49-52 Chevy frame

[Chevy]

G'day all,

I have a 50 fastback that I am about to start the frame work on. I would like your guys opinions on my plans. I found this car in Mississippi and sent it here to Australia earlier this year, so I have to put the steering wheel on the right side as well http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif. I have a 454/TH400 that I want to put in, so obviously strength/flexing is an issue.

First up I amm going to use a holden front crossmember (same deal as your M11, not trad I know). I was planning on recessing the frame into the crossmember an inch, I am not totally set on this yet??? but its got to sit pretty low. From what I have found out the strength in these frames comes from the bottom part, remember the 'tophat' design of these frames.I was planning to weld 3mm (or larger ???) sheet to the bottom of the frame for strength, is this really neccessary? If I do recess the frame into the crossmember I would have to cut the 'lip' off the frame where it goes through the crossmember. I planned on fully welding where I cut it, actually I planned on welding the plate to the bottom of the full length of the frame. I know to only do small sections at a time as this will warp real easy.
I also was thinking of adding more support(RHS) from the transmission crossmember back to the front of the rear leaf spring mounts. I think the convertable and hardtops had a simular deal from the factory???
Am I on the right track?
My welding skills or pretty good, but I haven't done a job as big as this before though.

I hope this made some sort of sense, your help and constructive critisism would be much appreciated.

Thanks
Chevy............

[choprods]

Hay Mate!Listen this is just my opinion -so treat it like that-I would not worry about "plating' the bottom of the fram as you mentioned. I feel it is sufficiently stout as it is[it's not rusted out right?]also remember if you "knotch' the crossmember higher into you frame in an effort to lower it some more you may have to make a cutout in each frame rail ahead of the crossmember to allow for RACK being moved up also. another thing you may encounter is after doing that the shaft coming from the rack will most likely shoot straight for the exact area wher the motor mounts will be. thgis can be eliminated by remounting the rack in an angled back position to aim the steering shaft[below] the mounts.Good luck-plan ahead and it will go allright.

[Chevy]

Thanks Choprods,

Opinions are what I'm after
Would you think that fully welding the frame along the seam, without the extra plating would be of any benefit, because originally it is spot welded, as I'm sure you know.

I had planned on welding the new crossmember in, but haven't ruled out bolting it in either, any opinions or advise on which way would be better if any?

Cheers
Chevy.......

[Rocky]

I agree with Kenny regarding the extra plating under the frame being unnecessary but your plans to reinforce the area where you'll cut into the "lip" are sound. You really dont' want to lose any strength here. If I was gonna put any extra plating on my old chevy frame, it'd be on those paper-thin frame rail sides before I welded on engine mount brackets....about 18 inches/2 feet before and aft of the brackets..
With a healthy big block, I'd rather have my front X-member welded in with plenty of gussets. Yeah, I know the stockers had bolt-in X-members but they only had 90-95 hp too.
With that said, I left the stock bolt-in member in my 50 chevy with a healthy 406 and 4 speed but everytime I'd launch that thing, I'd clench up when the left front would come up with the whole car feeling like it gonna twist in half... weld in the crossmember.

[Chevy]

Thanks for your thoughts Kenny and Rocky as always good info. Any one else?

Chevy...

[Fat Hack]

Hey, Chevy...wishin' ya luck with that 50 fastback o'yours!

I was originally planning to 'sub-frame' my 49, but I've since decided to retain the old stuff...just gonna be a six cylinder cruiser...so brutal torque and horsepower aren't a big concern for me!

If your frame is pretty clean (free from rot!) you should be okay with what you're planning. I found a couple of holes in my frame...but I'm just gonna have 'em welded up!

Keep us posted with your progress (PICTURES!! http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif)

http://www.jalopyjournal.com/ubbthreads/images/graemlins/cool.gif

[Chevy]

Hey Fat,
The frame has a few rust holes up front, behind where the bumper brackets, I should be able to sort that out alright, there are few pitted areas as well further down so i am not real sure I will use this one I am looking for another one, shouldn't be too hard to find. With a big bloke in it, it would make a mess if there was any weak areas from rust, as we all know. I'll keep you posted. http://www.jalopyjournal.com/ubbthreads/images/graemlins/cool.gif

Chevy...