Topic: Hood skin replacement, can it be done??

[Hipo giddyup]

Not sure where to post this question, I’m guessing this is the best area.? So my son’s 70 Mach I hood is totally shot underneath, with the frame completely rusting through in some areas. To me it’s totally unusable but the top of the hood is near perfect, no bubbles , no rust through, no dings or dents. It’s still retains the original holes for the twist locks on the Hood as well as the holes to mount the hood scoop / turn signal indicator’s. My question comes up because I have located a very very nice 1970 hood with a perfect underneath/frame but someone has cut out almost the entire center section of the hood, even much larger than to fill with a shaker scoop. My question is if I could pick up this hood at a reasonable cost, compared to a Ford tooling hood cost, could I remove and replace the skin by placing my original hood skin on this good frame? Looks to me as if the edges are only folded over and spot welded. I can’t see where it is spot weld it anywhere else on the hood.? Has anyone performed this before? I’m hoping to get the hood for $150 and put the time and effort into rescheduling the top. I do have a scanning tool for door skins which I’m used to doing, I’m just hoping that a hood is not much different. I’m thinking I can even sand blast, sand, and counteract any rust that’s on the underneath of the original hood skin while I’m at it.

[warwick]

Yes. I am just finishing it up now on a 66 KGT. It is time consuming. My hood seemingly had opened under speed and the hinge bracket was bent, the rear of the hood reinforcement was damaged, the hood bumper was ripped. The top skin was in very good shape.

I removed the top from the reinforcement, removed and straightened out the bracket, Removed the hood bumper reinforcement and patched the (underhood) reinforcement. In addition I patched numerous rust holes.

Yes you are correct you can unfold the metal sides (after you remove the four (as I recall) spot welds on each side, you then need to unfold the front and rear metal (once again you must remover the five front and rear spot welds. Lie the hood upside down and use a spare putty knive to split the adhesive on the underhood reinforcement-it is on the middle of the "ribs". Typically one or more will not be holding.

I prepared the inside mating sections, put the hood back together and decided not to use adhesive ( I have used bonding adhesive before but actually it is much cleaner to just prepare plug weld areas and put a plug weld where the adhesive was. Believe it or not the hood will be much more solid when welded-but you must be a skilled welder to pull it off and not cause issues to hood skin.

The one thing you really should check is if anyone used a rough grit disc to remove paint and hit the edges of the folds. It will cause you a lot more work but can also be done very effectively-living in the rust belt you learn to replace rusted edges on hoods and trunks.

I have pics of all the steps.

[warwick]

here is what the reinforcement looks like just prior to reattachment. You can see the hood bumper patch.

[Hipo giddyup]

Great information and very reassuring. Thanks Warwick.

 I am worried about plug welding on the skin. My concern would be about warping from heat. If I were to use a caulk or adhesive, do you have any recommendations? I'm still not 100% sold on the idea, but at appr. $500 for a Ford tooling hood, (I was told to steer clear of the typical repros), this idea is cost savings for my son's budget.

[bgp429]

Kind of on the same subject. Has anyone tried to repairing hood pin holes and the result not be noticeable?  Both of my cars have pins. Was thinking a patch could be fabricated for the back, use a panel glue to attach it. Then finish the top with body filler.

[warwick]

Bonding adhesive is very messy and your ability to provide the needed clamping is limited. I have used numerous panel bonding adhesives over years and they all seem to have there issues and place but generally require excellent prep and clamping.

You also need to align the skin to the reinforcement panel in spite of the metal edges.  The skin is flexible, it takes its (final) shape and strength from the reinforcement panel-but you need to get it on the reinforcement. Outside a production environment-without jigs, mating with adhesive is tough.

The first step in plug welding is to drill your plug weld holds-don't go too big (5/16"). After that mate the reinforcement panel to the skin, align (with drilled out spot weld holes) the reinforcement panel and mark the holes on the skin-I painted (epoxy) the skin. After marking, separate the panels and remove the paint from the marked areas. I then (with the skin on a dolly) mated the reinforcement panel back on the skin. To plug weld I then used a jack under the dolly to push up the skin to meet the rib of the reinforcement panel. The key is on the jack I put a piece of aluminum wrapped in copper- it will disipate the heat. Working with 50+ year old metal you must do this. Tune you welder, and this method will minimize and localize the heat. What you will see on the skin is a heat circle and a very very slight rise of were molten metal was. Start in the middle of the hood, and work to out to Ft/RR and sides. Continue to sheck your alignment. You never weld from the skin side (other then reproducing spot welds at edges) will not get any panel heat distortion of the skin if done correctly and your skin will never be mounted closer and better to the reinforcement.

Fold the edges back - a toll like the Wivco(sp?) skinner will roll the back flat-it will leave slight knurl marks to remove. Then weld edges-use the aluminum/copper again(at all times) to dissipate the heat and clamp tightly.

This is a process not for the faint of heart. If you count your labor ...your in the red.

I'll send some pics.

[warwick]

Here is the hood (hopefully in correct order):

from top after welding, and pics of both sides before epoxy.  As you can see after surface prep there are no waves.

[Hipo giddyup]

Thank you and very useful. I hope to reply back soon with my decision and/or progress.

[Hipo giddyup]

Well my son and I were able to remove the spot welds and take the good skin from the rest of the bad frame. We have purchased the hood that has a good frame but a bad top skin, where they cut out a huge hole. Next steps will be to salvage the frame from that hood and begin the process of sanding and rust prevention painting. I’ll try to post some pics and hope to be spot welding soon.

[warwick]

The skin is flimsy huh? It is just a sheet of 18g.  If you were able to unfold the metal clean you are ahead of the game. You got to get it at 90d to drop skin on. The front edge is the prob.

I tried Rustoleum Gel after the Evaporust Gel I got was bad. It worked pretty good. Once I separated panels I really saw the hidden rust.

I had a number of issues with reinforcement panel I had to square away as I said, but check it out real good it creates the final form of the hood. When I fixed hinge area and put in patch where bumper contacts I took a straight edge and checked every thing out.

I may not of said this before but I really wanted to use an adhesive and I thought about it for a few days but just didn't come to grips with process. You could probably come up with a method of clamping using 2x3's as a jig, but you would need to test fit panels and sand paint off spots where adhesive would be contacting panels before final placement.

To prevent burn-through you have to use something on backside of weld everywhere-even on replacing spot welds. Make sure it has good surface contact prior then welding. I made sure I cleaned every weld contact area, kept surfaces in tight contact and had the backer plate had surface contact. I did not have any burn-through on any welds and I had good penetration. I double shecked everything twice before welding.

I am aiming for a concours resto for my car but I decided the direction I took in fixing the hood (which is date coded and original to car) was best way to go. I am not sure a judge or others would think same or even notice.