That's just not right, Pt 2.

With the hood back on the car, I could finally get started on the important part, the top side(although really since the top is just for decoration while the bottom actually provides the structure, it should be the other way around).  The "repairs" on the top of the hood are another exercise in how not to do things.  Instead of diving right in with my grinder, I used my DA to sand the paint off, exposing the "repairs" in all their "glory."

The first thing I noticed was that this hood has been painted FIVE TIMES.  I don't mean there were five coats of paint on it, there were five distinct base/clear layers.  I know the bumper skin was repainted because it's flaking in places.  I had no idea that the hood it's self had been repainted, much less five times.  All the damage I found was from the crash that wrecked it just before I got it, so I don't know why the hood was painted so many time.  Anyway, lets look at a picture, because you're all really here for the pictures, right?

One pic, lots of trouble...
1.  There is a crack here repaired with fiberglass.  As you can see, the fiberglass is laid OVER the paint.   Paint is not a suitable substrate for fiberglass.  It wasn't properly ground down, and will have adhesion issues.   The whole repair could literally pop off the part because the only thing holding it on is paint.
2.  Cracks filled with bondo.  They didn't even bother to grind out the crack on the right(that's the one we took an in depth look at a few posts back).  It's no wonder it recracked, there is no structure holding the crack together.
3.  Loose/delaminated fiberglass.  We'll take a closer look at this area later on
4.  In a one-two punch, here we have more fiberglass on top of paint, and more crackes just skimmed with bondo.
5.  A crack that was ground a bit, but not completely gone so the crack continued to spread.
6.  Fiberglass laid in without a proper bevel.  These are major cracks and in several areas the only thing the new 'glass is holding onto is the vertical edge of the old 'glass.  In time, these crack would reappear.

Here's a closer look at area 2, where the crack reappeared.  You can see there is nothing holding the cracks together but a bondo bandaid. It's a wonder that it lasted as long as it did before recracking.

Here's an up close look at area 3.  The impact from the crash caused some of the fiberglass to delaminate.  You can see the ragged dark edges towards the center of the pic where some fibers of the top layer of fiberglass broke loose from the rest of the sheet.  They were just skimmed with bondo.  This sort of damage may or may not ever develop into a full crack, but it will definitely cause paint adhesion problems as the broken layer of fiberglass can move independently of the rest of the sheet.  You can also see a myriad of still existing cracks under the fiberglass repair on the left side of the picture.

One more picture, because everyone likes pictures.  Area 4 is basically all the other problem areas combined in one area.  There is just so much wrong in this picture...

SEMtastic!

It's still too cold to do any actual work on the Viper, so I'll do more posting instead.  It's time to finish the bottom of the Viper's hood.  Unlike the paint on the outside of the car, the paint on the bottom of a Viper's hood is not catalyzed.  If you wipe it with a strong solvent like lacquer thinner, it comes right off.  Because of that, I don't feel bad using non-catalyzed products to refinish it.  I'm also going to cheat just a little bit because I know my work isn't exactly as it was originally anyway.  I'm going to use a pair of SEM products.  As a company, SEM doesn't make any bad products.  Their Color Coat plastic/leather/vinyl/cloth paint beats Duratec as my #1 favorite product.  Here, I'm using a pair of products I've had good results with in the past.  The first is #39853 Texture Coat, the second is #39143 Trim Black. 

Texture Coat is just that, it's meant to give some texture to an otherwise smooth surface.  The Texture Coat is made to match OEM textured surfaces like you find on bumpers and some interior plastic parts.  You can also vary the texture by changing your spraying distance and how heavy you put it on(and as a benefit in my case, it will also hide sand scratches).  Here you can see the texture I ended up with on the Viper's hood. 

Trim Black is a satin black that very closely matches a lot of OEM finishes like you sometimes find under hoods, in fenderwells, and misc exterior trim. It's very close to the original black under the Viper's hood.  It's a good, durable, air dry paint that stick well to most surfaces.  It looks a bit shiny and uneven here, but it's still wet.  Once dry, it's a bit more satin, and very even.

The only thing left is to reinstall the hood pad and put the hood back on.  I expected the bottom of the hood to be a weekend project, but it was a month and a half before I actually got it done.  It was far more damaged, and the repair done much more poorly than I expected.  Even though it was off the car for a month and a half, because of the other demands on my time, I really probably only have 35-40 hours in it.  An actual professional bodyman probably could have had it done in 20-25 hours.

Just a little sprocketing

I mentioned some time ago that my Dad is rebuilding a Suzuki RE5.  The frame is set up to use later Suzuki Katana wheels.  Things like this are rarely a direct swap.  In this case, aside from basic wheel fitment issues, the Katana is made to use a 520 size chain, while the RE5 uses a 530 chain.  Swapping the RE5 to a 520 chain is pretty straight forward, but you need to buy a matching front sprocket and a chain.  It was decided that it would be easier to just adapt the RE5 rear sprocket to the Katana hub. 

The first thing I did was drill the new bolt holes.  In stead of doing the math to figure out where to put the new holes, I just drew up the bolt patterns in Solidworks.  From that, it was very easy to measure how far from center in X and Y the new holes had to be.  After center finding the hub hole, I drilled all the new holes.

