87 Fifth Ave Rust Repair after Bonnet removal

Justwondering

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As I continue the journey on this 87 Fifth Avenue, I got to the Landau vinyl roof replacement.

NOTE: Wear a long-sleeve shirt when you mess with the bonnet. I forget and every time I use my forearm leaning against the bonnet I get skin irritation from the fiberglass. Its not sharp but it does scratch the skin and makes me itch like crazy. I should know better.

I removed the interior trim and headliner and now have the compromised vinyl off the roof. This is going to be a bigger issue since I found rust.

So let me begin with a couple of pictures:
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This is a view from the rear of the car at the back window. The blue painters tape indicates places with rust at the edge of the fiberglass bonnet.

I quickly checked both spots and thought things were good to proceed with limited additional effort other than a little rust removal.

Based on advice from smarter forum folks, I went back and spent more time with a different tool (awl) and pressed on all the rust areas and guess what:

IMG_2814.jpg
The point of the awl is pointing at the hole I made when I pressed in that area.

This particular section where the bonnet meets the body is a single piece of metal; that is, it isn't a sandwich top and bottom like the hood. So that hole, which will be covered by the vinyl and the chrome trim, actually goes all the way into the trunk.

I cannot just leave it and I cannot fix it with the bonnet on it. So folks, this thread will detail removing the bonnet from my 87 Fifth Avenue and repairing the rust spots.

My current question is: Should I put money into getting a sandblasting machine (small) from harbor freight or northern tool? I figure the cost is low although the quality probably is too. Guess I should check to see if there are any other rust spots on the body.

My alternatives are: 1) use elbow grease and steel wool or 2) use 50 grit circles and small air tool and sand it out.

Then, since I'll have to patch it and I have zero experience in steel body repair, what do I need to know to do this correctly?

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kkritsilas

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Hi,

I used this one:

http://www.princessauto.com/en/detail/comfort-grip-gravity-feed-abrasive-blaster-gun/A-p8059966e

to blast the 5 on 5 wheel. I used crushed glass media (aluminum wheel), but you would need something a little bit more aggressive for rust removal from steel (aluminum slag or something like that). Depending on how much rust removal you have to do, it may be worth getting a siphone feed gun instead of a hopper feed gun like I used. I don't think there is much of a difference in the actual blasting result, as it is more a product of airflow and media type, but with the smaller guns, you spend a lot of time refilling the hopper.

Kostas
 

Aspen500

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Regardless of what media you use, be sure to wear a respirator ESPECIALLY if it's silica sand (not just a dust mask).
 

Justwondering

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Life has been getting in the way of bonnet removal but I snuck in some time today.

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These were the heads of rivets I drilled today. Even being super careful, you can see that both these locations had cracked fiberglass (bonnet). One tore out the fiberglass, the other didn't.

Course, after 8 steel rivets my drill bit was toast. Will get more bits tomorrow so I can get the bonnet off and the repairs done while the weather is nice.

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Darth-Car

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Drill Doctor drill sharpening tool. A great material saver on these jobs, and you always have a sharp bit at the ready; no compromising with a bit that is going bad.
 

Justwondering

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Busy day ahead so I worked on removing bonnet this morning. Here are the details.

Bought more drill bits yesterday. It took me a total of 5 drill bits (9/64). Got about 6 rivets to each drill bit before they became dull. These be steel rivets, no aluminum here.

The rivet:
Capture.JPG
The first rivet in this picture is like the ones you have holding the bonnet to the roof. Your goal is NOT to drill it from the top of the rivet all the way down the mandrel.

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Rather your goal is to drill enough of the center so that the rivet head (the collar) comes off. I started with very small diameter bits and kept going up in size until I found the one that worked best for me. If your drill bit is too small, you don't catch enough rivet material to make the head of the rivet come loose. If you have a drill bit too large, you make a larger hole in underlying material and have to get an even larger rivet to replace it.

These were the problems and solutions I used:

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1. A rivet with no indentation at the top, so I didn't have a 'guide' for my drill bit and it kept trying to wander off onto sheet metal. Take a punch or nail and use a hammer to drive it into the top hard enough to create an indentation.

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2. A rivet that I drilled too quickly and the bit wandered to the side of the rivet taking out part of the head (collar) and part of the fiberglass. I used a pair of dikes to nibble at the remaining part of the head until i could get it either small enough to pull the bonnet over it or completely nibbled off so didn't hold the bonnet any longer. Tedious, take your time. You'll still chip out some fiberglass.

3. A rivet that I drilled exactly in the center, went the same distance in depth as the others and all it did was rotate in a circle but never broke the mandrel body so the head (collar) would come off. Tried the dikes, tried a slight angle to the existing bit, finally used a bit one size larger and SLOWLY drilled so I didn't have to repair another fiberglass spot. Eventually the head broke loose.

Pictures:
IMG_2871.jpg
Messed up the fiberglass bonnet here.

Once all the rivets are out, take your putty knife and work it under the edge of the bonnet, all the way around. Old gooey, dried, black adhesive is there. You need to be sure the bonnet is pulled over every rivet, unless you take time to take a punch and hammer and push every rivet back through. Which I should have done but was to interested to find out what it looked like underneath to do that. ;)

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Go to the upper, inside corner of the bonnet and push gently up at an angle. This has adhesive under it that is getting old but still has some stick to it. So you don't just grab the top and pull back. You don't just grab the bottom and pull up. You risk ripping the bonnet itself. The inside corner, where the vertical window meets the top of the roof has the highest tension. Once you get that area loosened, you can easily pull the bonnet.

