71 suburban rust repair help

[04ls1gto]

So I've been working on getting the floor patched up and discovered that the corners of the vertical sheet metal where the floor transitions from metal to plywood are pretty bad to rotted. Are there any patch panels available for rear section of floor? Also need to find the cross member?

[Bigdav160]

Nothing available and a common problem. Someone on here made that repair (Frank72?) and said it was an involved repair.

Here's a pic of mine. Both sides are the same. What's weird is from underneath it looks clean.

[Travisarmenta]

Originally Posted by 04ls1gto

So I've been working on getting the floor patched up and discovered that the corners of the vertical sheet metal where the floor transitions from metal to plywood are pretty bad to rotted. Are there any patch panels available for rear section of floor? Also need to find the cross member?

My metal guy had to fab all of that, poor guy put 138 hours total into all the rust repair for my 72, I'm glad we're friends. ill try to take pics when I get home.

[Travisarmenta]

Originally Posted by Travisarmenta

My metal guy had to fab all of that, poor guy put 138 hours total into all the rust repair for my 72, I'm glad we're friends. ill try to take pics when I get home.

The PO riveted some aluminium sheets front/back;bottom/top, it was just a mess.

Ill get some updated pics up soon

[04ls1gto]

I was afraid of that, guess I'll start bending and welding. Looks like green is the only color that has this problem. I'll take some progress pics as I go

[HO455]

Please keep posting your progress as my 503 green has this going on too. It's not as bad as yours yet. But I'm pretty sure this repair is going to be in my future too.

[rocknss]

I don't have any pics of the area but my 69 has the same issue.

[Franks 72]

Looks like this is a common problem.Mine had pin hole porosity all along the top.I removed the cross member and had sections cut out and re fabricated. Where the cross member attach's to the body was also bad. You might try for a used cross member. There are about 30 spot welds to drill.When I did mine I had the floor out which allowed me to clamp the cross member tight to the vertical floor section when re installing . It was a big job. In retrospect I wonder if it would have been easier to fab a new cross member using a plasma cutter and steel U channel of some type. The problem is the bend at each end.You will need to find a good sheet metal guy with a strong sheet metal break. I found a magician who did mine for $250 but complained about how long it took. I was glad to pay anything! It was a solid repair!
If there is enough solid cross member remaining it is possible to repair it. I did repair mine and also the rear tail pan cross member. I will post some pictures. Hope this helps

[04ls1gto]

I was hoping to not remove the plywood floor but it looks like I'll have to bite the bullet and pull it out. Does anyone have any tips on pulling plywood? Obviously all of the bolts will have to be removed, is there any sealant holding it to the cross members

[Franks 72]

Depends on your plans for the plywood, save it or replace . I had the body off the frame and tailpan was removed.This made it easy,however if the frame is off ,the body must be cross braced VERY well to prevent twist and missalighnment.
Sealant is present around the perimitter of the plywood and none on top of crossmember. Expect the floor to be stuck to the crossmember with rust and years of road dust. Work slowly with a flat bar and try not to distort the lip of the body.The floor is actualy two pieces,a large piece and a small tounge and groove insert front right side. hope this helps

[04ls1gto]

Made some progress on the floor repair today. Took out the spare tire tub and removed all the bolts with a combo of drill, air hammer, chisels and every other tool I could think of. My father in law and friend showed up to help with plywood removal. After that I drilled the spot welds and removed what's left of the cross member. Next step I'll patch the bottom of the C pillars and rocker, after that I can build a new cross member

[1fast10]

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[randy500]

I have that panel that is rust free if anyone is interested, see my parting out ad in the suburban section and PM me.

[04ls1gto]

Got the rocker and a few small spots patched up today. One step closer to finishing rust repair. A little before and after

[HO455]

Great job! Thanks for the postings. It's looking good. Are you going back together with new wood?

[04ls1gto]

Originally Posted by HO455

Great job! Thanks for the postings. It's looking good. Are you going back together with new wood?

I am definitely putting the plywood back, just not the the original piece as the edges are shot. I have a few options just haven't decided which route

- one of my suppliers can get me a 3/4" 5x10 sheet of mahagoney marine plywood but it's close to $400 for one sheet

-i have the option of joining two 4x8's together with either a Kreg jig or routing a groove in both pieces and making a tounge to hold it together.

[nastety92]

Originally Posted by 04ls1gto

I am definitely putting the plywood back, just not the the original piece as the edges are shot. I have a few options just haven't decided which route

- one of my suppliers can get me a 3/4" 5x10 sheet of mahagoney marine plywood but it's close to $400 for one sheet

-i have the option of joining two 4x8's together with either a Kreg jig or routing a groove in both pieces and making a tounge to hold it together.

I think the Kreg jig would work well and can be almost completly covered over smooth with their plugs. I've just them on a few project and it's worked out well. Just use a good quality wood as thick as possible. $400 sounds like a lot of money for what it's for.

[04ls1gto]

I've been making progress on what seems like endless rust repair. Got the spare tire tub all patched up and ready for paint. Today I fixed the wheel houses and unfortunately there's more rust in the bottom of the C pillars that needs attention. I found a replacement cross member and floor section that's going to the blaster this week and hopefully going in next weekend. Here are some pics of my progress

[04ls1gto]

And some after photos

[nastety92]

Soooooo much work. Thank god you can do the metal work yourself. It's coming along nicely keep up the good work.

[Bigdav160]

Guess we're all in the same boat. These trucks are like onions. Once you start peeling the layers back you find more layers needing attention. Just before Christmas I removed my hatch to fix the rust before it got worse. Yesterday I started removing the rockers. I might as well re-skin the passenger door while I'm at it.

Hey GTO, are you going to put the lip back on the rocker panel? I think the weather strip attaches to it.

What my truck looked like at New Years

[04ls1gto]

Originally Posted by Bigdav160

Guess we're all in the same boat. These trucks are like onions. Once you start peeling the layers back you find more layers needing attention. Just before Christmas I removed my hatch to fix the rust before it got worse. Yesterday I started removing the rockers. I might as well re-skin the passenger door while I'm at it.

Hey GTO, are you going to put the lip back on the rocker panel? I think the weather strip attaches to it.

What my truck looked like at New Years

I am thinking of either getting a 3rd door rocker and replacing the whole thing or plasma cutting one out of a piece of 1/8" plate and welding it on. I have a Tig welder but haven't practiced enough to feel comfortable

[04ls1gto]

Originally Posted by nastety92

Soooooo much work. Thank god you can do the metal work yourself. It's coming along nicely keep up the good work.

Thanks, I enjoy doing it. Its therapeutic for me. Ill be glad when it's done and I can get the new seats, lowering kit, big brakes and wheels and tires on. Every time I get discouraged I just look at the pile of boxes in the corner of my shop

[HO455]

Great stuff here! Thanks again for all the photos. I'm like an addict when I see your threads email come through. I've been looking at the spots on my Burban that you have had issues with and making a plan. Keep up the good work.

[04ls1gto]

Originally Posted by HO455

Great stuff here! Thanks again for all the photos. I'm like an addict when I see your threads email come through. I've been looking at the spots on my Burban that you have had issues with and making a plan. Keep up the good work.

Thanks, wish I had more free time to work on it. My garage is 20 min from my house so I have to plan it out. I've been sneaking out SAT morning before 6 so I can get some time. Hoping to have the carpet and seats back in in a few weeks