Need some pointers... deciding if I should tackle this rusty floor pan

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I decided to tear into my winter car today, was going to give it a thorough clean out and just check everything over before I decide to spend more money on it.. Got the carpet out and found this waiting for me. There had been a leak from the windshield for the year I have owned the car and I never bothered to replace it due to lack of $$$.Well, here's a photo of the damage.I'm trying to decide if I want to tackle this project. I'm looking for tips from guys who have auto-body experience. How would you go about handling this sort of rust damage?The circled area has rust that goes straight through. I put a screwdriver right through it. I chipped away all the sound deadening to survey the damage. All the other rust appears to be deep to mild surface rust only. I can scratch it and see shiney metal looking back at me. There is no rust on the exterior of the car, this is all interior due to the water leak. If I could get another four years out of the floor pans, that would be absolutely brilliant. The rest of the car is more than happy to go another four years, but this is the one thing that is really stopping me.I can't decide if I want to take the seat braces out with a spot weld drill and cut out the whole floor and replace/reweld both, or if I want to just grind everything down to bare metal and try to weld in small patches. I am wary of taking out the seat braces because in an accident those are what hold the drivers seat in place. That seems like a huge no-no for a newbie mig weldor.
Reply:What make & yearLast edited by T E B; 06-25-2011 at 08:53 PM.
Reply:Check out the Eastwood Company....They have all sorts of things for this type of project...Since you do not indicate it is some custom car you want to keep forever..I would suggest sandblasting the rust with the small Eastwood unit which also picks up the sand.... no mess no fuss... then treating to stop it from continuing to rust with whatever base the POR15 people have available.... they have mats and things to put onto situations like this which will last way more than four years...  And I would not touch those seat mounts either....Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:Originally Posted by TaidenI can't decide if I want to take the seat braces out with a spot weld drill and cut out the whole floor and replace/reweld both, or if I want to just grind everything down to bare metal and try to weld in small patches.
Reply:If the seat mounts are solid yet and look like they will stay that way, then you could knock the loose **** off and use a good rust converter.  Then paint and give it a few layers of fiberglass.  Put the carpet back in and you're good to go.  That's kind of a hack, but it would get you a few more years of use for not much $$$.My name's not Jim....
Reply:It is a 1996 Subaru Impreza wagon.The more I think about it, the less I want to touch the seat rail mounts, due to the safety implications.I'm concerned that I won't be able to stop the rust that is under the seat rail mounts. I have never used a rust 'convertor' and I'm not sure how well they work. Can anyone speak towards these products?I'm honestly afraid to use POR-15. I read the MSDS and there is an active chemical in it that has a threshold limit value of 0.02 PPM. When welding in body panels, I'm assuming it's best to stitch weld it. Any thoughts on this?Thanks all for the help!
Reply:Originally Posted by BoostinjdmIf the seat mounts are solid yet and look like they will stay that way, then you could knock the loose **** off and use a good rust converter.  Then paint and give it a few layers of fiberglass.  Put the carpet back in and you're good to go.  That's kind of a hack, but it would get you a few more years of use for not much $$$.
Reply:The most common rust converter is phosphoric acid. Fairly harmless. It was used in the past to provide the unique taste for colas. Sure the high % stuff will burn sensitive body parts but used correctly and/or diluted it is as safe as can be. Depending on which version you use right down to just plain unconditioned acid there may be certain tricks that have to be adhered to but they are all pretty good stuff when the situation calls for it."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Is that why coca-cola is a rust remover?
Reply:Originally Posted by TaidenIs that why coca-cola is a rust remover?
Reply:plywood and new mats
Reply:Originally Posted by weldbeadplywood and new mats
Reply:Originally Posted by TaidenIs that why coca-cola is a rust remover?
Reply:Originally Posted by SandySilicon and plexiglass.
