The Stovebolt Site Forums The Shop Area The HiPo Shop box frame or no?

Hello Bolter's! pics here http://community.webshots.com/album/581220297RGQJgB?vhost=community&start=0
I have the frame in the garage and will clean it up this weekend. My helper(the boy) is raring to go LOL. Now my question is.... should i box in my frame? i did some post searching last night and the consensus is that the 30's trucks need the extra support but the 47-53's don't. i didn't find alot of info on the 40-46's. from the looks of the job the person who did it, did a good job. I can clean all of it up and MPI the welds(work at a vessel fab shop) to see if there is any cracks and such. If i do box it down to say just past the transmission mount, wouldn't that be a stress point and could lead to a crack or split? I'm just going to put a nice strong 350/700r4 setup in it. Nothing too radical. A nice street cruiser and it wont haul anything but maybe a beer cooler!I just want to do it once. Thanks for your advice and opinions.
Barry

If you're going for an authentic restoration obviously not. But since you're putting a SBC in it, that must not be the case. I'd say do it, I know I wish I had if only to improve ride quality. It flexes and shakes way more than I would like for a daly driver.

Roughly speaking (someone jump in here if I'm off track) with a 60/40 weight distribution you'll want to focus on a point 40% of the wheelbase back from the front wheels. That will be where most of the twist is happening. I'd also not just box the individual frame rails, but create some "X" braces to tie the tops and bottoms of each side together. This creates the effect of a large torsion tube.

Sounds like overkill to me but if it makes you feel better,go for it. I would attribute the flex and twisting to a inferior
suspension. Sway bars,shocks or any loose parts.

If you're referring to my flexing, the amount of frame flex is inherent in the structural rigidity of the frame design and is independent of the suspension design or condition. Further, it's not overkill if the OP is looking for improved ride. One of the biggest contributors to current vehicles' ride quality compared to vintage ones' is chassis rigidity. Springs and shocks, while certainly improved, are not multiples better whereas torsional rigidity is. And if he's dropping in even a stock 350 the frame will be subject to at least 50% more torque than the original 216 for which the frame was intended. Now, doing MPI on the frame MAY be overkill, but hey, if it's free, why not? It's a whole lot easier to repair the weld now than after the first coat of wax and a test drive.

the amount of frame flex is inherent in the structural rigidity of the frame design and is independent of the suspension design or condition

Except that 1,000 lb./inch springs stress the chassis instantly, and 1 lb./inch never do.

OK

I wouldn't. These frames were designed to allow for a little twist when traveling over uneven spots.

Walt

I beg to differ - the bodies were designed to deal with the flex of the frame. That's why the cabs have spring loaded bolts on the rear attach points instead of a solid connection. Removing the spring would cause the flex of the frame to "oil can" the cab sheet metal.

My philosophy has always been, "when in doubt add some more". It's always better to "over do it than to do it over".

well we have decided to cut the nova frame off and use a fatmans front stub. They will make the stub a little bit longer to give me a good length to weld on. The nova front will need to be rebuilt so ill pass on it. with the flat rails, i wont have to hack up the inner fenders, the front fenders, and the stub has all the support holes for the rad support and such. I talked to a fab guy here and he said to check the hight of the nova clip, and its almost too low for my liking. the roads around here suck from the frost heaves. i would rather have it ride nice and level and not worry about speed bumps etc. I might send the clip to sweet grass MT and go pick it up there and save cash on shipping and brokerage fees. Ill let you bolter's know how it goes.
Barry.

Im in the process of boxing my frame now. Go for it ! It sure can't hurt

54Belair is correct. The older frames, he said, are made to flex, more accurately, to twist. The body, already being a rigid box, is made to pitch and roll by use of rubber and other flexible fasteners. Also, welding on frames, while permissible, should be done by an expert who would follow proper procedures some of which are spelled out in the 55-59 maintenance manual (as a reference). The heaviest engine and tranny available in the 40's could be same or more than a 350 with aluminum tranny.(example: 216 + SM465=780 lbs, 350 + 700R4=710 lbs). Boxing is for hot rods with purpose built frames and the ride gives you HotRod Hemorrhoids. If it was a stock frame all the way, I'd say spread the load of the engine mounts with "L" shaped or "C" shaped channel inside the frame rails, bolted on. Make them about a foot, or so, long if possible.(Been there, done that) I don't know what the Fatman front does to all this. Sounds like you are going more hot rod/hybrid/stock to me.

