What frame to use for a 1950 Roadmaster 2-door

[BornBuick]

I am searching for the best frame/chassis with entire suspension to use on
a 1950 Roadmaster 2-door coupe conversion project with the least amount of problems to contend with. I intend to take the body off of it's original
frame/chassis and then bolt the body to the new frame/chassis.

I have seen where a 1986 Chevy caprice was used and a 1972 cadillac as well.

I would want to use the most modern setup possible with brakes, steering, suspension - the works.

I suppose I should look into when did GM stop solid x frame production and started making unibody framed cars?

Anyone know anything about this please chime in. It would be appreciated

Dave

 

[jcubed]

Frame for 50 coupe

I got the idea from a guy with a 51 merc at the Americruise show here in Lincoln several years ago.

I used the frame, LT1, 4L60E, etc. from a 96 fleetwood for my 52 hardtop. It fits like it was made for the car, front and rear wheels centered in wheel well and rear spring pockets right agaianst the rear seat.

Signifiacant overhang trimmed front and rear made the radiator mount a challenge. Tranny tunnel has clearance to relocate the engine back 6 inches to look better in the engine bay future work.

The wheel base was within 1/2-inch of the original. I had the car channeled which was more work than than I thought. I have not addressed the front wheel steering clearance yet but expect I will need to offset the wheels to keep from rubbing the fenders. Rear track width was same as 52 original. Front track width on 52 narrower by 3-4 inches if I recall correctly, maybe less.

Would love to keep the traction control, ABS, etc but maybe wishfull thinking.

I used two shops in Nebraska, both did great work, Shop No. 10 in Omaha did the floor, firewall, gas tank mounting, trunk, and frame mounts.

It will eventually be on bags but just cut springs for now. The 92-96 fleetwood frame is the same wheelbase. I understand the roadmaster/caprice wheelbase is 6 inches shorter same track wdith.

 

[BornBuick]

Most Excellent indeed.... thank you much for the info.

My goal is to create a complete stocko resto-original but on unseen steroids; therefore it will look and taste just like it did the 1950's but drive and go like a I want it to.

The challenges will be many including keeping the steering shaft and everything above including the steering wheel completely stock but with the rack and pinion goodies below.

My ride height goal is to keep it just 2-inches less than stock stance.

Any more tidbits of knowledge out there regarding this topic and the challenges one should expect to encounter - Let's hear them!

Dave

 

[jcubed]

frame under a 50

I have the same thoughts on the steering wheel/column a cruiser with modern suspension that is engineered by Detroit as a package. But plan to keep the LT1 as is for the near term so I can get on the road with it so no 502 for me.

This is my first build and I am not anywhere near done. Based on my experience so far, it may not be as painless as I hope but getting a complete donor car has been great, as long as you have room in your garage (and your significant other's life) for multiple "project cars" its a great way to go. I have the FW ar a very cheap storage lot and was able to make some money selling parts to pay for the rent and for a small part of the fabrication I can't do.

The FW tranny shift linkage lines up real close to the original connection on the column and the column end has a very minor angle relative to the FW powersteering box, so I anticipate an easy fabrication of a mailorder steering knuckle.

The FW vacuum actuator is huge (13+ inches diam) I guess so the blue hairs peering through the steering wheel can stop. So I am looking for a smaller substitute. I still have the FW brake pedal assembly, gas pedal, column, etc.

My donor 96 FW was from texas with less than 60,000 miles but had been rearended. The frame was laddered slightly but a frame shop took care of that easily. I lucked out, everything I needed was undamaged and I drove the FW to the shop to be seperated.

I salvaged the entire engine and body wiring harness so my winter goal, now that I have a floor and firewall, is to set the column, and get the engine wiring harness installed. Sold off the exterior parts and trim all of it on the LAYITLOW website (dealt with great people there ranging from Lincoln to Toronto) for widebody trim and parts. Still have the bells and whistles, power seats, motorized trunk latch, retracting antenna, backseat vanity mirrors, traction control button, auto headlight and rain sensors, rear taillights, etc.

I hope to have more progress to document as the winter progresses. Spent last weekend running gas to the garage for an IR heater to ward off frost bite.

Considering the cost for a you-pull-it yard engine, tranny, rearend, radiator, drive shaft, replacement a-arms, steering assy, etc. and the parts I was able to sell, I am ahead, if one uses hot-rodder math.

