Has anybody else been puzzled by subframe mount loc.?

[70_71_78]

Good Day! - I've been diving into my '78 body's rusty floor. I would not install new floor pan parts over damaged support parts. That would just lead to near future failure. The cross parts near the rear footwells are simple, but the subframe mount points have me trying to find the best way to clean, metal prep and coat with a sturdy rust preventative paint. Anybody been past this point and have any recommendations?
Thanks,
J

[roadking77]

If youre talking about the frame rail in your pic, I would clean it and prime it, then where you will need to grind off for some bare metal to weld use some thru weld primer. I tried to hit every bare piece of metal when I was putting my 77 together. I bought some internal frame coating from Eastwood that comes with a uni-directional spray nozzle and a long tube to reach hard to get places. It seemed to work pretty good as it was oozing out of any screw hole it could find. I think thats about the best one can do.

[70_71_78]

That kinda sounds like a 10,000 foot view of the task in question. To qualify - This isn't my first floor project. I have built an entire floor assembly for an S10 project, creating parts that were not available by hand including the mounts to the frame. I have put entire footwell and trunk/cargo areas in G-bodies, including creating unavailable support and body mount rails by hand. The difference here is that those are full framed vehicles and the mounting locations are quite a bit more spacious than the rear mount points for for the second gen. front sub frame. That, and the fact that these are intact and I want to preserve them without creating additional assembly, alignment, or corrosion issues makes this a completely different project. I am concerned that disassembling this welded assembly and re-welding after cleaning, metal prep treating and coating will introduce new issues involving assembly, alignment, or corrosion. Not disassembling them has the potential to not treat all surfaces, allow accumulation of abrasives such as sand or glass bead and trapping paint or other rust preventative coating that could prevent movement of the caged nuts that secure the sub frame, potentially making assembly/alignment difficult while creating a break in the corrosion protection when those nuts break loose from the location where the settled into the coating.

I am not building a show car, this will be driven rain or shine, and probably not babied. I do not put things together without assuming that they will need to be taken apart to maintain, repair or modify and I don't want to build in any problems in those future tasks. I am not looking forward to redesigning that whole area. I am thinking that I should inspect the drivers side before going any farther. If it is not in good condition it would force the issue.

[70_71_78]

I finally got back to the rear sub frame mounts and "popped the lid" on the left side. Still don't see the optimum path forward, pretty much the same situation as the right side.
 

[roadking77]

It appears as no one else has either done this or has the  ill-gotten advice. I see that you have disqualified me, but I stand by my original statement. I cleaned and treated mine in place. I had the exact same situation with my 77. 10 years on they have not rusted through, the floor is still solid and the car drives phenomenally. Leave them in place, clean prep and paint. Then weld the new floors on. Seam sealer around the edges. It will be exponentially better than hundreds of original cars running around with no repairs at all.

[81Resto]

Hello, thanks for the comment on my thread.  Unfortunately, I replaced my floors a long time ago and then my project stalled for about 15 years.  I, being young at the time just cleaned up the outside lips that I would be plug welding the new floor onto.  If I was to do it now, I would be following Roadking's advice.  Cleaning up and painting everything I can, grinding down the surfaces I would weld on then spraying weld through primer on it.  Eastwood does offer an internal frame coating with a long hose/nozzle that could be applied in areas that you cannot reach.  I wouldn't cut them out of the car to clean up and paint, just do the best you can to get everything possible.  They look to be in pretty decent shape that I can tell from the picture.  As far as the best way to clean it up, sandblasting would probably get all the corrosion. Any wire wheel would difficult to really get the corners.  Sandblasting is messy.  Or maybe wire brushes and a rust encapsulating paint.  I know people have differing opinions on encapsulating paint.  My car I am not to concerned about, it will be garage kept and only water it will see would be from washing.  Good luck on your project, I hope that this is helpful and you are not stalled out too long.

[Wallington]

I'm only puzzled by the answer you expect.

