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Doesnt look too hard.
Thick plate steel, riveted to the existing floor pan is the cheap n nasty method but works well.
the snobby correct way would be to get a section cut out of a wreck, or have a panel shop make up a mould of the area using resin and fibre, and then press a thin sheet into that to take up the shape, which is then tacked and butt welded into position, where the welds are welded through zinc rich primer, followed by a zinc phosphate primer top and bottom so that paint will stick to the zinc, and finaly a thick underchassis coating on the bottom and a durable epoxy enamel on the top.
I could see the floor pan being riveted in but I'd think the cab mount would need to be welded to the floor pan right?
I wonder how Tacoma cab mounts would fit the 1st gen pickup?
thanks guys
Well, see the problem is going from a thick steel section to thin sheet metal. Rivets, and lots of them, are the best solution for repair when going from one size to another. It can then be mug welded carefully around the seam, but the strength should be in the rivets.
and of course all this done with the entire thing preprimed in zinc rich primer.
Well, see the problem is going from a thick steel section to thin sheet metal. Rivets, and lots of them, are the best solution for repair when going from one size to another. It can then be mug welded carefully around the seam, but the strength should be in the rivets.
and of course all this done with the entire thing preprimed in zinc rich primer.
Once I get this truck fixed up I don't plan on bringing it out in the winter so that should help it out.
This will sound very newbie but are you saying to rivet the floor to the cab mount or both floor to cab mount and new floor panels to existing good floor?
what kind of rivet gun would be best for something like this?
I think what he said translates to "just shove an eighth inch plate under it, and rivet it in place..", for the cheap/dirty fix.
You have multiple layers here, heavy gauge mount reinforcement, cab floor, stiffening rib. The floor pan is sandwiched between two pieces of the firewall from the looks of it, you'll need to strip back more along the firewall towards the dash and clutch pedal to be certain it stops along that joint also just to weld in a patch panel.
Source a new mount reinforcement, pretty much anything will work like mentioned above be it a factory mount, bit of boxed in u-channel, or a salvage yard piece (the benefit with this last one is you can get the whole material in one go, make sure you get it cut oversized).
If you don't get a salvage yard cut off you will need/want to replace that section of the floorboard, and stiffening rib. It would be best to use the flange method of putting a patch panel in place for strength and ease of welding, but with a salvaged piece you'll have problems with that top layer rib and it will have to be a butt-weld there.
You can go hard core and fab up each layer with a hammer/dolly, English wheel, beed roller ect.
Yeh thats right, I was suggesting a piece of plate steel, as that is simple and easy. Here in Aus it's reffered to as floor plate, and is 3mm thick. It's just so much easier to repair it this way, that I almost garuantee after ur due diligence yiu will end up going this route.
the kind of riveting is that used in manufacturing airframes.
I'm not talking about a little hand rivet gun for blind pop rivets, I'm talking about a solid steel rivet. Which is installed with an impact hammer and takes two ppl. One to rivet and one to hold the bracing dolly underneath. After all this is done, they just braze up or MIG the pieces together to stop moisture penetrating the edges.
I was researching different methods online.
As far as finding a doner truck, that's not going to work as there are no old 1st gens near me that I've seen.
unless a newer truck could have a piece, the cab mount, retrofitted?
would a air powered hydrolic 1/4" rivet gun using those solid steel rivets work? Thing is, I won't have a 2nd person who is able to help with this.
I've also read about 2 part bonding epoxy that is supposed to be as strong as weld? Fusor by Lord it was called but there are many.
that with rivets maybe?
if welding is the way I go I'd have to buy all of that as it's the one area I have none of it. Also, coukd that area be welded without removing the dash and associated pieces?
Yeh I was thinking it'd be close to impossible to find a donor. Plus most others would probably have the same problem.
Cold weld, (steel epoxy) is actually better than welding when it comes to non structural rust repair, however u are dealing with a very structural part, so there will have to be rivets and then the cold welding and for thia to work u must get the plate to sit flush under the surrounding area.
For the mount underneath, a bit of RHS steel beam cut up would make a great support. This COULD be riveted to the new floor plate but I would go with welding due to vibration. However if welding is just not an option, you can bolt the plate to the mount uaing high tensile fine thread metric bolts or UNF thread bolts, with threadlocker / threadsealer applied around the entire bolt thread to stop moisture travelling up through the thread. Then prime and coat with underchassis bitumenized black paint.
