(What started as) Windshield sagging - 75 full top

[4x4blaze]

Hey guys! I recently acquired a 75 full top k5 that is in surprisingly good shape! It's a Washington truck so its relatively rust free, but still has its flaws.

The rocker boxes and floors are completely intact. But the rockers were "repaired" with fiberglass. They are pretty well shot and will need replaced.

My biggest concern thus far is the windshield sagging. The bottom of the doors are actually contacting the rockers. And when you close the doors, it ever so slightly pushes the windshield forward. So it definitely needs fixed before I can start the body work.

I've heard of guys using 2x4 pieces of steel stock, but I'm not exactly sure of how they are secured/welded to the floors. How many of you guys with full tops have tackled this issue?
Thanks a lot!

 

[nvrenuf]

Any chance the door hinges are real problem with the doors? Is the dragging issue the same on both sides?

You said it’s fairly rust free but why was the rocker(s) repaired? Are you absolutely certain the rockers / boxes are still tied to the tub like factory or could the fiberglass be hiding where it’s broke loose?

 

[fastazz81]

If the rockets or cab floors are repaired with fiberglass it’s probably flexing , the rockers and floor boards are a structural part of floor, mine flexed like crazy when they where rusted out , not so much now that I’ve replaced them.

 

[4x4blaze]

Any chance the door hinges are real problem with the doors? Is the dragging issue the same on both sides?

You said it’s fairly rust free but why was the rocker(s) repaired? Are you absolutely certain the rockers / boxes are still tied to the tub like factory or could the fiberglass be hiding where it’s broke loose?

The door hinges were my first instinct of things to check. And yes, it does scrape on both sides. And the hinges themselves actually feel relatively tight still. The truck apparently only has 36k original miles... That could be 536k for all I know, but the truck still feels very solid in the typical places that show wear and tear. Such as door handles, interior pieces, etc. It was owned by a hunting club and spent majority of its life sitting I believe.

And the rocker boxes are still very solid! When it first got here I spent an entire day power washing and degreasing. I took a hammer to them and they still feel very solid thankfully. The frame was covered by 40+ years of crud, but underneath it is surprisingly clean!

 

[4x4blaze]

If the rockets or cab floors are repaired with fiberglass it’s probably flexing , the rockers and floor boards are a structural part of floor, mine flexed like crazy when they where rusted out , not so much now that I’ve replaced them.

Bingo. Hope this this doesnt make me sound like a dumba$$, but I did not think the rockers served as a main structural piece. I figured the rocker boxes did majority of the bracing. But since mine are swiss cheese, that makes perfect sense!

Thanks a lot you guys, experience is gold when dealing with issues like this!

 

[4x4blaze]

Am going to go out and take some pictures shortly so you can see what I'm working with

 

[4x4blaze]

Here they are:
Passenger side


Drivers side




Bed floor is almost perfect


And the floors I am very satisfied with!

 

[bp71k5]

Yep, the rocker box needs to tie into the rocker panel, the firewall, and the b-pillar to do anything, and you got no rocker for it to tie into. And someone using fiberglass to “fix” that probably means there’s a bunch more to fix than you can see.

 

[4x4blaze]

Yep, the rocker box needs to tie into the rocker panel, the firewall, and the b-pillar to do anything, and you got no rocker for it to tie into. And someone using fiberglass to “fix” that probably means there’s a bunch more to fix than you can see.

Okay, good to know.. And I have the truck completely stripped at the moment and have spent most of today looking over everything, popping off all the fiberglass, etc. Its pretty easy seeing where it is since they didn't take the time to smooth it. So time will tell, but I really dont feel too bad about the rest of it. I'm expecting more rust in the rear quarters, but I'm not expecting it to be Missouri salt belt rust. Also planning on getting it blasted soon so I can see what actually lurks below here shortly.

With the taillights removed, I can also see in between the body panels and ca see that they havent previously been cut out and patched.

 

[4x4blaze]

I believe most the rust in this truck has also been caused from sitting while the top was leaking as well. I do not believe it has been caused form driving and throwing mud/water/slop up off the roadway. Because it is greasy underneath, but underneath that grime is perfect 1975 black paint. Which does make sense if it in fact does have 36k miles

 

[blazer74]

Front cab supports and rocker boxes from the cab supports to aft cab mount channel that runs widthwise keeps the body from flexing.
The doors sitting low is a product of the front cab mounts and rubbers.
Would be surprised if the front fender to door gap doesn’t get larger from top to bottom.

