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Cab floor / rocker panel rust repair Q's

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SafetyHelmet

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Hey guys,

I'm about to grind a ton of rusty metal out from under my cab body. Before I remove it, I'm curious- is the cab really just one layer of sheet metal? For example, my rocker panels look great on the exterior.. from underneath it looks like there is a whole extra layer of rusted out metal that they laid new metal on top of. It all appears to follow the same contours and lines as the good stuff.. Can I just grind this out, prime it up, and be done? Or should I weld in some reinforcement somehow?

Been trying to find a good exploded diagram of the cab sheet metal, but no luck so far.. :dunno:

I'll take some pics this afternoon if that would help explain. Half of my K5's floors are diamond plate, the P.O. went over the top of the original floor, I think. If it helps answer the question, I will be using 16ga sheet steel stitched in with MIG welding.
 
Upon further research, and hacking away at my floor, I can kind of answer this. It's normally one layer of metal. The floors are tacked on to an underlying crossmember / reinforcement bar, so that's something you'll want to weld replacement metal to.. or, make your own reinforcements instead. I will be reusing what's there after I clean it up.

My plan is to cut the entire passenger floor out, and replace with 3/16" diamond plate, using as few pieces (and weld seams) as possible. If it feels too flexible after this, I'll weld in some more bracing underneath.

Redoing the passenger seat mounts will be easy, I plan on just putting the seat in and marking where the holes want to be. Then I'll get those areas ready for tack welding the mounting bars that go on the underside. I may actually add more metal to those or weld some square tube against them, to increase the area that they reinforce.
 
You may still get some buckling and flex even using 3/16" steel,with no stiffeners,especially around the seat areas--it may feel rock solid,till someone sits in the seat and puts their weight against it..that'll eventually make the area the bolts go thru crack.....I replaced just about the entire front floor on a '72 K5 I had with galvanized 16 gauge steel,it felt super strong,till I bolted the seats back in..within a few months it was cracking around the seat track bolts..and the floor where my feet went would flex and "pop" like the bottom of an old fashioned oil can when I hit bumps or pushed against it with my feet..

(I decided to replace the stock front cab supports with the bases off a bumper jack I got at the junkyard,and welded them directly to the floor!--those were nice and beefy,looked almost like they were made to fit it too!--the OEM ones were thin sheet metal,and aftermarket ones here dissapear in a few years if you drive in winter--those along with some 1" flanged channel stiffeners made the floor nice and solid..)

You can add some angle iron or some flanged U channel steel to stiffen up any floor areas that flex,and it wont hurt to weld it where the seat bolts will go so they have to pass through both the floor,and the angle iron .....if you use flanged U channel,drill some drain holes in the bottom so water can escape,or it will rust out from the inside ..
 
Is the cab support on the pass side just tacked on to the floor, or does it bolt up to the rest of the body somewhere? I guess I'll find out as I remove the rest of the floor I marked above.

If it seems pretty rusted out and brittle, I will probably just remove it and build in my own supports with U channel or just some grid work with steel bar.
 
Square stock,like road sign poles, makes a good reinforcement too. Nicely spaced holes for bolts and draining. If there's a commercial construction site near you maybe see what they're tossing in the dumpster, I gathered alot of handy plates and corner brackets from the job. You can get some pretty thick plates from Tractor Supply,for example, and sandwich them with a few inches of overlay for strong seat foundation.
 
I've used "Uni-Strut" channels you can get at Home Depot or Lowes,or electrical supply houses ,to stiffen up floors,make cab supports and truck bed crossmembers..its strong and easy to weld..some is galvanized..another thing that worked well and was cheap were those green garden fence posts,they had the perfect shape and were thick enough to stiffen up a floor nice,and are easy to weld too..I grinded off the clips on them that would have held the wire fencing..

I bought a whole truck bed full of street sign square tubing many years ago one day when I went to a scrapyard to cash in some stuff I had piled up--got it for 100 bucks..I built a 10x24 foot "shed" out of it,numerous utility trailers and a dozen other projects!..I love the stuff...I just bolted the shed together like a big erector set...if the tubing was too short,I just bolted two together by overlapping them..its been standing for 22 years now,and has had 3 feet of icy snow drifted on it more than once..

The "U" shaped flanged galvanized stuff they use for some sign posts is the best floor stiffeners,but I learned not to use it for structural purposes,its designed to snap off if it gets hit hard,so if a car hits a sign,it'll shear off and go flying,instead of being an immoveable object I was told..

I'll see if I can find a photo of the bumper jack bases I used as cab mounts online and post back here...
 
Here is the type of bumper jack base I used...you flip it over so the flat side faces the floor,and the round part where the jack would have slid into goes against the cab mount rubber cushion that sits on the frame support..

restoring-your-original-bumper-jack_00.jpg
 
Daaaaamn Diesel you're my kinda fabrichanic:bow:

My father in law retired from Maryland state road dept. he gathered alot of road signs over the years. We all used them for floorboards,etc. Too bad it dwindled down before I got my 'burban.
 
