44-Year-old Cobra Wins Street Car Challenge

[D-CEL]

3170,

I thought I saw PS rack hiding in there.. I think about a power rack every time I come home with my arms aching lol.
With that kind of turn in I would have thought it would be a little twitchy , must be amazing to drive, It’s hard (for me) to imagine a Cobra you don’t have to wrestle with.
Wow 10 years! I think new package would yield some big improvements.
That steering arm looks…problematic for a big rotor swap. Is it just an optical illusion or is it really in the way?
Thank you, I’m happy with them. I’m still messing with the M/C’s, F/R bias and pedal ratio. I think they require a little more effort than they should.


Craig,

Yea well NO... LOL
When I was putting it together it up, a friend stopped by to hang out "I’m a pro at lock wire! I can do that"
So I said "Great!!" and moved on..
I was also building my master cylinder/balance bar assembly at the same time and it was giving me fits (not knowing the factory had the pedal ratio at 3.5-1!!)
So a couple of days later, in the midst of staring blankly at the car up on jack stands with the wheels off, I said "DOOOUUUUGHH!!!" lol


Jason

[Cobra #3170]

You are very observant D-CEL, the rotor is so close to the steering arm that I had to radius the inboard face of the rotor along the outer circumference.
I had to repackage the whole deal with the 13" rotors to make it work. I have a reverse hat that moves the rotor as far out as I can and still have adequate clearance from caliper to the wheel inner face. I cheated by reducing rotor thickness .125 to 1 1/8 and moving the wheel outboard .125. I still have my Ackerman with the new set up and don't have the outer tie rod on top of the rotor. I have 1" bore F and 7/8" bore R AP masters with a mechanical bias adjuster that works well with the current calipers, I'll have to see how it is with the new design, efforts have not been bad with the old set up.

I could not drive this car without Power steering now. You should really give it some thought, sometimes the car can do things that you would not believe, if only you could move the wheel fast enough. I also installed a smaller Momo wheel for hand clearance at the door, this really requires PS because of the reduced leverage.

My amateur racing experience is in Formula Atlantic cars so I am really spoiled in terms of steering and brake response this has driven me to try and improve those two areas over the years .

Originally Posted by D-CEL

3170,

I thought I saw PS rack hiding in there.. I think about a power rack every time I come home with my arms aching lol.
With that kind of turn in I would have thought it would be a little twitchy , must be amazing to drive, It’s hard (for me) to imagine a Cobra you don’t have to wrestle with.
Wow 10 years! I think new package would yield some big improvements.
That steering arm looks…problematic for a big rotor swap. Is it just an optical illusion or is it really in the way?
Thank you, I’m happy with them. I’m still messing with the M/C’s, F/R bias and pedal ratio. I think they require a little more effort than they should.


Craig,

Yea well NO... LOL
When I was putting it together it up, a friend stopped by to hang out "I’m a pro at lock wire! I can do that"
So I said "Great!!" and moved on..
I was also building my master cylinder/balance bar assembly at the same time and it was giving me fits (not knowing the factory had the pedal ratio at 3.5-1!!)
So a couple of days later, in the midst of staring blankly at the car up on jack stands with the wheels off, I said "DOOOUUUUGHH!!!" lol


Jason

[D-CEL]

3170,

If i may ask, what spindle are you using? Is there a different steering arm option? Gotta luv Hoerr

Jason

[Cobra #3170]

I made my own because of the critical ratio of upper and lower joints and wheel axis with relation to the chassis. The only thing I regret is not using a cartridge bearing. I started out that way but converting it to a pin drive set up would have taken a lot more time than I had that season. The set up that Kirkham has on their new design is very nice for the bearing and hub. If I were doing it again I would use a lot of their design and just modify upper and lower joint accommodations. I use a 1/2 Stainless NMB Rod end for the upper and a 3/4 spherical NMB for the lower joint. Mounted at just the right angles it gives me 5.5" of total travel with out binding at all possible steering angles, I did limit rack travel to avoid potential clearance issues. One critical design issue is getting the steering arm outer pivot far enough outboard to get the needed Ackerman, that in conjunction with relocating the rack rearward in car gave me what I needed. You can actually push this car at full lock with out a lot of resistance (other than the rear end clutch plates). Try that on a stock Cobra with big tires, you might as well put the hand brake on.

[D-CEL]

I figured the A arms and geometry were yours.
Are the “upright” forgings and steering arm factory Cobra pieces?
Do you use a suspension design program?

Jason

[Cobra #3170]

In the 1970's I bought a spare set of spindles, steering arms, and uprights from Shelby American. I used those as my starting point and modified the uprights and steering arms to get the right package. I actually used a mechanical drawing program to articulate the suspension for roll center location and movement, tie rod end points and length to achieve minimal bump steer. I have used a Ford Motor program in the past that was on the main frame called "Hfronts" that showed me all the weak points of the original design in the early 1980's. I knew pretty much what I wanted in terms of camber gain, toe change, Ackerman, caster, roll center height, antidive, etc. and also how much freedom I had in terms of inboard points so a lot of the input was a given because I couldn't cut or weld on the chassis. I just used the lower inboard pick ups and the tire patch location with respect to the frame and optimized everything else from there. If I were starting with a clean sheet of paper and did not have to preserve the original parts and just bolt stuff on it would have been a lot different. I have a poor motion ratio and that makes it tough to get proper shock control (like the originals). My Ford GT is close to .9 front and 1 in the rear which really helps the shocks do their job vs motion ratios around .6 or .7 especially when you square them.

Originally Posted by D-CEL

I figured the A arms and geometry were yours.
Are the “upright” forgings and steering arm factory Cobra pieces?
Do you use a suspension design program?

Jason