Stiffening the frame

[Blmpkn]

Most of my frame crossmembers are pooched.

Convieniently.. they're mostly all available to buy.

Unfortunately.. I'm too broke to want to spend that amount of money on boring parts (they're surprisingly spendy imo)

Fabbing some up myself sounds fun enough.. but also seems like a decent way to improve on the rangers floppy frame. I'd like this thing to handle as well as something with beams can so.. adding some rigidity to the frame would be super beneficial.

Apart from the very front crossmember and the engine cradle.. I'm open to cutting off whatevers there and making something better.

What would you do? I know the very basics but I'm no chassis tech or structural engineer so.. brainstorm time

 

[Brain75]

if ya had access to the rust free junkyards, I'd just grab replacements from the yard...

 

[Brain75]

just curious, if "most" of them are pooched how is the frame itself... if the issue is rust, I'd be scared of the frame too.

 

[Blmpkn]

just curious, if "most" of them are pooched how is the frame itself... if the issue is rust, I'd be scared of the frame too.

'Most' may be a bit of a dramatization lol.

The one furthest back (#8) is cracked through, 7 has been repaired but not well, and relatively sure 6 isn't too hot either.

Now that I look closer.. pretty sure I don't have #5 shown.. I think that diagram is for an extendo cab?

The rails themselves are nice though. Crossmembers are to be expected on anything with a full frame up here every ten years let alone the 30 that this things been kickin around..

Just figured I can repair and improve all in one go. Getting two birds stoned at once.

The trans crossmember doesn't do jack for torsional rigidity.. that can be easily remedied by turning it into a big k brace..

 

[lil_Blue_Ford]

I made a #4 not all that long ago… I made it with a plan for as simple and easily reproducible as possible because that’s a common crossmember to go around here. I need some time to work on the other ones.

 

[alwaysFlOoReD]

Box in the frame rails. Build cross member as needed. Roll bars really help, especially if tied in ahead and behind the cab. Tubes should land as close to suspension point's as possible... Ie: above spring brackets.

 

[Brain75]

Something funny about your comment the trans x-member doesn't provide torsional strength at all... In 1948 that was the only x-member in the rear and with any trans swap a guy has to cut it (old trans were ridiculously short front to back).... so far the only x-member I fabbed is that one, 3/16 x3" strap. Without it the bed will flex and warp just from a normal takeoff not even a hot rod racing showoff.

 

[Roert42]

X2 to box the frame to stiffen it up.

triangulation is the name of the game. After the frame is boxed add as many Xs as you can fit.

 

[Blmpkn]

Thanks for the input fellas.

I made a #4 not all that long ago… I made it with a plan for as simple and easily reproducible as possible because that’s a common crossmember to go around here. I need some time to work on the other ones.

Am I correct in thinking that #4 is exclusive to the extendo cabs? My trucks 2 towns over so I can't really check lol.

Box in the frame rails. Build cross member as needed. Roll bars really help, especially if tied in ahead and behind the cab. Tubes should land as close to suspension point's as possible... Ie: above spring brackets.

X2 to box the frame to stiffen it up.

triangulation is the name of the game. After the frame is boxed add as many Xs as you can fit.

Roll bars are out slightly out of the scope of this build in particular.. but boxing some select sections of the frame is definitely on my mind. I'd like to strike a decent balance of adding stiffness and NOT adding a bunch of weight.. if I could.

A big k brace to act as the trans member, boxing the section of frame that 'humps' up from the back of the cab to somewhere around the spring hanger, and then a big x brace or something to tie the back together real well seems like a decent plan of attack in my mind.. I'm gonna be ditching the stock fuel tank for an 8 or 10 gallon cell that'll hang where the spare should be as well.

Perhaps an x brace in the rear wouldnt be necessary.. mabey just adding some bigger round tube crossmembers with plates and gussets would do the trick.. hmmm.

Once I'm home I'll make some quick sketches of what I got rolling around in my head.. a picture is worth quite a few words I've heard so..

 

[Blmpkn]

Something funny about your comment the trans x-member doesn't provide torsional strength at all... In 1948 that was the only x-member in the rear and with any trans swap a guy has to cut it (old trans were ridiculously short front to back).... so far the only x-member I fabbed is that one, 3/16 x3" strap. Without it the bed will flex and warp just from a normal takeoff not even a hot rod racing showoff.

You gots a hotrod?

Pictures!

 

[lil_Blue_Ford]

@Blmpkn , I honestly don’t know if #4 is only extended cabs. I only have extended cabs, lol

 

[19Walt93]

When I bought my Ranger it was a gutted out former drag truck, the transmission cross member had been hacked up and the gas tank cross member had been cut out and was completely missing. I made my own cross members but most of the rear ones have compound angles in them, I'd buy replacements for those if they're available and just make the easier ones if you want. If you drive in road salt a fully boxed frame will trap moisture and rot like crazy. Ford used boxed frames in the 60's and early 70's. When I started at the dealer in 1975 any 5 year old car had to go on the one lift we shared to be checked for structural frame rust for state inspection- and we found it often.

 

[alwaysFlOoReD]

When I bought my Ranger it was a gutted out former drag truck, the transmission cross member had been hacked up and the gas tank cross member had been cut out and was completely missing. I made my own cross members but most of the rear ones have compound angles in them, I'd buy replacements for those if they're available and just make the easier ones if you want. If you drive in road salt a fully boxed frame will trap moisture and rot like crazy. Ford used boxed frames in the 60's and early 70's. When I started at the dealer in 1975 any 5 year old car had to go on the one lift we shared to be checked for structural frame rust for state inspection- and we found it often.

I never thought about the trapped muck. That's a good point. But a plate with openings cut in it would add just as much stiffness, be lighter, and make it easier to clean. Think of the triangulation you see in steel tube rafters in commercial and industrial buildings.

 

[Blmpkn]

@Blmpkn I only have extended cabs, lol

Jeeeeeze and I thought I had issues

When I bought my Ranger it was a gutted out former drag truck, the transmission cross member had been hacked up and the gas tank cross member had been cut out and was completely missing. I made my own cross members but most of the rear ones have compound angles in them, I'd buy replacements for those if they're available and just make the easier ones if you want. If you drive in road salt a fully boxed frame will trap moisture and rot like crazy. Ford used boxed frames in the 60's and early 70's. When I started at the dealer in 1975 any 5 year old car had to go on the one lift we shared to be checked for structural frame rust for state inspection- and we found it often.

I never thought about the trapped muck. That's a good point. But a plate with openings cut in it would add just as much stiffness, be lighter, and make it easier to clean. Think of the triangulation you see in steel tube rafters in commercial and industrial buildings.

I'm not worried about trapped muck all that much. It's gonna be a fair-weather driver.. hell.. might not even be driven on a dirt road now that I've moved lol. It'll also all get corrosealed, painted, AND fluid filmed before I drive it again.

A pretty thorough boxing that has the plates hit with a dimple die would be super awesome.. I have a 20 ton press and a good bit of 1/8" sheet already.. and also recently got a drill press that I could cut all those damn holes with..

 

[superj]

weld some .5" steel plate across from left to right frame sides everywhere you can. that will stiffen it up pretty solidly and help protect your powertrain from land mines