Bartamos, I still disagree. Feel free to find one of the original engineers and prove me wrong, and I'll eat crow if you do. The frame wasn't "designed" to flex, it just did. At that point in time chassis design was not highly sophisticated and economics as always dictated a simple approach to manufacturing using simple materials. The body is not nearly so rigid as you imply but more importantly the points where the body attaches to the frame are not "hard points" intended to tie the two structures together. Rather, they are there to literally keep the body from falling off the frame. Think of all the pictures of guys driving around on their bolt with nothing more than the frame, engine and a lawn chair.

I'd agree with your suggestion to have the welding done by a pro, good advice in that application. If the goal is to reduce flex, adding an L shape will do little to reduce it, stick with something that turns an open cross section into a closed one (think tubular). I'd also lean towards welding the shapes on rather than bolting. Bolted joints are horribly inefficient compared to a weld when it comes to load transfer.

Doesn't matter if you disagree. Not interested in proving you wrong. My post stands on it's own. I will try to explain what it says again. Engineers had known the strengths of materials, beam shapes, loads and forces before the 40's. Structural engineers with bridge, tall building, ship, trains and planes experience, traveled in and out of the auto industry. They knew that too rigid would break or break something and be a stiffer ride. The vehicles do twist and were designed to allow that. Those engineers were highly educated, knew strength of material and structure calculations and the Chassis were highly sophisticated using the materials at hand. Channel ladder frames are still used today. Did not say anything about "hard points", Did not say anything about a goal of reducing flex, the reinforcement I suggested was to strengthen/support any area the poster was concerned about. My whole post is about NOT reducing flex. Also: angle ("L" shape) is very strong, channel ("C shape) is stronger, both will have the necessary flex to a point. Tubing: round, square, rectangle or special, would be too stiff for those frames. They tested many configurations over the years and stuck with channel as a happy medium. A bolted assembly is very strong, clamping forces will be adequate to strengthen the motor mount area and is something any bolter can do and does not apply heat and no danger of weakening by bad technique. I did not imply that the body was rigid, I said it was. It's a box and is rigid. I think everyone knows that the attachment points are to attach the body to the frame. You may be misstating what I say and then arguing with a misstatement and asking me to provide you with an engineer from the 40's. The only engineer I can provide you with is me. I think the discussion of the engineers and all that is off the topic. I was just trying to help the guy with reinforcement of an old frame which I have done, with a TF truck using a BBC, in the manner suggested. No problems yet after 5 years. When I started my career in 1964 at Sperry Flight Systems (later Honeywell Aerospace) I met many Mechanical Engineers from the 40's. I assure you that they were as sophisticated as you are and were highly trained and experienced. What they designed in the auto industry was great. It was not guess work and they did not end up with a flexible frame by accident as you imply ("it just did"). They would not have succeeded in the aerospace engineering world that way. How do you like your bird? Fried with tomatoes?

OK, i retract my last post. they don't make a stub:( only a frame adapter for it. now what?

Now what, what? What is your specific question now? What do you have? What do you want to do? What kind of a truck do you want to end up with? If I had a frame that an unknown person welded a nova to and then was cut off at some arbitrary place, I would scrap it and get another stock frame. Is that what happened? On another note: If those close ups are of the nova before cut off, you are right, they did a good job. Depending on how you cut it off and if you can weld it back on that good, the good thing is it's cheaper to rebuild it than buy anything else and you have it off and can put it up at a good working height for access and to save your back while rebuilding. aye? I really do think that putting it or anything else back on and getting it true and square with correct geometry would be a nightmare, but it's close to Halloween!

bartomos,

First, I hope you're not taking any of this personally. I'm trying to add to the knowledge base and having a technical debate will bring out many thoughts, facts and ideas that no single person can contribute alone.

You misunderstood my comment about sophistication and seem to think I'm trying to elevate my own intellect. I'm not. To say that chassis design was not very sophisticated at that time does not mean, nor do I think, that the engineers of the day were not as bright or capable as today's (or myself). It's a matter of technology available at the time. You mention bridges so l'll take that as an example. Way back when (late 1800's -early 1900's) it was difficult to determine bending loads in indeterminate structures, so they designed the joints of members as simply supported ones (i.e. pin connections that could rotate) making the calculations possible. The result was a structure far heavier, costlier and less efficient than one possible with today's analytical tools, almost all of which are the result of computing power. They even used to have grease fittings at the joints because they were afraid of what would happen if the joint was subjected to a bending moment.

Chassis design is no different. You are correct, an engineer from one industry can transfer to another, the science and mechanics are the same. But it's still far better technology available today than back then. 60 years from now they will no doubt look back at today's analytical methods and tools and chuckle.

Yes, a bolted joint can be made to work, and you point out some definite advantages. The OP said he could weld (or had access to qualified welders and NDT methods to verify the quality), and welding will be more efficient (and faster) than bolting, hence my suggestion.

