Ok, I'm starting to fit my hood in prep for body priming. I knew when I took it all apart long ago that I had to deal with this ill-fitting hood sooner or later before re-paint, so we're at that point now.

As mentioned on D-FRESH3's thread over here where he is dealing with a similar, but much smaller issue (https://www.corvetteforum.com/forums...post1593970791), I've set the hood in place and shimmed the hinges so its flush with the top panel on the front corners. And its' flush with the fenders at the rear corners, as well as the rear center cowl. My hood top panel was either poorly made and/or been butchered by some shoddy body men over the past 50 years. So in a nutshell ...

- the rear (windshield) end fits nice and sits flush across the entire cowl panel section.

- the front is flush with the top surround on the front corners, but in between these front corners it sinks below the headlight panel by 1/8" across 2/3 of the width

- both sides of the hood panel are bowed up above the fender curve. The left side is 1/8" higher in the middle, and the right side is a bit higher yet at 5/32"

- someone along the way thought it would be a good idea to take an air sander to the side edges to clean old paint off before a repaint. I'm sure they used 80 grit on this sander because when I lay my 4' straight-edge along the side edge, the edges are gouged in about 1/8", so I will need to lay some glass in there to built that back up to make these sides straight again (and close up my gaps to something acceptable like 1/8-3/16".

My initial thought was to start by bonding the underframe tabs along each side edge with VBA and apply enough weight at the highest point on each side to drop the hood panel down flush before it goes off. I know in this step, by holding the panel down and bonding it there, it will slightly raise my front edge and solve part of that problem. But it won't raise the front edge high enough ... I can tell by watching what happens when I push down and hold on the left side, the front edge on the left side is still at least 1/16" too low. I have the hood panel blocked on each rear corner so it won't sink below flush when you put weight in the middle of the hood panel. And the concern I have with bonding the underside tabs is ending up with bond burn on the top side.

So now I'm thinking the best solution is to separate the bond between the top panel and underframe around the periphery on all 3 sides leaving only the rear edge of the hood along the cowl bonded. This would allow more flex between the top panel and the underframe along the sides, and also allow me to temporarily wedge the front edge of the top panel up flush with the headlight panel surface. Then re-bond those 3 sides with everything sitting flush all around the top panel.

I'm hoping DUB or John McGraw can comment on my challenge here. Its just my time so I'm willing to do whatever it takes to make it right and do it right. Cheers, Bill

 

Could it be that the fender is actually what's causing the issue? If the core support is damaged or bent back from crash damage, that raises the front header and causes the exact issue that you have. It drops the rear of the fender skirt and draws the fender center section to drop.

I don't know if a hood could warp to cause this but I suppose it's possible.

Also, if the front frame horns are bent up a bit from crash damage, it lifts the core support and gives you the same problem.

 

No I should have mentioned that Critter, but thanks for the comment. My rad core is perfect (I had it out to glass bead and repaint) and the upper support rods that go from the bottom front of the rad support to the headlight door openings are straight.

I also don't think the hood panel is warped because I've sanded off the paint & primer along the edges down to bare glass and there is no cracks or separation between the top panel and the underframe. Bill

 

The other thing I mentioned on the other thread which is worth repeating here ... where my inner fenders are bonded to the top of each fender under the drip rails, they are a nice clean 1/4-3/8" along both sides. I am not in favor of cutting them open, then wedging the fender panels up high enough to match the hood. That would result in over 1/2" thick under the drip rails and I prefer to keep them "factory thin" like they are now. Bill

 

If the center of the fender is 1/8" low, it shouldn't require more than an 1/8" of additional bond between the fender top and skirt to raise the fender to match the line of the hood. I've repaired a few that way and when I was done, I ran a grinder over the bond to make it look exactly like factory. I understand why you don't want to break the original bond at that point though.

If the core support is tipped back for some reason, it draws the center of the fender down but the front and rear stay at fender top level. Very common.

I suppose too many shims at the bottom of the core support could cause this too because it would only raise the hood hinge location but not the center section of the fender.

