 psi across all 4 cylinders. Spark plugs look pretty worn out. A couple of them were over .060" gap. Stock is around .042". AC Delco brand plugs with Delphi coil packs. Wonder if original or just serviced with dealer parts. 263k miles on the clock. Also got the body all squared up and stiffened with some cross bars. Doors are also tacked on for now. I think the next step is to build a perimeter frame for the floor and attach it to the pillars. Floor will be tricky because the frame will need to be channeled quite a bit into the body. The Colorado frame is surprisingly beefy at about 5.5" x 2.5" at it's thickest section. I am planning to modify (chop up) the frame to match the body channel in the floor, or build my own frame with 2x4 tubing. Hoping to avoid the latter for budget reasons. Also thinking ahead to incorporating a NHRA roll bar. I may not need it, but hopefully I'm fast enough. And I have a good opportunity for the roll bar to be the main structure of the body, tucking close and welding directly to the B pillars. The base plates of the roll bar will also serve as frame attachment points. At least 3 for each side. Got some ideas to noodle on.
Hopefully all these pictures are coming through. I found these diagrams. My regular cab frame will probably need some modification where it necks down to the front suspension. It stays too wide and parallel as the frame goes from rear to front, and my body is too narrow in this area. The rear is a great match though and I like how narrow the front is where it will be exposed. Engine mounts and trans crossmember will also be pushed back while I'm chopping up the frame.
This brings us up to Labor Day weekend 2025, working on the floor. The floor is absolutely key for this build, mostly because it is entirely missing. It will serve as the dimensional foundation for everything else. It sets the channel depth, which I guess is roughly 4", and it ties the door frames together with that key 4th side out of 4 sides. I started by bending up some sheetmetal into a L shaped rockers, lowering the body down until it was sitting on 1" tubing (I love the lift!), and tacking the rocker panels to the A and B pillars. I making up all these terms. I'm sure real Chevy restorers call them something else. Then I got my 3-point hydraulic tube pincher to gently shape some 1" round tubing into a curve that matches what I think the body shape should be. This tubing matches the round trim shape of the rest of the body. This tubing will be the lowest point of the body. The frame may hang about 2" below this level, which I think will be cool looking. Then I tacked the rockers to the tubing. Now the door frames should be kinda rigid, so I cut the tacks on the doors. I had welded them to the body to help it retain door gaps. Doors open smoothly! Sweet! Now uh...what next? Some bracing was moved around to make room for the transmission and driveshaft tunnel. I would like a slightly more solid body first before doing frame stuff, so it's time for patches. Might as well start with the worst one from the video above. I like that. I even used some 1" tubing to complete the rim shape of the fender. Inner fender itself will need more work, but I just wanted this front corner for now. First time using the shrinker. I rolled the edge of the sheet over some round tubing, then shrank that edge until it looked like a fender. Started on the front corners too. I really enjoy this part. I think once the full length of the rocker areas are patched, it will be time to look at that frame.
Some progress on this corner. At this point I was ready for a frame before continuing with the floor, tunnel, and firewall so I can see where all the parts end up.
Donor dis***embly day: The little red (express?) Colorado is now bedless, fenderless, bumperless and free of coolant. It also has lots of dirt where Midwest cars have rust. First recoup happened within hours of listing the part-out ad. Door weatherstripping, dash vents, headlight switch, and the gross vinyl floor went for $80. You never know what people want until you part out a car. Getting interest in the bed and cab too, both of which are off now! Rolled the frame outside and gave it a good scrub while inspecting it. Literally no rust, it's unbelievable. I love Georgia. Just that good red clay caked up everywhere. Lots of gears turning in my head. Like I thought, the drivetrain will have to move rearward by a foot or so. A regular cab 4x4 driveshaft solves this, plus some cutting and welding of the cross members. The gas tank might be okay where it is. And overall I like the curvature of the frame, how it kicks up over the front and rear axles smoothly. I can definitely work with this, especially without any rust. Next I'll roll it under the coupe body and see how the widths match up.
