1949 Cadillac Series 61 Build

[Qua-Hoon!]

Well I'm back. The car sickness has me again after a few years away. I found a 1949 Cadillac Series 61 for sale and picked it up for a reasonable price. Some people call this a Sedanette, but really that's for the previous body style. Either-way, it's the 2 door. It's still in shipping and should be here tomorrow but I thought I'd ask the questions now so I can research more on this rainy afternoon.

I've built a few cars in my garage before over the years, done frame off restorations, built engines, wiring, and a lot of welding panels for rust repair or improved gap fitment. I have this idea now that I think I'd like to build my own suspension for this car whether that be a front clip type of set up or just fully commit to the full frame. If I go full frame I know I need a frame table / jig. I've been trying to read any books I can get my hands on for this and have used the search function to find a couple main ones used. Honestly I know I can build jigs and level them, I'm mostly concerned with the math behind the forces and angles for set up and ride quality.

Since I've been out of the hot rod arena for a few years, I'm checking to see if my thinking is still the most current "best practice". This isn't going to be max performance or Pro shop built high dollar. I can only hope my skills make it look near that way at the end.

Car goals: 75% street and stop and go (I'm outside of Washington D.C. right now), 25% back roads and some autocross / track days if I can drive the car there. I'm not trailering the car to an event. Most companies don't make sheet metal, never mind parts for a 1949 Cadillac, which necessitates the fabrication approach I'm pursuing. The old C10, mono piston, front disk swap to 1949 Cadillac is not what I want to do here.

What parts should I look at / does my selection make sense?

1. Spindles - I'm looking at using used C5,C6,C7 uprights / spindles for this (I like this because if I decide to do AWD later I have something there to use) Brakes also bolt right on and are decent price.

2. Brakes - C6 or replacement

3. Control Arms - (This is the part I'm trying to math out along with control arm mounting, size, etc). I may be able to use stock C5 / C6 but I'm waiting to get the car to get frame measurements to determine if I need to make customs ones due to overall track width. Ball joints along with car weight / C.G. / ride height become my next thought - it's not a corvette.

4. Rims / Tires - I'd like to run a wider tire and plan on using rims that make the car look like it's still on a 15" rim to make it look period correct and use a hubcap. I'm open to rim and tire sizing opinions but my main concern is tire availability and cost. It the tires are so expensive it's a pain to maintain well that's just not for me. Common wider sizes from a Camaro / challenger /older Corvette is where I've been looking so far.

5. Rear axle / Rear Suspension - I may try to do an independent rear by using something out of a more modern Camaro. It may bolt up, or I may have to build control arms and may as well use Corvette uprights to match at that point unless a better upright is recommend. If independent rear is off the table, it's a 9" floating that I'll weld in a jig. Are we still using 3 links or has someone found something better for this type of application?

6. Engine - I'm going back and forth on this. I'm going to see what shape the 331 Cadillac is in first as 1, it's tied ot the VIN, 2. Its the original engine and kind of cool / different at this point for a build. I know it makes no power, but I'm thinking a mild rebuild (pistons rods, hone, balance) 390 Cadillac Heads and a set of VS mirrored turbos may push that thing to my power goal of ~450 RWHP / TQ. If it's trash, I have a 6.0 that was rebuilt with forged internals, Bullet cam, and texas speed intake with A/W intercooler and twin turbos. I have it kicking around.. but it's way more than I want this car to be... but it's an engine.

7. Transmission - T56 magnum or 8HP90 (or similar) I'd like to do AWD, but I cannot find a way to couple a T56 Magnum or 8HP90 to a transfer case (Maybe SCS gearbox - "Straight Through" and disconnect the front differential electrically, but I'm waiting on the car and for other things to be answered before I pursue that research more).

8. Suspension - Coil-over or if I can get a similar setup to the magnetic adjustable ride that Chevy uses, that would be nice and allow for more general use than all out track slayer and slammed ride.

Is there a program that people use other than building this all piece by piece in fusion 360 and seeing how it all fits and works together prior to raising the cutoff wheel and grinder? It's still cold enough that I wouldn't mind building this plan virtually first to test out a few concepts for the best solution. Please find the holes in my suspension idea. The engine and transmission stuff is mostly there for power, packaging and weight reference info for now.