 

[4x4blaze]

Front cab supports and rocker boxes from the cab supports to aft cab mount channel that runs widthwise keeps the body from flexing.
The doors sitting low is a product of the front cab mounts and rubbers.
Would be surprised if the front fender to door gap doesn’t get larger from top to bottom.

So you're suggesting I check the body mounts as well? The mounts are 100% solid, but the rubber is 44 years old..

 

[blazer74]

What I can see in the pics the rocker box at the front cab mount is not all there best I can tell and the the missing rockers is part of the structure integrity.
If the front cab supports above the rubber are solid and the floor is not as seen in the pics that’s odd.
My 74 when the top was off the doors and windshield frame would sag also.
My rocker boxes were so bad I rebuilt them with square tubing to restore the rigidity.
Wet noodle is best I can describe.

 

[blazer74]

Replacing your rubber mounts is not a bad idea at this point before you do your support work.

 

[4x4blaze]

What I can see in the pics the rocker box at the front cab mount is not all there best I can tell and the the missing rockers is part of the structure integrity.
If the front cab supports above the rubber are solid and the floor is not as seen in the pics that’s odd.
My 74 when the top was off the doors and windshield frame would sag also.
My rocker boxes were so bad I rebuilt them with square tubing to restore the rigidity.
Wet noodle is best I can describe.

I will take more photos from the underside shortly so you can get a better look and give me some more pointers. But yes, the inner rocker is non existent along with most of the outer. I believe it was from water leaking through the top, sitting in the corners, waterlogging the carpet/insulation, and then eventually making it's way through the floors.

& Do you by any chance have a thread/pictures of the tubing reinforcement you did?

 

[blazer74]

I cut back to good metal at the Front Cab mount rocker box as well as the rear connection point at the channel.
Basically built a ladder type box out of 3/4” sq tube extending front to back adding until it was solid.
Not the best looking but works.
Was going to add another longitudinal piece on the bottom center but never did.
Made Stainless covers to box back in but never installed either.
I also had to replace the longitudinal floor supports at the front. Was in very bad shape.
Plenty strong for a street machine.
If you have the top, use it to help line up the windshield frame and doors.

 

[4x4blaze]

Here are some better shots of my rocker boxes/cab mounts.. As you can see, they are pretty much intact!

Drivers side:





Passenger side:

 

[4x4blaze]

I cut back to good metal at the Front Cab mount rocker box as well as the rear connection point at the channel.
Basically built a ladder type box out of 3/4” sq tube extending front to back adding until it was solid.
Not the best looking but works.
Was going to add another longitudinal piece on the bottom center but never did.
Made Stainless covers to box back in but never installed either.
I also had to replace the longitudinal floor supports at the front. Was in very bad shape.
Plenty strong for a street machine.
If you have the top, use it to help line up the windshield frame and doors.

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Very good idea and nice fab work Looks like it does the job twice as well as the stock rocker boxes did. And okay, I was wonder what the best way of realigning the truck up would be. What did you use/hook onto to "pull" the windshield out and away to get the alignment correct? This truck isnt sagged terribly, but its sagged enough that the doors contact the rockers

 

[blazer74]

I used to factory top to line everything up if you have it.
Bolted it down where it’s supposed to be with the back window closed initially so that’s aligned.
Door hinge wear is a player here also, want them to be tight.
The Windshield frame will move easily by lifting the end of the doors.
Use whatever works to hold you windshield frame up to the top including the bolts frame to top.
2x4’s from top of frame to behind the seats to the floor.
I used jacks and supports under the body to lift the sag wherever needed, between the frame and body whatever.
I had the doors off so I bolted angle to the lower door hinge mounting and supported under that.
Some even tack weld a brace from the Wframe to the b pillar to keep alignment.
Don’t take any more apart than you have to. The more the sloppier things get.
Looks like you could just reinforce your existing rocker boxes if they have integrity.
Depends on your plans for the K5.
On another note, your going to need front shackle bushings, springs are close to the frame.


Couple of borrowed pics from this site.

 

[4x4blaze]

Thanks for sharing your tips on fixing this! I am definitely going to use them! & Those dimensions are very helpful! But I noticed those are on a first generation K5? Do any of you guys know where to find 2nd generation dimensions?

& Anyways, I have ordered inner & outer rockers, kick panels, and a few other steel parts. Still waiting on them to arrive so I can get going on this project! Hopefully they will be here soon..

I am also getting parts of this truck dustless blasted next week so I can see what else needs fixed. It is pricey, but much faster and easier than sanding, grinding, etc!