The setback needs to be more like 18", which is problematic from a driveshaft perspective. I may need another junkyard solution. Luckily it looks like very generic U-joint sizing on both ends. Off to Rockauto for some truck shaft research. Needs to be around 42" or less total length This 2wd one is 60", 4x4 is 48", maybe something else is shorter. Got the body down as far as it will go before cutting the frame. Had to trim a few brackets and strip the frame of the fuel tank, lines, and other things. Not sure if I want to cut and reweld the frame, or splice in a 2x4 tube or something like that. The whole rear half of the frame is the perfect width though. Will probably chop off everything behind the leaf spring shackle.
Rear half of S10 2WD ext cab 2-piece driveshaft. Might still be too long, but this one is cutable. Also got some later Atlas coilpacks off a Trailblazer which should help with boost since these are supposedly the same internals as the proven LS coils. Also a 3 bar MAP sensor off a turbo Chevy Cruze and a random steel gas tank. The plastic one from the Colorado is too big and I can't modify it. The new driveshaft is almost 15" shorter but that might still not be enough. The u-joint is the same size for the axle. The front is slightly diameters, but I bet my Colorado one will slip over the S10 one and weld up nicely. I cut all the crossmembers and random brackets off the frame, revealing something almost aesthetically pleasing. Careful measurements have been made for the frame slices. Still recouping money from the donor car, and removing some parts for myself like column, gas pedal, and gauges. Body is almost ready for s****ping, which will certainly be a relief to my neighbors. The manual trans stuff is selling well, since it's always cool to manual-swap anything. Here's $100 of recoup + plus shipping. Obviously I still need equivalent parts for the hot rod, but I figure I can build 2 pedals that package better for cheaper (recall the under-dash linkage contraption from the Rice Rod). I also have a brand new all-metal clutch master cylinder that came in the trunk of my Camry, which was apparently like 8 bucks on Rockauto. I plan to use that with a metal line and a $12 slave cylinder adapter as an upgrade over the OEM plastic molded junk that won't fit my body anyway. Plus it gets rid of the stupid GM quick-connect clutch fitting. More on that later. Of course that means I need to pull the clutch slave out to install the quick-connect delete fitting. Which happens to be a good opportunity to pull the flywheel off too and delete the balance the shafts while the motor is on the ground. Now over $300 in recoup with both doors sold. I pulled everything else I could think of off the body that might be worth selling and it's time to s**** it.
Here is some major progress - the frame pinch method worked well! I cut 3 pie slices out of each frame rail and squeezed them together. I had to do actual trigonometry to map out each cut of the frame. The frame width near the front of the body went from 46" to 36", just narrow enough to fit under the body. I will need to notch the leading 6" or so of the body, but I think that will look really cool with the frame poking out. Body on frame! Well, it's just sitting there not fully attached or with any brackets or bolts, but this is where it will live. The floor will build off that 1x1 square tube to span the width of the body. The 1" round tube hangs down over the outside edge of the frame, covering all but the lower 2" or so like I envisioned. The upper cross-member with the holes originally supported the truck bed, so that's another good support area for the body. The bulkhead between trunk and interior will probably be there too. I am not quite sure about the rear of the frame. It juts out too far from the rear of the body. I will probably lop it off just past the rear leaf spring hanger. There is obviously some body missing that I will need to build up, but I don't think it will extend naturally that far out. If you follow the curve of the trunk it will end near the front of the spring hanger. I may have to get creative with some kind of bumper to tie it all in. I would like to keep the leaf springs just for simplicity instead of fabricating a 3 or 4 link setup. They seem very well-designed, with plastic spacers between each leaf to allow free sliding and movement without binding, even with just my body weight jumping up and down on them. But overall I like the stance so far. I think it's going to look good, especially once the suspension squats down. The Challenge budget as it currently sits is $852, including $350+ in truck part-out and a pieced-together turbo kit on the shelf. Most of the remaining budget is big raw materials like the roll bar tubing, sheetmetal, windshield/door gl*** and/or plexig***. Plus all the little bits that add up to make a car run and drive. I saved a ton of useful parts off the truck, such as steering column and wheel, gauge cluster, ECU, seats, seat belts, and even cut the floor out of the truck bed to use for patching. It will be tight, but Challenge budget turbo hot rod is still looking possible.
This is relevant to this thread, and vice versa. I'm also paying close attention for the sake of a hopeful future project.
