47-55.1 Crew cab build

[jrbuilder]

Wanting to build a crew cab 3/4 ton 1950 chevy. Hopefully the photo of my idea loaded. Am wanting to put the cab i create onto a 3/4 ton c-k frame and suspension. Also wanting to put a more modern engine into it. Questions are what are going to be the major mechanical issues and would a 350 be a big enough engine for this new critter?

[mr48chev]

Here is one that I saved off Ebay a few years ago




The builder got the cab right.

[mongocanfly]

Welcome...
That's gonna be quite a project...do you have any experience at what your wanting to do?..
Having put a AD on a 3/4t chassis I can tell you it won't fit good..the c/k is to wide for a AD with out tires sticking out past the fenders..and itll sit high on the frame...if you can find a 1-1/2t or bigger front end they are wider and longer than the under 1t front ends.....you building 4wd or 2wd?
350sb should be fine...but if your building from scratch I'd consider going LS...

[dsraven]

kinda with mono here, look around for a big truck. they are wider but also a bit longer. maybe fit better. besides, a lot of the big trucks are less rusty than the shorter versions. just a thought. you could widen the rear fenders to fit.
there are those who would say use the floor and firewall from the donor crew cab.

[dsraven]

if you look at the wheel openings of the pic mr48 posted you will see they are quite large to accommodate the bigger 3/4tone tires. like a big truck front end would have.

[dsraven]

personally i would want the doors on like normal instead of suicide. just so the B pillar could have some added strength for seat belt mounting and rollover protection. even incorporate a hidden roll bar there in the build possibly.

[mr48chev]

That's not a big truck front end they opened the wheel wells up. Note the rounded hood corner.

[jrbuilder]

The metal work on the cab i feel cabable of doing the mechanical is my week side. Would it be better to keep the 3/4 or 1 ton frame from the 1950 then add modern parts to it. I read on this site how to do the rear end using ck parts. What about the front end thou? I would also need to strech the frame which i dont know how to do safely. I could have that done thou. Thanks for the help and advice

[jrbuilder]

My photo shop doesnt show it well but i do plan to have a center post between the doors. I do plan to have the doors still open suicide as i like the look of the door hardware next to each other.

[1948ChevyDumpFixer]

looks like a cool build

[mongocanfly]

stretching a frame isnt a big deal...but needs to be done properly...if you question your skills ,then it may be best to let someone else do that for you
2wd or 4wd?
if the 50 frame is in good shape youd be money ahead to use it...but with a strectched cab its not gonna matter much

[mr48chev]

A guy in Florida has done a few of them usually putting them on a later 1 ton dualie chassis. Later being late enough to run a Duramax. The 98 and later chassis has a slightly narrower tread width than the 73/97 Chassis

[dsraven]

questions:
-2wd or 4x4?
-intended amount of cab stretch
-track width of old vs new donor truck
-cab mounting widths of old cab vs frame width of new donor frame
-are your fab skills, shop space and toolbox able to do the work
-do you want the wheels to be sticking out or tucked in like normal
-have you thought of using the donor truck floor and firewall as a unit. that enables seat mounts for newer style seats with shoulder belts integrated, trans hump, brake booster mount, heater etc etc

using the stock frame with extension on a long truck and adding more power than it had stock may be asking for trouble. it will likely have some thin spots due to rust under cross member locations or old shock mounts etc. the old frame is likely tapered skinny at the front and wide at the rear which can make it a challenge to fit parts on as the frame gets longer and the rear part would get wider unless tapered back in, it may be better for you to find a newer truck with all the gear you need and use that as a donor. buy a complete running truck that has the power plant you want. that will give you a powertrain that fits the whole system, more modern suspension with easily found replacement parts, larger power brakes all around most likely without any upgrades and a master cylinder made for the brake system, all the fuel and brake lines will be in place, a fuel tank with integrated fuel pump etc as applicable, exhaust that already fits past the frame rails and steering parts (except for the steering column mod required to fit your cab configuration) and is upgradable easily by choosing an off the shelf part if you want to. keep in mind the wheel size diameter and gear ratio the donor truck had as this affects the engine rpm and speedo reading if you change that diameter. long story short, do a pro and con list for both directions of build as well as a list of things you would need to do in both directions of build. estimate some time and money and then go from there. just remember to build it safe, not just safe for you but safe for all the other people on the road. I have heard some guys say "it's me driving so if something goes wrong it is just me that gets hurt or killed". that may be true but only if you drive on the moon where there are no other drivers or families on the road.
anyway, get a plan going and try to stick to it. the longer the project goes the more chance you will change your mind on something and the project will end up going in a different direction or be sidelined because you get over your head or can't figure out what to do next. each time costing money, time and leaving a pile of parts leftover or a for sale sign hung. some guys will go as far as making a sketch of the frame and how the suspension will work, how the body will mount, the dimension between the engine and the rad, how much the donor frame will need to be cut, how the wheels will look in fender openings etc. like a pro shop would do. not a bad idea actually. flying by the seat of the pants usually means spending more time figuring things out and changing your mind a few times.

[jrbuilder]

Am thinking 2 wheel drive for the truck. I would want wheels in the fender like normal. Basically i would like to build it so that people thought it rolled of the factory floor like that. I do want it safe since i want to have wife and kids along. Think i need to start studying truck frames that i could fag this body onto. There are several i live in a rural area with a lot of 6400 chevys. Are those cabs different or the same as other chevy cabs of that era? Was wondering if they are bigger cabs they might work better for grafting onto more modern frames and floors. Thanks again for all the help.