[N PRGRES]

Wire wheel it and do a rust encapsulating paint then spray it with under coating.  They aren't that rusty and will more than likely outlast you

[70_71_78]

I'm only puzzled by the answer you expect.

Thanks all!

There are two holes on the underside of the structure that allow water, dust, dirt and other debris to enter and accumulate.  There are four parts welded into, or over the top of of the bottom rail that I have not been able to figure out how to clean between or reach the underside side of to clean, metal prep or coat the inside of. I have sand and media blasting equipment, (yea, real messy and hard to remove all the sand), boxes of different sized wire brushes and fine die grinder bits for tight areas. I have even considered making some kind of enclosure to submurse them in liquid rust remover, but the area's shape makes this really impractical. Is there something I have not thought of?

[N PRGRES]

I'm only puzzled by the answer you expect.

Thanks all!

There are two holes on the underside of the structure that allow water, dust, dirt and other debris to enter and accumulate.  There are four parts welded into, or over the top of of the bottom rail that I have not been able to figure out how to clean between or reach the underside side of to clean, metal prep or coat the inside of. I have sand and media blasting equipment, (yea, real messy and hard to remove all the sand), boxes of different sized wire brushes and fine die grinder bits for tight areas. I have even considered making some kind of enclosure to submurse them in liquid rust remover, but the area's shape makes this really impractical. Is there something I have not thought of?

You've been given multiple ideas, not sure what more you're asking for here.  It hasn't rusted much for the decades the car has existed, if it's not a how quality car, then paint it and move on

[TA301]

It appears as no one else has either done this or has the  ill-gotten advice. I see that you have disqualified me, but I stand by my original statement. I cleaned and treated mine in place. I had the exact same situation with my 77. 10 years on they have not rusted through, the floor is still solid and the car drives phenomenally. Leave them in place, clean prep and paint. Then weld the new floors on. Seam sealer around the edges. It will be exponentially better than hundreds of original cars running around with no repairs at all.

  Hillarious.

[wheels78ta]

When I replaced a section of the floor I only uncovered half of what you did.  It had rust about like what you have.  I wire wheeled the whole area that I could get to, used a wire brush in the cavities, cleaned it up the best I could and put two coats of primer on it.  Then painted the area with good ole rattle can paint.  Any place I needed to weld I would grind off the primer/paint and coat it with weld thru primer.  Pretty much what roadking77 did.  That rust has been there for over 40 years and any treatment will make it last a very long time.  If untreated.....it's not going to get much worse than what it is now.  It will still take many years for that little bit of rust to cause, if any,  damage.

[70_71_78]

I noticed that Dynacorn lists a full floor pan with braces for '74-'81 F. Starting a dialogue with them to see if the "braces" are, or are going to be, available separately.
I still see it this way: The layered construction in this area is like a sandwich that you can not separate the pieces of bread to see what is in it. Would you take a bite? This is a safety issue as well as an economic issue, why pour a bunch of money into correcting the other age related issues only to have this area fail somewhere down the road wasting the money and effort spent and/or injuring someone in the process. The safety portion is just a part of me. It has always been I high priority in the jobs I have worked, in many of them it was the first priority due to the number of persons that would be impacted by problems. It is just part of the way I do things.

[428Bird]

When I had my floor cut partially out, I wire-wheeled, then bought one of the cheap harbor freight siphon sand blasters and cleaned as best I could. Afterwards I reinforced the nut retainer and chased the nut with a tap, then applied never-seize. I Followed this by washing, drying, then painting liberally with Rust Bullet. That was followed by black epoxy on all sides.

It'll outlast me by at least 100 years.

Britt

[roadking77]

I understand your concern. In my humble opinion (which doesnt amount to a hill of beans) I think you are over complicating the situation. If you are that concerned over safety, it is probably time to forego the restoration of old cars and buy something new.

[70_71_78]

I paused until learning that the inner brace containing the caged nut assembly did not continue over the trans. tunnel. Moving forward.