1972 Monte Carlo - Resto Mod

[dr.bombay]

I am starting this thread to document the resto-mod of my 1972 Monte Carlo.

My very first build thread – its so exciting! This build is intended to be a resto-mod. I want to keep the major cues of the original design but with a huge nod to modern suspension, safety, brakes, tires, engine control, etc and some more subtle custom touches. I want to do as much of the work as possible, partly for $$ reasons, and partly to learn as much as I can which is why I am starting w a garden variety “survivor” and not an SS/Custom or other collector item . With the realities of a small garage, day job, family commitments, and no outdoor workspace, I will be realistic about farming out certain items. From a performance standpoint, I want a modern powertrain, 6 speed manual trans, good handling and brakes, and a platform for 450-500 wheel HP (eventually). not be a show car and I am pretty tolerant of body and paint blemishes (read “personality” rather than “patina."

"but I thought Montes were...well...lowriders?"

I have always loved the lines of the first gen monte and I liked the fact that they are often overlooked among the muscle car circles despite just being a big Chevelle. Here she is:

.172634

[dr.bombay]

172704
Monte after dark

[c4racer2]

Cool build. Keep us updated. I was considering doing a similar build a few times over the last few years but decided I didn’t need two PT classics.

[jaybee]

I too have always loved the looks of those Gen1 Montes.

[dr.bombay]

The car started out life as a plain ol 350 with a th350 trans and a 2bbl carb and AC in Placer gold (think sweet potato + squash baby food) with a black vinyl top.

Somewhere along the way, someone added an edelbrock dual-plane aluminum manifold and 4bbl carb along with some flowmaster 44s. The AC compressor went MIA at some point as well.

After getting the car home, pulling the carpet and going over its condition in detail, a few things jumped out.

First of all, it *really* a survivor. the basic maintenance has been done but there are a whole lot of original parts here (bushings, springs, etc).

There is serious rust through around the back window (thank you, vinyl roof) and at the bottom of the trailing edge of the front fenders (GM A-body “cowl clog”). After gutting the interior panels, carpet, saggy headliner and seats, there was a rust hole in the rear seat floorpan courtesy of a lone acid-spewing AA battery that probably fell out of someone’s pocket and last saw the light of day during the George W Bush administration. That was about the extent of rust that was found.

First order of business will be dealing with the rear window rust

[Peanut1959]

I love seeing builds of non-traditional models. Carry on. Subscribed!

[dr.bombay]

Appreciate the encouragement. I always feel that I am one line item on my to-do project away from being totally over my head.:nopity:

On that note, time to get the heat gun and glass removal cutter tool and liberate the rear window. with the window glass out, i can address the rear window channel rust.

[dr.bombay]

Aaaaand, we’re off

172768

[SSLance]

Love a long hood Monte!! Looks like a great starting base for a project.

[dr.bombay]

172816
Oof. Some compassionate amputation needed

[rickpaw]

Love these 1st gen Monte's. Learned how to drive in a 70 Monte. Wished our family had kept it.

[Peanut1959]

Ewwww, that glass channel is crispy! But it's not so bad it can't be fixed.

[dr.bombay]

Crispy indeed - The rust was pretty bad in this area. In addition to gearing up with whire wheels and freshly charged drill batteries, I feel like I needed a tetanus shot from just looking at it!

The next step was to take measurements of the window opening and panel surfaces and cut out the rusty sections on the channel, quarter panels, and center filler panel. To do this, I first center-punched the spot welds and then drilled them w a spot weld cutter. The last bit of coercion came from a few bumps of a pneumatic air chisel. I tried not to get too caveman on this step and distort panels. here's a pic near the end of the fill panel removal

[dr.bombay]

172841

and the drivers side "shoulder" of the window channel mocked up. This came from a vendor that specializes in patch panels and needed very little shrinker/stretcher work to blend in. it still took me a while though because it s a new process to me :scared::drive2:

[dr.bombay]

172843

[Peanut1959]

What a time saver that patch panel is! Sounds like you've got a good game plan.

[Kenova]

............. in Placer gold (think sweet potato + squash baby food) ............


LOL
At least you're not describing what comes out the other end.

Ken

[dr.bombay]

172896

Tacked in the patch panels after some weld through primer. Realize the weld through primer will have to get sanded off or sealed before paint since the zinc/etc in the weld through primer may not play nice with body filler, seam sealer, or regular primer. Next steps are to tack in the passenger side and weld up both sides and grind down flat being careful not to add so much heat from either welding or grinding to create warpage. After that will come the center fill panel

[dr.bombay]

172897

Reconstructive surgery on the pass side. Feel kind of like Dr Nick Riviera...

