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Learning how to build Lotus Seven replicas...together!
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PostPosted: July 4, 2017, 9:17 am 
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It was real interesting to compare so many different car. We had Caterhams, Birkin, Westfield, Super Performance, Ultra Light, Stalker and probably a couple more. The Locost is a little flat and disjointed looking, it looks like three separate sections the nose, the cabin, and the back end. But they do not flow together well, all the other cars look longer and sleaker. I think the answer is the cabin section is to long. If you look and where the top of the dash ends compared to the front of the seat there is a 3 or 4 inch difference. I think pulling the dash back 3 or 4 inches would make all the difference. I want to build a Aluminum scuttle to replace the fiberglass one I have, when I do I will try and mock it up and see what it looks like.

Graham


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PostPosted: July 4, 2017, 11:32 am 
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SkinnyG's Locost has the scuttle pushed back to roughly where the Lotus/Caterham/Birkin cars have theirs. In my mind it makes the car look much better.


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PostPosted: July 4, 2017, 2:16 pm 
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But aren't the other cars longer/larger? The original 7 was pretty much designed to fit Chapman, and moving the bits about might make it harder to get in and out of. I guess what I'm saying is that there's probably more to it than changing just one dimension.

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PostPosted: July 4, 2017, 2:28 pm 
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FastG wrote:
I think pulling the dash back 3 or 4 inches would make all the difference. I want to build a Aluminum scuttle to replace the fiberglass one I have, when I do I will try and mock it up and see what it looks like.

Graham


Agreed.

I also wonder if the driver is as far back between the two wheels as on the original Seven?

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PostPosted: July 4, 2017, 3:03 pm 
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"But aren't the other cars longer/larger? The original 7 was pretty much designed to fit Chapman, and moving the bits about might make it harder to get in and out of. I guess what I'm saying is that there's probably more to it than changing just one dimension."

The steering wheel would remain in the same place, So getting in and out of the car would not really be effected. I think the book chassis is the same as the SV Caterham, much larger that an early 7. The new high end ones are larger, but not by much.

It would be tough to do, as the stock shuttle stops on the transition of the angles inwards front frame rails and the parallel side rails. That would make it a little more complex to execute.

Graham


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PostPosted: July 5, 2017, 12:15 am 
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I've found a huge factor to the "sleekness" of a Locost is the door line. I was looking at various kits and I think it was the MK Indy that always looked leaner and sleeker than others. Eventually I realized that they lower the rear of the door sill which really adds to the look of the car IMO. I copied it on mine by dropping it about 1" in the back. Seems to give the car a bit of a waist as opposed to just a straight line.

Image

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PostPosted: July 5, 2017, 12:23 am 
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FastG wrote:
It was real interesting to compare so many different car. We had Caterhams, Birkin, Westfield, Super Performance, Ultra Light, Stalker and probably a couple more. The Locost is a little flat and disjointed looking, it looks like three separate sections the nose, the cabin, and the back end. But they do not flow together well, all the other cars look longer and sleaker. I think the answer is the cabin section is to long. If you look and where the top of the dash ends compared to the front of the seat there is a 3 or 4 inch difference. I think pulling the dash back 3 or 4 inches would make all the difference. I want to build a Aluminum scuttle to replace the fiberglass one I have, when I do I will try and mock it up and see what it looks like.

Graham


Those, and your later posting in this same thread. raise some interesting questions. Except for the really old versions of the true Lotus 7, as well as the versions of the Locost (Champion, Gibbs, McSorely) I haven't seen any layouts with dimensions for the other, more commercial cars like the Westfield,Birkin, Caterham, etc. It would be nice to have those posted if anyone has them.

Also, we might just be on the lookout for good profile photos. Photos wouldn't necessarily be on the same scale, but getting a look at qualitative, visual differences could be helpful. I do agree that some finished Locosts don't have the visual interest of the more commercial versions of the 7. On the other hand, some definitely do. So, the question might be, "Why?" Some photos might help.

I do have in mind that I'll have a second version of my body work, which will be a different, future phase of my build. For now, I'm going with fiberglass for the nose and scuttle.

Other subtle differences in the more commercial cars is the "Kick-up" at the rear and also the slight bowing of the top rail of the boot section. Some cars have both, some have 1 and some have neither. It makes a big visual difference.