Reply:what do you need a floor for?  Just don't put your feet down. Jessh kids today are spoilt. A floor, A FLOOR REALLY. Just kidding patch her up with a mig and away you go BUT look first for fuel and brake lines and that kind of junk.Yes I have drilled through a brake and a fuel line .... Damm pop rivets (pre mig)Miller thunderbolt 250Decastar 135ERecovering tool-o-holic ESAB OAI have been interested or involved in Electrical, Fire Alarm, Auto, Marine, Welding, Electronics ETC to name a just a few. So YES you can own too many tools.
Reply:I can't find the picture but last trip to the salvage yard I spotted a truck with a realtor sign and liquid nails for a floor board.
Reply:I had an old Jeep with rotten floor boards that I just wanted a little more time out of it. I put duct tape over the holes and mixed up a gallon of epoxy paint from work and poured it in.  It made a layer about 1/4 thick and it lasted for quite some time after I got rid of it, more than 4 years.“Life is not a journey to the grave with intentions of arriving safely in a pretty well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out and loudly proclaiming ... WOW! What a ride!”
Reply:Wire brush it real good, vacuum it up and get some rust converting spray primer from walmart or some where.  I use washing machine side panels and rivets on my VW bug pans.... didn't have a welder back in high school.   Epoxy maybe a good idea... It won't rust... It's strong
Reply:Hahaha, thanks all for the tips. Looks like I will hold onto her. All is not lost! Going to begin to tackle this today.
Reply:Taiden,  There is not one logical thing which would point to welding as a solution to your needs..... you are oriented towards fixing metal with certain methods... the guys on this forum share your orientation... if you take any piece of metal to a group of guys who use big hammers all day long, have used them all their lives... they look at it and say things like " I would hold my big hammer this way and swing it like so and so " to fix that... but if you took a piece of fiberglass to them.. they would instantly realize you had walked into the wrong shop... I used to work in a shop that restored old cars.... the orientation is totally different ... when you have that kind of rust you can not use a grinder to go down to good metal because the good metal may not even exist in any one plane...likely rusted from both sides, etc..... but a powered wire brush and then Metalprep..... magic...   I can tell you how to do this cheap and strong and longer lasting than you mentioned the car needed to last....    First you need to read on two other kinds of forums and read the catalogs they read.... Eastwood has been providing this kind of stuff and information for 40 years that I know of.... check out Hemmings motor news... those guys live and breath Preserving what you have and building on it... that is key when things are old and rusted... you need the scant amount of good metal still there to save the original plane or curves... just stop the rust and build from there..   Rand was lucky not to have a welder in high school for that project.. thus he was oriented towards things like rivets..   Go read on the Experimental Aircraft forums... see the tool catalog from places like http://www.aircraft-tool.com/  None of these guys would use a pop rivet, as strong as they can be, for an area like yours where access is so open.. they would use solid rivets placed the proper spacing according to what engineers call for... They would use ' clecos' http://www.lowbucktools.com/clecos.htmlwith typically 1/8th inch holes to hold the new sheet metal in place ..the proper place.. .then drill the holes for the solid rivets and put them in before drilling the next rivet hole ..... sometimes if enough good metal were extant which could be overlapped to... and not cause sound deadening behind it to catch on fire....plug welds...   But they can be skipped totally where access makes solid rivets easy to use like your situation.   If working on steel use steel rivets....   I am not suggesting you use POR15 all day long in your shop... but you are avoiding what most restorers would tell you is the direct cost effective strong fix for your situation..   DO it Outside, wait till the dew burns off the grass, use a fan if you want directed from behind you and in the same direction as the wind is blowing  and wear a mask if you really are that worried.... you are probably exposed by your welding to long term hazards worse than this job would require of the POR15 exposure.    The POR15 folks have developed matts or pads which are compatible with lots of their products for spanning real holes in floor boards in cars....    You would not primer or paint your metal before applying these other build up materials so read all the instructions before you start...    Stitch welding would not be advised where you have such rust..can easily burn right through... . and it changes the properties of the metal you are installing ... less strength, more corrosion, etc.... overlapping good metal if you need to add strength .. and holding  it in place with non heat methods like rivets or epoxy is the more proper fix given the physics of the situation..   I doubt you will follow my advice but maybe some others will remember these suggestions when they lift up their carpet and are greeted by the rust monster.Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:GBM, thanks for the informative post. I have been hemmin' and hawwin' over this project all morning. I have decided to skip the welding for these reasons:1) it doesn't appear to be necessary2) it's unlikely that i'd be able to properly prepare the area to be welded given the tools I have. Lots of sound deadening / underbody coating that would make things a pain in the arse3) good point on the POR-15I just purchased a 80 grit grinder/sander wheel (not a hard grinder, those things that look like grinder wheels but are stacks of thick sandpaper). Then I plan to paint what's left of the metal and rivet in 18g patch panels. These panels will get a body sealant applied to hopefully seal out moisture and whatnot.