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Justwondering

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I used a nylon brush to sweep out some of the crumbs.
IMG_2884.jpg
This rust spot looks pretty well contained. Wasn't any larger than first seen with the bonnet attached.

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Used my left hand to take the picture so the orientation is opposite of the other one (my apologies). After cleaning the area, I poked at the steel with the drill bit and punched through more rust into the trunk. So it was well worth it to take the bonnet off and discover I had a larger rust issue.

Once I get the adhesive cleaned off, I'll see how big a patch I need to put in. Luckily I kept the old front crumpled fender so I have plenty of material to use in my repair.

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Justwondering

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Well the good news is I got another hour in on the car before I lost daylight tonight.

Tried a brush on the dremel to remove rust. It does not like the rivet posts. So I tried tapping out each of the posts (pushing them through the hole with a hammer hitting a punch). Some went through, some didn't.

Then tried the grinding wheel with a wire brush. Kept it at an angle and it seemed to work better with less effort.

So the good news is I cleaned up the two problem areas.
The bad news is I checked the other rivet holes where the bonnet was riveted to the body -- every hole but one had rust.

Took picture of the top:
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Left side
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Right side

Then here are a couple of close ups after I used the putty knife to scrape away the sealer:
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More rust
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And more rust.

Then here is the underside of a couple. Inside the trunk, looking up at the holes:
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This is the backside of one of the original problem areas on the left. I will have to patch this area.
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This is the backside of a different hole (the one near the chrome christmas tree that broke off). Notice all the red rusts spots where the water must have been dripping down the metal.

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This is another backside shot of another location but it has no rust.

The takeaway is the inside of the trunk will need to be cleaned of rust in most but not all of the rivet holes where the bonnet attached to the car body. Apparently, there was only adhesive there and not sealer OR the sealer failed. I swept lots of black crumbs off this part of the car. However that could have been residue from the dead foam under the vinyl. Whatever, just means there were more issues than I first thought and I am very glad I took the time to remove the bonnet. Even though I see a much larger time sink to get everything properly prepped prior to the vinyl roof install.

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Justwondering

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I'm shocked. You telling me you are not looking forward to spending quality time on and in your trunk with a wire wheel grinder?
 

Jack Meoff

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I'm shocked. You telling me you are not looking forward to spending quality time on and in your trunk with a wire wheel grinder?

I know it's insane but you are correct.
I've already repaired around the vinyl but I've never removed one. Time consuming to say the least. One day when I do get enough time......

I thank you for the pics and tutorial.
This is invaluable info for anyone who needs to do it.
 

Justwondering

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After this morning, I can tell you that :
1. The trunk of a fifth avenue can easily hold an adult
2. Lying in the trunk of a fifth avenue, you realize the tension rods for the trunk lid prevent you from using the full size wire wheel grinder.
3. Using a dremel with a wire wheel easily removes the surface rust right back into your face (wear glasses or goggles)
4. Getting into a fifth avenue trunk is far easier than getting out.

Pictures:
IMG_2916.jpg
Lying in the trunk with camara pointed up there was about 2 feet of light surface rust in this recessed area. It looked like water was getting in around a rivet body and draining to the low side of the car to drip down. It was NOT the entire width of the car.

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Best way to remove the rust was with a wire wheel attachment on a dremel. Lie on your back in the trunk and hold the tool up and behind the tension rods. There are plenty of brackets and those tension rods taking up space so you can't use a full size wire wheel effectively in the tight space.

And look what else I found while in the trunk:
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If you look carefully at the center of the image where the two tension rods cross, there is rust.

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Justwondering

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My plan was to spot weld the holes multiple times holding brass behind the hole. Didn't want a lot of continuous heat from a 'flood' and didn't want it to droop. Spot weld then cool. Spot weld then cool. Welds won't stick to the brass. When filled, use the dremel with a grinder wheel on it and good as new! What a fine solution I saw in my head.

NOT.

I practiced on the old, crunched fender. Haven't welded in ages so I had to relearn everything. Got my wits about me and the solution worked for the hole in the fender. Excellent looking and strong after the grinding. One slight mis-calculation on my part. The thickness of the fender is much greater than the steel sheet under the window. As soon as I tried the same technique on the car sheet metal, I made the hole bigger. Tried the other damaged area since the hole was smaller and it hadn't rusted out as bad. I made that hole bigger. Dang it.

So I put up all my tools and welding gear and got out the JB Weld.

If you do try to repair the metal under the window with welding, you are going to have to use a welder with much finer heat controls than a 90 amp chicago welder from Northern that has Min and Max as the two options.
 

Justwondering

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Two low areas where the bigger holes were. So I will add more this evening to float it even. No rivets are going through it.
 

Justwondering

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Pictures from today:
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Original issue
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After my attempt using the welder, you can see that the two holes (left one, right one) are larger. My welder has two settings (min and max). I used min but it was clearly too hot for the sheet metal near the window.

Backup plan:
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jb weld, chopsticks, towel and chunk of granite
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Equal parts of jb weld (steel and hardener)
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End result to spread
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First round of jb weld (note the low area where the largest hole was)
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Second round of jb weld building up to the level of the sheet metal.

Wait for it to cure tonight and bonnet can go back on.

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