Here is a Westfield example:
Attachment:
File comment: Showing non-Locost features
Westfield Example.jpg
Westfield Example.jpg [ 124.07 KiB | Viewed 2444 times ]

Attachment:
File comment: Chassis break evident here.
Westfield Example 2.jpg
Westfield Example 2.jpg [ 137.19 KiB | Viewed 2444 times ]


Here's amodern Caterham:
Attachment:
File comment: Different features and proportions
Caterham 620R Example.jpg
Caterham 620R Example.jpg [ 125.33 KiB | Viewed 2444 times ]

Attachment:
File comment: Profile view.
Caterham-620R-Example 2.jpg
Caterham-620R-Example 2.jpg [ 49.43 KiB | Viewed 2444 times ]


These small differences make a big difference visually.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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PostPosted: July 5, 2017, 12:49 am 
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Lonnie,
The pic of the Caterham with the "chassis break" note has it in the wrong spot. The Cateringvan and Lotus chassis starts it's taper at the rear edge of the scuttle. The lower chassis tube does "break" again at the spot noted, but the body stays relatively flat/straight from the rear edge of the scuttle right up to the nose. The downside to having the chassis start to taper at the aft edge of the Caterham scuttle is the pedal box is a lot smaller.


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PostPosted: July 5, 2017, 8:11 am 
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My Centaur kit had a nice drop to the "door" area of the cockpit. Made for a very pleasing profile.

Attachment:
Tetanus.jpg
Tetanus.jpg [ 133.09 KiB | Viewed 2419 times ]

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PostPosted: July 5, 2017, 9:37 am 
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The angled side rail does make a big difference, but that would be to difficult to changed once a chassis is built.

Graham


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PostPosted: July 5, 2017, 10:29 am 
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I think Westfield was sued by Caterham to keep their cockpit rail level instead of letting it descend like the Caterham. THey had to avoid a couple "iconic" features of the Seven.

Perhaps you can raise the front edge of the cockpit side as it approaches the scuttle. You'd need something to provide a rolled edge, but it might give a bit of old fashioned roadster look to the cockpit. I'm considering that type of thing for my car, which already has tall sides.

I don't think the down sloped cockpit sides work with the height of the seats people put in these days, it worked with the floor mounted cushions though.

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PostPosted: July 5, 2017, 12:11 pm 
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cs3tcr wrote:
Lonnie,
The pic of the Caterham with the "chassis break" note has it in the wrong spot. The Cateringvan and Lotus chassis starts it's taper at the rear (?) edge of the scuttle. The lower chassis tube does "break" again at the spot noted, but the body stays relatively flat/straight from the rear edge of the scuttle right up to the nose. The downside to having the chassis start to taper at the aft edge of the Caterham scuttle is the pedal box is a lot smaller.


It could be just as you describe. However, my real point was that you can't readily or easily perceive where the break is, which is what I meant by invisible. Here is the most relevant photo of a Caterham chassis that I have. I wish I had a really good plan view of it. If you look at the square top rail, it appears to be perfectly straight in the photo. It looks to me like the bottom rail breaks at the front of the footwells, which I think is what you meant to say.
Attachment:
File comment: "Official" Caterham chassis photo
Small Caterham Front Chassis Shot.jpg
Small Caterham Front Chassis Shot.jpg [ 291.72 KiB | Viewed 2387 times ]


Some days I thing the lower rail is parallel with the upper rail before the firewall (not shown here), and some days I think I see the bottom rail goes inward in two stages. The first being a very slight angle inward where your legs go, and the second being the larger and obvious angle in the engine compartment. In any case, what we're seeing, I think, is a very skillful hiding of the chassis break that is so pronounced with a Locost. That big and obvious break on the Locosts (in my opinion) makes the Locost look amateurish compared to other commercial versions.

I kept the "big break" it in mine because I wanted to be able to use the available scuttle and nose pieces available through Jack at Kinetic, so it had to match the Haynes dimensions. If I actually do "version 2" of my own bodywork, I'll try to mask it more, if I can.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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PostPosted: July 5, 2017, 12:29 pm 
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Lonnie,
Attached is a Seven S1 partial chassis drawing, the Caterham (small chassis/original type/etc) shares the same exterior dimensions as the Lotus chassis, though the Seven S1 (as shown) had a different rear chassis arrangement. The Caterhams and Lotus 7 S2/3 dont taper at your elbow, the chassis stays the same width (39" to the outside) as the cockpit section.

In the drawing, the straight line from the dash hoop to the front is the upper chassis member, the lower has the break in it.

Rod


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Seven.JPG
Seven.JPG [ 153.41 KiB | Viewed 2382 times ]
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PostPosted: July 5, 2017, 12:32 pm 
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I'm pretty sure the Caterham lower rail transitions in 2 stages. There is a minor break at the vertical even with the slip yoke and a second break at the toe kick.

The upper rail on a Caterham has a single break at the slip yoke vertical member.

I went and looked at a stupidly expensive Caterham project last year.

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PostPosted: July 5, 2017, 7:29 pm 
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@cs3tcr
Thank you, Rod. The drawing is appreciated.

TooBusy wrote:
I'm pretty sure the Caterham lower rail transitions in 2 stages. There is a minor break at the vertical even with the slip yoke and a second break at the toe kick. . . .


I have some other photos of that same chassis, and the 2 stage transition is what I think I see. It's too subtle to be sure just based on the photos I have. Thanks for that info.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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