 

Is this the original hood as far as you know? I'm afraid you may be seeking a level of panel fitment exceeding anything GM ever planned for given how complex the assembly of a Corvette body is and then the manner in which it's bolted down solid on a separate frame.

Most body shops would skim those panel gaps with filler and block everything down level and feather it out - resulting in about an eight inch depth of filler in areas. Very common. Anybody who has ever built a Cobra replica is well familiar with the process. This is an ERA which is known to have one of the higher quality bodies in the replica business.






But I suspect this isn't the approach you want to take.

 

Ya, I realize this is probably the easier way to go to raise both fenders up the 1/8-5/32" required to match them up with the hood on the sides. If that was all I needed to do, I would likely proceed this way. But that still leaves the low front, and I'm just not wild about packing in 1/8" of filler on the front of the hood to bring it up.

I actually wondered the same thing and loosened the top core bolts thinking this might be pulling the fenders in too much and causing the headlight panel to bow upward. But even backing those bolts out enough so I can turn by hand did not cause the headlight panel to drop even a fraction. I don't have any shims on the bottom 2 core bolts. Maybe I'll try adding one on each side and see what happens.

 

Dan, as far as I know its the original hood. Is there some way to tell the difference between a repop hood and one supplied to GM? There is no visible damage on the hood on either side. It just fits like crap. Can you tell from this picture? Sorry for the dirt.

Ya as I mentioned to Critter, 1/8" of filler on the front section of the hood to bring it up to the front panel would probably be fine as I don't think the hood flexes nearly as much as the front headlight panel does ... especially across the front of the hood because the hinges are locked across from there on each corner. That might be the way to go if I chicken out from separating the hood top panel from the underframe.

Nice Cobra by the way. Black shows EVERYTHING and that body turned out awesome!

 

One thing I forgot to mention on skimming body gaps with filler - it's a fairly aggressive approach in that you not only are filling the low side with filler, but in the blocking process the high side is probably going to loose some material and end up thinning the panel a little. In other words, starting with a 1/8 inch panel offset, the high side might lose a 1/32 with the filled side ending up about 3/32 thick or some such division. If a person has time on their hands and doesn't like the idea of that much filler, the low areas can first be brought up with glass and resin.

My 66 had had the front clip replaced years ago with what I think was a 64 or 65 clip (except for the louver panels) and the original hood was a low across the front compared to the nose. I did separate the front of the hood from the support and use the popcycle shim and fill process on it successfully. To separate the hood and support is definitely do-able, I'm just not sure how well it will work to lower the curvature of the hood where it is higher than the fender. I suppose if the bond area were aggressively sanded out so that the two panels would clamp tightly together, a slower setting bonding material was used, and the hood was weighted in place while curing to match the fender, that the edge might hold it's new, flatter curvature. I'm not sure. As DUB said you would probably need to actually over-weight it a little more to compensate for rebound.

 

What does your hood fit look like if you just simply drop the back of the hood 1/8" low to the cowl? That would take care of some of the concern in the middle of the fenders. It will also raise the center of the hood in the center.

When you're trying to fit a hood in a fixed opening, you have to give some to get some. You may be trying to achieve something that wasn't there to start with? That's okay if that's what you want.

 

I did drop the hood a bit Mike at the back and as expected it does raise the nose up a bit, but not the full 1/8" as one might expect. And since it looks just as bad (to me) to have the hood lower at the rear cowl ... and still low at the front, I decided that's gonna drive me nuts.

I do agree with your point that you and others have said about splitting the difference, and if the car was painted already and I was dealing with this, that's exactly what I'd be doing. But since its not in paint, and I'm bulging on 2 sides and dipping in a 3rd, now's the time to make it right. I know I'll be happier with the end result once painted.

