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View Full Version : X-frame rigidity?



INTMD8
08-27-2011, 05:23 PM
My 57 Eldorado has an X-frame under it.

The 2 options I'm considering are-

1. Doing an AME C6 front clip on the stock frame.

2. Bringing the car to the Roadster Shop for a custom frame.

It would be nice to clip the stock frame as no floorpan mods would be necessary (Roadster Shop would be perimeter frame) but I don't want to bother if the X-frame is just going to twist like a wet noodle.

Am I correct in thinking that the stock X-frame is not the best in torsional rigidity?

https://static1.pt-content.com/images/pt/2011/08/eldoradobrougham079-1.jpg

68 stang
08-29-2011, 03:33 PM
I never liked the frame underneth Cads of that year. You might want to check out want some of the Impala guys are doing. I think the frame is pretty close. Besides you do not want to cut up the car. That 57 Eldo is worth quite a bit and they really do not like it if it is far from stock.

You could also think about welding in some huge gussets. I would really like to see what you would come up with. I have about 10 cars to do myself.

Where are the pics of your 57?

INTMD8
08-29-2011, 05:10 PM
It seems not many places keep the X-frame when doing an Impala build. The Roadster Shop makes an Impala frame which ends up being a perimeter frame.

You're right that I don't -want- to cut up the car but if in the end it would be better with say, a new Roadster Shop chassis than I don't want some floor sheetmetal to stand in the way of the end result. Regardless of whether or not I keep the stock chassis I don't think anyone would take this car and return it to stock. If that's what someone's after it would always be cheaper and easier to just buy an original car IMO.

https://static1.pt-content.com/images/pt/2011/08/eldoradobrougham044-1.jpg
https://static1.pt-content.com/images/pt/2011/08/eldoradobrougham032-1.jpg

68 stang
08-31-2011, 08:53 PM
I have alot of old 57 to 64 Cad converts in the family. My daily driver right now is a 57 Series 62 convert. It still has the drum brakes. We have driven this car to the east coast and back.

It all depends on what you want. Do you want to autocross it or have a nice driver. I think you could modify the original frame if you are just going to drive it. You might want to take a look and see if a frame from a 64 Cad will fit. The 64's are the best drivers. I am not sure why. If you are not worried about getting your money back out, I would go with a Roadster Shop frame.

What motor are you going to run? Please tell me a twin turbo 429.

silver69camaro
09-01-2011, 08:46 AM
We build a pretty good frame for those that need little if any floor work, but you would need to build your own bumper, engine and body mounts which will save you thousands at the end.

lnirenberg
09-01-2011, 11:44 AM
Muscle Car Review March 2009 did an article on strengthening a Chevy X frame. If you can't find it I have it scanned and can email it to you (PM if you want it). My frame has been modified similar to the article and I am pushing 450+ ft/lbs to the rear wheels and I haven't twisted it into a pretzel yet. I agree with 68 stang that it depends on use. Given the size of the car I would think your looking for a fast cruiser with a modern handling dynamic which can be accomplished using the x-frame.

I love that vintage caddie, what motor are you thinking? A nice supercharged Northstar would be sweet and it would leave enough room in the engine compartment to use as a family room.

INTMD8
09-01-2011, 12:04 PM
Thanks for the info guys. I decided to have the Roadster Shop build me a frame and they came out and picked the car up this morning to start on it.

Not sure on an engine yet. I have considered the supercharged northstar but it would only make around 400rwhp and this is a lot of car to move around. I like the fact though that it is a Cadillac specific engine and not a "corporate" motor.

Next idea was to do a tall deck LS, 472-500ci but get it to look somewhat like the original engine. (Dual 4bbl throttle bodies and fab a batwing air cleaner, painted in original colors).

Final idea was 400ci LS with twin turbos. Nothing new there but power would not be a problem.