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59flatbedford
08-12-2010, 10:15 PM
well ive been thinking of building a frame for a 4x4 59 ford f100 for quite a while now and the design of it would be pretty simple just two straight pieces of 2x4x.125 tubing for main rails. now the only thing that worries me is welding all the crossmembers in. Im a good welder and know i could make it hold but what about warping it all from the welding. So i was thinking instead you could take and weld flat plate onto the end of the crossmembers and use that to bolt them in. i was thinking probably at least 6, 1/2 inch grade eight bolts per crossmember end. So is this an acceptable ideal or a really bad one. would it just be better to skip around doing equal and oppisite short welds and hope everything comes out straight.

DYCE
08-12-2010, 10:56 PM
I'm a deisel mechanic, and if your talking about trucks crossmembers are bolted in. The main reason they do this is because the frame rails are heat treated. If you are building a frame with non-heattreated steel that won;t be in an extreme application you will be good.

Jim Stabe
08-13-2010, 06:31 AM
If you are using 2x4x.125 tubing for the frame of a full sized 4wd truck, I hope it just the bottom tube of the frame structure and that there is a very substantial roll cage tying it all together from front to rear. That 2x4 tube by itself will not be nearly strong enough. If you do have the roll structure welded in, welding in the crossmembers will be the least of your worries keeping it straight.

James(Western Canada)
08-13-2010, 07:59 AM
59FBF: Ever think of just BOXING the frame you have? And on a 4x4, I'm thinking 3/16" tube might be better?

James

59flatbedford
08-13-2010, 08:08 AM
Well the original frame is probably 2x4 or 2x5 c-channel with everything riveted in. I was thinking rec tube would be stronger than c-channel. Thinking about it i would probably use 3/16 wall tho instead of .125 and maybe even 2x5 or 3x5. would something like that be strong enough? The intended purpose of this truck is just a classy driver. it isn't a monster rock crawler with 1000 hp or nothing. The suspension would be leaf sprung straight axles front and rear. Any advice on this is welcome and any suggestions of books to pick up is also welcome, and don't worry about getting technical im going to school for mechanical engineering so im used to reading stuff thats hard to understand.;)

cbass139
08-13-2010, 08:33 AM
You can try this site for advice on the build as well. I am sure guys here will have a wealth of knowledge but you can never have to much support when doing a job like this.
http://www.ford-trucks.com/forums/forum41/

59flatbedford
08-13-2010, 08:47 AM
yea i am a member on fte also and get a lot of information from over there but im always looking for more help. The main reason for building a frame is because it would be really cool to build a frame, and it would be nice and smooth without a lot of extra holes and unnecessary things. Also the frame i have is a 61 so its just a little different.

TheRodDoc
08-13-2010, 01:15 PM
Rectangle tube is not good to use for a truck chassis. This type of tubing resists twisting and a pickup frame needs to be flexible. For a truck that will be used for anything but just for show a channel type frame is best. The original frame can't be beat.

A box tube frame can twist and will stay twisted and not return to its original state.

putting boxing plates on a stock frame will cause the same problem and shouldn't be done.

If your building a special truck such as a pulling truck box tube frames might be ok. but then a full cage is added to the box tube frame to make it even more ridged and to prevent it from twisting at all for it's intended use. But even this type of frame can be twisted when it reaches a point beyond what it can stand. Then it stays that way.

A channel can twist and be able to flex back to where it was when what ever twisted it is gone. Cross members also have to be designed to be able to let the main frame twist with out bending things permanently.

This is why trucks never use an X member.

A box tube withstands the twist to a point of its strength and then can bend and stay permanently twisted and not return to it's original form.