 

Ya I hear you Dan. If I go this route and fill the front of the hood, I will be taking the hood off and building it up on my stand 1/32 or so higher than needed. Then put back on the car and just like when I'm glassing something in, tape the top edge of the headlight panel and then block the remaining 1/32 overage down to the tape. That really minimizes how much of the mating panel gets reduced when you are blending the two together to match. And I would add a 6" wide layer of glass mat across the low section on the front of the hood first before adding filler to minimize filler thickness. Bill

 

Dan, can you tell me how you went about separating the top hood panel from the frame periphery? None of my inner underframe tabs are bonded to the top panel ... just around the periphery. The only thing I can think of is by hammering with a thin chisel on the underside between the frame and top panel and hoping it cracks at the mating seam all around. Bill

 

As MikeM and others have mentioned, unless you are up for some panel massaging or other 'tweaks' you may be 'f@rting against thunder' with original panels. Here is how I received my original '63 in 2013 (FIRST PICTURE -- it had been painted in 2009), I wasn't happy with the door or hood alignment. The hood was low against the surround in the front and the PS gap was unsightly with the not uncommon 'bulge'.

I played with things off and on for several months and it dawned on me that, without filling/grinding etc.. that I had reached the point of 'diminishing returns' with the fit. The hood is very acceptable now (SECOND PICTURE) and it was mostly a matter of adjusting the hinge shims and tweaking the rear latches... To get to this point the hood actually moves slightly sideways as it latches at the rear when its closed. I also finally had to cut about 1/2 coil on the male hood latch spring on one side to get enough adjustment for the height. I didn't like doing it but it made a difference and nobody will EVER know.

The fenders (inner and outer) weren't touched. Now my car is painted so that does limit what can be done. IF you are willing to do the fill/grind and other tweaks then the door is open to do better on an unpainted car and I think there is plenty of advice on here now on the best approach.

 

Bill - it's been 20+ years now so the exact process is a little fleeting in my memory. Generally it involved a metal putty knife with a little sharpening of the edge. A couple swipes of sandpaper along the edge should help reveal the upper panel/support bond layer. You could play a little heat from a heat gun on it to soften the bonding agent a little to get it started - but once started I remember it separated pretty easily - probably tapping it along with a small hammer. If you want a little extra insurance that it stays in the bond joint, you can apply some heat from a heat gun or hair dryer ahead of the scrapper to soften the bonding agent a little.

Just a little reinforcement of MikeM and Frankie's comments - once you get panel flushness down to 1/16 inch or less on a painted car it's not really a visible issue to 98% of people. My 2012 Mustang has nearly 1/16 inch panel offset at some panels but I have to lay a straight edge across them to really confirm it. A custom car builder or or custom painter might possibly note it but the average car guy probably won't. This is helped on a Corvette by the fact there isn't a flat panel or flat panel edge anywhere on the car and they all roll this way or that which helps hide a slight offset across the gap. Panel gap width variations are more visible to most people.

And something else - fiberglass is not as stable as sheet metal and moves over time from stresses - and Corvette bodies have lots of stress to deal with - frame shimming, road shake, hot weather, weatherstripping pressure. Even if you get it perfect before paint, it's probably going to be off just a little within a year or two in a few areas.

Good luck

 

That's some nice tweaking Frankie on a painted car. I agree ... looks awesome now. Well done!

Because I'm not in paint, I'm thinking I will bite the bullet and try separating the top panel from the subframe on the sides and front. I'm really not fond of the idea to build up across the front of the hood with 1/8" of filler ... especially with a (very) hot BB steaming away underneath. And it will likely run a little hotter cause I'm adding Vintage Air.

If I successfully separate the top panel on 3 sides, it should be easy to weigh down the high sides and wedge up the low front so its all flush with the surround panels and then re-bond the top panel. Like Dan and DUB said, I may over-weigh the sides by 1/16" to allow for some bounce-back when the weight is removed after curing. At any rate, this will greatly reduce any amount of filler needed to get it close enough. Cheers Bill

 

Thanks Dan. I agree with your comments about 1/16" or less once painted is "pretty good" on a Corvette. Its just my **** side coming out trying to make it perfect

Ok, a sharpened putty knife and heat gun it is. I'm gonna take the hood back off and get at it. Will report progress. Thanks for your help. Bill

 

Do NOT be afraid of getting the hood HOT....NOT smoking hot...but hot to the touch where you can not touch it for long. There is a temperature that will cause the adhesive release...and if you have an IR thermometer...you can find the temp that you need to get to. Do not forget to allow the heat to 'soak' into the fiberglass....the temperature on the surface MAY NOT be what it is a the bond surface.