It is almost impossible (I don't know of one, but I'll leave the possibility open) to strengthen something by adding to it without simultaneously stiffening it. I should have been more specific and instead of saying "flex" said "twist". My mistake. You pointed out correctly that his planned engine may well weigh less than the original. So there is no need to strengthen or stiffen the frame to handle the weight. If there were, you are correct, the L, a C or even an I would do the job just fine, correctly placed. However, that engine can produce significantly more torque, tending to twist the frame along its longitudinal axis.

The L and C shapes you suggest adding all in fact do add to the strength and torsional rigidity, and your 5 yrs of success certainly prove you added enough to achieve your goal. They just take more material and weight to accomplish the same result as a shape that closes the C of the frame into some closed shape like a box or tube. For resisting twist, a circular tube is the most efficient shape. The use of a C shape for the frame is economics - it's easy to make by stamping it out of heavy gauge sheet, takes no welding, the competition was doing the same and drivers didn't know any better.

The concept of stiffening a chassis to improve ride quality is fairly straightforward: keep the frame and body very stiff and let the suspension do the work of creating a smooth, controlled ride. Using the frame to act as a flexing member is less than ideal as it is an undamped member, continuing to vibrate after a deflection (pothole) - not good. That's why God invented shock absorbers.

Today's automotive chassis engineers know full well how to design even stiffer chassis than they currently produce (think Formula 1), but the economics of costs vs. consumers' demands for ride quality vs. competitive offerings dictate the end result.

I'm not ready to eat that crow just yet, but it never hurts to fire up the grill.

As per my last post I am stickng to helping the poster Probird. (Think Probird)

Easy guys, i appreciate the help! I,ve put a search on for a used frame. now if in don't find one near by, the cost wont be worth it. the other way i can go is progressive has a builder frame for 3300 for the 1940. I want to make it a hot rod truck. not to low but have a nice stance. the initial outlay of funds i think would be the way to go. everything would be new. Will keep you guys posted. Thanks!
Barry.

All good here, let us know how you come out. In hind sight, I likely would have come out cheaper starting with an aftermarket frame like that and starting from scratch.

I'm thinking along the lines as by the time I'm farting around with the old frame and trying to get everything lined up, this frame will be brand new and have the rad support etc in place to make putting the truck back together alot easier.

Roger that.

DANG! I didn't know I could cook that bird!

Probird,

If you're still thinking of welding, (even if stiffening up the new frame) this link was in another topic, might be of interest:

http://216.45.19.226/vocrefguide/VRG/Bullet/pdf_files/Frame_Alteration_Recommendations.pdf

FWIW my first AD was a 49 with an Olds motor and when you stepped on the gas, it was a flexiflyer. You all may be correct that a 216 and 4 speed weighs about the same as a 350 with an automatic but what you are missing is that the frame was designed for about 100HP NOT 200+HP. When you step on the gas, if you haven't stiffened up that frame YOU BETTER HANG ON cuz it's a wild ride.
My current build is a 49 with all 74 Camaro components and you better believe we boxed the frame. Also had a certified welder do it because I didn't want to do it over again.
http://img.photobucket.com/albums/v518/Blacktailer/IMG_5002.jpg

I dont see any boxing on that frame in the photo ?? And do tell, details on your boxing technique ? (where, shape, thickness,etc?)

We boxed it back to slightly past the firewall with 3/16 plate. When I grafted on the Camaro clip, I narrowed the rear of the clip and widened the truck frame (about 3 inches each) until they mated. Then after welding them together we boxed everything from the lower A arm mount back to the cab.
http://img.photobucket.com/albums/v518/Blacktailer/IMG_4813.jpg
http://img.photobucket.com/albums/v518/Blacktailer/IMG_4891.jpg
http://img.photobucket.com/albums/v518/Blacktailer/IMG_4895.jpg

Buy the aftermarket frame. My recommendation is Fatman Fabrications.
Check them out.

I ended finding a used one in Saskatchewan. he cut the excess parts off and i brought it home and bought new suspension stuff to put under it. will be alot easier and cheaper.

i liked the link the green farmer put up. i read somewhere the same thing, the only other sugestion i would make is let your welds cool naturally when welding anything you want strenght in. just something i got from an old timer long time ago. also to stagger just like doing body patch panels.

I work in a vessel fab shop and have received a bunch of info from the b-welders there. I'll add some more pics to my "rides-webshots" site in a bit.
ok here is my rides site: ://rides.webshots.com/album/581220297RGQJgB?vhost=rides
Barry.