Reply:Well, I am really glad I posted...as I think that is a much better plan.....That sander flap wheel will not address the soft rust recesses like they need to be addressed .... you need a loose wire brush probably the forward pointing type and use with a drill.... and vacuum as you go along ..Just for reference... the best tool for small jobs with rust like this is one of the self contained sand blasters.. it shoots it and sucks up the sand or proper grit all enclosed over a few square inches at a time.. really ideal all the way around ... I think Eastwood offered the first one I ever saw... decades ago... probably many available now...the perfect surface to do whatever the next process is...Like this guy is describing... but I can't find a good url ....http://forums.vintage-mustang.com/en...um-set-up.htmlsorta like this but vacuum would provide pickup....http://cgi.ebay.com/ebaymotors/Porta...motiveQ5fToolsAnd actual sand is not a good thing to use .... garnet .. for delicate stuff walnut hulls..or some of the other commercially available things are less bad on your lungs....but use a mask for everything...Last edited by GBM; 06-26-2011 at 01:37 PM.Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:"When all you have is a hammer, everything looks like a nail"  This being a welding forum you probably want a welding solution.  The best welding solution for a quality restoration job is to cut out all the rusted metal and weld in new replacement preformed floor pans.  Best way to do this is with a mig welder and a rotisserie to position the car body for welding.  However since this is a winter beater you only want to get four more years out of I'd do it as follows:I'm with not jim on this.sand, sandblast, wirebrush etc.apply metalprep, naval jelly, vinylwash primer whichever you have.fiberglass and you are done."The reason we are here is that we are not all there"SA 200Idealarc TM 300 300MM 200MM 25130a SpoolgunPrecision Tig 375Invertec V350 ProSC-32 CS 12 Wire FeederOxweld/Purox O/AArcAirHypertherm Powermax 85LN25
Reply:Originally Posted by norite.....  This being a welding forum you probably want a welding solution.  The best welding solution for a quality restoration job is to cut out all the rusted metal and weld in new replacement preformed floor pans.  Best way to do this is with a mig welder and a rotisserie to position the car body for welding. .....
Reply:Originally Posted by SandyThe most common rust converter is phosphoric acid. Fairly harmless. It was used in the past to provide the unique taste for colas. Sure the high % stuff will burn sensitive body parts but used correctly and/or diluted it is as safe as can be. Depending on which version you use right down to just plain unconditioned acid there may be certain tricks that have to be adhered to but they are all pretty good stuff when the situation calls for it.In the spirit of the budget I ended up picking up one of those cup wire wheels for my angle grinder. It seemed to do a fantastic job. I'll be posting pictures of what I did so far. Total investment at the moment is about $25.You were right, the wire wheel is the way to go. I have had bad experiences with wire wheels in the past, and this totally blew my expectations right out of the water.
Reply:Originally Posted by Taiden...You were right, the wire wheel is the way to go. I have had bad experiences with wire wheels in the past, and this totally blew my expectations right out of the water.