[jrbuilder]

Thinking 2 wheel drive. Wanting the wheels in the fenders like a normal truck. My goal is for it to look like it rolled off the factory floor as a crew cab. Want it safe for sure and figure that some of the work i will have to contract out since it will be over my skill level. No desire to build a death trap since i will have wife and kids along. Going to the drawing board and studying truck frames and floors i can build off of i think is my current direction. A few questions thou. I live in an area with a lot of 2 ton versions of these trucks, old grain trucks. The cabs on these trucks are they bigger or are they interchangeable like in the smaller trucks? Asking cause i wondered if the cabs are bigger they might fit a more modern truck better?

[mongocanfly]

All the cabs, for all ADs, are (basically) the same...firewall forward is where its different..
I would stay with a stock frame and add a ifs front..thatll keep the wheels tucked
You might also want to look for a burb or panel for a roof skin..

[dsraven]

since you are looking at doing a '50, it would have a split windshield, you could always split the cab and add to the width. the glass is flat so possibly easier to have custom made for you. that way you would get a wider cab for less of a shoulder to shoulder ride on the inside and possibly fit it onto whatever frame would tickle your fancy. you could custom build a frame as well. get some scrap i beam from a junk yard or whatever and build a frame stand and then weld up a frame to your liking from rectangular tubing. you could bolt in the front suspension from a 2wd '80's truck with disc brakes etc or something newer like a dodge dakota or a ford crown vic. whatever your width taste buds are craving. newer the better I would say because stuff seems to get better engineering wise for brakes etc plus parts are off the shelf at any roadside parts store if doing a road trip. try to keep the original wheels from the donor along with the tire size because this will keep the steering geometry correct as far as scrub radius and steering kingpin inclination angles are concerned. also the wheelbase is good to keep somewhat the same as the donor due to steering arm geometry. if looking for rack and pinion steering keep in mind how the steering column will fit to connect the dots from the column to the rack or box. if you buy a donor vehicle you could be money ahead in terms of stuff you will need like driveline, steering column, rad, heater/ac, brakes, park brake unit, seats, etc etc. if you use the floor from a donor you will have no problem finding a new carpet that fits like a glove.
here are a few videos with some theory on steering angles and references to other helpful videos that you should know before starting. google ackerman steering angles, or scrub radius, for starters. you don't want to build something from parts off other vehicles only to find they don't work well together as an assembly on your put together vehicle. that would be one reason to start with a donor vehicle frame and driveline. it was engineered to be that width and length. also, if using a donor, try to pin the suspension at the stock height with the weight of the complete donor sitting on the frame, using solid bars where the shocks mount for instance, so when building the old truck on top you will keep the suspension where it is made to be at ride height. then, when done the project build portion and before paint, remove the bars and adjust the ride height by increasing or decreasing the spring or using air bags or adjustable struts. this way you can keep things where they were engineered to be and the unit will ride and steer properly.
if you use a newer style vehicle you may benefit from having seats with built in seat belts. a bonus for a truck build that would have limited "strong" places to install shoulder belt mounts.
just a few thoughts.

https://www.suspensiondesigner.com/k...centre-offset/

https://www.youtube.com/watch?v=mh_BUOguZQk

https://www.youtube.com/watch?v=oYMMdjbmQXc

https://www.youtube.com/watch?v=IUcZ63unEyU

https://ismasupers.com/downloads/tec...steering-4.pdf

[dsraven]

here is another link that may help you. you can go through and look at the frame dimensions and general shape for different trucks until you find something you like. less time and effort than a trip to the junk yard and more accurate than a tape measure.

https://www.gmupfitter.com/pages/body-builder-manuals

[jrbuilder]

Found on this site an awesome build where they took a burb and skined it onto an envoy. There was some issues with tire clearances. One of the ideas was to raise the body to increase clearances which i think would be my route. I would need to get a envoy xl then chop it in half behind the second row of seats and stretch the frame. That way i could put a short box over the rear wheel. Would love the spare mount on the side but might not be room. Envoy has a 129 inch wheelbase do you guys think adding to the frame would be a bad idea? They are box frames so by what i read it could be done but might create steering issues. Rough sketching everthing out and think i would need to add 20 to 30 inches? Thanks for the help and the links. Tried to add a drawing that i have been using to base some ideas off of but dont know if it loaded.

[mongocanfly]

adding to the frame wont cause steering issues....and it would be simple to stretch a envoy frame...the part I would be concerned with would be the track width...ADs are narrow

[mongocanfly]

Dug did this on a 59....http://67-72chevytrucks.com/vboard/s...d.php?t=515876

[whitedog76]

An Envoy/Trailblazer chassis isn't all that bad of an idea. There's been quite a few vintage trucks put on the Envoy/TB frames. The front track width is a little on the wide side for AD trucks, but some narrow tires or custom rims will help that out. The front and rear sections of the frame actually slide together so lengthening shouldn't be a real issue. Since there's plenty Tb's and Envoys in the salvage yard, you can probably get the center section of a frame for adding material. I know the folks with the XL version complained about frame flex and handling issues. Adding cross braces seemed to solve the problem. One thing to keep in mind is that there was a difference in the V8 and I6 frames. So, if you have a donor with an I6, it may be and issue trying to swap a V8 into it.

Another thing to think about is maybe trying to find a 3600 or 3800 AD chassis. The 3600 is 125.5 wheel base and the 3800 is 137. For one thing, all the front sheet metal will fit where it's suppose to. Secondly, they are both plenty strong. The frame rails are fairly flat, so lengthening and shortening is fairly simple.

Just some thoughts.

[whitedog76]

Here's a shot of a TB frame. One thing i didn't mention is the rear kick up in the frame. Needless to say, the bed floor will need to be raised.

[whitedog76]

Here's some useful pics and some old crew cab pics.

[mongocanfly]

whitedog, those crew cabs look to be well constructed...any info on them?
I see those are done with the big front ends like we discussed above