The Jenny (Craig) Chronicles -AKA DOOM

[RobNoLimit]

Got some parts from QA-1 and my machinist friend for the rear suspension. The uprights had rubber bushings all around, andwhile I am going to use the upper rubber bushing, the lowers have to go. My plan is to use a cam-bolt to have some static toe adjustment, so I need the lower bushings to pivot to allow some slight angle change. So, I came up with a plan, drew up some parts and off we go. The new bearing shells are aluminum, and have an internal shoulder to hold the bearing and an external shoulder to act as a stop for the shell. My first step was to press the bearings into the shells. The bearing is a chomoly PTFE lined unit from QA-1, with a 5/8" I.D. Then I put some red loctite on the shells and pressed them into the uprights, from the 'inside'. This way the shell shoulders and the lower control arm will hold all of the parts in place without the need for lock rings. The stand-offs, or bearing spacers are stainless, and fit into the 5/8" eye of the bearing and have a 1/2" I.D. for the mounting /cam bolt. Later on the control arm, the rear bearing mount will be fixed, and only the front will have a cam bolt for alignment. !/2" bolts may seam too small, but the load calc for the bearing/spacers/bolt assemble in dual shear is over 28,000 lbs, and there are two per upright. So, I feel pretty confident that this will be plenty strong enough. This is the little stuff that I think is really cool. And, no one will ever see it when the car is done.

[RobNoLimit]

Ahhh sanding. Not my favorite part, but it's got to be done. I started on the band saw to get the foam blocks close, then its on to a file and sanding block. The idea is to get the block to fit in tight from the back side, and push through enough to line up the face of the blocks even with the lower standoffs on the cart. the blocks then tip out 2 degrees from the bottom to the top. My goal is to have the top of the fender cover the tire, with room for the tire to travel up inside, then have the wheel opening be flush with the sidewall at the height of the tire centerline, then start to show a small amount of tire as the wheel arch goes down from there. Once I had all four fitted, I used some construction adhesive and expanding foam to glue the blocks in place - I don't want them to move. You can see some of the shape now, and yes, the front looks really wide. I think it will look a little leaner when I'm done.

[Motorcitydak]

Awesome build! Going to follow for sure. What kind of foam is that? Need it for something similar

[RobNoLimit]

Awesome build! Going to follow for sure. What kind of foam is that? Need it for something similar

So I asked the guy I got it from and he said it is 2 lb B grade. (Styrofoam) This is the same stuff that the Home stores sell for insulation. - This guy cuts it for a lot of them.

[RobNoLimit]

More carving. After looking at the whole door/side/fender area, I decided to make the doors longer. So, I fabbed up some more body tabs to hold things in place, and a side panel to hold the arc, then cut the body at the bottom of the door opening. I pulled it back 3" to the OE front/rear location, so I could use the body locating fixture that I already had. I do think the door/fender area looks more Cobra like now, and the shape should be a little more pleasing. Once in place I used expanding foam to fill some of the gaps. This stuff can be rough sanded once it cures, and makes a good enough backer to work from. The down side is that now I have to make doors.

[RobNoLimit]

So, one week of sanding and shaping is done. I still have a ways to go but the shape is coming in. Now don't laugh to hard, but, yes, the shaping filler is drywall mud. It goes on smooth, it's very workable, and it sands easy. And, I only need it to hold up one time. I know that some of you that love the traditional Cobra are thinking "NOoooooooo", but, this isn't your car, and it's not that kind of Cobra. - so be kind, it's OK if you hate it. No new mechanical parts this week, but some are on the way.

[brawls43]

Are building in a bit of aero in front there too? With a little bit an air dam to work with a future splitter?

[RobNoLimit]

Trying to get the wheel openings to shroud the tires from the wind, and smooth the airflow around the car a bit. - these cars are almost as bad as the truck aero, almost. The front will have a splitter attached to the chassis, to protect the nose and front fender edges from possible cone smacks. More sanding today.

[RobNoLimit]

Time to get serious. I'm starting to get some of the quarters in shape where I want them, so it's time to lay some glass. I have a few prep steps beforehand. Once the foam/filler is in shape, next is to cut and fill in a separation line. Some of the OE glass is still under there, and soon I will want to cut it out so that I can lay glass on the underside. Using an 1/8" cut-off wheel, I cut a small groove right next to the edge where the mud meets the OE glass. I try to cut 'almost' through, but not quite. Once I have cut the perimeter of where the 'old-to-new' blend will be, I filled the cut with drywall mud, let it dry, and sand it smooth. This will be easy to see later from the inside. Next is to scrub and wash the 'bond' areas on the OE glass. Warm water and a scrubber, then wipe with alcohol. Last is to create a 'mold release'. No normal release product will work on the foam/mud, and the resin will eat the foam in a heartbeat. So, I carefully cover the 'mold' areas with masking tape (the cheap kind) the waxie surface on the tape acts as a mold release and protects the lay up mold. Then it's time to pre cut the glass cloth and matt, and set all of the peices out in order. I usually mix up 12 oz. at a time. I was able to lay up one quarter (fender and door seam) with a 12 oz. batch. Using a playing card to chop out bubbles and extra resin, and to wipe the surface is a great trick.

