The Kelsey Replica: Work in progress

William Kelsey · **Joined:** Wed Jul 18, 2007 4:01 pm **Posts:** 66

Well, the third frame was a success! Built it this time from mild steel. Actually, most of the material is a little thicker than the original Bugatti. From the information I have, the original thickness was 4 mm. That is not generally available and in stock in the U.S. . I went with the next size up which measures (nominally) .172inch instead of the 4mm which measures .157 inch. The total weight gain should be of no serious consequence. Not warping this time either.

I will post some pictures as soon as I can figure out how to do it.

The rear end assembly is also finished and I am very happy with the way it turned out. Doesn't look like original Bugatti but it is built in a way that is quite similar from a performance point of view. The gear ratio is 3.78 and it has a limited slip differential which should be a welcome addition.

The wet plate clutch assembly is almost finished also. I have no idea how it will work out but it looks like it may work okay. At least there is enough room for my feet with the much narrower bellhousing afforded by the multiplate clutch design.

My friends think I am crazy for installing a hand crank for starting it. Their right. I am crazy. My goal from the start was to capture as much of the excitement of driving a T-35 as I possibly can. Part of that excitement is cranking it by hand to start it. In a way it could be seen as exercise to get used to the one turn lock to lock steering which I'm told requires a lot of effort.

I have read several blistering comments about Ralph Lauren's T-57 and the "restoration" he had done. It seems he ruffled a lot of feathers. I'm sure we can all agree he had the "right" to do it - it is his car. I also think we can all agree that we wish he would have stayed more faithful to original Bugatti design and practice. Such words as "whored", refering to the car, come to mind, for example. I'm sure I am going to hear some comments like that too but I really am trying not to, in any way, insult the Bugatti name, reputation, or image. If imitation is the most sincere form of flattery, I am doing the best I can to build my project in the Bugatti tradition. It will never be presented as a Bugatti but rather as a replica that hopefully behaves like one.

Johan Buchner · **Posted:** Fri Dec 14, 2007 8:25 am

Hi William

It is Ralph Lauren's refusal to acknowledge that his cars are bigger than his ego that bugs the hell out of me. EXK 6 was built in 1938, and the company that made her is gone now. Jean died in 1939, then the war broke out and Ettore passed away in 1947. The glory years lasted from 1910 to 1939 during which time approximately 8000 Bugattis were made, of which about 1500 survive. This is a valuable heritage and should be protected. Few collectors understands the importance. More's the pity.

As the ringleader of the Lauren bashers I feel it my duty to clarify. To be disrespectful to your creation would be spitting on a man's dreams. That is what you started with, a dream and your two good hands. You are on an intensely personal quest to give shape and form to your vision. This is engineering. This is creating. This is art. By the time you are done, there will be something that did not exist before. Your journey is unique, and I find it mesmerising; made more so by my own lack of mechanical ability.

Regards
Johan Buchner

J.J.Horst · **Posted:** Fri Dec 14, 2007 9:23 am

Johan Buchner wrote:

I am not sure I agree with you Jaap. What William is trying to do is to "touch the cloth" but, like most of us, he cannot afford to pay millions for the real thing. Given the limitations described by Mr Kelsey, I find his out-the-box approach quite fascinating.

The question is not whether carbon fibre is an appropriate material, but whether an authentic Bugatti experience can be had using this material. Remember, we are talking about an individual building a car; it has to satisfy only William.

A carbon fibre Bugatti, like a Lamborgini engined Ferrari P4 replica, has to please only the creator. The opinion of onlookers is irrelevant.

Allow me to conclude with a story: The great composer Wolfgang Amadeus Mozart was once asked by a young musician for some advise. "You are still very young", replied Mozart, "why not start with something simple first." "But you wrote symphonies when you were nine" exclaimed the youth. "True" said Mozart "but I did not ask how"

Regards
Johan Buchner

You understood me wrong, Johan; I was thinking purely about the mechanical consequences. The Bugatti frames are designed for steel. As Carbon fibre reinforce epoxy is a totally different material, a steel design is not at all the optimum design for carbon. Reason for this is that the materials have a different strength / stiffness ratio. Therefore; a steel frame should be designed for strength, while the carbon fibre frame must be designed for stiffness. Then a totally different design would be the most logical (optimum) result.

