New 550 build - kitman

Re the wheelbase: make sure the engine still fits under the clamshell if you're moving it aft. Per @chines1 it's probably fine, but do make sure.

Here you go.

BTW what brand of tire and what size rim do you plan on using.

Most of our Spyders use a 4.5 wide rim up front and a 5.5 in the rear. Then 185 65 15 in the front and 195 60 15 in the rear. Most of us.

A lot of us have gone with the Vintage 190 aluminum wheels. They're lighter than the steel rims and the 4.5s have an offset that makes for less rubbing on the front fenders. I have my summer tires on the 190s and some old P4s on steel wheels for the winter.

Jus wondering.

@edsnova posted:

Re the wheelbase: make sure the engine still fits under the clamshell if you're moving it aft. Per @chines1 it's probably fine, but do make sure.

Will do 👍

@Carlos G posted:

Here you go.

BTW what brand of tire and what size rim do you plan on using.

Most of our Spyders use a 4.5 wide rim up front and a 5.5 in the rear. Then 185 65 15 in the front and 195 60 15 in the rear. Most of us.

A lot of us have gone with the Vintage 190 aluminum wheels. They're lighter than the steel rims and the 4.5s have an offset that makes for less rubbing on the front fenders. I have my summer tires on the 190s and some old P4s on steel wheels for the winter.

Jus wondering.

Thanks for that mate, I'm a little way off putting tyres on, so that's cool to have a preview 👍

I've read the Vredenstein tyres are the go? Probably something around the 175/70F and 185/70R sizes.

I've picked up a set of wheels in 4.5 and 5.5 👍

Don't presume the offset is the same for 4.5 and 5.5 wide wheels.

@RS-60 mark posted:

Don't presume the offset is the same for 4.5 and 5.5 wide wheels.

Roger that. Front wheels seem fine. I'll mock the back wheels up in-place, and work backwards from where they sit when measuring axles, control arms etc

Happy, happy, joy, joy. This is where I'm at with the clamshell. A number of relief cuts and bracing required to get the shape right. I've riveted some sheets of scrap stainless behind the cuts in the wheel tubs to get everything in the right plane to start glassing it back together. Then I'll have to rejig the bracing so I can get at the cuts from the other side without everything springing back to where it was.

I like your wood bracing!  I painted a few off road buggies when a couple of friends were into racing and the front hood was always cobbled together from a mold from another car.  One hood came out of a single seater mold and had to be widened and lengthened, another was from a 2 seat mold and had to be narrowed (and probably shortened or lengthened).  The 3rd and 4th hoods- after 40 or 45 years, I forget.  Nothing was ever any where near 'paint ready', and so there was always fiberglass work, cardboard backing if it was being lengthened, taking out rivets/metal pieces holding it all together and then more fiberglass, grinding and filler to make them smooth and flowing.

Temporary bracing looks really good. You've got this. Obviously you are a smart and experienced fabricator. Keep going, can't wait to watch this step by step.

Dude's a wizard.

"Smart and experienced fabricator"

I've obviously got you guys bluffed 😄

I do appreciate the compliment though. I am a builder/carpenter, and only do renovations, so there's probably a bit of crossover in problem solving. This is definitely the first car build.

I'm trying to temper my annoyance at having to do all this to get the panel to fit, with the fact that I'm improving my fibreglassing skills

I hear and feel that. I had ZERO fiberglass skills. But now that I race Formula Vee I have had to learn.

It isn't hard, and the learning curve isn't steep. It's just messy. Hearing(air sander/grinder) and breathing protection are a must, as are safety goggles. And cover your body with some clothing to prevent the itchy.

Metal tape, cardboard, wood strips, and clamps work really well for fixing stuff, as long as you grind out all the broken stuff. ALWAYS rough up/sand any area where you will glass over.  I use mat exclusively instead of cloth, and polyester resin. I'll do a couple layers, then let it set up. Go back and sand, then add more layers until you're back to original thickness. Do a couple layers on the inside, then do the outside. That's how I would fill in those pie cut cracks. It just takes time. Your work won't add much weight at all if you don't make it too thick.

Have fun with it. I'm glad you were able to fix the clamshell.

X2 what Danny said about working with fiberglass for those that haven't had the pleasure- it's not complicated at all, just messy!  I will add- when fixing an existing surface, start by making sure it's clean by washing down with a de-waxer.  Don't try to add resin/mat (or cloth) over paint or gelcoat; it will eventually separate.  Your best results will be with a freshly ground surface.  Use clean containers to mix in, as previously mixed in containers can set off your resin faster than you anticipate.  You can set off a batch that won't harden by heating it with a halogen light, or if that doesn't work, making the next layer a little 'hotter' with more activator (but not too much or you'll never get it out of the bucket!).  It's always a good idea to drill a small hole at the start of a crack to de-stress the area.

These are just a few of the things I've learned- some were passed on to me and a couple I learned the hard way...