BTW, I learned most of my fiberglass tricks from a guy named Manny Flores, in Mira Loma, Ca. - The best boat painter I ever saw. I'll have to tell you all about Manny in some upcoming posts.

[Rod]

looking AWESOME!

[wfo guy]

Are you itching?

[Peter Mc Mahon]

Are you currently working on the frame or are you literally making the body the way you want it and then building the frame to match that?

[RobNoLimit]

Are you currently working on the frame or are you literally making the body the way you want it and then building the frame to match that?

Getting the body in shape first. But, I am collecting and prepping parts for the chassis. Also doing some design stress analysis with CAD software. And, I am testing and learning about materials and hardware and epoxies. Kinda fun.

[RobNoLimit]

Still sanding and laying glass. But I am making progress. While most of the planning is going on in CAD or on paper, I do feel that I need to have actual parts to measure and hold, and just to look at. I'm doing a lot of fab/build in a style I have never done before, so I am a little apprehensive (but not too much to stop me). After a lot of searching and number crunching, I ordered a wheel and tire to look at and measure. There is a slight chance I may change from this size, but I doubt it. Here is some of my reasoning.

As a basis, this build is about mass and size. As a comparison I use the HellBoy as a baseline. (I have also been very impressed with Ryan Mathews Camaro, at 3500 lbs with 275 tires on all four corners). The truck weighs in at 3100 lbs and has a 315 tire all around. The wide five hubs on the truck open the door to a very light wheel, the 18 x 11 weighs 18 lbs. (a similar Forgeline would be 20+, which is still very light) and the 315 tire weighs 34 lbs. So the trucks wheel/tire combo weighs 52 lbs. Remember this is unspung, rotating mass - the worst. The 315's tread patch is appx 11.8" wide. So, four tires would total up to 47.2" of tread width to support 3100 lbs, or 65.7 lbs per inch of tread. - Now, this is a very basic view, because I am looking at the tread width vs. weight in a static form, and driving forces are all dynamic, but for simplicity, the comparisons are very close. For the Cobra I am using a 17 x 9 wheels from Wed's Racing (TC-105N) the wheel weighs just 15.5 lbs. The only draw back to this wheel is that the lug holes are machined for a 12mm stud, so I had to drill them for a 1/2" stud. The 255 tire weighs in at 24 lbs, so the wheel/tire combo comes in at 39.5 lbs. This is 12+ lbs lighter than the HellBoy's combo. Or, 24% lighter. The target weight for Jenny is 2100 lbs. (which is 32% lighter) The 255 tire has a tread patch appx 9.8" wide, times four ties = 39.2" of total tread width. Do the math and you have 53.6 lbs per inch of tread. That's 18% reduction in weight per inch of tread width. If I can get the geometry to stick it to the ground it should be awesome.

While there are a ton of other factors, this is an insight into the thought process that is leading the build. Also here is a pict of a Cobra that I like, but alas it is not real, a CGI myth, Oh well, it looks cool.

[Z06killinSBF]

Man this is awesome! Have you looked into the UV activated resin? Looks like you can work it all day, set it out in the sun and it instantly (almost) cures. Just a thought.

[RobNoLimit]

Man this is awesome! Have you looked into the UV activated resin? Looks like you can work it all day, set it out in the sun and it instantly (almost) cures. Just a thought.

Haven't tried this yet, but it looks cool.

[RobNoLimit]

I hope to never see Jenny in this position once she's done. But. for now, it make the work a lot easier. Trimming off the bottom edge of the front valance I decided to add an aluminum panel into the lower edge. This will help establish a flat surface for future splitter mounting, and stiffen the leading edge. After some sanding and prep on the body, I fashioned what looks like Spock's Scimitar from some .090 5052 alum. This is now sandwiched between two layers of matt glass, and will get some more layed up on the inside later. I'm now in at 40 man hrs on the body work, and just about ready to start pulling the foam blocks out.

[2ndroundko]

I love this build! do you plan to finish the flares with a small lip like the rendering or leave that as they are. will this be a track only car. and will you be selling the frame for these in the future?

[RobNoLimit]

I love this build! do you plan to finish the flares with a small lip like the rendering or leave that as they are. will this be a track only car. and will you be selling the frame for these in the future?

The flares will be close, but the lips on the rear will not be as pronounced, and they will start a little farther back (about 2 o'clock) Jenny will sit a little lower than the average Cobra, so the rear tire has to go up inside the fender

[RobNoLimit]

Now that the outside of the new shape has some strength to hold itself in place, I can go in and clean out all of the mess on the inside, foam, tape, mud, .... and sand and prep the inside to lay up some more glass. This is where the rear body strength will be.