Here you can see the new holes.  One new hole overlaps one of the old holes.  With a 5 hole pattern(RE5) and a 6 hole pattern(Katana) so close in diameter, you will always have an overlapping hole somewhere in the pattern.  On something like this, it doesn't make much difference.  Even a modern high power 2L sportbike doesn't have anywhere near enough torque to shear off the bolts. 

Then I set about enlarging the hub hole, it needed to be opened up by about 1/4".  The easiest way to do this on a manual mill is with a boring bar.  I had a whole long explanation of how these things work and how to use them, but it was just boring...

That's really all there is to it.  I don't have a pic of the RE5 sprocket on the Katana hub, but it fit like a glove. 

Back to the grind

Try as hard as I might, I couldn't get all the bodywork done on the Viper.  Every time I got going on it, other people would start making demands on my time.  Now, it's too cold out for fiberglass and bondo to cure properly, so I figured I might as well catch up on my blog.  When we last left the Viper, I'd just finished laying in all the new fiberglass on the bottom side of the hood.  Since the fiberglass is what makes up the structure, we could just leave it as it with some minor trimming.  But, it's the bottom side of a hood in an engine compartment that a whole lot of people ask to see so it has to look pretty too.

Before we can really start grinding, we need to know where to stop.  In a few areas where there was original undamaged fiberglass, I left some spots of the original black paint.  I know that paint is where it should be, so I know that that is where the surface should be when I'm done.  None of it is super critical on the front of the hood, but you still want to make sure the latch hooks are close enough to their original position that it will latch properly(even then, the latch has a lot of adjustability in it).  The round circle is one of the hood scoop nut recesses, the odd shaped black splotch is original paint telling me where the surface should be once we're done.

I started again with my trusty Harbor Freight grinders, first the 7" to knock down and level the big flat areas, then my 4.5" to hit the smaller areas, and finally a 2" pneumatic grinder for the tight spots.  Grinding it down serves two purposes, first to knock down any high spots, and second to roughen up the surface for additional filler work.  Here it is all ground up.  You can see the shape is roughed in pretty well.

You'll notice that three of the four the hood latch hook holes have been completely fiberglassed over.  Before I put any filler on, I want to be sure I know where they are.  Here is where Mineral Spirits works some more of it's magic.  Wiping the ground fiberglass with mineral spirits turns it transparent enough that you can see through it.  here you can see one of the hood latch hook holes under the fiberglass.  It shows up as the dark circle about in the middle of the picture.  All the holes will get drilled out before I add any filler.

Here's the part that I don't generally recommend, but am going to break my own rule and do anyway.  I've mentioned filler a few times.  Standard body fillers work good for a lot of things, but they don't have much strength.  Fiberglass is strong, but is hard to work with(and sands like concrete.).  There is a product that lands directly between the two, fiberglass reinforced body filler(often called Kitty Hair or Tiger Hair).  It's essentially bondo with chopped up fiberglass in it, and has the added benefit of being waterproof like fiberglass(and unlike standard bondo).

I don't generally recommend it for two reasons.  First, because it's fiberglass reinforced and stronger than standard fillers, a lot of people use it instead of doing proper repairs.  This hood had several areas that were just filled with kitty hair instead of being repaired properly with fiberglass.  Far too often I see kitty hair band-aids on things that need actual repair, both on fiberglass and metal cars.  Second is the bubbles...

Because of the fiberglass strands in it, kitty hair doesn't mix or spread as well as bondo(especially the long strand variety).  As a result, you often end up with large bubbles or voids in the filler that might cause problems down the road.  I decided that for the bottom side of the hood, I wanted the extra strength of the reinforced filler and would just deal with the bubbles.  You can see here the kinds of voids and bubbles you typically get in kitty hair:

You can't just fill the voids because filler won't stick to the (relatively) shiny surface of the bubble. The only way to deal with them is to grind them out first, then fill them.  Using a carbide burr in my die grinder, I ground out all the bubbles I could find.  In addition to the big obvious ones, there were also a whole lot of pinholes that needed to be filled.

Once the bubbles were ground out, I filled them with regular body filler and sanded it all smooth:

Unlike the outside of a car, the bottom side of the hood has lots of odd shapes and small contours, so it took a variety of sanding tools to work everything smooth.  For all the filler work, I used 80 grit sandpaper.  I bought a big roll of sticky back 80 grit, it's the most economical way to buy it.  From top to bottom I have my rigid 6" block, a flexible 6" block, a rigid 3" block, half a tongue depressor wrapped in sandpaper, a whole tongue depressor wrapped with sand paper, and my trusty 8" Durablock.  For this kind of work, improvised sanding blocks are often necessary too. Find something that fits where you need it to fit, and wrap it in sandpaper.

Even though most of the surface is covered in filler, it's not very thick.  Just like laying the fiberglass down, I worked a section at a time until I had the shape I wanted.

Once the filler was sanded down, I renewed my love affair with Duratec primer-surfacer.  It's just such a wonderful product, and it's made specifically for fiberglass to boot.  The repaired areas of the hood got a healthy dose, followed by sanding with 220 grit paper.  Normally, you'd want to sand much finer than that for paint or you'll get sand scratches showing through, but I'm going to do something a little bit different and don't need a super fine finish.  For now, just enjoy the Duratec'd goodness...