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If you dream of building, owning, and driving an AC Cobra, you’ve come to the right place!

FFR Roadster CAD drawing

BUILD MANUAL details the construction of an all-new — that is, non-donor — Factory Five Racing (FFR) Roadster, generally referred to as the Mk3 or Mk4 1 as well as the 289 USRRC period-correct version and the MK4 Challenge racer.

The FFR Roadster is a replica of the AC Cobra: see also Legacy of the FFR Roadster.


BUILD MANUAL content preview

BUILD MANUAL covers 12 major topics in clearly written how-to sections illustrated with over 650 photos, drawings, and diagrams. Click on the 12 tabs above for a overview of our detailed instructions and technical assistance. Full access requires a membership pass.

Getting Started

Initial decisions

✔︎ Understand the AC Cobra legacy (development history, race results, vintage car photos)
✔︎ Is this the dream car you really want?
✔︎ What is a replica?
✔︎ Build one or buy one?
✔︎ Kit car manufacturer comparison: picking the right primary vendor
✔︎ Build the FFR Mk3, Mk4, 289 USRRC, or Challenge kit?

Project planning

✔︎ Articulate a build objective
✔︎ Understand rear suspension alternatives
✔︎ Define specifications and explore customizations
✔︎ Review state registration requirements
✔︎ What about insurance coverage?
✔︎ Establish a realistic build budget
✔︎ Select wheels and tires
✔︎ Consider customizations and special parts
✔︎ Select vendors and place orders
✔︎ Record keeping: orders and inventory
✔︎ Learn technical terminology

Work area setup

✔︎ How to prepare your workspace
✔︎ Comprehensive part labeling
✔︎ Procure tools and supplies
✔︎ Attend a FFR-oriented build school
✔︎ Construct engine block holder and body buck

Basic preparation

Kit staging

✔︎ Receive FFR kits, wheels and tires, and other parts
✔︎ Unpack, inventory and validate vehicle ID
✔︎ Inspect and remove body
✔︎ Chassis weep holes
✔︎ Crate engine setup

Aluminum fabrication

✔︎ Remove emergency brake bracket and fill cutout
✔︎ Fabricate custom transmission side tunnel fresh air vents
✔︎ Position custom fuel pump and sending unit access covers in trunk area
✔︎ Breeze radiator shroud
✔︎ Test fit Breeze battery box in engine bay
✔︎ Foot box removable cover
✔︎ Panel preparation
✔︎ Screw holes for seat belt bezels
✔︎ Anodize or powder coat all aluminum

Crate engine readiness

✔︎ Crate engine delivery and setup
✔︎ Flywheel dowel pins
✔︎ Swap oil pan
✔︎ Engine mounts
✔︎ Intake manifold
✔︎ Thermostat including heater bypass
✔︎ Clutch including clutch fork and release bearing
✔︎ Transmission


Front suspension

✔︎ IFS overview
✔︎ Lower control arm (LCA)
✔︎ Upper control arm (UCA)
✔︎ Spindle and bracket
✔︎ Hub and brakes
✔︎ Steering rack
✔︎ Preliminary front alignment
✔︎ Koni front shocks

Rear suspension

✔︎ Understand rear suspension alternatives ❗ 240-258
✔︎ Differential
✔︎ Rear axle and CV joints
✔︎ Control arms, spindle, and rotor
✔︎ Koni rear shocks
✔︎ Fabricate and install driveshaft safety loop
✔︎ Preliminary rear alignment

Mechanical controls


✔︎ Install driver side (DS) front foot box aluminum panel
✔︎ Foot box panel assembly
✔︎ Pedal box
✔︎ Install firewall aluminum panel
✔︎ Accelerator pedal
✔︎ Upgrading pedals
✔︎ Upgrading brake pads


✔︎ Steering system including steering shaft and steering wheel
✔︎ Modify DS foo tbox side panel for hose and harness access


✔︎ Brake master cylinders
✔︎ Wilwood Balance Bar
✔︎ Remote brake fluid reservoirs
✔︎ Brake lines
✔︎ Emergency brake cables
✔︎ Emergency handbrake
✔︎ Bleed brakes

Electrical system

Automotive electricity

✔︎ Understanding switches, relays, fuses and diodes
✔︎ Wire specifications
✔︎ Dash overview
✔︎ Wiring overview
✔︎ Wiring connections

Mounted components

✔︎ Ron Francis/FFR fuse box
✔︎ Solenoid
✔︎ Battery switch
✔︎ Firewall attachments
✔︎ Breeze battery box installation with chassis grounds

Dash fabrication

✔︎ Dash construction
✔︎ Dash wiring
✔︎ Gauge wiring
✔︎ Russ Thompson turn signal
✔︎ EFI computer, underdash filler panel, and related components
✔︎ Gauge calibration patch panel