You also can't just bolt something to the side of a box tube. you have to weld in tubes for the bolts to tighten on. If you just drill and tap into one side of a thin box it will not hold and or will just pull the side out on the box tube when strain is apply ed to it. If you drill all the way through and just insert a bolt it will just crush the box tube when tightening the bolt. And when the object bolted to is pulls on the bolts it will just crush the tubing even more loosing the bolts.

drawing shows some methods of bolting to a box tube.
left side of drawing shows a method of only welding on one side with a flush smooth weld on that side and nothing but a hole showing on other side.

must bevel insert tube for the weld. must put a bolt in from other side and tighten it before welding. Since the bevel was large enough to weld pieces solid you can grind that side smooth and when done you will only have a hold showing or in the case of the blind hole, nothing showing.

Right side of drawing shows a couple methods where insert tube is put clear through the box tube then welded on both sides. Can be flush or protruding on one or either side.

5434

59flatbedford
08-13-2010, 01:33 PM
thanks for the pictures and yes i was planning on doing that exact thing. The flex vs rigid thing has got me pondering. I do not have a stock 59 4x4 frame (which i believe is straight and flat the whole way) what i do have is a 61 frame but its got lots of little holes and bends and stuff that i don't need. Can you even get constant thickness c-channel? The only c-channel i have ever seen (except on factory frames) is industrial stuff with the thick corners and tapered sides. I guess you could take 3x5x.25 box tube and cut one side out of it in order to get 3x5 c-channel and a bunch of .25 plate.

BarryA
08-13-2010, 09:01 PM
Can you even get constant thickness c-channel?

Just bend up (or have it bent) from plate.

Peter Miles
08-14-2010, 12:39 AM
Rectangle tube is not good to use for a truck chassis. This type of tubing resists twisting and a pickup frame needs to be flexible. For a truck that will be used for anything but just for show a channel type frame is best. The original frame can't be beat.

A box tube frame can twist and will stay twisted and not return to its original state.


While I greatly respect Richard's opinions and experience, GM is taking a different approach in 2011 with a fully boxed frame. It could be that they are increasing the strength beyond the point where permanent deflection is a realistic possibility:
5437

kit
08-14-2010, 06:45 AM
It would be interesting to know the box diamentions, wall thickness and what steel that GM frame is made from, anyone know?
Also interesting to note it has no X members.

59flatbedford
08-14-2010, 07:06 AM
well it seems that all you hear about any more is "fully boxed frames ". i think ford made a big deal about it hear a couple years on the f150. maybe the new bodies are not designed to twist like the old ones did?

Peter Miles
08-14-2010, 01:23 PM
well it seems that all you hear about any more is "fully boxed frames ". i think ford made a big deal about it hear a couple years on the f150. maybe the new bodies are not designed to twist like the old ones did?

I couldn't find any good images of the current Ford frames, but here is one for the 2004 series:

http://www.metalmeet.com/forum/picture.php?albumid=178&pictureid=1850

Peter Miles
08-14-2010, 01:38 PM
Here are a pair of Dodges:
http://www.metalmeet.com/forum/picture.php?albumid=178&pictureid=1852

2002 above and 2009 below:

http://www.metalmeet.com/forum/picture.php?albumid=178&pictureid=1853

Rondo
08-14-2010, 04:00 PM
According to a ford book I have the 4x4 frames changed very little between 59 and 64. The running gear stayed the same as well. The picture of the 59 and the one of the 64 frames look identical.
Rondo

Steve Hamilton
08-14-2010, 08:07 PM
The chevy picture states that the frame is hydo formed High strength steel. That is a whole different ball game. I don't think you can compare the two. High strength steel parts are not repairable if bent, they are junk and must be replaced. Some of the body panels even use lsteel that will harden at low temps, when run thru the paint baking process.

Who knows what steel they are using on the new truck frames!

Steve

59flatbedford
08-14-2010, 09:30 PM
hmm, very intersting discussion seeing how the frames have changed over the years. i think i might see about having some plate bent or get box and cutting one side out and making a c-channel frame the is basically a copy of stock one just without all the extra holes and bends i dont need.

cbass139
08-14-2010, 10:48 PM
Are the 4x4's that different then the 2 wheel? The 57-60 which have a fairly similar body style to the 61 and overs where not uni-body like the 61 and over. If the 4x4's are the same then I would guess the frame would not be the same for 58-64. Again, dont know anything about the 4x4 versions of these trucks.