I need to change this user name.. it's not "Cadillac's and Dinosaurs" enough.

Pics tomorrow / Friday once it's here and I start tearing into this. May start a youtube channel too idk.

- Alex

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[dhutton]

Looking forward to this one. Awesome project.

[wfo guy]

I'm a believer in full frames. I would use the aftermarket suspension because I'm not a suspension engineer. I'm not a fan of old engines. Your car, your choice. But if you intend to drive it a lot and don't have modern items, I think you may find a reason to not enjoy the car. In my world, all of my projects have to be as good as modern stuff or I failed. Just my plan, nothing else meant for anybody else. When you spend your money, it should be your plan. :)

[OLDFLM]

If you haven't seen this thread already it may provide some inspiration:

https://www.pro-touring.com/threads/118218-1950-Chevy-Fleetline-quot-Fiddie-quot-build?highlight=fiddie

[Joris69velle]

Cool project.

I make and sell adaptors to incorporate the full c5 front subframe and suspension. That might be an idea for you

Joris
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[dhutton]

I stuffed a full C5 suspension, steering, brakes and drivetrain including a stretched torque tube under my 56 Chevy Cameo pickup. Send me a message if you would like more info. I don’t want to muddy up your thread.

Don

[Qua-Hoon!]

I'm a believer in full frames. I would use the aftermarket suspension because I'm not a suspension engineer. I'm not a fan of old engines. Your car, your choice. But if you intend to drive it a lot and don't have modern items, I think you may find a reason to not enjoy the car. In my world, all of my projects have to be as good as modern stuff or I failed. Just my plan, nothing else meant for anybody else. When you spend your money, it should be your plan. :)

Thanks for the reply! I always appreciate the dialog. Totally understand this point of view as I'm usually in this camp as well. 5 of the 6 cars I've built and restored have been LS swap, T56 or 4l80 and I do keep getting better at doing the swap each time. I'm approaching the Cadillac engine idea like a caveman.. "piston go up, piston go down - make powa, head = restriction, boost maybe fix all problem, displacement = displacement, add cooling".

After I pulled this thing down the driveway I also agree with you.. this age of a car needs a full frame. They just are not beefy like cars from even 5 years later.

I built a 1957 Cadillac with a 365 Cad motor and 4l80e it's not a rocket ship but still has fun torque. Currently I daily drive a C7 and know I can't build a car to contend with anything like that with my current budget and car knowledge / fabrication tools and ability. So I'm hoping to make this just something a little different (mostly suspension focused), and challenge myself with making enough power out of the 331 if the engine is still salvageable. Should know more this weekend if it stop raining.

- Alex

[Qua-Hoon!]

Hi Joris! I may go this route so I'll keep you in mind for sure. Current opinion of my frame by me - a non expert - is that it's too weak to do any sort of spirited driving in. But we will see. Stick around and find the holes in my plan though, I always can use a second opinion from others that have done something like this before.

- Alex

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Thanks for this link OLDFLM. I'm checking this out now over coffee. Similar era car = similar problems I'm sure.

- Alex

[Joris69velle]

[QUOTE=Qua-Hoon!;1396620]Hi Joris! I may go this route so I'll keep you in mind for sure. Current opinion of my frame by me - a non expert - is that it's too weak to do any sort of spirited driving in. But we will see. Stick around and find the holes in my plan though, I always can use a second opinion from others that have done something like this

Those would be to use with a new frame of 2x4 tubing. Not to tie into an existing frame.
But either way ill watch the progress

[Qua-Hoon!]

Just a small update. I stripped out the interior and power washed the car. I think 5 lbs of dirt / mud came out of it.. I wish I thought of doing the frame as well because it has a ton of dirt on it .. but oh well.. it'll get dusty. I then pushed this tank into the garage and took the front end off to gain clear access to remove the engine. Hoping to remove the engine and transmission today and do the assessment on the engine. Check out this suspension. The upper control arm is also the shock. One thing that's good that I've noticed so far is that the engine is further back than I thought, and the front suspension is in front of the engine. I can also move it 2 more inches back before the firewall needs modification.