Wiring integration

✔︎ Multiple electrical grounds
✔︎ Terminal blocks
✔︎ WeatherPack connectors
✔︎ Integrate harnesses (Ron Francis and MassFlo EFI)
✔︎ FFR fuse box modifications
✔︎ FFR and EFI fuse box wiring
✔︎ Headlight switch connections
✔︎ Ignition switch connections
✔︎ Neutral safety switch
✔︎ Sending units
✔︎ EFI 9-pin connections
✔︎ Rear harness
✔︎ Front harness
✔︎ EFI harness
✔︎ Alternator wiring
✔︎ Sending units

Component diagrams

✔︎ Horns
✔︎ Radiator fan
✔︎ Fuel pump
✔︎ Wipers

Fuel system

Fuel delivery

✔︎ Install gas tank
✔︎ Install fuel lines and filter
✔︎ Breeze EFI bypass regulator

Electronic fuel injection

✔︎ Mass-Flo fuel components
✔︎ Distributor
✔︎ EFI fuel lines
✔︎ EFI harness

Engine bay

Engine installation

✔︎ Install engine bay panels prior to engine installation
✔︎ Engine drop-in
✔︎ Drive shaft
✔︎ Attach chassis grounds to engine block and cylinder head

Engine bay components

✔︎ Alternator
✔︎ Starter
✔︎ Wiper motor

Cooling system

✔︎ Assemble radiator-shroud-fan unit
✔︎ Mount radiator
✔︎ Pressurized coolant fill port
✔︎ Connect radiator hoses

Exhaust system

✔︎ Exhaust headers and oxygen sensors
✔︎ Exhaust side pipes, see also engine mount adjustment
✔︎ Heat shields

First engine start & test drive

Cockpit construction

✔︎ Cockpit overview
✔︎ Clutch cable
✔︎ Transmission tunnel
✔︎ Install transmission tunnel vents and cockpit floor panels
✔︎ Modify tunnel cover for emergency brake and shifter assembly
✔︎ Trial fit seats

Go cart stage

✔︎ Install remaining trunk panels
✔︎ Install fire extinguisher
✔︎ Install remaining cockpit panels
✔︎ Trunk license plate wiring
✔︎ Drill roll bars
✔︎ Preliminary seat belt installation

Engine start and test drive

✔︎ First engine start
✔︎ Distributor timing
✔︎ Run diagnostic codes
✔︎ Professional alignment
✔︎ Go cart test drive

Body completion

Gel coat prerequisites

✔︎ Hood hinge preparation
✔︎ Radiator cowling
✔︎ Trunk hinge preparation
✔︎ Foot box gap fills
✔︎ Prepare rear and front splash guards (elephant ears)
✔︎ Foam tape and rubber seals on chassis, aluminum panels
✔︎ Exterior front and rear light wiring
✔︎ Mount gel coat body

Body-on components

✔︎ Check gauge and dash fitment
✔︎ Connect fuel filler neck
✔︎ Windshield install
✔︎ Adjust roll bar cutouts and install
✔︎ Lucas wipers
✔︎ Pre-fit doors and bottom trim
✔︎ Prepare trunk lid
✔︎ Pre-fit hood
✔︎ Exhaust side pipes
✔︎ Exhaust heat shields
✔︎ Gauge calibration
✔︎ Gel coat test drive

Shell preparation

✔︎ Paint plan, including options, schedule and budget
✔︎ Fiberglass shaping
✔︎ Hood scoop
✔︎ Paint selection
✔︎ Paint process
✔︎ Clear coating

Interior and exterior finish

Trim and fixtures

✔︎ Emergency brake boot
✔︎ Shifter knob, rubber boot, and bezel
✔︎ Safety harness
✔︎ Seats

Carpet and insulation

✔︎ Heat and vibration protection
✔︎ Carpet overview
✔︎ Driver foot box finish
✔︎ Passenger foot box finish
✔︎ Passenger side lock box
✔︎ Transmission tunnel finish
✔︎ Rear cockpit wall finish
✔︎ Trunk floor gap

Exterior trim

✔︎ Painted body mount
✔︎ Trunk lid mount
✔︎ Side louvers
✔︎ Body badges
✔︎ Fuel neck and gas cap
✔︎ Wind wings
✔︎ Final hood and latch
✔︎ Side and rear view mirrors
✔︎ Headlight assembly
✔︎ Over-rider bumpers
✔︎ Wiper arms and blades
✔︎ Fender spats



✔︎ Headlamp adjustment
✔︎ First time wash and wax
✔︎ Ear protection
✔︎ Driving shoes
✔︎ Road handling adjustments
✔︎ Maintenance checklist
✔︎ Engine oil analysis
✔︎ Driving technique


✔︎ PDF documents, FFR supplemental instructions
✔︎ Common automotive abbreviations
✔︎ Vendors, parts, tools, and more


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  1. identified by “RD” at end of chassis number; Mark I and Mark II are stamped with “K” instead