59flatbedford
08-15-2010, 07:52 AM
well the frames are very similar with just a few slight differences. in fact i have had my body sitting on the 61 frame before and it works. However the frame i have has a lot of little holes and stuff that i don't need or want, also im going to be using a different engine, trans, and t-case than i was originally planning to use and than what this frame is set up for. that means i need to change at least three of the crossmembers and the frame only has 6 or 7. I think it would be a good learning experience to build a frame and i could customize it how i want and need it to be. any advice or links to threads with frame builds are welcome still.

TheRodDoc
08-15-2010, 11:33 PM
Why don't you just find some plate steel the same thickness as your stock frame rail center section and cut plugs and weld them in the holes you don't want. The welds don't have to penetrate deep. only enough so that when you grind them smooth you won't be grinding through the welds showing a crack. strength isn't an issue.

If there is a bump or lump in the center section of frame rails that you want to remove, just cut it out and make flat patch to replace it.
Don't cut your frame rails though. just in the center section area in between them.

Sam Yellowbird
08-16-2010, 11:45 AM
One of the things that we have found in the trucks is that we need a stiff chassis and the flex is taken up in the suspension. I use a 2x6 120 wall tube for my chassis iand this gives me adequate room for other things like exhaust systems and such..On a full cage race truck one can use 2x4 and get away with it..

Sam

Rondo
08-16-2010, 12:40 PM
I have a 59 that I plan on converting to 4 wheel. I plan on boxing and filling hole that are not needed. A thick piece of copper clapped behind the unwanted whole will allow you to fill the hole like you would a spot weld. Clean and no garbage on the inside of the frame.
Rondo

59flatbedford
08-18-2010, 07:12 AM
yea now im thinking about cleaning, smoothing, and building new crossmembers for my frame but im not sure yet. this is turning into a really good discussion.

kit
08-18-2010, 09:06 AM
So, what kind of steel do manufacturers use for the chassis sections of unity bodied vehicles, the same as the rest of the shell?
That's what we all seem to use when we do a welded repair, I have often wondered if that is under spec.

Doug Hawkins
08-18-2010, 10:24 AM
The chevy picture states that the frame is hydo formed High strength steel. That is a whole different ball game. I don't think you can compare the two. High strength steel parts are not repairable if bent, they are junk and must be replaced. Some of the body panels even use lsteel that will harden at low temps, when run thru the paint baking process.

Who knows what steel they are using on the new truck frames!

Steve

Here is what I was able to find for the new GM HD truck frame from the design engineer.

Low Carbon Sheet Steel per GM catalog library and spec GMW3224.
Nothing special or confidential. Thickness and material strength determined as required by design/usage.
.

Peter Miles
08-18-2010, 11:36 PM
Well, Doug has the access that the rest of us dream about!

Here are some interesting links that I found:

Tips on truck frames:
http://trailer-bodybuilders.com/mag/trucks_tips_truck_frames/

Light Truck Frame Joint Stiffness Study: (Caution - big file 11.5 MB)
http://www.a-sp.org/database/custom/Light_Truck_Frame_Joint_Stiffness_Study_Phase_2_Fi nal_Report.pdf

This is just an outline for a course on sectioning and repairing frames, but the section headings are interesting:
http://www.i-car.com/pdf/3tier-outlines/SPS03out.pdf

This article on the (Dodge) Ram line mentions using 50,000 psi steel for the frames:
2011 Dodge Ram Chassis Cabs: Ram 3500, Ram 4500, Ram 5500:
http://www.allpar.com/trucks/ram/ram-chassis-cabs.html

alan coulson
01-04-2011, 01:43 AM
Hi
I'm a little late but at the moment I am making a new chassis for a mitsubishi 4x4 to replace cracked and twisted original chassis, the new chassis is box section with welded in crossmembers.
http://i257.photobucket.com/albums/hh227/acdc351/canter4x4007.jpg