I tend to put things to use for purposes they were never intended for --I'm not a real good "fabricator".I can cobble things up but they rarely look good--,so I try finding some ready made item I can use instead...

When I went to a junkyard one day when I was in the process of replacing the floor in my K5,I saw stacks of old bumper jacks piled up near the office,and the base looked to me like it was ready made for use as a floor/cab support!..cha-ching!...best part is the guy gave me 4 of them that were identical and looked like new...

I noticed not long ago at Lowes in the section where they sell those metal brackets for rafters ,etc (Simpson Ties) ,there are some thick ones that look very similar to a stock cab support that might be useable on the older square body trucks...some of the other items in the bins are usefull for things like brackets to hang radios or CB's from,or exhaust pipe hanger brackets..galvanized,wont rust,and best of all,ready made and cheap!..

Every time I go there,or to other stores,when the guy asks "can I help you find something"?..I say "I doubt it!--I almost never use what I buy here for it's intended purpose!"....like the day I was in the plumbing aisle,and I found some perfect sized brass "bushings" to use on a wheel on a riding mower,that is originally intended to mate a copper pipe to a brass one...cost me about 90 cents--if I could have found proper "bushings" they would have been 6 bucks each...:D
 
:haha:Diesel, like I said........
I'm exactly like that. I've used things that nobody would ever think of. Ideas just hit me when I see something. Thats also why I said fabri-chanic because I'm not a full fledged mechanic or fabricator...I don't weld for one thing ( ruined my eyes watching the pretty blue stars down the shipyard as a kid) I'm not quite a framer-metal or wood- but I can build things with the right materials and tools ( sometimes the wrong tools) and I seem to have 1/10th of my Dads natural mechanical talent. He and his twin brother built some of the first Hotrods around here...55s,57s,etc...I'd give my pinky to know half of what he forgot ! But I think his ghost whispers stuff over my shoulder sometimes.
Most people can barely make what's designed for something work as intended (sometimes me too) but I always had a knack ( err...obsession) for taking things apart and rebuilding them in insane ways. I was psyched when I found this forum! Guys rebuilding and modding badass Chevys? YYYYEEESSSSSSS!!!!!
I get alot of " Why ya wanna do that??"s and " Just leave it alone"s from friends and family but when I'm done they either love the result or I rethink it into something else before they see it.

My 'burban is now an 85 base with 3 other vehicles major parts in it. The fabs and fixes are half what Walmart threw out back during a Supercenter addition and industrial grade construction stuff....heater duct, brackets,metal studs,etc.
The new materials they're coming out with make excellent modding stock. I love Azec :waytogo: Perfect solution to crappy headliners. The 'Zip System' that's replacing Tyvec...great liner,awesome rubber tape...
Self tapping,gasket headed screws. Plastic conduit. Sprinkler pipe-both black steel and PVC.
There's a world full of better things to build with and a headful of crazy ideas....and if those ideas don't work don't worry because tomorrow there will be another bushel :rolleyes:
 
Speaking of that,and metal studs,I once used 2 metal stud pieces back to back to make a square tube of sorts,to use in place of the rotted out "manifold stove" on my exhaust manifold on a Chevy truck I had,you know,the one that crinkly aluminum foil/paper tubing goes on,to the air cleaner snorkel..it even had a perfect sized hole to shove the tubing into,and it looked decent enough not to look that hack..

I used two hose clamps to attach it to the exhaust manifold..
I closed off one end of the "stove" up front,and left the rear end open...I think it worked better than the original one did..and it was galvazined,so it didn't dissapear instantly too..

Electrical items are fair game for "universatility" too...I've used conduit clamps for everything from hanging pipes to making coffee cup holders (3" ones work pissah!),and the electrical "lugs" you can find in house breaker boxes work well on many other things,like where your battery cable needs to be bolted on at the starter solenoid...many of my vehicles have had exhaust systems made out of chain link fence tubing --the 2" corner posts are big enough for a healthy V8,they are actually closer to 2-1/4" and I have had them on more than one vehicle over 8 years with no sign of the galvanizing coming off or rusting..(but I had to put 3 mufflers on during that span!)..
 
diesel4me said:
Speaking of that,and metal studs,I once used 2 metal stud pieces back to back to make a square tube of sorts,to use in place of the rotted out "manifold stove" on my exhaust manifold on a Chevy truck I had,you know,the one that crinkly aluminum foil/paper tubing goes on,to the air cleaner snorkel..it even had a perfect sized hole to shove the tubing into,and it looked decent enough not to look that hack..

I used two hose clamps to attach it to the exhaust manifold..
I closed off one end of the "stove" up front,and left the rear end open...I think it worked better than the original one did..and it was galvazined,so it didn't dissapear instantly too..