DO NOT point your heat gun straight at the panel. Angle the air so it is heating up the surface that you are heading towards....it makes it go faster that way. Also...you will more than likely start at the corner of the hood by the hood hinge area...that is where I would start. So...I would heat up both surfaces in the beginning...one going across the front about 8"..and then the surface going by your hinge area.

Also....if you are concentrating the heat on ONE surface....whether it is the underside...or the top side. Keep in mind that THAT panel is what will get HOT...and thus...that micro thin line where the adhesive adheres the backside of that surface is where you want to get you tool to go in at. So...if all is going as planned....when the panel begins to separate...the adhesive wills till stay stuck to the other panel where the heat is NOT applied.

Did that make sense???? The reason I wrote that is because on the later model Corvettes that does make a huge difference due to the adhesive type changed drastically. I do know the adhesive thickness can be a bit thin and this may not matter. But I did not want you damaging the other panel.

Also...once you get it started. I take paint sticks and grind then down to a chisel end and use them as wedges to apply just enough tension on the bonded area to aid it but NOT break/split/crack the panel.

Lastly I would more than likely heat the exterior panel due to it is flat and it will be able to release much better that the narrow bonding flange on the under structure.

As for the filler if you need to use any to get the hood just right. I would use the Vette Panel Adhesive (VPA). I have had to skim coat hoods entirely due to damage and the VPA never fails me and I never worry about any engine compartment temperatures possible causing a problem. It has never happened.

AS for you hood where you posted the photo of the level going down the sides and you can see light. I have seen that many times and I only worry about that is IF I can actually see that problem when the hood is installed. I have a very sharp eye for stuff like that...and if I can not see it...then I know no one else ever will and it saves a butt load of time. Because I apply gelcoat on Corvettes like this. And I take very special attention to applying the gelcoat on that edge so I am actually building it up and then blocking it back down to where the fiberglass is bare and the very front and rear where your level is contacting it....thus...closing in that line. Then when I apply the polyester primer for the next stage..I do it again. So...often times I basically filled it in to the point that it would be not able to be seen as a flaw.

ALSO...not that it matters....but if the inner skirts are correctly bonded in place. Attempting to use the radiator support bracket angles to cause the front clip to get bow in it ...or out of it ....is pointless. There are too many angles going in that area and the front clip is STOUT. And so stout I might add...that moving it too much unless it has been heated really good will cause for the fiberglass to crack at the lip of the fenders. And the same basically holds true for the headlight area of the top hood surround. This area is REALLY STOUT and even though it can be very slightly adjusted ( I do it from time to time). Too much movement will cause for a person to start to hear cracking going on.

I make a rod that allows me to raise up the headlight panel right there by the emblem if needed.

DUB

 

I had to do the hi/lo fill thing to get my trunk lid to sit even.

Bill

 

Ok, here's an update guys. Today I went nuclear on my hood as I could see no other way to properly fix my side bulges and front dip. It wasn't easy to separate the top panel from the frame, but by tapping with a sharp chisel on the bond line between the 2 panels I was able to start with a small crack. After tapping the chisel all around the front and both sides, I then tapped a sharpened putty knife through the 2 panels. Did that 1" at a time around all 3 sides and got it separated. Then smoothed out the old bond material on both panels. I purposely left the rear edge bonded as this was the only side of the hood that fit the cowl panel really nice and flush.

So before I put it back on the car, I decided now is the time to strip the underside of the hood while I can move the frame out of the way a bit. I don't know how many coats of black paint have been sprayed on it in the past by previous owners ... but there is A LOT! Hopefully tomorrow I will be done sanding all that off so I can get back to fitting and rebonding. Bill