That home made sports car

It looks like I'll be retiring in 2 years or less. So then I'll have time to make my sports car. WOOHOO! To that end I am reading, for at least the 5th time, Racing &
Sports Car Chassis Design by Michael Costin and David Phipps. And have been browsing the web for folks who have done similar. Lotsa variations on the Lotus 7 I see. I like the Lotus 7 from the front and the side but the squared off back end bugs me. The open cockpit looks great but living just a bit north of Seattle makes me think I need a hard top. Reading about the first iteration of the Lotus 7 I find that it had considerable lift in the front starting about 70 miles per hour. I will only ever be driving it that fast on straight roads but any lift could seriously affect the steering in a negative way. I guess this problem has been addressed in later models and in the Locost and Caterham versions. But it looks like all the newer versions have fenders that have a channel cross section, not a curved cross section like a motorcycle fender. To me they look like shit. The original Lotus had the curved cross section rear fenders and front fenders which were basically just curved sheet metal, with no sides. The front fenders may not be legal for street use. Anybody familiar with the original Laguna Seca race track logo? I really like that body style and I could place a body like that on a proven Lotus type frame. Still, it's an open cockpit car and I really think I need a roof. Doors too. I know doors complicate things as far as torsional rigidity go, but that can be worked around. A high sill is a problem for me because I have vertigo now and have had it for about 35 years. Standing on one leg to climb into or out of car could be problematical. At least I no longer fall out of chairs. I have decided that I want from 120 to 140 HP. That will be plenty to make a really light car zippy. Especially if the engine is already zippy. I like the look of carbureted engines and really like SU carbs. But I don't know if I want the hassle of dealing with carbs. BUT WTF, my tractors have carbs and they all start and run pretty reliably as long as I use ethanol free fuel, even after sitting for months during the winter. I also like multiple carbs with velocity stacks. 4 cylinders, 4 carbs. Even if nobody can see them under the hood I'll know they are there. I guess I'll need to take a class to learn how to shape sheet metal for the body. There are at least two places on the west coast that offer classes. Probably be a bunch of young guys with sharp minds in the classes too that can teach me some stuff. I have the machine shop but not the sheet metal shop. So I will either need to build another shop or rent one for a while. I have the machining and welding skills but my sheet metal working skill set is pretty lacking so the class will be fun. If anybody wants to give me any input I'll gladly accept it. I have two years to figure out just what the car will look like, what the power train will be, and what the frame should be like. Or at least an outline of it all. I'm excited. Cheers, Eric
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On 12/19/2019 2:29 PM, snipped-for-privacy@whidbey.com wrote:

Well, doors do dictate that you must have a little more than a hard top. Needs to be a full cage of some kind in order to maintain rigidity. On the car shows they always bitch and whine about how the convertible version of a high end sports car or super car has to much flex and is sloppy and harder to control, blah blah blah...
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wrote:

If the doors are incorporated into the frame, as part of the frame, it would help a lot. I have been thinking a lot about how this can be done. An ideal space frame should only be loaded in tension or compression and this means that every joint could be loose, just a pin through a hole, and the frame would work. A way to envision this would be to imagine a rectangle made from rods, each of which has a eye at each end for a pin. Connecting the 4 rods with a pin at each corner would result in a frame that could easily be deformed by pushing at any corner. But then add a diagonal connected with the same pins through the same eyes and the frame becomes stiff. Welds and gussets add strength but the real strength comes from triangulating the frame. So maybe there is a practical way for a door to latch with some sort of tapered pin to give a no slop fit. I'm still thinking about it. Eric
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On Friday, December 20, 2019 at 2:59:36 PM UTC-5, snipped-for-privacy@whidbey.com wrote:

If you read the Costin and Phipps book, you know that the closest thing to a true space frame was the Lotus 8. It was a failure. <g>
Look at the early MB 300 SLR to see what kind of hoops they had to go through to make a true space frame. Or look at the frame on a Maserati Tipo 61, which was known as the "Birdcage."
A Lotus 7, Locost, etc. has no lateral stiffness (no triangulation) above the floor, in the passenger bay. To race them, they cheat like hell with the roll bar triangulation to get some stiffness in there. Otherwise, they're a Flexible Flyer.
--
Ed Huntress

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On Fri, 20 Dec 2019 13:26:29 -0800 (PST), snipped-for-privacy@gmail.com wrote:

If they had doors they would only close ONCE.
A bit like the early Dart Swinger 340. If you dropped the clutch with the door unlatched, good luck!!! The Duster/demon was moderately stiffer.
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On 12/19/2019 2:29 PM, snipped-for-privacy@whidbey.com wrote:

