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Learning how to build Lotus Seven replicas...together!
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PostPosted: Tue Apr 29, 2008 12:07 pm 
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Mid-Engined Maniac

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Details the design and construction of a minimalist two-seat mid-engine sports car. The layout may still change at this early point, but the figure below gives an idea of where it's headed. The exposed tubes are a debatable feature. They're like this because it was easier to draw that way, but the paneling could be moved to the outside to cover it.

Features:
True low cost. How low is up to you.
Miata suspension uprights, no custom fabrication.
Stock Miata rack - no fussing about with shortening it!

Mid-engine, using overwhelmingly available powerplants.
Large footwell for real-world sized feet.
No exhaust making you deaf in one ear.
No hot exhaust cooking your feet or burning your legs when you get out.
Increased rear weight bias improves braking and acceleration.
Fewer tubes than a Locost chassis = faster to build.
All metalwork is either flat or single plane bends.
Improved side-impact protection.
Integrated rollcage instead of a bolt-on affair.
Zero composite work, fenders and nose are off-the-shelf.
No engine torque twisting the chassis messing up wheel geometry.

Specs:
Engine - up to you, but most any FWD drivetrain will fit.
Wheelbase - 94"
Track - 60"
1300lbs, estimated
Estimated 8000ft-lb torsional stiffness.
Accomodates two people and a 5' - 6'-4" driver.

A cookbook is in the works, but the builder will have numerous build options that suit his situation.

I'll add more here as I think of it.
Image

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Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


Last edited by Anonymous on Mon Sep 15, 2008 10:45 pm, edited 8 times in total.

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PostPosted: Tue Apr 29, 2008 1:13 pm 
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Very interesting. Can't wait to see one being built!


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PostPosted: Wed Apr 30, 2008 1:45 am 
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Locostering Information Liaison
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So cool to finally see your idea here.....

I am sure I am not alone in saying "I look forward to any progress and reading your next book".

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PostPosted: Wed Apr 30, 2008 9:04 am 
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This is neat. I plan on building a full-bodied middy in the near future that's a little larger than the Fiero I currently drive. I'm eager to see what you plan on doing for clutch hydraulics and shift cables.

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PostPosted: Wed Apr 30, 2008 9:23 am 
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Mid-Engined Maniac

Joined: Sun Apr 23, 2006 8:26 pm
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Location: SoCal
A hydraulic clutch is no problem, just make the cable longer. I have a pretty elegant solution for the shifter cables which I'll show once it's mocked up and tested.

Now if only someone would buy Kimini it would free up the garage so I can get started!

_________________
Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


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PostPosted: Mon Sep 15, 2008 10:10 pm 
[quote="KB58"]Details the design and construction of a minimalist two-seat mid-engine sports car. The layout may still change at this early point, but the figure below gives an idea of where it's headed. quote

I always love a good discussion on middies.
Are you going to write a book on how to build a rear (mid)engine sevenesque Locost? Personally I am curious about mid engine arrangements which do not require redrawing the seven's lines and I do hope someone will write up the subject.

A typical 4 L transaxle powerplant (I think) requires that axle shafts be moved approximately 5 to 6 " aft of a "Book" live shaft position ( I am just eyeballing it). This means longer trailing arms and better suspension. In order to retain the Seven's visual proportions I would suggest to stretch the chassis from tube "p" to front chassis member by the same length. The resulting car would still look like a seven, as long as a Viento.

And as a Locost builder-uk lister (Akumabito) was demonstrating to me three years ago a side picture taken of two sevens, one RWD the other Middy could fool any one.

Just my thought ...of the day.

Philippe.


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PostPosted: Mon Sep 15, 2008 10:43 pm 
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Mid-Engined Maniac

Joined: Sun Apr 23, 2006 8:26 pm
Posts: 4833
Location: SoCal
Geez, kind of forgot about this thread.

Kimini is in the process of being sold - a bittersweet experience as you can imagine.

In the April 22 diary entry there are CAD pictures on the midlana website. The area behind the driver does have to increase - there's just no way round needing a bigger area to install a transverse drivetrain.

The hard part is to keep it from looking like a.... dunebuggy, a very hard thing to achieve due to it having a integral rollcage.

The book will be a cookbook, much like the Gibb's book. As these things go they tend to take on a life of their own. The renderings are very rough and it'll evolve, but it's the general form.

Alright, back to endless CAD drawings...

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Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


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PostPosted: Mon Sep 15, 2008 11:16 pm 
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Kurt,

Since this thread has bubbled back up to the top it's probably as a good a place as any to ask you a question. In the MidLana diary you said:
Quote:
The free drawing program Google SketchUp is looking better and better after discovering plugins that make it more than adequate.
Could you expand a little on what plugins you're using and any you tried that weren't very useful?

