Boxing a SWB frame

[Justin Jones]

Hello, I was just curious if there were any areas that might benefit from boxing on the frame or if it was over kill. Street truck, not big power.

[Rich69shortfleet]

Originally Posted by Justin Jones

Street truck, not big power.

You just answered your own question right there. No need, yes overkill.

[leddzepp]

Overkill

[Justin Jones]

Thanks guys. So there aren't any weak areas at all? It doesn't flex at all?

[Rich69shortfleet]

Well sure, it's a pickup so of course it flexes some. Tying the cab and the box together would do more to eliminate flex. But there is little you can do to the frame alone without adding a BUNCH of weight and complexity that would greatly reduce flex. Are you planning to run your truck on a road course?

In addition the frame is freakin' HEAVY (I mean, it's a truck so it should be). The suspension is heavy, huge amounts of unsprung weight, and a solid axle. The best way to carve corners in one of these would be to make a tube frame chassis and wrap the truck sheetmetal around it. They are also tall with a high center of gravity. Even with a lowered truck, the engine still sits a mile above the frame. Not to mention the obvious forward weight bias found in any pickup.

[Justin Jones]

Well I figured there wasn't much point in boxing it. My brother wanted to box it in some of the areas, I don't think the entire thing. I was trying to ask all of the questions really to make sure. Thanks.

[hewittca]

Throw some jackstands under it and let it down, you'll see how much it flexes! I'm always surprised and slightly concerned when I see the nose continue to go down several inches after it contacts the jackstands. But as mentioned above, it's an old truck, it's going to flex.

[Fatherflash]

Originally Posted by Justin Jones

Well I figured there wasn't much point in boxing it. My brother wanted to box it in some of the areas, I don't think the entire thing. I was trying to ask all of the questions really to make sure. Thanks.

Partially boxing a frame will only stiffen one part of a frame and not the rest. In doing so, you move the load and stresses from the boxed portion of the frame to areas immediately surrounding that boxed area. If these areas are not improved to accept this additional load and stress, then you will encourage damage (cracking, distortion, etc.) in these areas.

Like others have said, not necessary.

[Rich69shortfleet]

Originally Posted by hewittca

Throw some jackstands under it and let it down, you'll see how much it flexes! I'm always surprised and slightly concerned when I see the nose continue to go down several inches after it contacts the jackstands. But as mentioned above, it's an old truck, it's going to flex.

A good part of what you are seeing is the front of the truck lifting the rear of the truck off the rear springs. The truck is kind of pivoting on the jack stands if you will. Of course if you already have the rear of the truck on stands under the FRAME, what you are seeing is indeed frame/body flex.

[KQQL IT]

Only real weak point is the frame rail by the steering box mounts

[hewittca]

Originally Posted by Rich69shortfleet

A good part of what you are seeing is the front of the truck lifting the rear of the truck off the rear springs. The truck is kind of pivoting on the jack stands if you will. Of course if you already have the rear of the truck on stands under the FRAME, what you are seeing is indeed frame/body flex.

That's a good point. I was actually thinking that might play into some of what I was seeing after I posted that. Thinking about it, I do still see some flex when putting it up on all fours. It's noticeable at the cab to bed gap which is normally very even when on the ground.

[Rich69shortfleet]

Originally Posted by hewittca

That's a good point. I was actually thinking that might play into some of what I was seeing after I posted that. Thinking about it, I do still see some flex when putting it up on all fours. It's noticeable at the cab to bed gap which is normally very even when on the ground.

Yep, you can see the cab to box gap change just while you are traveling down the road. While some of that is flex of the frame, some is also movement of the cab on the rubber body mounts, especially if the body mounts are old originals. As beefy as the frame is, it does move.

[CANUCIT]

Continuing the thread,

So I should box the whole thing, and how thin of metal can I get away with,
and I will be pro streeting my 62 with a full back half

[Justin Jones]

We are replacing the body bushings with poly urethane from Energy Suspension. And that's pretty much all trucks going down the road because the bed is rigidly mounted and the cab is on bushings.

I'm curious KQQL IT, is there anything that can be done in the area of the steering box mounts?