- Alex

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[ZZ430]

I am really liking this project!

Alternative body style is an understatement. Going to make a really cool ride.

How about that hood release cable? Talk about ahead of it's time, wow.

I like the idea of using the old motor for a base power plant. Maybe with modern touches such as fuel injection.

Good luck and keep us posted!

[Qua-Hoon!]

Thanks for the post!

I may attempt fuel injection but I know the way the heads sit with intake manifold opening I'll have to lay those injectors nearly horizontal to get them aimed at the valve. I may give this more thought when I build the custom intake manifold if this 331 is good to use.

- Alex

[wfo guy]

Just a thought: any old engine can be improved with a slight raise in compression, a modern ignition system and some kind of efi. Eventually it will come down to whether you intend to drive it everyday or just for special events. because you have exp., you are aware of the parts availability to achieve your goal. :)

[Qua-Hoon!]

Completely agree. I'd like to actually drive the car as it's fun to see on the road. This is why I'm not shooting for the 1000 hp LS build. I want to say the 331 came from the factory with something like 7.5 to one compression. I figure if I can move that closer to 9 to 1, better breathing 390 Cadillac heads, and maybe quick spooling twin turbos, this car should have tons of pep and be fun and weird. Now if I can figure out this frame stuff and setting ride height so it all makes sense.. then I can look into doing this as AWD as well. Currently figuring out the bends to acheive X ride height and performance is the part I'm researching and making sure I have a solid grasp on before I start cutting anything.

I purchased an engine hoist and it didn't come with any hardware.. I thought I could just bolt my leveler in today and yank the engine.. but the slot on the hoist boom was too small.. so I purchased a hook.. it'll be here Tuesday. Until then.. I get to try an learn more frame design.

- Alex

[dontlifttoshift]

If the track width works, and I think it will. I would use Corvette stuff for sure. Cut the frame off near the firewall and build from there. This was a Heidts clip on a Buick but everything is quite similar to your Caddy.

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[Qua-Hoon!]

Hi Donny! Thanks for the reply. I think I'll find some used C5 / C6 uprights and control arms to start planning this thing and see how it lines up. Looking at the pictures you provided, how did you know how much to move the front stub / cross member up / vertically? This is part of the design I'm trying to determine for myself as the frame rails are quite straight on the 49. I know adding that bend would drop the body.. but wouldn't that also mess up the rest of the front panel alignment? (I have about 1 inch of shim on the front core support). . Also what did you set the ride height to and does it scrape? I've been considering 5"

- Alex

[dontlifttoshift]

Pick wheel and tire diameter.

Pick ride height.

Set frame at that height and cut off anything that is in the way of new suspension.

Install new suspension.

Everything in between there is simple math based on spindle centerline. 5" is a good number, the Buick isn't that low because it didn't need to be. We wanted the wheels wells full and for it to look pretty stock.

Before cutting the front of the frame off, I made fixtures to locate the core support and bumper mounts. That is why I included the pic of the whole chassis on the table. After the new clip is on you can either weld those pieces back on or fabricate from scratch like was done here.


Sidebar. This is an enormous amount of planning and work, especially if you have never done it before, and doubly so if you are equipment, space, and ability limited. While I am capable and have everything needed to pull this off at a relatively high level I would absolutely do this first.

https://roadstershop.com/chassis-and-suspension/vehicles/1948-53-cadillac/


I also understand that everyone has different priorities for builds. For some the build is the fun, I would rather drive.

[Qua-Hoon!]

Thanks for the walk through. I've looked at RS stuff and previously purchased a front clip for my C-10 when they still made them. I'm just not in a position to buy a 30k frame with brakes and an axle right now. Maybe in a couple years. Also, this is the next step for me in building cars. I'm not incompetent, just trying to learn and plan before I make the first cut because I've never done it before. I still think I can do it myself. I just need to plan it completely to make sure it's right, as it's a big planning event like you said. I'll post some drawings soon for some hopeful feedback from everyone in the coming weeks. Thanks for sharing how you did your build!

