I'm Bringing Guacamole to the Challenge in 2024

lookin good!
 

In reply to MuSTANK :

I found it locally on marketplace. 

Boy, corrugated is such a pain to make templates with. It's even worse when stuff printed on it isn't square to what you're templating! It's a mini mind berkeley looking at this in person.

Alright. 111 days until I leave for the Challenge. Tons of progress has been made but there's still a long way to go and I haven't even ordered brake parts, spark plugs, etc. Must. Stay. On. Task. 

I just, I love clecos.

The passenger A-pillar is leaned back from the wreck and it distorts the polycarbonate a bit.

I cut this out with a jig saw. Previously when making race car windows I've had the jigsaw bounce around so much that it scratched through the protective film. I came up with a solution to that.

AxeHealey said:

I just, I love clecos.

The passenger A-pillar is leaned back from the wreck and it distorts the polycarbonate a bit.

I cut this out with a jig saw. Previously when making race car windows I've had the jigsaw bounce around so much that it scratched through the protective film. I came up with a solution to that.

I just use a circular saw.

In reply to wvumtnbkr :

Put the blade in backwards also.

Just in case some poor schmuck (or schmuckette) tries to get it registered.

Ok so I didn't quite nail it.

Close enough! It's now riveted in place. I've left all the protective paper in place so it's not much to look at. I also painted the capped A-pillars.

I like the felt furniture pad solution for the saw!

Most of the progress on Guac this week has been in the form of bugging Sleepyhead offline and just a'thinkin about the path forward. Now, we start down that path.

The tailgate is going to be pinned up for competition and the wing is going to be mounted just at the rear edge of that. Sorta like...

It's hard to hold the wing and take a picture with only two hands but, you get it. 

I spent this morning helping to strip a parts NB that one of my racing friends bought and I realized I could make use of the rear tow hooks so my friend plasma'd them off for me.

Both the wing mounts and the tie downs are going to use the factory rear bumper mounts. I didn't take any pics of the process but I made the mounting plate out of a piece of a big chunk I cut out of Elmore's rear bumper years ago. I also removed the tow hook from the rest of the section.

I'm pretty sure I'm going to use some tube welded perpendicular to the plate as a way to pull the wing mount away from the body and tailgate. Square tube I have in the scrap pile or maybe some EMT that was left by the PO of our house will be the vertical pieces.

I was working down this path, getting a piece of tube tacked into place on that plate and realized that without a complicated bend there's no way I could open and close the tailgate with the wing mounted. I had the wing sitting on the tailgate working on measurements and thought, hm, why not just mount it TO the tailgate? If I have to remove the wing to open the tailgate anyway, why not just K.I.S.S. and save some weight/materials. 

The old chain guard from my mini bike that no longer fit after I swapped the engine could be perfect, I thought. So I spent some time making this. 

The idea is to have the brackets riveted to the tailgate and then wing will then just bolt to the bracket. It's not as cool as a separate mount and I couldn't get the wing quite as far back as I understand to be ideal but it's definitely the simplest solution.

Thoughts from the aero team?

Also - more detail on the wing construction now that it's cut down. 

I'm getting "Liebeck" vibes from that profile.

The structure is different than I'm used to.  I guess that nomex can't bend around the nose radius at this scale.  Still a bit odd, to me, that the underside core isn't 'slid' further forward.  Front edge "should" probably match the upper surface chord.

One thing to be careful about is (iirc), the profile is going to drive the nose "up" due to the generation of downforce... although it really ends up force the back edge down.  So, the rear of that mount will need something to catch it.

Figure Cm of ~0.3; 80mph.  50in by 10inch foil?

Skipping some math and unit conversions...

0.5*.002377*(118^2)*(3.472)*0.3 = 18# for both.  Figure 15#s on each rear mount to be secure?

if we carry the same math forward, and assume a Cl of 1.8 on the carbon fiber foil....

0.5*0.002377*(118^2)*(3.472)*1.8 = ~104#s for the rear foil you picked up; so make sure the mounts can handle 60#s?

In reply to sleepyhead the buffalo :

Thanks for that math. I was realizing today that I likely needed support out back and started into it.

