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Floor Pans... Getting screwed?

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I used a small air powered body saw and a die grinder with a cut off wheel. Take zip screws and screw the floor pan where you want it. cut a section so the old panel and the new panel are cut at the same time. Butt weld that section then work around the panel skipping from side to side and end to end. This also allowed me to take a hammer and dolly and work the edges of the pan so they matched the transmission tunnel shape. After a little grinding and some primer the repair is invisible.

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I used a small air powered body saw and a die grinder with a cut off wheel. Take zip screws and screw the floor pan where you want it. cut a section so the old panel and the new panel are cut at the same time. Butt weld that section then work around the panel skipping from side to side and end to end. This also allowed me to take a hammer and dolly and work the edges of the pan so they matched the transmission tunnel shape. After a little grinding and some primer the repair is invisible.

 

 

Charles you are genius!  That is the best method I have ever read!   So clever and efficient!

Edited by Blue

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Thanks, that sounds great. I really didn't think the over-lap method was the best option. Guess I wanted to hear it from some one that had been down this road before.

 Harbor Freight sells sheet metal welding clamps (8 pack) that I will use for aligning the edges. They worked great for aligning the footwell insert that I welded in. That one I carefully cut & fit. It turned out good but it took a lot longer than I estimated. Doesn't everything? I wasn't looking forward to precisely fitting the floor pan prior to welding. There had to be a better way.

 I'm working on the right side only at this time. When it's done, I'll take a look at the left. It has to be better than the right. No battery. I didn't want to be overwhelmed at the size of the project. Kind of like eating an elephant-you can only do it one bite at a time.

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I can't take credit for that. I have the Kevin Tetz videos and that is how he recommends fitting panels. Rough cut them, then overlay and screw in place then when you finish cut them they are the perfect size and ready to weld in

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I was going to do the same thing basically with cleco fasteners. Butt welds are best! Seamless repairs....

 

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Edited by wheee!

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I don't own any Clecos but they would work. The 1/4" zip screws like heating and air contractors use work great, are cheap, no predrilling and you end up with a small hole to fill either way. I use a magnetic 1/4" bit holder so it can be set with one hand, leaving the other hand free for panel placement. For what a few Clecos cost you could buy several hundred zip screws and the bit holder.

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Yeah, that section of welding the new frame to the old frame under the car is tricky. You can make it a little less upsidedown by jacking up just one side of the car. The 240Z floors go in MUCH easier than 280Z floors. I installed 280Z floors/frames in my race car over the winter and it was tough even with a helper and having the car on a rotisserie!

Chuck

 

Wow.... I'm almost at that stage now... It looks like you left the seat rails in place, cut underneath them, then tacked the floors in from the bottom with a slight overlap. Then welded thru from the inside thru weld holes, then spot welded around from the bottom. I assume you then seam sealed or did you do a complete seam weld?

I was almost thinking of doing a butt weld for the whole pan but that seems a little overkill for this job; too much risk of warpage etc. Thanks for the pics and ideas!

 

I am still torn about doing the zip cut butt weld method too though.... arrggghhh!

Edited by wheee!

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I probably did a complete seam weld. I think that I then used some filler to eliminate then edge so debris wouldn't catch it.

 

I'm currently working on my AAR 'cuda and am replacing part of the floor pan. I'm going to lap weld because the metal is thin. Years from now I'll put it on the rotisserie and do a more complete/better job.

 

Chuck

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Butt weld. Do it right the first time and forget it.

plus like Chuck said no edge to collect debris...

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Butt weld would make the job a lot harder and prone to mistakes of over cutting. It also makes welding more of a challenge. No one will see it, so I would go the easiest route and lap weld. It's easier to secure in place for welding also.

I plug welded my floors in place holding everything together with clecos. Then I welded seams .

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I didn't find it difficult but that's me. I cut both panels at once and that leaves a perfect gap for welding...

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What if you overlap, plug weld and hold in place with clecos, then do a seam weld on the bottom an grind smooth? No lip, overlap on the inside to make it simple and then either seam weld the inside or seam seal after plug welding...?

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That would work and be strong but it is twice the welding so twice as much heat and or time. Your welder is son or son in law? ask him what he thinks. I suspect the butt welds would be child's play for anyone who welds for a living. I actually find the welding to be the easy part it's the grinding that seems like work...