Really liking how you narrowed the frame I'd maybe look into having each main leaf spring shortened (chopped with new end rolled) and move the spring hangers forward enough for the body to hide the hangers. If there's a spring shop near that could do it, it might not be too expensive and would, in my mind, add a lot to the overall look.
We are almost up to present day. Before: After: I can make this work. I think next I'd like to mount the powertrain to help guide floor fabrication, so I removed the engine mount brackets in order to reposition them rearward. Now I'm thinking about how to clean up the front of the frame. I might bridge between the two rear LCA mounts, which would make the 2nd cross-member unnecessary. Steering rack may also have to rotate down to straighten out the u-joint angle since the steering column will be further away. Frame horns will need to be shortened like the rear. The radiator and grill shell should live just forward of the steering rack where the front cross member is. I should probably find a radiator and grill shell. Shuffled the shop around last night and got the powertrain sitting on dollies for some fitment and positioning. I am debating between a flat firewall or a concave one to set the engine even further back. Keep in mind the frame is sitting several inches higher than target ride height. The OEM Atlas engine mounts are pretty easy to work with. Just a simple vertical rubber donut bushing with a bolt through it. Some m***aging of the brackets and they will be ready for welding.
This brings us up to October 2025 Engine is stripped down and mounted to the frame. Trans still unsupported but I wanted to get a feel for the proportions. Driveline angles are looking okay so far. I like how the engine looks with AC and PS removed. I also loosely positioned the alternator in the low spot where AC normally goes and I like that much better than the high spot near the intake. Engine mount brackets cut out of some s**** These mounts put the oil pan flush with the bottom of the frame. Engine could probably safely go lower but this is looking good so far. I put some wood blocks in place of the front springs and I ratchet-strapped the rear suspension down. Removing the UCA revealed a potential modification to the double-wishbone geometry.I can simply re-drill that UCA bracket to get a more aggressive camber curve. Hmmmm. Front is a bit too low but it was fun to see it here. Playing with the loose UCA, camber set to autocross kill mode. I haven't touched the LCA adjusters yet. The rake is a bit extreme, but in autocross mode the rear and front tires will probably be the same size. But, I like it. Heck, even looks good from the back It's starting to look like a hot rod to me! It just need the front raised back up a little bit and maybe some lowering blocks for the rear leafs. And a radiator grill shell. And the roof chopped. And a high-mounted turbo with the exhaust pointed up...
Good start on the trans cross-member. At first I thought I would simply shorten the original one. But I also moved the motor down a bit, so the cross-member would hang too low. So I raised the s**** bin to fab my own. This will be lighter too. Then I got distracted by the other cross-member, got it fit up and welded in. Next I'll make brackets for the trans one so it'll be removable. I also started reverse engineering the exhaust manifold flange to build my own turbo manifold. There is a file on the 4200 wiki that Calvin Nelson was nice enough to share, but it's for a 6 cylinder which is not really matching this engine. This probably be a sendcutsend expense unless I learn how to use the water jet at work. Back to the trans crossmember. I got hung up on how to make it removable. I wanted one that could drop out from below to make pulling the engine easier. After debating a few fully custom solutions (lots of cutting and drilling and welding), I looked at the front of the frame and realized I could re-use this extra crossmember I was planning to cut out anyway. It has a bolt-in center beam that removes from below. That saves me from having to invent something worse. I am planning to brace between the rear LCA mounting points on the frame instead due to the engine setback. This crossmember is a 2WD frame thing only, while the 4x4's use a front differential in its place. So I guess I just inadvertently made room for a front differential...no no, stop that, focus... I cut down the square tube I made last week that the trans attaches to and welded pieces of the new crossmember to it. This whole piece is removable from the frame and trans from below. And that's a fully mounted powertrain! I'm running out of ways to cut up and modify this "stock" frame, so I guess soon I'll take everything apart so I can flip it over to finish welding it up and fish-plate over the pinch joints.
