Art & Inspiration Billet Aluminum Chassis by Kirkham Motorsports

Okay it's really getting old to have to keep looking in a dictionary to figure out what it is you just said. No wonder i make a living working with my hands!!!

 

Ah, shit disturbing.

Very good, carry on.

Everyone needs a hobby.

 

David-I'm not about to partake in the debate,just wanted to say damn nice work!All car guys,in whatever style they choose to work with can appreciate the skill level,creativity and effort involved with what you do.Until one tries to take that flat piece of steel or aluminum and shape it,one can not fathom what you've done.I ill pick up your book and I'm sure to enjoy it,well done,thanks for sharing,and yes all the guys on here are a great bunch!(Shit disturbers,but great) Shaggn

 

If I remember right, the number crunching we did was to use 14,000 psi as the "endurance limit" for our design, recognizing the actual yield of aluminum is 30,000 psi. We then used 2 G's as the max loading--a number much higher than the car will ever see (unless you hit a pot hole--tough to model as they can be anything from a bump to a a monster that will swallow your entire car).

Also, in the book you can see we were pretty conscience to eliminate stress risers (sharp corners, areas with too small a radius in transition, etc.). Can't bee too careful with the fatigue boogey man.

Vibration:

We have several vibrators, tumblers, and other cleaning machines around here. One day I heard this awful noise in the back and noticed the lid had come off one of the vibratory bowls. On closer inspection, I noticed the 5/16 hold down bolt had simply snapped off.

AHHH, time for an autopsy. I love mechanical failure autopsies. You can learn so much!

Sure enough, the characteristic fatigue marks radiating in from the root of the thread traveled until I saw the even more characteristic 45 degree SNAP and POP the lid fell off.

Hmmmmmm,

A 5/16" bolt has a 6,000-7,000 pound UTS. WOW! How did it break holding the PLASTIC lid down on my 20 pound vibratory bowl?

Fatigue. That bolt had no more than maybe a 25 pound load on it--if that. But it was vibrated for years and years and years and years. The high stress concentration at the root of the thread, combined with intense vibration, combined with time and BOOM goes your part.

I never looked at stress risers the same way again after that.

David


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That's nice.

I guess if you can't find an original AC a hand build one will do.

 

Hi David,
Just sent a link to your site to a friend of mine who used to work for AC building Cobra bodies in Weybridge here in the UK. He moved to the States a few years back and we only recently got back in touch. Turns out he came over to Poland and worked for you for a while his name is Alex Prosser.........small world.

 

I am sure we could have optimized the structure further. There is no doubt of that. You do, however, reach a point of diminishing returns. At some point you have to stop and actually MAKE something.

I think the rear cross member is a good example of how we tried to make the entire car:

The center of the cross member is the support for the front of the differential. Right next to that is the mounting place for the drive shaft safety loop. Further out and we pick up the inner seat belt mounting. Go out a bit further and the cross member supports the main chassis rails. Go out bit further and you pick up the inner seat mounts. Further still and you pick up the outer seat mounts. A bit further and we have the outer seat belt mounting point. Out at the end, the cross member ties the rear wheel well to the rockers.

Certainly, there are more forces on the chassis cockpit area that have to be taken care of. We opted to use the floor pans, undercarriage, foot boxes, tunnel, and belly pan to pick up the rest of the loads (in the cockpit area).

To make something stiff, you have to move mass away from the neutral axis. We used the cross members to do that. We also designed the cross members to pick up a lot of extra loads (anything in the area that we could get a hold of).

David




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Alex was one of the guys we imported to Poland to help the Poles take their game up a notch or two. He is a great guy who showed us a lot of tricks.

Tell him Hi from the Kirkhams! I love to see him again. He was working on a Hurricane (if I remember right) the last time I saw him.

David

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David Kirkham,
Tom Hand from Honeywell! Great to see you on here, this is one of the most diverse and interesting sites on the INTERNET. When it comes to all types and styles of cars, they are here. You will find some of the most talented artists and fabricators anywhere posting and advising on this forum.

Tom Hand

 

Tom!

I keep running into people I know on this site. Oh, the memories if Siberia in February! Interestingly, I just heard from Vladimir the other day. I guess they are plugging along.

Great to hear from you again. Tell Jack, Paul, Curtis, and the rest hello!

Seems like a great bunch of guys here. Hope you like the billet car. Now you know what I have been doing with my time lately.

David

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Thank you, I will go back and take another look at the rear cross member. You sound like a latter-day Colin Chapman, making each part play many roles.

And thank you again for taking so much time and trouble to reply - very helpful (and generous). I hope you will keep posting your projects here?

 

David, I've read the sheet metal chapter 4 times and pick up something every time.

Are there any inner fender panels? If not, how do you protect the body from rocks thrown by the tires denting the aluminum fenders?

 

Thanks for the kind words.

Colin Chapman was an extraordinary engineer who pushed the envelope further and further. The racing world learned an incredible amount from him.

Carroll Smith was another extraordinary engineer. I had lunch with him right before he died. What a brilliant mind.

