Can anyone school me on how the 73-75 k5 doesn't collapse on itself?

[Vbb199]

I'm talking full removable top!
Without the pillars in place on the 76-91 k5, what keeps the body from bending?
I know there's brackets underneath the truck body that keep it from bending, but can anyone show me what they look like, where they're located?

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[Frankenchevy]

Since it’s body on frame I don’t think there’s much stress on the body as long as the rubber side is down.

 

[SquareRoot]

I'm talking full removable top!
Without the pillars in place on the 76-91 k5, what keeps the body from bending?
I know there's brackets underneath the truck body that keep it from bending, but can anyone show me what they look like, where they're located?

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They call it a "frame" Poncho.

 

[Vbb199]

They call it a "frame" Poncho.

Simple enough.
Thinking of a future project with my current k5, just crossed my mind, "what keeps it from bending"

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[nvrenuf]

The frame does help but it does not and cannot prevent the windshield frame from leaning back towards the seat.

It's the rocker boxes under the floor that keep the door opening from collapsing. There's some small channel attached to the floor running front to rear but most of the strength comes from the flat pan that encloses the rocker areas. The pan is welded to the body tub and also has some structural holes and bends for strength / rigidity.

If you were planning to convert a 76+ to a full top then you'll need to reinforce the firewall area somehow to prevent movement, most folks (myself included) add a roll cage and tie the body to the cage.

 

[bucket]

I always thought it was strange that the floor bracing went away for '76. Figured it would have been easier for GM just to leave it in place.

 

[Keith Seymore]

Keep in mind the frame fully supports the pickup cab and box: there is no body structure bridging the two like there is with a Blazer/Suburban.

K

 

[Vbb199]

The frame does help but it does not and cannot prevent the windshield frame from leaning back towards the seat.

It's the rocker boxes under the floor that keep the door opening from collapsing. There's some small channel attached to the floor running front to rear but most of the strength comes from the flat pan that encloses the rocker areas. The pan is welded to the body tub and also has some structural holes and bends for strength / rigidity.

If you were planning to convert a 76+ to a full top then you'll need to reinforce the firewall area somehow to prevent movement, most folks (myself included) add a roll cage and tie the body to the cage.

Well what brought this topic up is one of things on my "to do" list of my k5 is build a roll cage. Which brought Me to the thought of piecing it together around the inside of the cab.
I got to thinking "this would be so much easier with a full top k5"

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[Vbb199]

I always thought it was strange that the floor bracing went away for '76. Figured it would have been easier for GM just to leave it in place.

Coming from my career path, I know someone built a tool for GM to stamp out x amount of those braces....
If the tool only ran from 73-75, seems like a waste doesn't it?

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[nvrenuf]

Yessir, building a cage is WAAAY easier without a roof!

 

[Vbb199]

Yessir, building a cage is WAAAY easier without a roof!

Figured I'd make the windshield pillar all the way to behind the B pillar or whatever, them work it into place, then Weld on the back pillar, the rest from there won't be a lot of work

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[Keith Seymore]

Coming from my career path, I know someone built a tool for GM to stamp out x amount of those braces....
If the tool only ran from 73-75, seems like a waste doesn't it?

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You can bet they did their homework and got their money's worth out of that tool.

In fact, they were still using temporary tooling to make the rear header on the Suburban when it went out of production.

K

 

[legopnuematic]

Since it’s body on frame I don’t think there’s much stress on the body as long as the rubber side is down.

You would be surprised how flexy they are. Even the body mounts play a role in keeping the body from flexing. My friend 75 K5 I'm working on, the doors would rub the rockers (doors sagging) with the old body mounts. He put a set of new mounts on and the body lines lined up again and doors no longer rubbed the rockers. Driving it down the highway the firewall/windshield frame would wiggle/bounce. The inner to outer rocker connection plays a big role on full tops to as it is what connects the floor to the pillars, so when that rusts out it gets floppy

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[shiftpro]

It only takes about two feet of wet snow to collapse a square cab that doesn't have the front and rear glass in it.

 

[Snoots]

I always thought it was strange that the floor bracing went away for '76. Figured it would have been easier for GM just to leave it in place.

It wasn't needed for the 'half-top'. Cheaper, lighter, faster to assemble, gained MPG.
Whoop dee do.