A pile of tube, 50 pages of blueprints and 1 week later...

Lotus Super Seven replica cars are nothing new for the sports car enthusiast. There are countless forms with various frame designs, power plants, suspension layouts and bodies. It seems as though as of late, the most common donor vehicle is the Miata. How could one not be interested in doing a Miata Seven replica? Modern suspension design, fuel injection, tons of aftermarket support, just to name a few of the good points. But then enter the BMW M10 engine, one of the most successful engines designed by BMW with over 3.5 million produced in a 25 year span ranging from 1.5 liters to 2.0. The M12 variant, a spinoff of the M10 design, was used in the BMW Powered Formula One cars and produced roughly 1,500 horsepower. BMW’s proven track record of reliable performance, state of the art engineering (For 1974 anyway) and uniformity among engines make the M10 power plant and transmission an excellent donor selection for a Locost Seven.
This series of build logs will chronicle the fabrication and assembly of a BMW powered Locost Seven Replica Car. Beginning on, 12/23/2010 I embarked on Locost kit car utilizing McSorley plans available for free on the web at www.sevenesque.com. With the help of my brother Chris at Performance Fabrication, and parts sourced from Performance Supply I began the frame build on my Seven. The donor vehicle will be my 1974 BMW 2002 I acquired back in August and failed to sell several times on eBay. The scope is to use the BMW 2.0 liter power plant, transmission, and rear end including the trailing arm suspension. The front end will be comprised of mostly Ford Pinto/Mustang II components that are readily available and cheap. The goal of many is to see how little they can build their Seven for, while I am going to try and stay thrifty, I still want to have a sharp car that has performance oriented components and materials, and is worthy of both road use and the occasional track day.
The top and bottom main frames were layed out on a 4'x8' sheet of MDF layed on a square welding table. The frame plans are pretty straight forward and the McSorley plans were followed except with regards to the rear-end layout. Since I am using the trailing arm design that comes in the BMW 2002, I needed to make some revisions for both clearance and overall mounting of the sub-frame and components. The sub frame has become integral to the frame and the trailing arms, and differential assemblies will remain mounted in their stock configuration.


The front A-Arms were designed to incorporate Chrysler ball-joints and standard Pinto/Mustang II spindles. These are fabricated from 1" 10 gage D.O.M. tube and TIG welded to the screw-in style ball joint sleeves.

The chassis specs are a 100" wheel base, and 60" of track. Due to the inherent length of the BMW trailing arm design, the rear end was stretched to accommodate, which left me with a healthy trunk size and plenty of room for a 12 gallon fuel cell. The frame, a-arms (both upper and lower), and rear-end sub-frame, were completed in this update.







The next update will include fitting of the power plant and transmission, and assembly of the GM/Ford Pinto hybrid rotors and GM metric Calipers.


Every update I will estimate my cost for that particular stage. This will include any gain from parting of the items not needed from the 2002. The overall purchase price of the '02 was $800 I'll rough in expenses based on a percentage of the parts used from the car into my overall budget.
Update 1 Estimated Cost Breakdown:
Spindles $170.00
Rod Ends $40.00
Ball Joint Carriers $40.00
Ball Joints $50.00
A-Arm Bushings $20.00
Frame Tubing $115.00
A-Arm Tubing $27.00
BMW rear end components $200.00

Total: $662.00

In addition to cost, I will estimate the man-hours of assembly and fabrication for each update as well as a rolling tally.


Update 1 Estimated Man-Hours:
· Update: 62 Hours
· Rolling Tally: 62 Hours


Resources
www.sevenesque.com
www.perfabinc.com
http://stores.perfabsupply.com