Here's a few tips from someone who may have done similar once or twice (or 1000 times, who's counting)

It was only mentioned briefly and would be easy to glance over, but DO NOT fiberglass over the rivets.  They will expand due to engine bay heat, and they will expand at a different rate than the fiberglass and create issues on your finished product, even if ground down flat.  Glass between them and then drill them out and glass where they were.  It is very rare that I find myself re-bracing after initial tabs, they are generally song enough to hold everything in place once dry.  After they are drilled out use a cabosil powder or finely stranded filler to fill the rivet holes.  DO NOT leave them open, they'll form small air pockets and will show in the final finish eventually.

Don't be afraid to grind too deep.  You obviously don't want to go through your existing layer, but you want your repair to be near flush when you are done, anything over you just have to grind off anyway, if you want a smooth(er) finish.

I assume you know what resin your body was made from? And what resin you are repairing with?  3 common 3 are Vinyl Ester (VE), Poly Ester (PE) and Epoxy.  Based on the cost of these DIY kits, I'll assume they are made with PE, so you can get away with repairing poly with any resin (PE, VE or Epoxy) you just can't repair epoxy with PE or VE, it will eventually separate and causes other issues as well that we don't need to get into, just know not to do it.  I don't recommend repairing VE or PE with epoxy anyway, unless you specifically need added structure, like in a high impact area of a boat or something.  

Regulate your temperatures and regulate your mix ratios.  Most industrial PE/VE are catalyzed 1-2% by volume (check your data sheets for your own product) and it is important to get that right to avoid issues down the line.  They will also have summer and winter mixes for most parts of the world which react slower/faster and are designed to be catalyzed differently, a few % make a HUGE difference.  The quality of your resin DOES MATTER.  I am in the fiberglass capital of the US, yet I still import my resins because I cannot get the quality resin I demand locally.  The RV industry just wants cheap and will dump a brand for pennies a pound.  We want quality and can't follow suit to the RV guys.  It DOES matter in the long run.

We always gel coat over a repair with an automotive grade gelcoat primer.  They are anaerobic, so we top coat with PVA to get a full cure.  You can overcoat it slightly and let it sit a few days and then wipe the top layer with acetone to get down to the anaerobic cured area.  They also make a wax additive that forms a skin coat in gel and helps it air cure, personally I do not use these additives.

I don't see signs of any cloth backer in your body, but that may just be the photos.  I use cloth backer on everything we make and I do it on all repairs, but for the underside layer ONLY.  The amount of strength a cloth backer adds is not to be understated.  BUT you do NOT want to use it on a surface, the cloth pattern will print through over time, it always does.  We use cloth on a surface repair only to aid in excess resin removal and "squeegeeing" and then is removed and discarded.  In the rare case that removal of a top side cloth backer is not possible, we over-build the repair layers and grind off all the cloth after dry.

I'm sure I've missed several tips here, it's hard to recount a lifetime of experience, but between this and the above info you have way more ammo than most going into this...

@chines1 posted:

. . . . 3 common [resins] are Vinyl Ester (VE), Poly Ester (PE) and Epoxy.  Based on the cost of these DIY kits, I'll assume they are made with PE, so you can get away with repairing poly with any resin (PE, VE or Epoxy) you just can't repair epoxy with PE or VE, it will eventually separate and causes other issues as well that we don't need to get into, just know not to do it.  I don't recommend repairing VE or PE with epoxy anyway, unless you specifically need added structure, like in a high impact area of a boat or something.  

That quote is worth re-reading again, and maybe should have been written in all caps.  NEVER use epoxy on top of PE/VE unless you have professional justification.  And NEVER, NEVER use PE/VE on top of epoxy under any circumstances.

In fact, the whole @chines1 post should be enshrined in never-forget-this memory.

I agree! Carey might know what he's talking about...

Yeah, definitely NO rivets left in there.

Wow. What an incredible resource this place is. Thanks all for the information and support.

I'm pretty sure it's PE, and luckily that's what's readily available where I am, from the local marine supply shop. I was going to drill the rivets out later so I could remove the  stainless sheet from the back and add to the repairs from that side. I hadn't really considered all the other reasons why the rivets should be removed though, and hadn't thought about air pockets either 😬

Unfortunately, given the way I had to brace it, the "visible" areas have to be patched first. I think I'll have to use cloth to get the strength I want. Given that these repairs are mostly hidden from view, ie, up under wheelarches etc, I may have to live with the possibility of the cloth weave being visible at some stage. Unless I grind it off after I've done the backsides of the repairs and redo the front?

Again, thanks for all the input and advice, it's greatly appreciated.

Repairs are "nearly" finished. I just have to do the back of the wheel wells and then try and tidy things up. The bracing seemed to have worked. I had it pushed out a few mm more than I needed, and it ended up being pretty well spot on.

Next step is to dismantle the front beam while it's bolted in, which seems easier than doing it on the garage floor or trying to get the whole shebang in a vice, and then remove it for a rebuild.

Once that's out, I'll glue and screw the chassis into the body permanently. I've test fit and trimmed the internal panels that were supplied (no frunk panels are included?) and can't think of any reason to keep the body and chassis just clamped together any longer.