[SPLATT71MC]

Nice to see another Monte Carlo build. I've been working away at mine little by little for about 7 years now.
https://www.pro-touring.com/threads/107227-Project-Hiway-Star-71-Monte-Carlo

[Alwhite00]

Looking good. Make sure to fit your chrome trim before paint.

[dr.bombay]

Nice to see another Monte Carlo build. I've been working away at mine little by little for about 7 years now.
https://www.pro-touring.com/threads/107227-Project-Hiway-Star-71-Monte-Carlo

Love it! :cheers:

[dr.bombay]

Some more surgery around the back window. Picked up a replacement trunk fill panel. It fit pretty well except one of the sides seemed to have a slightly different angle on the drop down tabs than the existing quarter panel. The location of the channel and the overall shape was dead on though

172933

[andrewb70]

Looking good. Make sure to fit your chrome trim before paint.

This is excellent advice. When this area was repaired on my GTO the shop actually used the OEM as a guide to build the area around the window.

Andrew

[TonyHuntimer]

Cool! It's good to see people building more than Camaros. :)

[dr.bombay]

173172

3d Tetris coming together. This was one of the major rust areas of the car. Once this is done, the decision will be to move onto mechanical or patch up the roof. I started using 0.023” wire but that was not conveying enough heat to get good penetration for plug welds so I switched to 0.030” wire which is working much better after I spent a little time on the welding table getting my amateur technique dialed in. I am using MIG process with C25/Ar75 shielding gas.

[dr.bombay]

173440

Done! Now time to move on to the front suspension

[TanMan]

Great! Since you wrapped up that metal replacement around the back window I can go ahead and bring over my ‘70 Grand Prix so you can do the same thing;)

Seriously though, loving this thread. Great work so far. Montes and GPs have so much in common so I enjoy these builds a little extra.

[dr.bombay]

I am a fan of the early GPs and also the colonnade era GA’s if only I could find one. The bird beak and catwalk grille in a world of bland camrys and accords is just too cool


Up next is the front suspension. After much research and considering my budget and use case, I decided to go with UMI Stage 4. I like the Viking front shocks and the swivel (roto) rear control arms. I am also replacing all the steering linkages and the steering box. This car is a survivor meaning that there are dust boots and bushings on here that were manufactured when Orange County’s very own Richard M Nixon was in the White House. And like tricky dick, I am also “not a quitter” when it comes to wrenching into parts unknown. Approaching this with a 1/2” ingersoll-rand impact and can of Kroil penetrating lube.

The suspension came apart fairly easily. The front spring are OEM and were fatigued enough that after splitting the ball joints and swinging down the lower control arm, the springs just fell out. Almost didn’t need the floor jack to contain the potential energy in the spring after all



173637

[dr.bombay]

Cleaning up the factory welds. There are areas of the frame where the old stick weld bead is not even on the seam and other areas where the pieces seem to be held together by weld spatter. It is truly shocking that these cars have survived 45+ years

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173824

Plan here is is to reweld the key load transfer/stress points like the cross member-to-frame joint and the abutting channels near the control arm pickups

[dr.bombay]

174923
Viking Double adjustables and UMI tubular arms mocked up

Then came a ton of additional grinding and re-welding of the frame: 1) seams on the front frame horns (the OEM weld beads weren't even on the seam in places), 2) the engine crossmember connection to the longitudinal frame rails 3) seam around the rear lower control arm ears and the frame

Then front suspension mocked up
174924

And here is the top view with fender liners out. 12.7:1 boregeson steering box and UMI bump steer tie rods. Next will come a new center steering link and idler arm drag link. The gear looked original and there was a decent amount of play in the idler arm joint and the inner air rod links. I will reuse the original Pittman arm as I can't really see how that thing would even need to be replaced based on its design.

174925

I can thank all this quarantining for the push of activity on the car!

Some bugger-ey welds on the frame below. looks like I need a little less wire speed and maybe a but slower travel speed. I am certainly no pro but I am having fun!

[dr.bombay]

Now time for brakes. I decided to go with a C6 Z51 setup to keep as many OEM parts as possible (pads, rotors etc). I had a bunch of c6 parts lying around from the corvette I used to own so why not recycle? I used KORE 3 for the brackets and other components (Tobin is awesome). I used a 72 A-body from DRUM hub and had a local machine shop turn them down and chamfer the outboard face to fit inside the corvette rotors. I also replaced the studs with 7/16x20 ARP extended studs. upon pulling everything together, I realized how much of a pain the long lug studs are - you can't get the rotors on/off without unbolting the caliper housing from the spindle bracket. ugh. Live and learn.

The tolerances on my drum hub and spindle were such that I had to slightly shim the caliper brackets to center the caliper over the disc. Kore 3 was super helpful in answering my 1000s of questions and getting this sorted out.

Note to self/others - never use a crescent wrench to disassemble brake lines - trust me and use line wrenches instead!