[OLDFLM]

Just throwing this out there... you could graft a 2nd Gen Camaro/Firebird front subframe on the car and bolt on some tubular upper/lower control arms and add a sway back and a quick ratio steering box and be light years ahead of what the 49 came with originally. There's probably a bolt on kit somewhere something similar, and not have to graft on a different subframe, idk?

Rear suspension could be redone with RHE truck arms easily or a torque arm or 4-link. Upgrade to C5/C6 brakes all around (KORE3) and add coilovers of choice for ride height adjustments. Then find a 500ci Caddi and put a Terminator TBI EFI and drive the snot out of it! 1000hp LS motors are cool, as is rebuilding the stock 331ci motor but I think there's a better way to get to your desired goal. My dad always said "all it takes is cubic inches or cubic money to go fast!"

The biggest question you have to ask and answer for yourself is "what are you REALLY going to do with the car?" Auto-cross? Cruiser?

Look up Jeff Schwartz 82 Cadillac Fleetwood Brougham that ran the Car Craft Real Street Eliminator back in the day... that 4,000lb car didn't have a C6 suspension nor an RS chassis and embarrassed a lot of expensive sports cars by upgrading the bushings, increasing positive caster, shortening springs for ride height, big sway bar, etc. IIRC he narrowed the rear frame rails to get a wider tire out back, boxed the stock control arms and added a 1" sway bar out back with KYB shocks all around! He used a Trans Am 14:1 steering box and 12-in GM brakes with performance brake pads and stainless steel braided lines. And he did it all with a 500ci Caddi! .

[aaroncorvette]

What a fantastic looking car those old Caddies are.

It'd be nice to keep the Caddy engine, up the compression, 390 heads, cam etc ignition and FI. The old engines look better and perform great with a few updates.
The newer engines are great but there's just something about the old engines.

Looking forward to updates!

[Qua-Hoon!]

Just throwing this out there... you could graft a 2nd Gen Camaro/Firebird front subframe on the car and bolt on some tubular upper/lower control arms and add a sway back and a quick ratio steering box and be light years ahead of what the 49 came with originally. There's probably a bolt on kit somewhere something similar, and not have to graft on a different subframe, idk?

The biggest question you have to ask and answer for yourself is "what are you REALLY going to do with the car?" Auto-cross? Cruiser?



I thought about doing something like this. But honestly if I am that far into making things work, I may as well just build it to spec. Currently have the engine pulled and am going to do the suspension measurements on what I have vs what I hope it to be. That should start with determining what I need. Maybe I can use off the shelf stuff, or maybe that would be bad. Either way, C6 stuff is cheap.. and you can nearly bolt it up. My current main concern is track width if stock C6 components and rack and pinion things and how that integrates with the uprights.

I'm also trying to determine.. do I go T56 magnum again? My T56 Magnum I have was in a fire and likely needs a light rebuild.. it was new. But it also has a twin disk clutch and was very nice..

or...

8HP70 or 8HP90..

I've been following the Schwartz Cadillac (he just got it back not to long ago) and other builds for years. I was in New Mexico for a bit and drove past the "Cad Company" so many times without realizing what it was.. lol.. they sold me forged parts for my Cadillac 365 build.

This 1949 Club Coupe is NOT going to be a cruiser. Yes I will likely drive it to work once or twice a week and it will likely look kinda period in how it looks on the exterior and some of the interior. I'd also hope to take it on the Hot Rod power tour. If it gets an LS, then maybe an LS fest. But I have a 1957 Cadillac Coupe de Ville that I frame off rebuilt (forged 365 Cadillac, 4l80e, 4wheel disk brakes, stainless valves in ported heads.. waiting for interior and turbos)... and I call that the "Super highway Cruiser".. I don't need another one. The 57 was designed to seat 8 comfortably... granted 1957 sized people comfortably. This is hoping to be something closer to this - https://www.youtube.com/watch?v=JUPfkwO9yhk This car inspired the idea for this over 10 years ago. Finding the 48/49 was the hardest part.

I also found out out that the SCS "straight through" transfer case is straight cut gears and always a 50/50 split. If I do AWD, I hope for a 20F / 70R split. Or around that.. more research. Could get around 50/50 a bit with gears and tire sizes.. but more than likely I'll be looking on how to adapt a production AWD transfer case to a T56 or 8HP70.

