The Jenny (Craig) Chronicles -AKA DOOM

[RobNoLimit]

It's time for another one. The Roach is about to go together for the last time, Tina's Mustang is getting well sorted out, and the HellBoy and Velocity are going through some winter tune-ups. so, it looks like I may as well load up my plate with a new build. I have wanted to do a Cobra since as far back as I can remember. Honestly, after driving a few Cobras in the '90's, I kinda lost interest. They really didn't live up to my expectations. Lately, seeing Bruce's OG Cobra on track has re-kindled the idea. Then, as fate would have it, a B.S. session with Mike Maier a year and a half ago put the bug back in. "we've got a body up in the rafters..." he says, "..my dad used to make them. We still have the last one he made. You wanna buy it? - we're cleaning up the shop." OK, so we were getting ready to move, and I had no time to drive up to Hayward to go get it. "... no problem, my dad has this old guy that hangs out at the shop, he'll bring it down for the gas money". So, that's how I got a Cobra body. It already has history. The last Cobra body to come from Maier Racing. We put it in a container to Tennessee, and it's been up in the rafters since. Until a few weeks ago, when I got it down.

Here's what I've learned about Cobras. The wheelbase is appx 93", pretty short. The rear tread width space avail is close to 68", and the front is around 63". What? Yes, a 5" difference between front and rear track width. Hmm, no wonder they have a tendency to 'push' going into a corner and the 'snap loose' in the middle and exit. Gonna have to look into a fix for that. I have a big list of goals for the car, and at the moment the only real bummer is the 'no kit car' rule in the USCA, but maybe they will address that this winter, If the car turns out how I think it will, it will be a great competitor at the OUSCI.

Some basic build plans : Light Weight. Square track. IRS. Smart build, updated styling and safety. Simple enough, stay tuned

[Peter Mc Mahon]

Probably my favourite car of all time so I will be following along. What is square track? Same WMS front and rear and square set up for wheels?

[LS7 Z/28]

Looks like a lot of fun Rob. Looking forward to watching it come together.

[bmbrzmn101]

liking the approach to one of my favorite cars. Looking forward to more!

Chris

[wfo guy]

I'll be watching. Years ago, I was going to build one. I found many downsides so I moved on to something else. Is your goal just an autocrosser or an all around fast car?

[RobNoLimit]

Thanks guys. Yes Peter, I would like to run the same wheel/tire/offset on all four corners, with the same tread width (or very close) front and rear. But, I don't want an overly "wide' car, as I already have that in the truck. WFO, We probably noted many of the same downsides, I had moved on from the Cobra as well, but now I've come around full circle. I really think i can build a nice functioning car from this platform. - All around fast and fun.

The wheels in the pict are off of the Roach Camaro, not for Jenny here. If you want some interesting 'enginerding' IRS info, check this out from my old Alma-matter http://digitalcommons.calpoly.edu/cg...1&context=mesp it's cool to see this progress, I worked with some of these instructors in the early '80's (damn that hurts to say)

[RobNoLimit]

My first project on a list of many was to figure out just what a Cobra is supposed to be. Or, what this one is. After much measuring and head scratching I finally made some decisions. #1, This body is not perfect. It was after all a race body, so I'll just roll on. #2, I will have to cut it apart and and do some glass work. - not my favorite thing to do, but, if I am to get what I want out of the car, it has to be done. and #3, At some point you have to stop staring at it and get to work. So, step one was to fab up a cart for the Cobra to sit on. I built the cart as square as I could, it measures out with a laser level to be +/- .030", close enough for me. The crossmembers in the base are set the front and rear body edges ('new') the front and rear axle C.L. ('new'), one under the engine center, one under the trans center, and one under the seat area. The cart is 48" I.D. and 56" O.D., so hub mounting uprights will have to be spaced outboard. To set the body on square, I struggled with this a bit, I came to the conclusion that the headlight and tail light centers were as good a place as any. After plotting out the centers, I drilled them out to 1/4" and put in some stands to hold the body square. I also set the mid section ride height at 4 1/2" with some cut blocks, When finished, the scrub line is to be 4".

[19,69camaro]

Just an idea you can take it or leave it but if you cut a line right down the middle and added 3 or 4 inches you could effectively make it a wide body without having to do a crazy amount of fiberglass work. It would have more of a square stance like the GTD z4's http://www.turnermotorsport.com/race-cars.aspx. Also more enging bay room for those big ass Coyote motors

[RobNoLimit]

Just an idea you can take it or leave it but if you cut a line right down the middle and added 3 or 4 inches you could effectively make it a wide body without having to do a crazy amount of fiberglass work. It would have more of a square stance like the GTD z4's http://www.turnermotorsport.com/race-cars.aspx. Also more enging bay room for those big ass Coyote motors

Nice! widening and Coyote power are on the table. Today may be the day she goes under the knife. Just a little plastic surgery, a nip here, a tuck the, a few more cc's here and there.....

