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HybridZ

A bad roof is a major job to fix


bjhines

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Holy cow, what a pain this is.

 

I was lucky to have a relatively rust free 240Z shell to start with, But someone had a party on the roof.

I knew it had problems, but I had no idea how bad it was until I sandblasted it clean. Even then I had no idea how much effort it would be to get it straight.

 

This is one of those times that I am glad I did this myself. I would have had a hard time understanding why this kind of fix either looks like crap or costs a thousand dollars. I have spent 3 DAYS(20+hours) just getting the unibody blocked and filled. I still have doors, fenders, hood, and hatch to go. The roof has taken most of the time spent so far.

 

I am still unsure of how this will turn out. I think I can put up with a little wavyness.

 

 

 

Roof start:

I wish I had a good shot of how bad it really is. There are 3 MAJOR dents that want to pop one way or the other(2 in front and one big one at the rear). I worked the metal enough to get them close to level and relatively stiff. I tried to get a few hammer marks to stick up to the point I want the curve to follow. I used a straight edge and a cardboard template I made off my other 240Z. That way I use the hammer dents as a sanding guide. When I sand through to the "guide" dents, I know to stop.

 

I started the filler process with Tiger Hair, long strand body filler. This stuff is like laying up glass. It is hard to mix and it takes a long time to harden. It does lay out nicely and feather well. It is tough to sand though. The bright green stuff is Everglass with short-strand glass/Kevlar. This is actually the second filler coat.

roofstart.jpg

 

 

 

Here is some progress with most of the heavy duty filler sanded out and leveled. I am using a lighterweight sandable filler that you can see in white to get things leveled. the heavyweight fillers require too much pressure to get them level. The white stuff is called Halftime. It is good to 1/8" but it is backup up by some pretty durable undercoat.

roofprogress.jpg

 

 

 

 

More progress through the stages:

roofprogress2.jpg

 

roofalmostsmooth.jpg

 

 

Here is the roof 90% straight. Most of the work left to do is filling pinholes and feathering some edges. I am going to prime it again tomorrow and see how it looks.

roofissmooth.jpg

 

 

 

 

The rear clip had "normal" amounts of filler work, but I spent a lot of time metalworking this panel. I even used musicwire to reinforce the edges and the dual exhaust cut outs.

rearclipsmooth.jpg

 

exhaustcutoutinside.jpg

 

 

 

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Wow, that looks like a major undertaking. I am getting ready to start stripping and working on my bodywork. I am hoping that I am not opening Pandoras box. Everything looks pretty straight right now, with only a little rust on the lower rear wheel well area. Good luck with the rest of your bodywork, it looks good so far! Great pics, too.

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When I went to visit my Z at the body shop after it was painted, the body guy came over to me and asked me how many girls had danced on the roof with high-heels on.

 

He was totally bitching about how difficult the roof was to get right. :icon8:

 

I had set up for a friend to paint my car at the body shop he worked at over the weekend. When the shop manager saw my car he was like "I won't let that be painted here (referring to the roof and some 'minor' imperfections). This was even though he said he it wasn't a problem before. I guess he was expecting a show car, when mine is a daily driver. To me it wasn't a big deal, but for him it was (even though it was being done after hours and not "through his shop" officially ... wasted a full day of my time and pushed my schedule back two weeks. But it did give me time to repair the roof more ...

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I guess all these cars have some roof damage. My car had two dogs dancing on the roof after ripping my car cover completely off my car and taking the side view mirrors with it. I wanted to shoot them dogs.

When I finally started my roof i decided I was going to see how many of the dents I could beat out with my hand. I was suprised how well it turned out by hitting upwards with the palm of my hand. My hand was sore when i was done but I know I saved half a gallon of bondo.

BJ, those exhaust cut outs look good and familiar- is this a v-8 car??

 

i

z pics 186_thumb.jpg

z pics 182_thumb.jpg

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It is a V8 track car.

 

A friend who has helped keep me on track with this project with moral support and encouragement told me to "put down the bondo and walk away from the roof". He would agree with J. Mortensen that I have spent too much time on a track carr's bodywork.

 

I got the doors done last night. They are truly straight. They are MUCH EASIER to get right than the roof!

 

doorisstraight.jpg

 

doorhassharpcrease.jpg

 

The inside is sandblasted and caoted with OSPHO

doorwithOSPHO.jpg

 

 

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Wouldn't it have been easier to cut the roof and weld in a skin? The PO installed a sunroof on my car. It caved in around the edges and rust started to form so now it looks like the sunroof was installed with a hammer and a can opener. So this is the approach that I'm going to take i think.

 

Your work looks awesome. i hope to get the body strait on mine also.

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I can't stress enough the key to a good, straight panel is Evercoat Metalglaze, basically a watered down version of bondo. Your roof and door look good, but I would coat the entire panel one last time and sand it down with this stuff. I was amazed how "good" a panel felt after sanding and how much more continued to show up. I typically do the initial sanding with a random orbital, then a longer hand sanding board, approx 18", and finally a traditional sanding block. My roof looked about as bad as yours initially too.

 

EDIT: I also wanted to add, the Metalglaze sands much faster than the thick stuff, not much more time required in comparison to all the other work.

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  • 7 months later...

So lately I've been working on fixing the dents in my roof as well. For the most part the dents are all filled now, but the roof isn't completely smooth yet. I think I'll try that Evercoat Metal Glaze and see if that will give me the results I'm looking for. I'm wondering if I need to purchase a flexible long board sander as well. I've been using a flexible sanding board, but it isn't that big and uses standard size sanding paper.

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Are your arms sore yet ? They should be . You doing some things the hard way. A suggestion or two if I may.

 

When applying any type of filler ALWAYS apply the filler material in the direction of the curve of the panel.

 

The roof skin has two curves, front to back , and side to side . It is not a flat panel. Make shure your sanding blocks are flexible enough to adjust to the curve of the panel and as long in length as possible . This will assure getting the panel restore back to its original contour. ( Notice I didnt say straight ).

 

Apply your plastic as smoothly as possible. You want your plastic to look just like a perfectly repaired panel before you start sanding. No edges from the spreader . No clumps or visible low spots. Feathered nicely into the metal.

 

Apply a piece of 3/4 masking tape to the top of your bondo spreader. When applying the filler keep all your fingers on the tape. You will be amazed at how well this little trick helps get the filler on straight and smooth.

 

Always apply filler in complete coats. Try to avoid applying a small patch of filler in the middle of a spot of already sanded plastic. All you do is chase the low spot around the area.

 

Learn to read the plastic and metal. This may sound confusing but once you start this step you will be able to see immediate improvement in the process.

 

Tiger hair or other types of heavy reinforced fillers are for the most part not needed. If your metal work is properly done , you wont be applying filler any thicker than 3/16" . If its oil canning you need to correct the condition as any filler applied over a streched area will crack regardless of the filler used. It also makes the job of getting the correct form back in the panel because the metal is always shifting even from just the light pressure of the sanding tools.

 

Happy Sanding

 

Larry

http://www.wgmauto.com

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