Would you patch or cut and weld

[mally002]

I finally got all the tar coating off the 73's floor boards today and only found these small areas of rust. The rest of the floor is solid with the minimal surface rust you see. Can this small of an area be patched without welding or should I cut it out and let someone weld in a patch....

Thanks for any suggestions.

PS.....Here's an updated picture of the "Z Cave" hopefully will be finished end of next week.

Cheers,

Randy

[Walter Moore]

Nice garage!

As for the holes, that depends on what you can do, and how you want to use the car.

A LOT of the advice here is always to weld in new metal. That makes sense if you intend to drive the car fairly often and are likely to get the repaired area wet at some point. If you rivet a patch in place, the multiple layers of metal will hold any water to which the repaired area is exposed, and the old metal will rust away quicker than if you had done nothing.

On the other hand, when you weld in a new piece of metal, be aware that the weld will rust first.

Now if you are like me, and only intend to drive the car on sunny summer days, and are willing and able to always leave it parked in a nice comfy garage when the weather is wet or snowing, then patching the holes with sheet metal and pop rivets is both cheaper and perfectly acceptable. Understand however that doing this will lower the car's market value significantly.

It is your choice, based on your intentions for the vehicle and expectations of its future value.

Fair warning to anyone who might at some time consider buying my Z: There are over 1000 pop rivets in my car, and I know this because I put them there!

[MikeW]

Another option is the POR-15 Floor Pan & Trunk Restoration Kit. This is what I ended up using on mine but my rust was less severe. It's a combination of POR15, epoxy putty, and a fiberglass mesh.

[EScanlon]

Randy:

Part of the problem in recommending one method or another is knowing how much $ and time you have/want to spend on this.

The BEST method is to have the bad metal cut away, and a new floor skin put in. But another good fix is a new piece fashioned to fit properly and then stitch welded around the perimeter until it's a continuous weld. the next best is to have the patch brazed in (as long as it's not going to be a stress point/area). But the key on any of these is to have the rusted metal removed.

If the holes in the firewall/floor bend weren't so big, you could probably use the POR paint with their Power Mesh matting, and you probably still could but this is the next best after welding/brazing in my opinion. The holes on the side of the pan, just in front of the seat mounts could probably be done this way.

A plain patch which gets riveted or screwed in, should also have the bad metal cut away, but too many people short cut this in order to have a smaller patch, which ends up being a problem. Then you have to consider that it's just a patched hole, and you have to caulk/seam seal properly to avoid getting water in. Then you have the problem of structural integrity, which will be minor unless you rivet every couple of inches and that must be done onto strong metal. And lastly the problem with dissimilar metals and before long.... you have rust again. I would rate this just above a fiberglass patch.

Some guys will do the fiberglass mode, but in my experience this is a sure fire guarantee of hiding the rust until it's catastrophic discovery... like when you put your foot through the firewall at speed.... not a pretty thought. I have yet to see a fiberglass job as a patch on metal that didn't start rusting .... right away. I can't think of anyone on this site or others that has discovered a fiberglass patch on the floor that hasn't vilified the prior owner that did that.

I would rate the fiberglass and riveted patch jobs as the "El Cheapo" of repairs. (Sorry Walter.) In my experience the POR / Power Mesh repair is much better than either one of those. The best is a proper weld patch or a new floor pan.

FWIW

E

[lonetreesteve]

I agree with E, do it right and weld in new floor pans. You can buy a set of new floor pans for about $300.00.

[Sailor Bob]

I have no opinion - those stated so far are very good though.

I only wanted to say that is a beautiful looking cave.

[BRE-240Z]

In my experience the POR / Power Mesh repair is much better than either one of those. The best is a proper weld patch or a new floor pan.

I agree, and I've done it both ways.

I had a 510 that was solid everywhere but in one spot where someone had tried to lift the car under the driver's side floorpan, and they ended up punching a small hole (you could fit two fingers into it, but it was starting to rust). I removed the interior of the car and POR-15'd the floorboards and patched the hole with the mesh. It's a very strong repair, and is good for small holes. I was extremely satisfied with this.

On my Z, I had some larger issues (a baseball-sized hole under the passenger seat, along with a disassociated rear frame rail), and so I elected to replace one of the pans. There was also a smaller hole (very similar to yours) in the passenger footwell, at the bottom of the firewall. I purchased the pans (pictured above) from Charlie Osborne and have been very happy with them.

My personal opinion, Randy, is that you should get under the car and poke around with a sharp object to see how rusted the metal around the holes is. If it's good (and I doubt it is), you can patch these areas with some new steel. Otherwise, bite the bullet and buy a set of new floorpans.

That's my two cents.

[geezer]

By the way you posed the question, I don't think you wanted to hear, "replace the floor". But that is what I would recommend also. Take a good look at the area where the floor overlaps and is welded to the cowl/firewall. There is no way to remove the rust that has formed inbetween these two stampings without cutting it right out. The same goes for the seat supports. There is no quick fix to stop the advance of rust between them and the floor either. A little more disassembly is needed to get a good look at the inner rockers & inner rocker panel. This is where a little detective work is required to find the source of water infiltration & entrapment and subsequent developing rust. After all these years it has held up better than some but needs attention now.

PS - The garage is coming along nicely!

Edited September 7, 2008 by geezer

[mally002]

Thanks for all the suggestions,

It is not a car I plan on keeping for a very long time, it is going to be my fall/winter project that I'm hoping will provide me a better understanding of how to do more advanced mechanical work. I have never rebuilt and engine and I'm hoping this will be my "learn as you go" car.

I also want to learn more about body repair, so I may get someone over here to teach me some basic welding, if so I can go that route with the floors. I was thinking that the holes wern't bad enough to warrent new floors, but it seems they do qualify.

That's what I love about this board, there are so many folks out there with so much more experience that see's issues I don't. Thanks again.

PS....Walter I love the 1000 rivets comment..........:laugh:

[xray]

Looks just like my floorpans when I pulled up the undercoating...I considered the PowerMesh, but went with new floorpans. I think the rust is ultimately worse than it looks, particularly around the seat mounts. They could fail if stressed--not worth the risk IMO. You may still have to add some patch panels if the rust extends too far up the firewall, sills or trans tunnel. Good luck!

BTW, that Zcave went up fast! Does your contractor do out-of-state work?

[mally002]

Hey Steve,

Thanks for the input. Greg (contractor) has done a really great job, by far the best contractor I have ever worked with in all my building ventures. I doubt he goes out of state, but if he did I would highly recommend.

Are you in the market for a new garage? If so let me know and I'll give you my costs so you can make a comparison with quotes in your area.

Z ya

Randy

[Rockr69]

VERY NICE garage! You should call it your DAT-CAVE.