I am happy to answer what questions I can. I certainly can't answer all of them--but I will find the answer if I don't know.

"If I look further it is only because I stand on the shoulders of giants." I am surrounded by an incredible team of talented guys. I wish I were as good as they are in their respective fields. They are the ones who pulled this off.

David

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I'm glad you like the book.

There are no "inner fenders" on our cars. We take black 3/8 closed cell foam and glue it directly to the underside of the fenders. That stops all but the boulders. I haven't had a dent in my car in years and years.

David

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Hey David,
Jack Q retired a few weeks ago and Paul and LaCurtise and George are still around. I'll give them all a hi tomorrow.

Do you still have the Willys body you all were making (was it a Willys)?
Tom

 

David, I posted the link to your book on AllMetalShaping.com. I expect will find it's way over to MetalMeet.com soon if it hasn't already. These two sites are the largest sites on the internet devoted to sheet metal shaping.

Is your substructure tubing aluminum or stainless? I'm assuming it's aluminum but steel was the norm for superleggera structures.

Would you mind sharing your source for the closed cell foam you use? I'd just as soon go with something proven to work and last.

 

Just awesome David...Traditional or not... then, now, or forever.

 

I hope Jack is happy in retirement. He was one hard-working, funny guy.

We sold the Willys some time ago. Maybe we'll make another one some day.

David


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We get the foam for our fenders from:
Cypress sponge/Rubberite
714.546.6464
Black, closed cell, 3/8 thick

However, I don't know if they only sell wholesale or not???

David


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We used aluminum for the sub-structure. Years ago it would have been extremely difficult to make the substructure from aluminum tubing. Aluminum tubing is pretty brittle. Standard, extruded 6061 T-6 will crack and break in most body bending applications because the radii are too small. For body work sub-structure you need 6061 T-6 DOM tubing. (Drawn over a mandrel). It is extremely expensive, but it bends like a dream.

David


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ok ive seen what you do, and yea its real nice! but it sound like you are advertising here? so what gives, not trying to sound like an ass. im just saying.

 

I don't see him selling anything, just giving a free book download and lots of good advice and techniques.

 

did you see what his web said? 4500 bucks for a book! thats stupid crazy! and its cool to see his work, im no fabricator! so i appreciate the free down load. but it looks like big money for the cnc machines, money i dont have!
im not trying to be a dick.

 

Actually, I think you are trying to be a dick.

The guy isn't "advertising" here. Hell, I'd wager that most folks that frequent this site couldn't afford to buy something he's built anyway. God only knows what that billet chassis roadster cost.

He came to publicize his book, and has shown great generosity by giving it away for free. I'm sure he'd be happy to pick up a customer or two by doing so, but he's undertaken the action with no guarantee of any benefit in return.

BTW, that $4,500 book is machined from aluminum plate. It's not just a bunch of paper stapled together.

You guys ought to be tickled shitless that talented folks like this come here and post at all. Instead, you attack them for being evil business owners who (God forbid) want to make some money with their talent and tools.

This place would not be the mecca it is without their contributions, so if you find that you dislike their participation, just don't click on their threads.

I know that being a dick to people is a time honored tradition on this board, but maybe you ought to just stow it for a while, especially when dealing with folks who bring a wealth of technical skill and knowledge to this board.

(Translation: If you don't like it, don't read it, and if you do happen to read it, STFU and keep your bitching to yourself.)

 

ok sorry kirkham motorsports! you do amazing work! coolhand calm the f down with the stfu shit! i never disrespected anyone here!

 

Thanks David, your work is amazing and certainly pertains to our hobby
I hope you stick around here. There is a vast wealth of information and knowledge here and unfortunately a proportionate amount of ignorance you would expect with 80 some thousand members

 

You aren't really unique, brother. I, too, like cars in a variety of flavors.

Traditional hot rods
Contemporary rods
60s muscle cars
Vintage sports cars (British, German, Italian, etc.)
Brass era cars
Art Deco Era coachbuilt European masterpieces (Like the 1937 Talbot-Lago T150C SS Figoni et Falaschi ‘Goutte d'Eau’ seen HERE ... Those things are sex on wheels)
Old school customs
Old-style dune buggies (remember the Meyers Manx?)
Vintage racing cars (all kinds)

I'll stop there, but that isn't really the end of the list.

The point is that this forum can actually be fairly eclectic and fun to read at times despite its attempts to remain narrowly focused on a few very specific genres of car. This thread is a good example of a topic that manages to work well here even though it does stretch a bit from the primary focus of the forum.

 

This is a major accomplishment and a true masterpiece. I love the quality of the work and have forwarded the links to a few friends.

What's next, assembling a team of former panel-beaters from the SR71 Blackbird project and doing one in TITANIUM?

 

Pay no attention to the haters! They ride the shortbus anyhow

 

I realize the book is expensive. Please understand the book is extremely time consuming to make and hence the price.

That is why I posted the information online for free. I wanted anyone who wanted the information to be able to have it.

David


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