I thought it might be fun to use a modern Jeep engine and drive train for a sports car build. Obviously gearing would need to change, but horsepower is more than adequate. With the right suspension you could spend an afternoon just passing people on the inside lane on a roundabout for fun.
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wrote:

Drive train of a Jeep has WAY too much mass for a good handling sports car - - - -
My brother started to build a sports car years ago - He was going to call it an XR12 ( as in Ex R12 - or used to be an R12)- using the front of an R12 Renault bolted to the back of a tub with the front a arm suspension from a vauxhall? - can't remember for sure, on the front. It was going to weigh in just over 1100 lbs - and with a "gordini-ized" Renault 12 1300 cc engine ( about 53HP stock, but easy to get over 85 HPout of it) or a real Gordini 1500 (111 HP stock and well over 150 easily released) it would have been QUICK!!!! Our 2100 lb R12 Rallye car with the stock 53 HP engine managed to place as high as second in the regional navigation rallye series when it was about 8 years old - The unsprung weight on the 12 was VERY low and it had an incredible suspension travel.
Another friend built a very lightweight rebodied Fiero with a 3.8 liter supercharged Bonneville engine in it.
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On 20/12/19 12:21 pm, Clare Snyder wrote:

Isn't that basically what Lotus did with the early Europa? Except it was an R16 engine, before they built a suitable engine themselves.
CH
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On Fri, 20 Dec 2019 12:44:02 +1100, Clifford Heath

Basically yes.
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On 20/12/19 1:36 pm, Clare Snyder wrote:

I have long wondered whether it would be possible to turn around a Subaru engine like that, to make a mid-engined all-wheel drive race car. The boxer has such a low CoG.
Does anyone know if this could be done with a Subaru diff?
CH
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On Fri, 20 Dec 2019 17:33:33 +1100, Clifford Heath

easier to get a reverse rotation camshaft
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On 20/12/19 6:22 pm, Clare Snyder wrote:

The gear teeth would be driven in the opposite direction too. Does that matter?
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On Fri, 20 Dec 2019 21:08:14 +1100, Clifford Heath

Likely some effect, but you aren't likely going to attempt to drive it 500,000km.
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wrote:

I've seen a Subaru boxer engine fitted into a motorcycle.
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wrote:

Or look into the DF Goblin kit car -- - - Uses a Chevy Cobalt as a donor - and being a Kit Car you get a VIN. A street Goblin can be pretty quick. The stage 1 and stage 2 kits run about $6000 combined and get you a running chassis with no body panels, interior lights, etc - which you can fabricate to your liking or buy the stage 3 kit in several formats.
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wrote:

"modern jeep" aka Fiat?
--
There is nothing more frightening than ignorance in action.

--Johann Wolfgang von Goethe
  Click to see the full signature.
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On 25/12/2019 00:22, Larry Jaques wrote:

I wonder if that comment might explain a mates situation when he had to replace a diff in his Jeep here in the UK. Apparently no way to know whether it was a US made diff or a Italian one from the VIN number you just had to remove it and measure the fasteners. The US one used inch still but the Italian one used metric, fortunately for him it was the
shipping, customs, and VAT.

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Still inch, even after Daimler owned them?
My 1991 Ford, made in Kentucky, is all metric. I had to buy 18mm wrenches and sockets to work on it because they aren't included in sets.
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On Thu, 19 Dec 2019 13:29:20 -0800, snipped-for-privacy@whidbey.com wrote:

Don't know where you are, but you will want to check into what is involved in getting a VIN number and insurance. Here in Ontario getting a VIN isn't TOO onerous, but geting insurance is pretty close to impossible for a "home-built" car. A "kit car" is a lot easier on both counts. Starting with a "donor car" and "modifying " it is a lot easier. I'd consider "modifying" an MX5 Miata. It's got a sweet powerplant and decent suspension. It's designed with doors and you can run open or with a roof. Parts to convert to coil-over suspension are readily available. Performance parts are readily available. Replace everything except the engine, running gear, and cowl and you still have an MX5 with a VIN. Take off the sheet metal, build a tube frame to give it strength with less weight and skin it in aluminum or carbon fiber (or whatever), install cycle fenders, even narrow the cowl if you want. The insurance company will ask if it has been "modified for speed" and you will likely have to answer to the affirmative, which WILL in all likelihood raise your rates a bit. Keep enough Mazda parts that you can still (somewhat) legitimately call it a Miata - - - -
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Id agree with this (kit+) approach, I had two Lotus back in the day, (11 and Elite) and I also built up a Kit car (Ginetta G15) in a week-end! I would not build from scratch, you may never finish to enjoy it! The 11 had a very thin Al body all butt gas welded and hand rolled, I would never do enough to make a job that perfect even though welding Al with modern welders is a lot easier, mastering the English wheel is quite something else! C+
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