- Alex

[Qua-Hoon!]

Pics from the engine removal and tear down.. look at that sludge. Yikes! Waiting till after I pull the crank for a better decision on the engine. The engine and transmission are stuck together because it wont rotate.. so I need to tear it all apart to separate the engine and transmission if just for better use of storage space. .. I'm also waiting to decide on the 331 to see if I can dry sump a 331 Cadillac. How to route the pressure / supply line is my main problem.. How do people do it if there is no oiling system like a SBC where you can provide supply from the spin on oil filter location?

- Alex

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[wfo guy]

Nothing a few days in the vat won't fix. :)

[Qua-Hoon!]

Hi everyone! I've been plugging away at the project this last year slowly. Picked up a S550 Mustang differential ( 2015 - 2023) with New Ford 3.55 with New Ford Traction Loc. ( FRPP M4204-M Diff and M4209-88355A ). I also found a 390 for sale and spent too much for it. Luckily I got it checked out and nothing is cracked (pics later). More pics and smaller explanations to follow.

I also started to 3D laser scan this car. Mostly so I can hopefully one day start building parts for it out of carbon fiber and by 3D printing. It's a skill I want to learn, and would allow for new parts to be made for this type of car that's near unobtanium.

Not nearly enough 3D targets (reflective dots) in this picture. You'll see later I've bracketed to both extremes.

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[Qua-Hoon!]

The beginning of too many dots. The scanner to resolve to .5mm accuracy needs a lot of processing power and ram.. both of which I didn't have enough on on my mega gaming rig I built for VR flight sims. So I've had to scale the scanning back and remove dots later. The more dots you put the more data points, which means another point for memory to hold. It was too much for this size of a scan in 2024. The sequence of adding the targets and seeing the progression in pictures I always found interesting.


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[Qua-Hoon!]

I really went heavy on the targets for emblems because I'd eventually like the 3D print these for others. I know the emblems they rare to come by and with the process to add actual chrome plating to plastic it could be a nice way to complete a car without having to find 1948 and 1949 pieces. Not perfect but better than a hole or a necessity to fill it in. It would at least give people an option.

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[Qua-Hoon!]

I came up with the idea through some research that I wanted to use C6 Corvette suspension to facilitate my all-wheel drive design plan. Mostly because the spindles / uprights / knuckles use the same hub bolt patter front and back. I found C7 Grand Sport brakes and thought they would bolt up.. nope. So now I am waiting on my C7 knuckles to show up. I will need to change the upper control arm from my reading as the upper ball joint changed from C5/C6 being the same to C7 being different. I don't want to modify the hard part so buying off the shelf parts will be easer later on. Luckily C7 upper control arms are easy to find and not that expensive to find new. The lower control arm from my research can remain C6, but I will verify this later. The pics show C6 rear suspension being mocked up in the front.. I thought the lower control arm from the rear would fit the C6 front cradle, it does not.. Later I get C6 lower control arms for the front to achieve a better mock up.

Here you can see my doing a a very general fit check for the concept.. I'm mostly concerned with ride height and front differential clearance at this point. Honestly this is still something I'm looking at and may need to run a different front differential for this reason. As it's AWD, both front and rear gear ratios must be the same AND the wheel diameters with tire must be the same. I know there can be a slight amount of variance, but currently I'm planning for same same to keep it easier. I'm also looking into different differentials mainly due to the front differential rotation.. need some recommendations if anyone has any.

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Getting serious about the mock up now. Overall it looks like I do not need to narrow the front C6 cradle. Not 100% certain yet but by macro level mock up it is looking ok.

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[Qua-Hoon!]

I braced the front and tig'd it in before removing the cross-member. I wanted to save it incase I discovered along the way that this wouldn't be feasible. Good thing I did I may have to move before I complete this front suspension swap. Overall I'm surprised at how thing thing looks like it wants to nearly bolt in. I roughly clamped up the front suspension to see if I'm crazy. I know the suspension angles / arcs aren't remotely correct but it's more about macro fitment right now. The rim used is off of the rear of a C7 Grand sport and it's huge. The hubs of the C6/C7 are quite large with means you can't use certain rims on them without machine work or spacers to adapt them. I MAY be able to run a large steel rim setup on this with the C7 Grand Sport 2 piece rotors and calipers, but I'm not sure yet. C7 has a 19x10" rim on the front and a 20x12" rim on the back. I'm wanting to run x4 19" rims all around currently.


