Zink Formula Vee

My wife and I took a little vacation to Colorado to see some friends while Jack made a part. 

It came out better than we expected. So much better, we're probably going to use it. We're going to make up a few other small parts to get more practice in mold making, then we may go back to iteration #2 of this tail as previously mentioned.

Here's another picture of the mold.

Jack said the part came out pretty easily. He used some wedges at the sides, then drilled this little 1/8" hole, blew air with an air blaster, and it popped.

He trimmed out the back part.

Inside detail.

And a quick test fit.  He's moving on to the exhaust. I'm going to pull the king pins off for annual magnafluxing and build up a 2nd set for spares.

Oh man that is a nice piece. I wonder if a fillet on the inside of the opening would be worth 1/4 MPH at somewhere fast? Finishing the edge off flush would make it fast also, but way too delicate on the edge.

In reply to TurnerX19 :

Thanks! Jack is so competitive, he will chase that 1/4 MPH...

In reply to Carl Heideman :

Put it in a wind tunnel and let us know!  The biggest thing you can try to do with a Zink is figure out how to minimize the draft behind you.  The different tail pieces definitely make a difference--I've been told the one on mine is one of the worst.  I'll also say that following something like a Mysterian is like following an invisible car, but you pretty much can't win a race in a Zink if you're in the lead the final time you head down a straight before the finish line.

Jack decided he wanted to make another tail and save some weight. We also wanted to try some new things to help with our fiberglass learning curve.

As long as we were using the mold again, we decided that we wanted to front top edge a little longer, so Jack lengthened the mold with some luan. There is body filler and gel coat on the inside, feather edged into the existing gel coat. 

Since the car may stay black this season, we thought we'd tint the gel coat so we bought some black tint. We were skeptical that it would turn white gel coat black, and even with 3x the amount, it just made it darker shades of gray. It will still look better than white if the paint gets scratched.

We've been spraying the gel coat in with an undercoating gun, a tip a friend gave us. It's much faster than a spray gun or brushing it in.

Our first part was 2 layers of 1-1/2oz chopped cloth. For this one, the first layer was the same chop, but we used 6oz mat for the 2nd layer. Jack pre-cut all the pieces and laid them out in the order they would go in.

We mixed up some resin and brushed it in the base with a 2" brush, then started laying the cloth in.

We rolled all the air bubbles out.

Then we put the weave layer in.

After rolling that layer at the bottom, we used a body filler squeegee to move the excess resin up to saturate the top areas. One of our main goals in weight reduction was to use less resin and the squeegee did the trip. 

Then we played the Waiting Game. We left the shop at 70 degrees (F) overnight.

We learned some lessons from this part, so here they are. 

First, as mentioned, we didn't like the tint very much. We're going to get black gel coat next time.

Second, we leave the shop at 50 degrees overnight. We turned the heat up to about 60 when we started, our normal winter working temperature.  The air warms up quickly, but the mold, the resin, the cloth etc. warm up more slowly.  After we sprayed the gel coat in, it took too long to set up. It was hanging about 65 degrees when the mold was 55. We finally used a heat gun to get some heat into the mold, keeping it about 100F and it set up in about 20 minutes.

Next time, we'll have the shop at 70 overnight before starting.

By the way, the unused gel coat peaked at about 165 as it was setting up. 

Our third lesson, which you'll see in the next post, is that the surface finish of the gel coat wasn't quite as nice this time. One of our gurus said it was probably because we didn't use enough gel coat. We used a full quart on the first part, only half on this part. By the way, it was nice to spray in a contrasting color of gel coat, so we'll probably make most of our molds orange or another contrasting color in the future.

We left the part in the mold for about 24 hours.

We started to break the part free with these plastic wedges.

We couldn't use the air trick to pop the part this time because we didn't lay up any glass in the center oval section of the tail. Jack popped out some gel coat there and went to work with the wedges, sometimes using a mallet.

It took us about 30 minutes of careful work to pop it free, but the part finally came out. We'll see if we learn tricks to speed it up. A two piece mold would be nicer if we made a lot of these.

Jack did a rough trim with a die grinder.

The white tail is about 9 lbs, the new one is about 5. The new one is noticably weaker in the flat areas, but should be fine once mounted. We're considering it a success.

As mentioned, the surface finish is a little goofy and shows the swirls from the mold release. We wet sanded a trial section and it will be fine under the paint, but we hope to do better next time at the expense of a little weight. Of course, if the surface finish is decent, we'll save weight on the paint... 

Jack's been busy...

He reconfigured the exhaust as a 4->2->1, hoping for a little more torque out of the turns. We'll get it on the dyno and see how it does. He may change the length of the intermediate tubes depending on what the dyno and lap data says. Or go back to the 4->1 if this configuration doesn't work out.