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LOL, he loves grinding... It is an art form to him.

I too like the idea of no seams. Butt welding is not difficult I suppose but the possibility of pinholes concerns me. Especially if you are spot welding in a ring over and over versus a straight seam.

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That is what the skim coat of fiberglass is for...knock it down, prime it. Perfect... B)

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I've been butt welding mine except where the floor pan welds to the rocker panel. Half the welding and grinding and no overlapped seams to eventually collect moisture. I have more trouble with patience (letting it cool) than I have either type of joint.

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I've been butt welding mine except where the floor pan welds to the rocker panel. Half the welding and grinding and no overlapped seams to eventually collect moisture. I have more trouble with patience (letting it cool) than I have either type of joint.

Ditto,

Hate waiting. I use compressed air to help cool things down but I still hate the waiting

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 Patcon

  When cooling the weld with air do you notice any warpage? I realize the weld probably adds enough stiffness to prevent much warpage. The reason I ask is the other day I was working on my hood when my neighbor came over and asked me if I had ever shrunk high spots with heat and compressed air? He has restored a 52 Pontiac and a 54 Studebaker, both look good. He explained the process, heat it with a torch (not too hot) and control the shrinkage with compressed air. I don't have the courage to try it. Especially on the thin sheet metal of a Z. Z hoods are thicker than some of the other panels but I'm not going to experiment on a reasonably straight hood.

 Curious if you've tried it or even heard of it?

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Since this topic has been revived I'll use it to ask a question that I haven't seen addressed in any of the floor threads I've seen.  I have two reinforcement pieces welded to the inner rear underside of each floor panel.  I outlined them with blue tape in the picture.  There is also the reinforcements for the transmission support.  

 

So what do you do with these?  Cut through them?  Separate them and re-weld?  Cut around them?  Remove and replace them with new?

post-1284-0-19389000-1450631868_thumb.jp

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 Depends on the condition of the sheet metal of the body, the doubler and the surrounding area. If there is a possibility of rust between the layers, They should be separated and treated or replaced. I've replaced and added a few doublers (fish plates) on mine. 16g galvanized sheet metal with zinc rich primer on the body is my choice. In lieu of those options, a good rust converter should be used. I'm going to be using Ospho on the rest of mine. Wish I had looked into it previously. I don't mind rinsing some areas with water but I can't bring myself to use water to rinse the seams out. Ospho, it appears, can be left to dry.  :)

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 Patcon

  When cooling the weld with air do you notice any warpage? I realize the weld probably adds enough stiffness to prevent much warpage. The reason I ask is the other day I was working on my hood when my neighbor came over and asked me if I had ever shrunk high spots with heat and compressed air? He has restored a 52 Pontiac and a 54 Studebaker, both look good. He explained the process, heat it with a torch (not too hot) and control the shrinkage with compressed air. I don't have the courage to try it. Especially on the thin sheet metal of a Z. Z hoods are thicker than some of the other panels but I'm not going to experiment on a reasonably straight hood.

 Curious if you've tried it or even heard of it?

Mark

 

My brother has his own body shop and has been at the trade for about 30 to 35 years.

I watched him straiten and smooth both the hood and roof on my Z prepping for paint.

The roof was dented due to being sat on some where in a previous existence and the hood he just got fussy.

He used the heat  and just worked the metal that way.Using expansion and contraction and a little impact here and there.

That is something you will not see today but he spent about 10 hrs just working on the metal before he skimmed it and started blocking everything.

With him it is pride in his craft plus he didn't want his big brother to pout LOL

The roof is really good but the hood is amazing how absolutely straight it turned out.

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post-20199-0-26233200-1450639486_thumb.j

post-20199-0-47347200-1450639588_thumb.j

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 What does he use as a heat source. I'm getting frustrated with my hood. I tap the high spots down just below level and they want to pop right back up. I could bash them down and I know they would stay down but I want as little filler as possible. I'm thinking a little heat would help. Opinion? Also, Is he using compressed air to control the shrinkage?

Edited by Mark Maras

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Acetylene torch,body hammer, one squinty eye, some cussing and a grin when he is happy with something sometimes a damp rag and then he is usually cussing ;) 

 

He apprenticed with a craftsman 30 plus years ago. If you ask him it is eye and feel. When he is finishing a panel he rubs and looks.

 

I did the rough work and paid him for his skill set.

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