http://i257.photobucket.com/albums/hh227/acdc351/canter4x4004.jpg

http://i257.photobucket.com/albums/hh227/acdc351/DSCF6530.jpg

http://i257.photobucket.com/albums/hh227/acdc351/DSCF6526.jpg

http://i257.photobucket.com/albums/hh227/acdc351/DSCF6519.jpg

larry mullen
01-04-2011, 02:28 PM
Hello
Interesting discusion on frames . currently working on 40 chev'Rear wheel drive frame and suspension . Its from a 3/4 ton ,frame thickness is just under 3/16 .I,m taking its not needed to box frame or add stiffeners??. This is going to have small block with auto , gm subframe and rear .
Larry

wingedexpress
01-04-2011, 05:58 PM
I think you will be happy with a stock frame and filling the holes you can see from the outside of the truck. I drive a 59 chevy 4x4 daily with a stock frame and it works perfect and is very competent for offroading.Your ford frame is just as strong.
http://i323.photobucket.com/albums/nn476/wingedexpress1/037.jpg

32chevy
01-07-2011, 06:33 PM
What year of you mechanical engineering undergraduate are you currently at? You should realize that the chassis can be modeled as a simple supported beam with a concentrated load for determining stress.There are text book equations for determining max deflection and max stress.

My 1932 chevy chassis wheelbase is roughly 109in with a 1/8" C-notch type chassis. Reason for the chassis being C notched was for it flexibility on the standard dirt roads. I decided to box my chassis with 1/8 plate and it firmly stiffened up the chasis.

If I was to use a 2x4 by 1/8 square tubing: 1.5 in^2 crossection area

supports at the both ends of the wheel base of 109". My engine is 700lbs aluminum tranny 50lbs but lets just say the combined engine tranny weight is 900lbs and that its CG acts 24" from the supported end.

1018mild steel has a yield stress of 53700psi

Summation of moment at point R1 ( left support) show a R2 of 254lb and summation of forces with new info shows R1 to be 646lb. 646+254=900

Max moment occurs at 900lb application location according to moment diagrams. Textbook equations show that moment at this location is M=FBx/l <--refer to Shigleys text.

M= [900lb (85in) 24in] / 109in = 16844lb-in
C=2in
I= 1/12 *2*4^3 - 1/12*1.75*3.75^3 = 2.97in^4

Beam stress (MC)/I= 11,342psi . The max beam stress due to engine tranny weight is safely below the yield strength of the steel, 53700psi. This does not include the body weight.

a body weight 1000lb lets say located at mid way with the engine/tranny weight located as previously stated will create stress a max beam stress below 30000psi.

Further investigation needs to be complete for your analysis of your chassis. Analysis of moment diagram would suffice, with it you would use the max moment. Then find the max stress with that. But I wouldnt worry about using boxed square tubing or even the original chassis

strada shop
03-09-2011, 06:07 AM
The only crossmember I have that bolts in is the transmission member.
http://i563.photobucket.com/albums/ss76/stradarx150te/ranger/55.jpg
My frame is 2x3 1/4 over kill I know.

Overkill
03-10-2011, 08:10 AM
In my experience, when you do this to make a C channel out of it, the c channel will usually bend away from the side you removed. I know it's worse with thinner materials, but have also had it happen with thicker.

If C channel is the way you want to go, find someone with a large press brake and have it bent up.

Notice that on the Morrison and other aftermarket box tube frames, many are now 4x4 and 4x6.

2x4x.120 is way too flexible. Buddy has a 32 PU truck, stock length bed, front end pushed out beyond the radiator, hemi in it, and you can see the frame bounce like a rail dragster does.

I have a TCI box frame in my 31 Ford Coupe, but plan on adding a cage when I put the new motor in to stiffen it up. The torque rating on the frame is a third of what the motor made on the dyno.

When you take a 70 Chevy 4x4 off road, a common problem is the frame wraps up so much that the bed hits the cab. All due to flex. Of course, that helps them, as the older suspensions can only flex so much. But at some point, there will be an issue.

John