He made new downtubes for the front of the roll bar. He figured it would be safer and maybe faster to be lower in the car, so he also reconfigured his seating position and moved the belt anchors down.

He had to build a new seat to make this all work out. The seats look pretty similar but the new one (left) has a different rake to it to get him about 2.5" lower. He put much bigger holes in the sides to make dealing with the seatbelts easier.

We took the car apart for paint.

This is the first time we've had the floor off. 

Jack did some more finish welding and detail work. Tomorrow, we'll sandblast it and get out the spray gun.

Is it legal to glue the floor on with Hysol when you re-install it? Due they enforce a minimum rivet pitch?

In reply to TurnerX19 :

I appreciate the way you think. We were talking about that yesterday.  A friend was hanging out when we were drilling out the rivets and suggested we use a lot more going back together. Jack didn't remember seeing much in the monoposto rules, but has seen a spacing guideline in SCCA rules. While it's tempting to stress the floor, we keeping this car fairly era correct and keeping the spacing pretty wide as it has always been. 

By the way, early Zinks had stressed skin side bodywork that was quickly outlawed. We have a friend with a stress skinned chassis that was never finished and our other chassis was originally a stress skinned chassis that was converted after the rule change.  I'd love to see pictures of a stressed skin car if they're out there.

I drew the short straw and did the sandblasting.

Dang.  You have a full blasting room.  That's baller.

Good progress on the composites.  Switching to fiberglass cloth & epoxy will give you a lighter stronger part without much extra work.  A bit more expensive, but much more forgiving in my experience.  Less smelly too.

If your large flat areas are still floppy consider adding a little strip of core material.  Even an 1/8" thick bit of balsa or structural foam would make a huge difference.

Assuming any of this is allowed by your rule book!

TVR Scott said:

Dang.  You have a full blasting room.  That's baller.

Good progress on the composites.  Switching to fiberglass cloth & epoxy will give you a lighter stronger part without much extra work.  A bit more expensive, but much more forgiving in my experience.  Less smelly too.

If your large flat areas are still floppy consider adding a little strip of core material.  Even an 1/8" thick bit of balsa or structural foam would make a huge difference.

Assuming any of this is allowed by your rule book!

We don't have a blasting room, but close. A few years ago we walled off a 16'x16' corner of the shop and put a big spark-proof fan in it to create what we call the "dirty room." We have two stud walls with dairy board on them and two block walls with glossy white paint on them. The walls are easy to blow or vacuum clean. We use it when we're making a big mess like stripping paint or spraying paint (we don't do paint work in house, but sometimes paint engines, suspension parts, or wheels). It's been in a lot of the pictures in this build thread, like the wheel painting and fiberglass work.

We recently decided to see how the dirty room would work for sandblasting and it's worked out very well. Sandblast for about 10 minutes, sweep up the sand and refill the sandblaster, rinse, lather, and repeat until done. The downside of finding out that it works for sandblasting is that we'll probably do more sandblasting in-house instead of sending it out. To me, sandblasting is much more pleasant when I write a check, but it's harder to find sandblasters that are careful and cost-effective (many are neither around us).

It takes about 30 minutes to completely clean the sand out of the room for the next dirty project that makes a new mess to clean up. So far, my insurance company and local officials haven't complained about it and I hope it stays that way because it's been a great space for us.

Thanks for the tips on the fiberglass. We've done some epoxy projects too, just not of this scale. We're appreciating everything everyone offers and you're doing some nice work!

If you're not too sick of my details, I thought I'd post how I like to paint race car parts. My overall philosophy is to have the least amount of paint on chassis and suspension parts so that it's easy to see cracks and flaws on anything. I also want just enough paint to keep things from rusting. I like glossy paint because it's easier to clean. I like light colors because they make it easy to see fluid leaks and find things when dropped. I like the paint to stick well enough so that it doesn't peel off when we clean it, but does come off fairly easily the next time we blow the car apart for inspection and paint. So my go-to formula for years has been one coat of quality epoxy gray primer with 1-2 coats of cheap urethane clear.

My favorite epoxy has been PPG's DP series, which keeps evolving with environmental regulations but still works well. I mix it 2:1:1 as directed. Two parts DP50 LV, 1 part catalyst (DP401LV), and 1 part of a cheap urethane 870 series reducer (barely seen in the background). I let it dry 1 hour, then cover it with the cheapest private label urethane clear from my local  paint supplier. That's mixed 4:1 with its catalyst, no reducer. For small parts, I use my trusty 30-year-old touch up gun at about 35 psi. It has about a 2-3" pattern that wastes very little paint. Sometimes I will break out an HVLP touch up or regular gun, but I still like the old school siphon guns I grew up with for these types of jobs.