Reply:I went to the store to pick up some rust converter. When I read the label it said that it would turn rust into a black primer type surface, but that it would also turn bare metal into rust. I thought that was strange so I opted to skip it. I wanted to get the surface coated before night time so I decided to hit it with some Rustoleum automotive primer, after wiping the entire surface down with acetone.Do you all think this will be enough prep to keep rusting at bay for the next 4 years? I plan to go with a topcoat over the primer. Or should I strip all the primer off and use a different process.Tomorrow I plan on making up my rivet patch panels. I want to use solid rivets, but there are many places where I don't have access to the back in order to properly set solid rivets. Should I use a combination of solid and pop rivets or just go straight pop rivets?I think I should paint the patch panels before installation. I wish I had clecos, but alas I do not, and I don't have the patience to order them.Also, I am thinking of maybe using some clear bath silicone that I already have around the edge of the patch panels before riveting to provide a weathertight seal. Any thoughts on this?Here are the photos showing my work for the day.How it looked when I woke upTook out the dead pedalFront, all ready for the wire wheelRear, ready for wire wheelSome wire wheel action (front)More wire wheel action (rear)Primer up frontPrimer out back
Reply:Having gone that far if you just top coat it... and then do your panels.... should be fine..  I would use the solid rivets where you can, pop where you can't get behind it to buck them...   I would fully prep and primer and paint the panels before you put them in...but Silicone is not good for this type of thing.. will allow and possibly encourage rust underneath it..... I need to take my back glass out of my car for that reason... PO used some black thinking it was the same as the usual 3M sealant used around car glass....urethane...   Good to have skipped the ' rust converter'... I mentioned Metal Prep.. that is the usual phosphoric acid .... creates great primer coat adhesion.. but you are past that stage now... and Rustoleum is fine for what you are doing...   If you check with your local 3M rep... they have a huge amount of material they can share about all sorts of sealants... sometimes plain old automotive seam sealer ...which stays pliable is just fine...and if you need to take it out not the mess some of these other things are... It is really looking nice... you will feel good about it when you get finished... ready to tackle some other project on it... I had three matching Sube 81 station wagons at one time.. I love that pushrod 1800 that the experimental aircraft people use so much...Last edited by GBM; 06-27-2011 at 12:46 AM.Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:GBM: Any tips on what could be used to replace the undercoating?Also, I have some 22g metal in the garage, but I'm afraid it will be too thin. It's not going to be holding any weight as far as I can tell, so I'm curious what your thoughts are. My only other option is to go buy a 4x8 18g sheet of steel which will cost me $60 out the door.And yes, these subarus are fantastic cars. It's a work of art everywhere you look. It drives like a dream and takes all the abuse I throw at it like a champ. It is the reason I decided to keep it as my 'college car' which is why I would like it to last four years. I will be going to school in central Maine so as you can imagine we get a lot of cold weather and snowy days which this vehicle is perfect for. Plus all the dirt roads you can imagine makes this a really fun vehicle.
Reply:If you knock off any loose stuff underneath.. spray wash, let dry....wire brush on handle... .and it is dry..... I have found that the undercoats available in spray cans at normal auto parts stores really works better than you would expect..Keep can as upright as possible...sometimes hard under a car... . I will try to find the brand name on one I have used.. you spray it on and let it dry.... it expands and sticks great... then do another coat ... and leave it alone...only warning... each time and every few minutes you shake the can for a timed one minute revolving the can in your hand as you shake... when stopping turn upside down to clean out the nozzle with short burst...   18g would sure be more appropriate .... if you have it there I am sure you will find lots of other uses for it... if you can afford that investment on this project...Can't go wrong with 3M if you have read their instructions and picked the correct product..http://www.shop3m.com/60440096497.htmlDuplicolor has them also...http://www.caswellplating.com/vht/undercoatingk.htmlhttp://www.autotoolworld.com/Bondo-M..._p_109192.htmlLast edited by GBM; 06-27-2011 at 12:29 PM.Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:try brush on seam sealer for overlaps in the metal when riveting.....     you could use some bedliner, that stuff is polyurethane and if you have your metal clean it sticks well and is waterproof..  plus you dont get the petroleum effects as with an undercoating which can be a pain if you have to work with it in the future.. for a source of cheap metal go to a salvage yard or body shop.. they have all kinds of scrap sheetmetal, would be sure they would let you have a small fender or even cut you off a piece..  also tractor supply and hardware stores such as ace hardware, lowes,and such will usually sell smaller 2x2 sheets although they overcharge for them, but would beat purchasing a 4x8 sheet.. that repair, i would probably go to the underside of the car and cut out the bad portion and rivet in a small patch panel and then seam seal both sides then paint with some chassis enamel with a paint brush and call it good.tackleexperts.comwww.necessityjigs.comhttps://www.facebook.com/groups/mach...dingequipment/
Reply:Actually, I just remembered I have a rusty fender from the Subaru kicking around the garage. I checked the thickness of the steel with my dial caliper. It seems to come in right at 30 thou. I like that it's already painted with automotive paint though, I feel like it will hold up better than some 18g with rustoleum, although the fender will definitely get some of that on top of it.
