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How to repair rust pin hole and cracks in floor?

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MTribe

MTribe

Jedi Hopeful
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I'm prepping my TR6 floor panels for paint, and discovered one rust pin hole, and a couple 1" hairline cracks emanating from the rear seat mounts in the floor panel.

Having taken a welding class years ago and looking for an excuse to get more a welder and more practice, I went out and bought a $179 mig welder from Kragen thinking I'd repair both with it.

Then I had visions of blowing holes in thin metal, and wondered if another repair might be better, especially for the pin hole. I read some people use epoxy, or just seam sealer.

Any tips on how to repair the pin hole and the hairline cracks before I fire up the welder?

Thanks!
 
Hey Norton,you got photos of that pretty brassing job you did?
 
Re: How to repair rust pin hole and cracks in floo

Don
I don't think so, we covered it with POR15.
Anyway for the pin holes just use POR15, see their website. Seems to work well, gets hard as the hubs of he**.
The cracks should have a reenforcement added. I brazed the ones on my friends car, but really think I should have added a thin washer as reenforcement also. I think the crack will be back. I still may regrind that and add the washer.
 
Re: How to repair rust pin hole and cracks in floo

Hey, I might need you to bring that welding stuff up to Lynnwood if the floors of mine are bad.Boy that'll cost me!
 
Re: How to repair rust pin hole and cracks in floo

If it's *just* pinholes and small cracks, you can use POR15 and masking tape.

Clean the surfaces (both sides), treat with phosphoric acid spray, wipe off, then put masking tape on the *bottom* surface and paint POR15 over the other side. When the POR15 is dry, peel off the masking tape and put POR15 on that bottom side also. If a hole is slightly larger than a pinhole ... you can paint POR15 around it, cover it with fiberglass matting, and then paint the whole surface with POR15. The POR15 actually "cures" the fiberglass.

Worked great for me!

Here's a link to a previous thread on what I did:

https://www.britishcarforum.com/bcforum/u...true#Post306219

Tom
 
Re: How to repair rust pin hole and cracks in floo

I think POR 15 and fiberglass is a great way to
go. I agree with Tom. I suppose you'll want to find
a way to protect the threads in your floor panel.
Maybe you could obtain extra bolts, thread them in,
paint with POR 15 and fiberglass in and around as
closely as possible. Certainly don't leave the bolt
in with this POR to dry cause it might be hard to get out.

Wear gloves cause the stuff wants to stay on whatever
it gets on and you'll have to live with it on you for a
while before it comes off.
 
Re: How to repair rust pin hole and cracks in floo

If you have pinholes, your floor is thinned out in these areas. The floorboards in the area where your feet rest are the usual spots that have held moisture and the sheet metal will be very weak here. A few pinholes might be acceptable, more will mean that a proper repair is to cut out the floorboards and replace. When I bought my current TR6, I found a rust-free example and restored from there. I used the car for two years and took a carefree attitude towards maintenance, ie, I left the carpets in for extended periods, even over new paint, and paid the price. The floorboards rotted. I had fiberglassed a previous TR6 and was never happy knowing that the repair was stop-gap. I looked at fiberglassing this one and instead chose the new Heritage floorboard route. Because the floorboards were very solid at the rockers, I cut out the old boards to the rockers and did a 90% replacement. Was a pita.
 
Re: How to repair rust pin hole and cracks in floo

Get a foot long piece of copper roof valley from HD, cut out a smaller piece and double it over to double the thickness. Then place the copper in a visegrip to hold it and use it as a backing behind the splits as you MIG welding the cracks. The copper will help prevent blow through and allow you to weld the cracks and fill the pin holes.

As always, try this on scraps before welding up the real things to get the feel of it and adjust your new welder wire speed and voltage settings correctly.
 
Re: How to repair rust pin hole and cracks in floo

I've done the POR/fiberglass route in a unibody car. I had many pinholes in the pans and some thinning but they looked saveabale.
I cleaned the pans and painted with POR then placed the fiberglass matting on top and painted again. Use a thin fiberglass matting and it will follow the shape of the pans once wet with the paint.
I could stand on the pans, jump up and down with no issues, once cured.
4 years later they looked like new but I've sold the car since.
If yours are basically sound this will work.
 