Johan Buchner · **Posted:** Fri Dec 14, 2007 10:32 am

There is a difference between strength and stiffness. Jaap I promise you I never even gave it a moments thought. A seperate chassis would be strong, but a D Type's tub is stiff.

I'm having the Mother of all lightbulb moments here. Strength will protect during an accident; stiffness allows the suspension to work properly. Let me stop writing, my mind is going all over the place. Thanks Jaap, I am learning and thinking.

Please post more about this subject, my brain won't let it go. I tell you, joining this forum is more rewarding than I ever could have dreamed.

Thank you to all who share their knowledge and experience, it adds VALUE to my life.

With Grattitude
Johan

Herman · **Posted:** Fri Dec 14, 2007 3:49 pm

If one would develop a car in carbon, and it should look like a Bugatti type 35, I would come up with a more-or-less monocoque idea.

However, just making chassis rails is a relatively easy task, using simple tooling, where a monocoque requires more and more expensive tooling.

So I can fully understand the choice for carbon frame rails, and even when not designed for carbon, my feeling (no calculations made) is that they should be more than effective bearing the loads encountered during its life span.

Therefore it is a shame that the black material bought by William was not carbon. (and it is always tricky, as there are more types of carbon, some more suitable, others less suitable). I usually sell T700 Toray carbon in various UD, wovens and multi axial patterns.

---

About Lauren and his Atlantic:

William is making something new, which is magnificient.
Lauren is destroying something old, which was magnificient.

But all in all it is not too bad: De-chrome the wheels, paint the thing blue, put some new cream leather in the interior, and spray some caustic soda over the engine and mechanicals. Then polish the aluminium with an oil-dirty rag. Definately improves the look...

William Kelsey · **Joined:** Wed Jul 18, 2007 4:01 pm **Posts:** 66

A very good friend of mine - a British automobile engineer - has given me many pointers during the past twenty years or so. He is the only man I have ever known who truely understands automobile design from an engineering standpoint. Of course, there are thousands of other engineers who know what he knows but I don't know them.

One of the pearls of wisdom he shared with me was this: "If it is rigid enough, it is probably strong enough." I have thought about that statement for more than ten years now. It changes everything. The flying leap from the two rail frame to the creations of the engineers at Jaguar and those of Colin Chapman is based on that understanding. Many older frame / chassis designs are built with a certain amount of flexibility accepted as tolerable. The Bugatti frame would be much more prone to twisting if it wasn't for the engine employed as an integral part of the frame - at least in the front.

My design is as close to Bugatti's as I possible, as far as using the engine as a stiffening member. It is no possible for me to build the bottom of the engine as he did. Instead, I have made steel and aluminum mounts that facilitate the bolting of the engine to the frame directly in three places each side. This essentially stiffens the frame from the front of the engine to the read of the engine. At that point, the frame is much more robust and less prone to twisting. When Herman shows me how to post pictures, you will see.

Herman · **Posted:** Fri Dec 14, 2007 4:07 pm

Posting pictures: I will write an extensive howto, but it will be tomorrow. I need to run now for an appointment (company dinner for Christmas, somewhere in "Bob's Country Bunker")

the place:

me and my brother. We're twins:

Just send over the pictures to me, and I will post them tomorrow morning, together with a howto to post pictures.

Herman · **Posted:** Sat Dec 15, 2007 8:53 pm

Here's the pictures. Great looking machine! must be satisfying to see it assembled to the frame. Oh, and great steering wheel!

Click the images for large versions.

Herman · **Posted:** Sat Dec 15, 2007 9:00 pm

And the info that William sent me over the mail:

Quote:

Here are some pictures of the project as it is now. Please note: the transmission aluminum castings have not been machined yet. Decided not to do that until all the mounting issues have been resolved. The single dry plate clutch on the engine is not the one that will be used in the final product. The wet plate clutch in the following picture will be used. The rear end is completed and even holds oil without leaks. The torsion arm is some departure from that of the original but I am confident it will work just fine. The one big issue to be resolved are the two back springs. I can not find a company that is willing to bend the long leaf 13 degrees the hard way to compensate for the angle of the springs (as a result of the radical taper of the frame as it tapers to a near point at the back) to the rear end. If I can't find anybody to make them with the bend, I will have them made without the bend and heat and bend them myself abd have them re-heat treated afterward. The only other large issue is the front axel. In that case, I know what I am going to do. I am having a piece of 4130 bent and tapered and then welding the spring mounting in place. This will involve some additions of stock to shore up the tube at the spring mount but I think it will be at least as strong as the Bugatti type. Of course, some testing will have to be done to be sure the strength is there as axel failure can be a source of embarrassment...to say the least!
William Kelsey