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[Qua-Hoon!]

More fit checking. The fender is roughly hung off the car in roughly the right spot. I think I may be ok but I'd rather that wheel be in about a half an inch more. I may just sendit for now to see if it all works before I final weld. I can't remember the required degree change in front wheels to allow for best case scenario steering. I found a number a while ago but lost it. But with that much deflection for the front wheels to turn I may be ok as a general guess. In the beginning I wanted to mock this up completely in a CAD program like Fusion 360, but my CAD skills are zero and I do not have a background in it.

I recently bought some laser cut C7 upper control arm mounts to weld in. I'll do some paper design work soon and see if I can roughly draw out the suspension articulation and tack weld it in for a test. I want this to be super safe as I'm wanting to push this car in autocross more than doing 100 mph passes, strength and reliability are key for me.

Also a point I like to highlight is the potential front differential axle shafts. These are just there to show where they might be running in the photos. They almost look like they will go without major issues or tons of fab work.

The more you look at it the more you start to realize that the 49 Cadillac is nearly mid engine.. and I might actually push the engine back another inch. The design problem then is where the firewall is, the drivers cylinder head and where the driver places their feet. I'm thinking right now I may run a floor mount pedal system for more space, push the driver seat back 2-3 inches. This isn't an issue as the column of course will be aftermarket unless I can find someone with a lathe to spline me a new steering shaft for a modern steering wheel spline pattern.. ooorrr modify the old steering wheel to cut it down while retaining it's current look when re coated / covered. More posts I hope soon, just trying to find my first job post military retirement. It's a wild market right now.


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[Qua-Hoon!]

A couple points I could use some help with:

1. Opinions on front differential or getting gearing for a super 8.8 to rotate the correct way in the front of the car.

2. Degrees / sweep from center (straight forward) that the front wheels need to make normal turns on the street.

3. Dry sump oiling system. If I'm correct, I only need to plug the main cap (threaded bolt with sealant?) where the old oil pump was mounted and have a supply line to the engine where the external oil filter was? Return will of course be from the bottom of the custom pan and potentially the valve covers. There are no known gotchas that normally need to be plugged in most engines?
3a. If I remove the distributor does it need a blank for any reason or can I just cover the hole at the top? (I'm considering a custom cam and LS style coil near plug ignition for the update and because Cadillac custom cams of this generation are pretty much gone, removing the need for a rear cam gear opens up options leaving valve train geometry the issue to overcome.)

[Vimes]

I think your best bet will be to drop the Corvette front cradle if you want AWD. There's no provisions there to allow for a front diff, engine and coil springs. I'm using one on my own 2WD project and don't see how it could be modified for it, especially with it being a front steer system with the rack mounted high and in front of the front wheels.

I would look at a newer Charger/Challenger AWD front cradle to see if it would work. The Charger is a rear steer (rack mounts behind the front wheel centerline) with the rack set low, and offset A arms to make room for both coil springs and front drive axles. It also has the provisions to bolt a front diff in place. The Hemi engines make the same power as the LS engines so the front diff will be strong enough, and the Hemi is a bit wider so there should be plenty of room to fit. The Charger is also a bit of a fat boy at some 4300lbs, so it'll be plenty strong enough for that big Caddy you're building. Where you might have a problem is the Dodges only use 3.09 or 3.92s in the cars, no idea if anyone makes different ratios. The good news, a Chevy or (if Ford makes it) a Ford IFS 4x4 front diff should fit with some modifications and at least the Chevy opens up several ratios.

[wfo guy]

I realize that a great deal of a project like this is to do the undoable. :) Starting with an all wheel drive differentials and transfer case would sure simplify a lot. I'm not familiar with the last gen of Ford explorer but I believe it uses the super 8.8 also. That would be a starting point for me. I used the mustang irs in my last project. I'm a fan of it but I didn't try to adapt different spindles to it. I used a c4 front and drilled it to match the Ford's 12mm stud and pattern.