strengthening frame?

[mudranger]

I have noticed quite a bit of "flex" since putting the 5.0 in and now I am thinking about beefing up the frame a little to eliminate the twist. I was considering using thick-wall 2" box for laterals, and sections of 1/4 plate for the side plates, with gussets at the ends where the side plates meet the tubing. I was planning on welding the braces together, and bolting them to the frame, as well as welding them.
What do you guys think? Has anybody done anything like this?

 

[AKBroncoII]

Just bolt them, no need to weld.

 

[mudranger]

Yeah, I know, I was just gonna take a belt and suspenders type of approach, on the premise that it couldn't hurt...on the other hand there probably isn't much purpose to the additional welding....Do you have any thoughts on design?

 

[krugford]

On a ladder frame, you're better off running diagonals for rigidity instead of lateral beams. A lateral beam isn't going to do much for the weight added. There are, of course things like driveshafts, transmissions, and fuel tanks that tend to get in the way of diagonal braces.

Without looking at my truck closer, I would try to find a way to brace the area between the tranny crossmember and the front spring mount for the rear springs. IIRC, that's the largest open area of the frame. Next on my list would be to connect the rear springs mounts with diagonal braces. (Front mount to rear mount on other side).

 

[mudranger]

Diagonal...Interesting. I have a body lift, so there is a bit of space to deal with. I was also thinking about welding/bolting a large section of plate across the top of the frame from about where the rear of the fuel tank is back to the rear bed mount. there is no spare, so there's lots of space. I was gonna weld angle steel to the edges of the plate where it meets the frame and bolt it there on the vertical sections. I really like the X brace design. it would clear everything in the rear, but the left fron section would be obstructed by the gas tank. what would you think of building "legs" on the brace, and putting it above the frame, in the gap left by the body lift?

 

[krugford]

A plate (shear panel) wouldn't be a bad idea. You could also split the brace and frame around the gas tank too. Putting the bracing on "legs" is going to weaken it (depending on how high you put it) and it will also increase the shear loads on the bolts (or welds) used to attach it to the frame. Unfortunately, there isn't going to be a perfect solution because of reality. Any of these ideas will be better than what you have now. It's just a matter of cost/weight/space versus strength.

 

[mudranger]

Thanks, I think I am going to do the plate, with some type of x-brace forward. I am also going to do some sort of laterlal brace the incorporates the driveshaft loop. As you said, anything is better that what I have now. Luckily, I have a fairly good supply of scap steel to work with, so the cost will be minimal. as for weight, well, its going to be heavy for sure, but I'm not drag racing it, so it should be o.k. .

I'll let you know how it goes!

 

[predator]

whatever happened to boxing the frame in?? it would be easy to put some plate steel on the inside of the frame and weld it in sections, i dont see a need for a ginourmous shear plate in the gap between the frame and body, i think thats kinda on the OVERKILL side, its not like you have 800 hp to worry about......

 

[mudranger]

I had considered boxing the frame, but I was afraid that by using sections and leaving gaps to be able to access lines, wires, etc, It was going to lose alot of its integrity, so I came up with the plate idea...if I was gonna box it, do you think 3/16 plate would be enough? Or too much? I don't mind overbuilding a little, it always seems to prevent future problems....

 

[Forcus]

I had considered boxing the frame, but I was afraid that by using sections and leaving gaps to be able to access lines, wires, etc, It was going to lose alot of its integrity, so I came up with the plate idea...if I was gonna box it, do you think 3/16 plate would be enough? Or too much? I don't mind overbuilding a little, it always seems to prevent future problems....

You can use cardboard templates to cut the plates out and then space them in by a 1/4 or so, which will leave room to recess lines, wires, hoses. If you look, there are only a very few places where lines, wires, and hoses cross through the frame and those would be easy to accomodate.

Boxing the frame will tend to lessen vertical deflection (good for heavy bed loads, stability, etc) but may still allow a fair amount of torsion (twist). This is where additional crossmembers or X frames come in.

To be honest, if I was going to only do one of the above, I'd do crossmembers / X frames. I have my Ranger down to the bare frame now and while there is noticable flex in the frame, the amount of torsion allowed in the factory design is substantial.

 

[krugford]

I've actually got a 67 F100 frame that I boxing in right now as well. Although it's more for looks than any other reason, but I'm still using plate the same thickness as the frame. If you're looking for a quicker, easier way to add torsional rigidity, the x braces would be the number one option in terms of strength and weight. But like I said, anything is probably better than nothing...