First I got the second mount done.

Then was visualizing the support.

Since I'll need to remove the wing when I close the tailgate anyway, a straight support down to the tube stub will be just fine.

So. Brackets will be riveted to the tailgate and then I'll make a support for both sides likely out of square tube in my scrap . The support will bolt to the wing mount and I'm going to cap the tube stub and thread the cap.

Next step is to get the mounts riveted so they're not just clamped and then determining the final angle of the tailgate in it's open position.

I decided to use bolts to affix the mounts to the tailgate. On to trimming and capping the stub.

First this.

Then.

Then.

That bolt (and it's match for the other side) came off of Guac somewhere. The stub and cap were bits than came with the Mustang roll bar I bought. I didn't weigh the stub and the cap but I'll try to remember for the other side. It ain't much but it will be accounted for. 

In reality, I started into the wing mount before drilling and threading the hole in the cap but I liked the progression there. I'm making the wing mounts out of square tube I have in my scrap pile. I took my length measurement and added 1 1/4" on either side for the mounting tabs. A good bit of fitting, slicing, folding, welding and finishing left me with this. 

I'm really happy with how it's come out. My plan is to have speed holes and/or slots in it for looks and weight but I'm going to make the driver's side before doing that. The bolt and nut (nut welded to the mount), I believe, are from a Miata and were just in my nut and bolt drawer. 

On to the driver's side.

Getting there!

In reply to AxeHealey :

I had to take a bit of a break for the holidays.

I'm glad to check back in here and see progress.  looking good!

In reply to sleepyhead the buffalo :

Thanks! My little family unit always likes to get out of town the week after the holidays. We got back yesterday afternoon. After about a week away, I was ready to get back into it today.

First was finishing the driver's side mount.

Same deal as the other side. Top side twisted a bit to fit, nut welded to the under side and the bottom bolts directly to the stub.

On to the tie downs. I've been pretty happy with the welding so far on Guac but this was tough. I think it was butting up against the limits of my machine and there was some weird stuff going on. The driver's side was welded first and the passenger side is better but they're both done.

The backside welds on both were the cleanest looking.

I hung all 155 lbs of me off the wing with it all bolted up and it was no issue although I may want some sort of lock washer on the adjustable bolts for the wing angle.

Updated beauty shots. 

The carbon wing is its fully "up" position in these pics.

loving this fully!

The beauty of the Challenge is that weird E36 M3 shows up to keep things interesting. This build qualifies !

so, one thing "axe" and I have been mulling over offline, is the best way to try and help the air that's be disrupted by the roll bar.  I've thought a little about a tonneau cover behind, although that might be a too-big project (time & material).  I'd also suggested a panel that slopes down from the harness bar.

but, seeing more shots, and being reminded of how short a length there is from the roll bar to the back of the car... I think something more like the following would be of the biggest benefit:

it doesn't necessarily have to be that "deep"/long.  ~9inches, would probably be a good place to start.

I don't know if anyone else following along has opinions about that... or if there are ways to use that form for other/additional performance/display benefits?

In reply to sleepyhead the buffalo :

I keep seeing this thing looking somewhat like an F-prod road racer. I'd fill the space from the main hoop to the trunk lid with a sheet of plywood, or MDF, coated with bedliner. I'd also put the trunk lid down if you did that. Just my two cents.

In reply to Robbie (Forum Supporter) :

Thanks, me too!

In reply to DeadSkunk and Sleepyhead:

I have thought that just simple plywood would do the trick to fill the space between the main hoop and the rear of the car. I was also wondering if it would be worth molding the rear of the tonneau to match up with the tailgate when it's in the up position. It would end up looking like a little like a Porsche duck bill when there's no wing and the tailgate is down.

I tackled a couple simple jobs today. First was cutting the crash bar out of the passenger door. Second was a door pull for the driver's side. The outside handle was completely destroyed in the wreck and pulling on the stub of the cable isn't easy. Time for the tried and true cable looped through small engine fuel line.

AxeHealey said:

Updated beauty shots. 

The carbon wing is its fully "up" position in these pics.

Glorious.