I put fresh paper down on my painting areas. People ask me why not just paint on the boards underneath or the saw horses. I used to do that, and the paint would build up, then contaminate the next thing I paint. So that's why. Plus, it just feels cleaner overall and cleanliness counts. Speaking of clean, I clean the parts at least three times with a medium evaporating grease and wax remover (private label from my paint supplier). I spray my first coat medium wet so it doesn't have any dry spray, but also dries quickly.

After about 30 minutes, I flip my parts to paint the other side. I try to strategically paint the sides so that when I flip them, there is minimum contact with the paper and therefore little damage if the paint sticks. I'll often space the parts up with some 1/4" nuts or blocks of wood or nails into the board below to keep the parts from sticking down. By the way, I love those old hand-cut Zink pieces that were stick-welded together. They wouldn't look great on Instagram, but have held up just fine all these years.

Then I paint the other side of the parts.

After the primer dries for 60 minutes (at about 65-68 degrees in the shop), I repeat the process with the clear. I again strategically plan the "flips" so that the most-seen sides are up for the last coat and there is little contact with the table or saw horses.  In this case, the beam is sitting on nuts. Also the nuts are placed where the beam contacts the frame, so any nicks in the paint are covered up.

The picture doesn't do it full justice as the gloss is very nice. I really like the color as well.

My last detail is that I always wipe out the lip of the can before carefully sealing it back up. If there is paint build-up in the lip, it may not seal well and wreck the remaining paint at $108 a quart (thanks supply chain). I used less than 1/4 of the quart for this job thanks to my touch-up gun.

Anyway, TL;DR, the brackets and chassis bits were all painted this evening. Tomorrow night, it's the chassis itself. Please share your own methods if you have better ideas.

Last season, we ran the car with many of those parts wearing DP90, the black version of DP50, but no clear, so the finish was flat. It always looked terrible and was hard to clean. We're so excited to have these parts in glossy gray this year.

p.s. No powdercoating on race car parts for me. Too thick, too hard to see those pesky cracks or other damage. 

Carl Heideman said:

p.s. No powdercoating on race car parts for me. Too thick, too hard to see those pesky cracks or other damage. 

Back in the long time ago, when I was racing, my powdercoat decisions were based on the following:

1) If I don't see a crack under the powder, and it breaks, will it hurt me?

2)If I don't see a crack under the powder, and it breaks, will it put me on the trailer for the weekend?

If yes to either of the above, it got paint

This was a really fun thread to scroll through, i will soon jump into vintage vee racing but in a different part of the world, where it's done a little differently. I tried a race in a loaner car and it was mega fun. I have never worked on them though, so theres alot to soak up wherever possible, vee guys arent very internety though :)

Chassis is painted. 

Cedricn said:

This was a really fun thread to scroll through, i will soon jump into vintage vee racing but in a different part of the world, where it's done a little differently. I tried a race in a loaner car and it was mega fun. I have never worked on them though, so theres alot to soak up wherever possible, vee guys arent very internety though :)

 

That's what we discovered and why we're putting so much detail in this build thread.  What part of the world are you in?

When dad and I raced short course off road buggies, we used to paint the chassis with black rustoleum. There was quite a bit of contact and the mud and dirt would remove some paint during the race weekend. We could easily touch up any time between races. It would have cost us a fortune if we did it any other way. 

Carl Heideman said:

Cedricn said:

This was a really fun thread to scroll through, i will soon jump into vintage vee racing but in a different part of the world, where it's done a little differently. I tried a race in a loaner car and it was mega fun. I have never worked on them though, so theres alot to soak up wherever possible, vee guys arent very internety though :)

 

That's what we discovered and why we're putting so much detail in this build thread.  What part of the world are you in?

In sweden, Vee was really big in the 60-70s (And some of the fastest cars were made here by some small manufacturers), so alot of cars are still around. Actually vintage Vees are one of the most crowded race series in sweden with full starting grids, which is quite fun as its pretty affordable racing. They have two subcategories (65-68 with the early front suspension, and 69-71 with the later ball jointed suspension), all run 1300cc engines at 70hp (they say). But its also under FIA appendix K so its pretty strictly regulated from a historical point of view on what you can change on the cars.

Keep updating :), im sitting here in the snow, still a couple of weeks before I pick up the car, need some motivation :)

In reply to Cedricn :

There will be plenty of updates in the next few days. We have chassis dyno time on April 7 to dial in the headers and probably should put the car back together by then.

Please post some pictures of your car when you get a chance.

I've been doing other things but Jack and Owen are making good progress on reassembly. 

They cleaned up the old floor. 

Jack made a new firewall.

Well, the gray paint is doing its job. We found the crack once the Z bar was tightened. 

Powder coat would have hidden that just long enough to frustrate the hell out of chasing the setup, until it broke. Especially a darker color. Even dark paint is wrong.