So damn sexy!!

174926

[dr.bombay]

Since stock wheels or even 17" stock "reimagined" wheels are not going to work with the caliper diameter of the C6 z51 brakes, i needed to go to 18" for wheels. rather than getting out the micrometer and trying to nail stance and fitment with all the new parts coming together (aftermarket suspension, brake hubs, calipers), i decided to keep it simple for now with the expectation that once i get alignment, ride height, and some real-life miles, I can think about custom offsets etc.

ended up going with TT2s in 18x9 up front with 265/40/18s. I will go with 18x10 with 295/40s in the rear. to lear the depth of the c6 calipers, i had to run 3/8" spacers upfront (not ideal but will work for now). I havent dialed in the camber but it looks like it will be pretty tight against the outer lip with upon compression to the bump stops.

177447

[andrewb70]

Nice progress!

Andrew

[dr.bombay]

Next step is the rear end and rear suspension. I know the cardinal rule of car restoration is to tackle things system-by-system to not end up in a demoralizing morass of loose parts. However, i will bend this rule a bit to pull the fuel tank and fuel lines to get access, inspect the trunk floor/drop panels for rust.

Pulled the stock fuel tank which was actually in good shape. Since the car had been regularly driven, the innards were clean and there were no leaks or rust. there was a small dent on the bottom which my son wondered if it might have been the result of 1970s style / Fast and Furious Tokyo Drift (yes a Monte was character in that film) car chase jump... i think (hope?) not... Which gets me wondering - how did that golden era of car chases coincide with the rolling sofa cars of that time? It didnt cross my mind as much as a kid watching Steve McGarrett chasing bank robbers on twisty highways in Hawaii in a 5000 pound Mercury Marquis with 7" tires :drive:

But I digress. The tank and sender went up for sale and went to a new home in a local kid's chevelle build. My plan is to get a dedcated EFI tank rather than messing around adding an internal sump box. With the tank out, i could get a good look at the floor which looked great and free of rust. the whole area was washed down, scotch-brited, and primered with factory-esque Zinc Phosphate. I think it was Zinc Chromate from the factory but i understand that stuff is mega toxic.

177594

Oh and the drab green primer color was chosen to match the remaining primer i see under the floorpan and inside the inner structure. Some archeology tells me that this was consistent with GM assembly practice in the Van Nuys plant where the Monte was built in '72. Again - not going for a purist restoration but want to keep the history where possible and where it doesn't conflict with my modernization goal.

[dr.bombay]

One big chunk of the decision-making for the driveline (and the budget) was the rear end. the car was originally a 350 2bbl with a TH350 so maaaybe it was making 200hp from the factory which justified the 8.2" open carrier 10 bolt. I heard from builders that the best case scenario for this with upgraded guts was about 400hp. That was not going to work for what i had in mind for the car (manual trans + 475-500 whp end of day). Although it is probably overkill, i decided to go with a 9" assembled by a local builder with whom i have worked with before. Used a Currie housing with 1967 width (slightly narrower than 68-72 but with the same mounting points/spring perch location) True-trac diff and 3.50:1 gears. Corvette c6 z51 rear brakes went on (again - hardware from Kore 3 less c6 rotors and calipers I had laying around) with fitting for parking brakes which i will have to figure out later. the UMI bushings didnt quite fit in the currie housing so i went with the currie articulating joints on the housing end (the UMI joints are on the frame-tab end) so the upper trailing arms will be double-jointed. UMI verified that this there are no issues with doing this. the only thing i am a bit worried about it NVH but i wont be able to judge that until the car is on the road.

[dr.bombay]

Hey All,

Between work and general life responsibilities, the Monte has been catching some zzz's. To add to that, my son convinced us to let him launch another car project (yes - two concurrent car projects is a recipe for getting 0 car projects done...). I will say wrenching on car is a bit therapeutic with all the goings on in the world. Here is the rear end in the car with the UMI UCAs and LCAs. I'm using some heater hose on the two spring ends as isolators. With the fuel tank out, and shocks out and rear end at droop, i can start routing brake and fuel lines. I am a little worried about doing those with the body still on the frame but i am also not thrilled about doing all this on the car and cruising around with 49yr old critical hardware. Its a little hard to see in the pics but i did some gusseting of the rear frame "bridge" to the longitudinal rails and some reinforcement of the UCA frame ears. both ears showed some small cracks near the frame end which I had diagnosed as likely-impact related rater than fatigue-related by a retired metallurgist i know. crack or no crack, those tabs seem really flimsy to me - especially with the limited frame-to-tire clearance that I will have to maintain here (about 3/4" at the sidewall bulge).

183245

[72'Monte]

How's the monte coming along. Hopefully soon I can start my monte build.