Re: How to repair rust pin hole and cracks in floo

I like the fiberglass-with-POR15 approach to strengthen the weak area (with the pin hole), since it's only ~4"x10" and the rest of the metal is fine.

Welding the pin hole... copper sheet sounds like it'd help, but my welding skills are rusty enough I think I'd best not try to plug the pin hole!

Welding the cracks... there is actually a square "nut" welded to the back of the floor pan immediately below the cracks. That sounds like it might be a safer bet to try to weld...

I actually have to finish prepping the floors today to stay on schedule with the painter. What do you think.. is using POR15 over the weak area significantly better than brushing out the rust (which is done) and treating with "rusty metal primer"?
 
Re: How to repair rust pin hole and cracks in floo

I'm not familiar with the "rusty metal primer" but have had long lasting results with the por product.
The only issue with por is making the area free of other contaminants (oil etc.) so use a cleanser (marine clean) to remove any other stuff.
Painting it directly over rust is what it is designed to do so remove any loose rust with a wire brush and paint it directly onto the rusty surface. You do not use a primer with por as it must contact the rust directly to seal. It will adhere to the surrounding paint (if present) if you scuff the painted surface up a tad.
POR can be ordered and shipped thru the mail fyi.
Good luck.
 
Re: How to repair rust pin hole and cracks in floo

Do you put the fiberglass tape on before the first coat is cured and dry??
 
Re: How to repair rust pin hole and cracks in floo

DNK said:
Do you put the fiberglass tape on before the first coat is cured and dry??
Click to expand...

I did. Painted first coat of POR15; laid fiberglass over the wet surface. Fiberglass "stuck" to the wet POR15, then I immediately brushed more POR15 over it. Let that dry, then one more coat.

It's *very* solid now. Also did the same to the bottom of the battery box. You can see the results and step by step in the thread I referenced above.

Tom
 
Re: How to repair rust pin hole and cracks in floo

I've had pretty good luck with the various "rust converter" coatings (Extend, etc), then fiberglass over.
 
Re: How to repair rust pin hole and cracks in floo

Do yourself a favor and just weld in patches. They are easy to make. If you can get to the bottom side, grind off all paint and rust. Use paper to make a pattern. Tack weld on the patch, then come back and weld all the seams, then weld up the cracks. The patches give you some mass to weld to. I have never felt comfortable fixing metal with plastic.
 
Re: How to repair rust pin hole and cracks in floo

Jon80spit said:
Do yourself a favor and just weld in patches. They are easy to make. If you can get to the bottom side, grind off all paint and rust. Use paper to make a pattern. Tack weld on the patch, then come back and weld all the seams, then weld up the cracks. The patches give you some mass to weld to. I have never felt comfortable fixing metal with plastic.
Click to expand...

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif
 
Re: How to repair rust pin hole and cracks in floo

Years ago I'd have agreed with the 'weld' boys but not after doing the POR deal.
If the panels/pans are basically sound why weld in 'spots' when you can stop the rust and strengthen the pans in another fasion. Lighter, less work, and fixes the holes and the cont. rust.
My POR repairs looked like new 4 years later and not a hint of rust.
If we were talking about framework or other critical structural issues I'd differ but floor pans with pin holes hardly fall into that catagory. Overkill in my estimation.
Try it, if you think it's not effective you can always weld away later.
 
Re: How to repair rust pin hole and cracks in floo

"If we were talking about framework or other critical structural issues I'd differ but floor pans with pin holes hardly fall into that catagory. Overkill in my estimation.
Try it, if you think it's not effective you can always weld away later. "

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif
 
Re: How to repair rust pin hole and cracks in floo

I think he said the cracks were around the seat mounting so I agree on the metal patch for reinforcement at that location.

Pin holes can eaasily be fixed with tiger hair on a driver. Follow either method with your choice of rust sealer.
 
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