 

[phiftybuick]

Hi Guys-
I used a '78 Coupe deVille chassis for my '50. The wheelbase was exactly the same...121.5"......
Like Dave says, there's a lot of fitting to be done, but you keep all the stock geometry for steering, etc.
Good luck!

 

[alleycat]

Dave, you are indeed asking the right questions long before putting a wrench to the car. Normally I don't comment on chassi changes because I don't do it, but I have buddies that do, and I help out, so I get to be around these really BIG projects and observe. One of the most intresting was a 1936 Auburn speedster. A guy I knew bought a kit, a good one, just like the read deal but in fiberglass. He put it on a 78 Caprice frame. I thought it looked a little "spindly" and voiced some concerns. He was having none of it, "it's a huge car! Handles great! Has all the cool stuff! The Auburn is only a body, it's gonna work great!" Well...He got the car done. Way cool. Could'ent pull it out of the shop without drawing a crowd. Car was horriable on the road. The doors would fly open if it was going over a broken concrete road. Even over a normal-ish road the body panels would work against each other and chip the paint, etc. I think the car got about 1200 miles on it, and it disapeared, I never saw it again.

Original Auburn's have a huge X-frame under them, almost identicle to Buick's frame. They need it. Most all the car manufacturers put huge X-frame chassis under the cars for a reason: the bodys have no strenth. In spite of all that metal, they are just panels spot welded togather. That frame is not under there because Buick had the extra metal.

Starting in the mid 70's, bodys became a serious part of the overall structure, frames progressivly played less and less a part of the package. A new-er car with all the stuff is attractive, but pulling the body, ploping the Buick on it and expecting it to handle the same may be expecting a bit much. Can it be done? Sure. I'm involved in one of these "do it the hard way" projects, but I scrounged up a 47 convert frame, even heaver than the regular frame. It's impossiable to do better than the original frame. It's probably a bit overkill for todays roads, but you can do anything to these things, there's metal everywhere! Hope this helps. Just my spin on things. alleycat

 

[jcubed]

frame swap

The frame stiffness issue is a very real concern especially for hardtops and convertables. The shop fabicated 1/8-inch steel inner rockers that are attached to the body at multiple locations front and rear. The tape roll in one of the photos below is on the inner rocker. Also there is a new 2x4 steel tube cross beam in the floor gusseted to the inner rockers and factory stampings behind the door located under the front of the rear seat cushion. The new floor has continuously welded seams and a significant driveshaft and tranny hump that will help stiffen the body.

There is still potential for some frame twist, going in and out of the driveway for instance, but I'm building a cruiser not a wheel hopper and will live with some frame twist.

 

[sleepyweasel72]

This is how addressed the frame problem.

I have a '51 Special 2 door hardtop. I put a subframe under it and located it where it sits 3 inches lower than stock. In the rear I swapped rearends and in the process of using a triangulated 4 link. Here is a couple of pics. By the way the car will be airbagged.

 

[BornBuick]

Yeah guys these are some great points. I can see from what has been said that going too far forward in years could lead to a weaker frame set-up.

One would have to make sure the frame was comparable in overall shear of design and weight to make the conversion a success without having a flexi-flyer on your hands.

David

 

[Jim Carmichael]

I thought about using a later frame for my 1955 Buick but knowing how flexable they can be we decided to add the parts we wanted to the stock frame. I think it was easy to add power disc brakes and change to the 401 and turbo 400 transmission and the only hold up so far has been getting the 4 bar set-up welded in. That is not hard and we are using the Art Morrison triangulated system so just need to have Russ feeling better to do the work. I also wanted to have everything appear stock but drive modern.

I am thinking about using a steering box converted for a 1955 Chev to connect to the stock steering colume and adapted to fit the Buick frame but don't know how it will work out until I have all the parts to compare.

 

[BornBuick]

Your right on that aspect of it. It is tempting to use the stock frame. But I have to add up the time factor and the micro engineering to accomplish my punch list.

That is: Rack n Pinion Steering, Preservation of complete interior items including dash and steering column and wheel, disks at all corners, articulate suspension components, modern overdrive transmission and modern electronic fuel injected power.

It would appear that by taking the most durable modern donor that already accommodates my punch list, then applying where needed the attention to details needed to make things all work together would be the least painful way to go.

Otherwise, the project could resemble a house remodel gone wrong. The more you dig into it the more you have to reinvent the wheel. Ultimately in the end do you end up with what you wanted from the beginning. A classic modern mod. - Just my thoughts here.

Dave