By November I took it down to bare frame for welding, plating, and shaving. Fully welding the cut joints and cross-members, plating over the joints, and shaving off unnecessary brackets. Lift was great for dropping the suspension and axle off the frame. In the spirit of the Challenge, I harvested the fish-plates for the frame weld joints from discarded pieces of ...frame. Probably overkill to fully plate these joints, but why not. I even made some of them decorative. Then a little flat black to keep the rust off. I did not finish the engine mounts in case things moved around while welding, but the engine dropped right back into place. I really am running out of ways to hack up my "stock" frame. But the steering rack pinion angle is all wrong. The rack is held in by a circular clamp, allowing me to rotate the rack back by 45 degrees without upsetting bump steer geometry and whatnot. This allows the steering shaft to aim perfectly at the firewall while avoiding the engine mount and keeping the u-joint angles to a minimum. Once satisfied with this angle, I will have to weld the rack mounts back to the frame. A keen eye will also notice that I shaved some unsightly bracketry off the upper control arms.
Last we left off, I had the steering rack mount all chopped up to point the pinion at a different angle. To determine that angle and fab the steering rack mounts, I really need the column in position. To position the steering column, I really need to look into driver ergonomics and seating position. So to do that, I need to put the body back on and start fabricating a floor. So it goes with custom cars... Not quite finished, but enough to slap some plywood down, throw in the seat, and sit in it. I suspended the steering column with copper wire until it was just right. This will help me weld in a dash bar too. The vertical bars in the firewall show where the engine is set back slightly behind the main firewall plane, so I will build a niche in that area above the trans. With the seat loosely positioned, I was able to make the required vroom-vroom noises. I think this driver position will work out well. Plenty of leg room and still tons of head room for a helmet and possible roof chop. The front right corner of the seat is awfully close to the shifter, but it all fits with the door shut. There is room below the floor frame to sink the seat downward if necessary. With all that positioned, I think the steering shaft and u-joints will work well, just need to extend the steering shaft a few inches. But first I mounted the rack. The chunk of cross-member with the big huge bolt holes is welded back in and reinforced. This took probably 10 hours. CAD method of course. I like how simple it looks. It will probably be covered up by a radiator anyway. Had to push this out to work another car. Seeing a project in daylight is always motivational. Speaking of aesthetics, it's about time to remove the wooden front struts and replace them with springs. I tried 2 ideas: chopped stock springs (free in budget) and ultra ****py ebay-spec coilover "conversion kit" which is just the threaded sleeves you slide over a stock strut. 1.75 coils seems to be just right, allowed a slightly bit of preload only from the shock absorber's nut. Any shorter and the spring will be loose in the perch at full droop. I will wait to see what final weight does to the ride height, just like with the rear leafs. Side-by-side comparison to the coilover sleeves. Good to know this option will work if I want more adjustability or different spring rates, but I don't think I'll need it, so that's budget saved for now. I repeated the other side with the 1.75 coil chopped stock spring and I'm happy with the subjective "bounciness" from jumping up and down on the front cross-member. Which got me looking at the frame horns. Very pleased with this. The frame horns cannot be any shorter with the stock sway bar mounting. A little paint cleaned up the steering rack mount too. Then I decided to make the steering wheel turn the wheels. Just had to extend this shaft between the rack and bottom of the column. The OD of this section was exactly 1", so a piece of 1.25" 1/8" wall tubing from a past harness bar project was perfect to lengthen it. The steering wheel did this! Rack still needs to be de-powered properly, but that's for another day.
And this brings us up to present day, focusing on the driver. Steering is pretty well sorted, so how about seat mounting and pedals. The seat bracket slides forward and back quite a lot if the 4x 3/8 bolts into the floor are loosened GM was kind enough to include a template to trace in the form of a booster spacer. Decided to go with an under-floor brake setup. I don't have as much room or access behind the dashboard for bell crank system like on my '31. I think this will package nicer, though the floor will be a little uneven. Planning out a bottom-hinged brake and clutch pedal setup. The brake pedal will extend down below the pivot shaft and floor to push on the rear-facing brake master/booster. The clutch will probably be on the firewall due to the m***ive frame rail in the way. It's very small and close to the frame, so I don't think it will disrupt aesthetics too bad. This is actually for a manual Camry, which I found new-in-box in the trunk of the one I souped up last year. I also made a bracket for the GM electronic throttle pedal but the positioning is still in flux. This is about as far as I should go on the firewall for now, while I still have access to build the pedals.
I once heard a big-cammed Audi 5. Fives have a deep sound, and this one sounded a lot bigger than it was.
...pretty cool project, can't believe it turned out that well with what you started with...very nice work.
The Jalopy Journal