[RobNoLimit]

One of my reasons for wanting to go with an IRS, is the total reduction of un-sprung weight. The total weight may be equal to or slightly more than a solid axle, and the suspension build is more complex, but the reduction in un-sprung weight is the the goal that wins out. I looked at all of the common units. Vette, Nissan, Mustang, BMW, and a few odd-balls that didn't make the grade. I need a WMS width of 60 1/2", and all of the units I studied are wider. Some can be narrowed, and some are more difficult. Those got the early axe. Then there is the expense, and lack of aftermarket support, gears, posi's.... Again, some got the axe. I t really came down to Vette of Ford (and I don't really mean the Cobra Mustang IRS). In the end I chose the Ford mix/match plan for several reasons. Then the E-bay and Craigslist search starts. Once I had a few parts to play with I could do some mock up and move forward.

Ford put IRS units in Mustang Cobra's, T-Birds, Lincolns, Crown Vic's and Explorers. Some shared parts and some were vehicle specific. I keep having to remind myself of the weight and HP targets to keep things in range, I don't really need an axle or gear set built for 600 hp in a 3500 lb car. I found some differences in the 8.8 cases. The 'car' case has two front mounts, and a goofy rear case mount off the back of the diff cover. The Explorer case has a nice two point mount on the back cover, but only a single mount on the front of the case. I rounded up one of each, and some other spare parts, and this is what I came up with. I used the 'car' front case, and the Explorer rear cover. This will give me four mounting points that are easy to plot out. I also got some half shafts to play with for mock up, but they are too wide.

[RobNoLimit]

I plan on using a 4 1/2" bolt pattern, I'll get into why later. This was another reason for choosing the Ford IRS parts. - Because all fords are 4 1/2" right? Unless it's an IRS, then there 4 1/4". Imagine my surprise, I made a neat hub stand that I could use to hold the hub at Ride Height, and it didn't fit. First I went back and checked my math for the bolt circle, it was right on. Then I pulled out my handy plastic bolt pattern gauge, and it showed the pattern to be 4 1/4". A quick google search confirmed it. Rats, Forded again! Next was to make a drill guide and fix the problem. I also put the bubs in the lathe and checked the surface run-out and trued them up. I chose a Dorman press in stud, 1/2" x 20, and went to work.

[RobNoLimit]

Well that wasn't too bad. It took about two hours to do all the machine work and press the studs. The uprights are Lincoln Mark-8, And while these cars had no toe adjustment, these will when I'm done. The uprights are aluminum, and weight 5 lbs empty. Once I had them blasted clean I pressed in new heavy duty bearings and pressed the hubs back in. The complete assembly (upright/hub/bearing/studs) weigh 9.8 lbs each. I will be re-using the OE Ford upper bushing, but I am going to replace the lower bushings with spherical bearings, so that will add a few ounces each.

[sdg0080]

Very interesting on the rear suspension. And the 8.8 is a very strong setup. I've seen the solid axle hold 1200 hp with only upgraded shafts.

[iadr]

To me, I sat in a Factory five, and was very sad- I wouldn't want it.
Driving position. Shoulders had to be inward of hips, feet tight together & both splayed left. Impossible to get comfortable or even in a position I could do my best driving. That Texas Co (IIRC, Lonestar) who extended the wheelbase a significant amount, had a good idea.
Don't suppose for this built you'd move the drivetrain forward, but for 95% of builds, that's a legit solution, too.

[RobNoLimit]

To me, I sat in a Factory five, and was very sad- I wouldn't want it.
Driving position. Shoulders had to be inward of hips, feet tight together & both splayed left. Impossible to get comfortable or even in a position I could do my best driving. That Texas Co (IIRC, Lonestar) who extended the wheelbase a significant amount, had a good idea.
Don't suppose for this built you'd move the drivetrain forward, but for 95% of builds, that's a legit solution, too.

I felt the same way in the Cobra's I have driven. So, if I close my eyes, and dream, - what would a cobra be like if it was built in '66, but with the knowledge and insights of today's car builders? - or something like that. The simple fact is that when it comes to automotive design, we demand more today than we did 50 years ago. More comfort, performance,..... Even in our Hot Rods.