Electrical items are fair game for "universatility" too...I've used conduit clamps for everything from hanging pipes to making coffee cup holders (3" ones work pissah!),and the electrical "lugs" you can find in house breaker boxes work well on many other things,like where your battery cable needs to be bolted on at the starter solenoid...many of my vehicles have had exhaust systems made out of chain link fence tubing --the 2" corner posts are big enough for a healthy V8,they are actually closer to 2-1/4" and I have had them on more than one vehicle over 8 years with no sign of the galvanizing coming off or rusting..(but I had to put 3 mufflers on during that span!)..
Click to expand...

fence poles :thumb: thought i was alone on that :waytogo:
 
Yup--fence pipes..I went to a fencing company locally once to see if they had any "leftovers" I could paw thru,and I was surprised to learn they also have different "schedule" tubing,just like in plumbing..for uses that require more structural strength they have a schedule 40 !..and sizes up to 6" in stock!..:eek1:..I wanted that size for my wood stove when I saw it,but the guy said the zinc would make me ill if used indoors,and it was about 10 bucks per foot...pass!...

Here is a picture of the electrical lugs I was talking about...I've used these bor battery cable ends when I used welding cable to make "custom" cables,or to use as a common point to ground several wires under the dash or hood..

images (6).jpg
 
Here's the other "Strong Tie" Simpson product I said looks a lot like a cab mount too..picture came out small,sorry..

050c-2013.gif
 
Hey yeah I've seen those lying around on jobs!
Fence post...I pulled mine out of my driveway after hitting it with my Buick:waytogo: used it on my 70 C10
Maybe you can see in my build thread...I've got 4 joist hangers ,Simpsons apparently, lying in the pile of stuff.
I'll be looking for those you posted when I do my body mounts real soon
Gotta love ingenuity...poor guys can't always afford the hyped up products
 
Should I drop the fuel tank and lines before welding floors in, or would covering the frame rail below the area I'm welding on with a fiberglass blanket be good enough?

The lines look clean and poking around there I never smelled vapors or anything, but I thought I'd see what you guys have done, or if I'm worrying too much about it.

Thanks!
 
I was brave (or dumb) and never did anything to prevent a fire or explosion .other than drape a wet blanket over a gas tank & lines if I was welding or cutting close to them...rubber hoses are what will get you in trouble if slag lands on one--or vapors,those will go off in a flash,litteraly..

I once brazed a rear wheel well repair panel on with a torch on my '75 K5,and I had to braze it right around the gas cap opening--I left the gas cap on,but put a baggie over the filler neck,then put the cap back on,hoping it would seal well enough so any fumes wouldn't ignite...it went OK,but it took my butt about a full day to un-clench fully!...I've seen guys mig weld gas tanks,oil pans,and not have an explosion,but they were probably just lucky...

The absolute safest way would be to pull the tank off,blow any remaining gas out of the fuel lines with compressed air,and keep a fire extinguisher handy..

I had a lot more trouble with old body seam sealer,undercoating and jute padding catching on fire in hard to get at places while welding my floor patches in--I had a garden hose right by my side and had to use it several times ..never had a problem with gas or a tank,but again,I was probably just lucky...

My boss at the junkyard was a big risk taker with torches--he used to cut everything with them--brake lines,rubber hoses,he often had some impressive flare ups when the torch cut thru them and ignited the fluids inside.."Ah,they only go "whoof" for a second--dont be such a pussy"--he'd often toss a lit ciggarette in a 5 gallon bucket of diesel we'd drained from something,and say "watch--when its below 50 degrees,it'll go out like its water"..sure enough,it'd just go "sssssssss" and go out..

Till one day when a co-worker cleaned out his new paint gun,and dumped the laquer thinner in the bucket with the diesel in it...the boss flicked a ciggarette at it,and it went "BWOOOF" and flames 6 feet high roared out of it!...I think he needed a change of underwear by the time he figured out how to put it out...he scurried around like his pants were ablaze till he found a hub cap,and dropped it on top of the bucket,and luckily it went out,just as the plastic was getting hot enough to start melting...:eek1:..

One of the loudest explosions we had at the junkyard was when one day he cut off a charcoal canister on a car that had come in recently,when he was removing the gas tank (yes,he cut the straps with the torch 90% of the time!)...it was like a cannon or bomb went off--boss said his ears rung for a week!..
I think the only louder "boom" we had there was when a loader tire exploded,when we had clipped the air hose chuck on it to inflate it,and "forgot" about it when the roach coach pulled in...about ten minutes later,--BA--BOOOOOOM"...the loader actually came off the ground and moved over 2 feet when it landed...we got a good reaming for that "mistake"..even though the tire was junk to start with!..
 
Well, sounds like I should pull the tank. Need a new filter unit anyways.. Do you think two guys would be enough to push a K5 with a 454 up a standard garage entry skirt? Mine's not flat between the garage and driveway, it's got a slight incline. I'd just push the damn thing with my Jeep, but the Jeep isn't tall enough to push bumper to bumper! :doah:
 
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