Reply:Originally Posted by TaidenActually, I just remembered I have a rusty fender from the Subaru kicking around the garage. I checked the thickness of the steel with my dial caliper. It seems to come in right at 30 thou. I like that it's already painted with automotive paint though, I feel like it will hold up better than some 18g with rustoleum, although the fender will definitely get some of that on top of it.
Reply:Originally Posted by weldbeadplywood and new mats
Reply:Originally Posted by denrepPatch panel set with panel bonding adhesive. And I'm serious too. The car would tear in half before the adhesive lets go.Good Luck
Reply:I have quite a bit of butyl rubber here. It's 3m window weld, the snake like black sticky rubber that goes in window channels.Methinks it would be perfect for the patch panels and I already have more than enough laying around the shop.Thoughts?Also I'm considering picking up some clecos. I was looking at the work I have in terms of riveting and some clecos would be soooo nice to have. Any ideas if these can be purchased locally or are they mail order only?
Reply:That rubber sounds great...---Clecos---  Back in the bad old days before the internet  .. 1979.......I drove from Austin to an industrial park near Dallas and begged them to sell me some of them..I knew they existed because of that Ron Fornier book .... could not find a retail place to get them...and they were wholesale and me just an individual.. they are wonderful things if you do any sheet metal work... or play... LOLhttp://www.fournierenterprises.com/BookPage.htmlThis next url is a really good discussion.... http://www.homebuiltairplanes.com/fo...ggestions.htmlLast edited by GBM; 06-29-2011 at 02:32 PM.Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:I have a copy of the Ron Fournier "Metal Fabricators Handbook" around here somewhere, I recommend it highly, reveals some of the magic behind how they fab race cars and shape custom sheet metal."The reason we are here is that we are not all there"SA 200Idealarc TM 300 300MM 200MM 25130a SpoolgunPrecision Tig 375Invertec V350 ProSC-32 CS 12 Wire FeederOxweld/Purox O/AArcAirHypertherm Powermax 85LN25
Reply:Originally Posted by TaidenI have quite a bit of butyl rubber here. It's 3m window weld, the snake like black sticky rubber that goes in window channels.Methinks it would be perfect for the patch panels and I already have more than enough laying around the shop.Thoughts?
Reply:I thought he was talking about using it like seam sealer....Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:Yeah I ended up using the butyl rubber to seal the panels with rivets. Came out pretty good if I may say so myself!
Reply:Originally Posted by noriteI have a copy of the Ron Fournier "Metal Fabricators Handbook" around here somewhere, I recommend it highly, reveals some of the magic behind how they fab race cars and shape custom sheet metal.
Reply:LOL, any book on sheet metal by Ron is great...that one ...looks to be the original...""Winner of the prestigious Moto Award for "Best Technical How-to Book" in 1984, the METAL FABRICATOR'S HANDBOOK applies master metal craftsman Ron Fournier's unique metal fabricating skills--developed during years of building Indy cars, drag racers, stockers, custom show cars, and sports GT race cars. Covers MIG, TIG, arc- and gas-welding, fuel and oil tanks, exhaust headers, and much more. ""Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.