[iadr]

Agree, although the first problem is the 302 is small, smaller than any current mass-produced V8. So right there, you are a step "backwards" further yet.
IDK... for me, I examined it, and reexamined it. Small, short engines (rotaries, Subaru's- no seriously) are going to give you room, but needless to say going to pale in comparison to what "should" be in there! They might, on paper come up equal on power, but they just aren't of the culture the car is. Even the Euro supercharged V12 build isn't a proper Cobra.

Ax15's and T5's can do OK and will stand up if built with aftermarket parts, and they are pretty small trans. Build the tunnel tight.

I didn't want to sit quite as far back in the wheelbase as stock, let alone move the seating back further yet.
So, seriously, what I came up with was - offset the engine several inches and around 8-10" forward. I do believe, especially with the tunability of IRS, you could make a very, very good handling car with the drivetrain moved "diagonally" quite a bit. But I knew if I was building for anyone but myself, that would be, basically, mocked.

So I gave up.

[RobNoLimit]

Harley Earl is one of my designer heroes. Like his work or not, he took everything down to the most basic shape, and then started there to build it back up. There is no secret that his design basis was the female body, Just look at a '48 Buick. When I look at the Cobra body I can see the same thing (I know, H.E. was not involved in the Cobra design...) but this really is a goofy looking gal. Great shape on the hips and rear end, but the shoulders and rib cage are far too narrow. How can this poor girl wear a backless gown to the Big Ball? The Egyptians charted out the most beautiful women as having the tips of the shoulder blade being the same width as the hips. - and I have to agree with them. Poor Jenny here isn't even close, so under the knife she goes. The plan is to split the rib cage and pull both sides out 2", as well as stretch the torso 3". There are other procedures to follow, but this will be the most drastic, and require the most recovery time.

OK, The key here was in the prep and set-up. I had spacers, blocks and alignment holes in place to position each front corner 3" forward and 2" out. I also roller strips of .090" aluminum to match the shape of the hood/nose top. These each had two sets of holes in them for Cleco's, one set at a 'beginning' spacing, and a second set of hole 2" out on each side. These were all on the same line. I was carefull to measure out the placement of each aluminum strip so that the Cleco lines were parallel to one another. This way, once the body was cut, The Cleco's would be move out to the second set of holes in the aluminum, and re-use the same holes in the body. Back at the door latch area, I fabbed up a tab to hold the latch pin location. This had to move out 2" (second set of holes) and forward 3" (this was done with material choice). The cross bar for the latch pin was 2" square, and the movable tab for the latch pin was made of 1" tube, with a small tab on the end. Moving the tab from the 'back' side of the crossmember to the 'front' side of the crossmember gained 3". The prep to about four hours, the actual cutting and moving only took about an hour.

[sdg0080]

It's going to awesome. Love the layout table you set up.

[brawls43]

Did you consider the MkIV Toyota Supra IRS? I believe they had a ~60" track width. Fairly light weight, and the Twin Turbo IRS can hold plenty of power, or if you're staying more manageable, even the naturally aspirated cars had a nice, lighter IRS, with LSD options including helical from the factory. Kinda weird throwing Toyota parts in a Ford, but a decent option. Unless you're too far along.

Also, did you consider the Corvette setup with the torque tube and rear mounted trans? Not sure if that would help with some of the footwell issues from engine/trans placement.

Either way, can't wait to see more of this. I'm sure you'll make the Cobra right.

[RobNoLimit]

Did you consider the MkIV Toyota Supra IRS? I believe they had a ~60" track width. Fairly light weight, and the Twin Turbo IRS can hold plenty of power, or if you're staying more manageable, even the naturally aspirated cars had a nice, lighter IRS, with LSD options including helical from the factory. Kinda weird throwing Toyota parts in a Ford, but a decent option. Unless you're too far along.

Also, did you consider the Corvette setup with the torque tube and rear mounted trans? Not sure if that would help with some of the footwell issues from engine/trans placement.

Either way, can't wait to see more of this. I'm sure you'll make the Cobra right.

I did look at the Toyota IRS, but when it came down to it, And I'm really only using a few of the parts anyway, I went to the Ford 8.8. The availability of parts for the Ford diff was a big factor, gears, posi units and such. I looked long and hard at the C-6 platform, and although it is tried and true, somehow it didn't match up to the spirit of what I wanted to do. Also, narrowing the C-6 IFS into the range I need would have negative effects on the turn in. - I could work through them, but then again I'd be using very few of the OE parts to do it. Thanks for the positive push, I hope I can turn my vision into reality.