Johan Buchner · **Posted:** Sun Dec 16, 2007 9:23 am

I'm with Herman, that steering wheel is gorgeous. On a not entirely unrelated matter, William you are the first person to ever mention the strength of the front axle. I have allways wondered if the square opening for the springs weakens it. There does not seem to be a lot of metal surrounding that spring, and the shape seems "uncomfortable" compared to rest of the axle.

I agree, front axle failure could be a problem! Here's another one one of my "Educating Johan" questions: When designing the axle how do you ensure sufficient strength - or perhaps more pertinent, how do you calculate the forces that will act upon the finished assembly?

Most chrashed Bugattis seem to have at least one front wheel assembly torn off. Design fault or early example of a crumple zone?

Regards
Johan

Whitney Paine · **Joined:** Tue Dec 11, 2007 9:24 pm **Posts:** 154

"the strength of the front axle"

1) The spring box dimensions varied to suit the two spring thicknesses.
2) The axle is lacking in torsional strength and with the larger brake drum cars there is a risk of twisting the outer part of the axle and king pin eye ends.

As a point of note, the cable layout means the brakes have a servo action caused by the twist of the axle/springs....an idea lost on some prewar cars, where poor cable layout led to the twist causing the brakes to be less effective the harder you braked.

The source for the above information is Grand Prix Bugatti by H G Conway. A superb book that I would recommend as essential reading to any Bugatti enthusiast. It can be purchased via the Bugatti Trust in Gotherington.

Herman · **Posted:** Sun Dec 16, 2007 1:46 pm

Twisting the front axle is exacly what happened to Bart Rosman at Het Loo 2005, during the sprint.

William Kelsey · **Joined:** Wed Jul 18, 2007 4:01 pm **Posts:** 66

I'm a little like Bugatti in that I sort of look at the structure and, if it looks strong enough, it probably is. (I know what you are thinking.) Test piloting machines designed and built like this is not for the faint of heart or devoid of faith.

That front axel doesn't look right to me. A box in the middle of a tube - just seems like a disaster in the making. However, I am determined to have my front axel made in a manner similar to the original in appearance. I am going to depart from the Bugatti design is that the "box" will be a box made from one piece of 4130 welded in the proper place of the axel. That place will be cut out using a milling machine to keep the shape and size accurate. After the parts are TIG welded, additional pieces of chrome moly stock will be added to basically bring the tube structure around the box to add tortional rigidity. The ends will also be different in that they will be longer from top to bottom. The "eye" end of the Bugatti simply doesn't look long enough to me. The angle of the bore of the hole in relation to the axel will, of course, be critical because there will be no adjustment.

There is only one test that will prove the design is sound. However, many tests can reveal if the design is unsound. To test for tortional rigidity, I will simply place a bar through one of the eyes and fabricate a bar through the other end. The first end is anchored to the concrete wall and the other end is turned to put a lot of twist force on the axel. I don't know what values I will be looking for yet but If it doesn't feel right, I will scrap it and start over.

One thing is certain in my view: Bugatti was a clever man. That axel is a very interesting design. All failures are remembered but most of them seemed to work just fine. They also survived many crashes intact.

J.J.Horst · **Posted:** Mon Dec 17, 2007 9:24 am

The trick with the front axle is that it was forged from one piece. I would recommend not trying to weld it up from pieces, that makes the whole product a lot weaker.

There are a few people that can still make them, a group of enthusiasts made a bunch here in the Netherlands a few years ago.

Johan Buchner · **Posted:** Mon Dec 17, 2007 10:02 am

3 Quick questions:

During an accident does the twisting and/or shearing of the front axle help to absorb some of the forces away from the driver?

Will William's intended method of constructing a front axle definitely make it too weak?

How expensive is a reproduction front axle?

johan

The Kelsey Replica: Work in progress

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