Dominic


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 Post subject: bump
PostPosted: Thu Dec 18, 2008 9:54 am 
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Saw you started cutting metal, a good feeling after so much planning.

I'd like your opinion on sketchup, also what k series engine are you using? What's the weight on that, and do you have it modelled? I'd like to check the dimensions


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PostPosted: Thu Dec 18, 2008 10:21 am 
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Mid-Engined Maniac

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Location: SoCal
I need to check on this thread more often...

I like Sketchup a lot, enought that I recently bought the Pro version. It's exactly the same as the free version with the big exception that it imports and exports files in many more formats. For exporting DXF files to vendors or TIFFs to the book, it's a must-have.

There's already a thread here on using SketchUp for building a chassis: http://locostusa.com/forums/viewtopic.php?t=4515&highlight=sketchup

If you have questions on how to use it I can problem answer since I've been through the School of Hard Knocks.

The engine is a 2.4 liter Honda K24A1 with an A2 head on it which will be turbocharged. The complete drivetrain (engine, tranny, intake, intermediate shaft, clutch, flywheel, starter, upper header) weighs 403 lbs. See the July 6 2008 diary entry.

The drivetrain must fit the following space with a couple caveats:

Width: 45"
Height: 24"
Depth: 20"

Caveats:
Width:
Width is absolute max including side engine mounts. Less is better.

Height:
Height is absolute height, from the bottom of the pan to the top of the valve cover. This is flexible; it depends how high you're willing the valve cover (and maybe intake) to stick out above the horizontal chassis tubes. I myself don't mind the engine as a "feature." BTW, unlike a Locost the pan does not hang down below the chassis rails.

Depth:
Fore/aft. 20" means from the rear face of the head (not including whatever's behind it, to the fire wall. In my case the intake is on the forward side and the exhaust is on the rear, extending under a lateral cross tube. If your engine is reversed, with the intake on the rear, the tube must be rerouted.

Also, chassis tubing is flexible around the transaxle, of which a portion will stick out aft around the axle ports, this is okay and is not part of the 20" value - within reason.

_________________
Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


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PostPosted: Sat Feb 21, 2009 10:19 pm 
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Location: Simi Valley CA
I read in your build dairy you were thinking about eliminating the rubber bushing at the top of the rear miata upright. Could you share some info on this?

The Midlana looks great.


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PostPosted: Sat Feb 21, 2009 10:32 pm 
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Mid-Engined Maniac

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Location: SoCal
Using Miata OEM rear uprights greatly complicates matters but it's the double-edged sword of using what's available and not making people fabricate anything more than necessary. The bushing issue will be discussed in more detail on the midlana forum.

_________________
Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


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PostPosted: Tue Dec 07, 2010 1:35 pm 
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Mid-Engined Maniac

Joined: Sun Apr 23, 2006 8:26 pm
Posts: 4833
Location: SoCal
It's been a very long time since this thread's been updated, but work has been continuing: the frame built, drivetrain's in, car is wired, and was run on the dyno several months ago. Currently I'm on vacation working on the paneling. Here's a picture from yesterday - there's just too much to write about here (again) so please check it out in the build diary on my site, http://www.midlana.com/. For those who don't know, it uses a FWD powerplant mounted mid-engine that attempts to keep much of the Lotus look. Below is also a render of the (latest) color selection.

Image

Image

Image

Image

Image

_________________
Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


Last edited by KB58 on Tue Dec 07, 2010 1:47 pm, edited 1 time in total.

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PostPosted: Tue Dec 07, 2010 1:42 pm 
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We are Slotus!
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Yo, Kurt~
Lookin' good! Looks as though test drive isn't far off!

(That was supposed to be an exclamation point after your name, but the ~ thing looks kinda cool, doncha tink?)

I was looking at the row of cleco's along the top of the side panel, as well as the other rows. Are those going to be "structural" rivets, put into a frame rail? If so, what's the spacing along that top row? The other cleco's don't seem to be as evenly spaced, I'm guessing some aren't drilled yet. (?)

Take Care-
JDK

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PostPosted: Tue Dec 07, 2010 1:51 pm 
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Mid-Engined Maniac

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Well, I can say that 50 Clecos aren't enough, so I have to pick and choose wgere to put them at any one time. Rivet holes are uniformally spaced, typically 2" on-center, though the lower row alternates. Some panels will be removable via rivnuts, those are on 3"-centers. Yes I know all about the issues of drilling into chassis tubes but for better or worse that bridge was crossed a long time ago with Kimini. No the rivets aren't structural since all the work is done by the chassis.

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Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


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