Last edited by Thommo Thompson; 02-01-2018 at 09:29 PM.
So, to summarise, once u have bolted a new mount support to the new 3mm thick floor plate, u can then river the new floor plate to the existing floor area, with a good 20cm overlap, with one line of rivets around the outer perimeter, and another around The 8nner perimeter.
Then u can use the cold welding epoxy compound to seal everything. Top and bottom.
By cold weld, are you talking about a product like the Lord fusor 2 part bonding epoxy?
If you look at the picture taken from underneath I noticed the actual body mount bracket is solid still. It's the angled C shaped floor piece that is rotted out. Which appears to be just the floor pan itself! So I don't think I actually need new mounts, but I feel I will need something like a plate of 10 gauge?? To sandwhich between the mount and the 18g?? Floor pan???
does that sound right?
I know this truck won't be a show piece so I care about strength and not beauty but want it secure. This truck will be used maybe 2k miles a year tops for fun not a daily driver.
thank you very much for your help btw. Do you think using the fusor to sandwhich a thick piece of plate to the bottom of a Floor pan then bolting it all together will work well?
it appears the cab mount bolt is the only bolt holding it all together .
if you see on the left side of the picture that mudflap is bolted to the floorpans I think. That vertical piece of steel is the bottom of the Floor pan it looks like. You can see how it's cracked on the other side across from the mudflap , on right side of pic .
As you point out, its just the floor pan, you still need to strip back some of the firewall panel to insure its good after that almost any donor will work (its essentially flat)..
You don't want to use an epoxy for the bonding, its not flexible it will crack and leak, you can use it for a sealer to keep air/water out I guess but if you want. Better is a modern seam sealer that doesn't fully harden (or takes another 30 years to dry out), or old school buytl type.
You can use the rivet tool you have so long as it works with a steel not aluminum (soft, prone to fatigue) rivets, its size and pulling power will determine how many you need to put on there.
Yeh the vibration that this area would get, would make sandwiching epoxy between riveted steel a bad choice. Don't sandwich it, that will likely pop the rivets out. The rivets work best when they are tight, sheet to sheet with no movement possible. The epoxy stuff, yes just like the lord range is all really for skins and bodywork. This situation is structural and will shake the stuff to death.
A seam sealer would be good as co94 sais, but I know from experience that seam sealer can't really do it's job in wide gap applications, and I feel that this approach of using perfectly flat steel plate butting up to wavy, pressed, random floor pan will leave some big gaps. 2 pack around the perimeters I think is the safest bet, with emphasis put on the need for rubberised emulsion underchassis coating over the bottom when ur finished (in case it does crack).
You are best avoid using bolts between plate and sheet metal, (new plate and cab floor) as the torque required to firmly lock the nut in place will put too much pressure on the flexible sheet metal at a small point. Rivets, and lots of em, work best for this.
U can, and should use bolts (hi tensile fine thread) for any joining of plate to plate, or plate to extrusion. (like the new plate to the new cab mount)
Which brings me to ur cab mount. I would replace it with a bit of new square section cut up to roughly the same shape. The area has rusted, and that means that cab mount is going to continue to rust, so definately remove it and start again. If u reuse it, I would be very worried about it rusting out and making all ur efforts fruitless
You guys give a lot of great advice. So using thick plate, like 10ga maybe? Bolted to the mount with the mount bolt/bushing set up would be good but then rivet the thick plate to the floor pan right?
I will wire wheel the mount to see what it looks like.
I will also strip back more of the cab floor up the firewall to see where good metal is.
I was planning on steel rivets if I go that route. Would like every 2in spaced be about right?
If I did weld it, coukd it be done with the dash and stuff in the truck? I'd worry about sparks. Maybe use a barrier of some sort under dash area?
It's six to four or so welds that hold the reinforcement to the floor pan. For the patch panel in the floor pan at least every 2 inches, but more (to a point) is better.
The reinforcement is about 10 gauge already, so bigger especially if you don't plan to box it off.
You will need to assess the quality of the frame mount once you get the rusted bits out of the way.
My mate set fire to himself welding our roll cage into our corolla race car haha. Sparks are frikn hot.
I wouldn't go to the extents of removing the dash. The wet towel idea will do just fine.
01-30-2018, 11:21 PM
