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How to Build a Mini Marcos

To give you a feel of the simplicity of building a Mini Marcos, what follows is a warts and all (with a few concessions to html) retype of the assembly guide supplied with the D & H Mk. IV kit.

It goes without saying that the registration and after sales sections are now obsolete, but the Club can provide advice and some assistance to members who are completing kit builds or restoring cars. Marcos Sales Limited will make replacement panels to order, subject to the availability of serviceable moulds.

Disclaimer: neither the Mini Marcos Owners Club nor the author of this web site accept any responsibility for inaccuracies in these instructions or for any consequential loss, damage or injury.

Assembly Guide for Mini Marcos Mk IV

This guide is intended to give you the best sequence in which to assemble the mechanical components into your Mini Marcos. It is recommended that you also have access to a workshop manual in order to correctly overhaul the mechanical parts from your old Mini before final assembly. Before starting work, lift the bodyshell onto blocks placed at the four corners of the floorpan to raise the floor about 18" off the ground. These blocks should be placed at the edge of the floorpan where it begins to angle upwards. Make sure the bodyshell is secure in this position.


A Minivan or Mini Traveller fuel tank must be used. Before installing, cut off the filler pipe 2" from the top of the tank on the shortest side. Cut out the hole in the body recess for the filler pipe, using your original rubber grommet. Use a straight edge to extend the line of this pipe to the floor of the car, and mark the floor, making sure that the centre of the hole is 2" from the rear edge of the raised portion. Cut out this hole. Put a ring of Dum-Dum seal round tank filler and offer up the tank from underneath. Drill six " diameter holes and mount tank. Connect tank to tank filler pipe by 2" I.D. Rubber hose and clip.

N.B. A minivan fuel gauge sender unit must be used with this tank. Run the fuel line from the fuel tank, across underside of rear floor and down nearside floor recess (If hydrolastic suspension is being used, run the hydrolastic pipes brake and fuel down central tunnel at 9 o'clock and 3 o'clock) Offer up rear subframe temporarily to make sure you have clearance on the pipes.


Bolt this to the front of the bulkhead with the large hole in line with the clutch master cylinder.


The pedal assembly mounts into the front cross member, and scribe lines for the necessary holes will be found on the front crossmember. Cut out these holes and bolt in the pedal box assembly loosely. Drill two holes for the lower mounting bolts and bolt loosely. Drill up through rear mounting hole and bolt through dashboard support box, using a penny washer behind the fibreglass. Mount master cylinders, making sure the clevis pins that connect the pedal to the master cylinder pushrod do not foul the pedal box. Do up all the bolts tight.


Mount T piece on front bulkhead in line with brake master cylinder. The rear brake line runs from this down the bulkhead, adjacent to the steering rack mounting moulding, and along the offside floor recess (Make sure that this pipe follows the bulkhead as closely as possible as the front subframe comes very close in places. Better still, temporarily fit subframe to check clearances) At rear of car remember to leave a loop of brake pipe to fit a rear pressure valve on rear subframe. Connect front T piece to brake master cylinder. Do not connect the pipe 'T piece to subframe' until the front subframe is fitted.

Accelerator Pedal

Position the throttle pedal horizontally until is in the right position relative to the brake pedal, and vertically so that the throttle cable socket is level with the lower bolts holding the pedal box. Drill two " holesthrough the bulkhead and mount the throttle pedal with the bolt heads outside the car. Drill a hole in the bulkhead to accept the stop for the outer throttle cable.


N.B. Make sure you have a Mini wiring diagram before you start working.

Wiring Loom

There are several wiring looms available for the Mini, so if buying a new one make sure it corresponds with the year of your car. The looms we supply are all for the Mk 3. Mini, which allows use of the headlamp flasher/horn/indicator switch on the cloumn. A good idea is to use a Mini clubman wiring loomand instrument pack (available very cheaply from a breaker) which gives you a 'plug-in' instrument console. The wiring loom is in two halves, the rear half runs across the back of the car in the well under the rear panel, over the near side wheel arch and down the nearside box member. Run it up the front face of the door aperture, through a hole and into the glove compartment. Run it along the bottom front face of the glove compartment, tucked under the opening rebate, and through another hole into a space behind the dash.

Now turn to the front loom. This runs along the outside of the engine compartment and through a hole in the offside of the bulkhead. Drill this bulkhead hole and lay the loom roughly in position, making sure that the various 'branches' of the loom reach the appropriate components e.g. rear loom, speedometer assembly, light switch etc. (For recommended layout using standard Mini instruments see drawing). When satisfied, secure loom with P clips and self tapping screws, keeping it as high as possible inside the engine compartment. Fit a control box, fuse box, flasher unit to the side of the engine compartment, their position being determined by the loom. The horn is situated at the front of the engine compartment.


Cut out the headlight aperture and fit lights, connect to loom. The feed to the nearside light runs across the top of the front inner panel. Go to the rear of the car and fit the rear lights of your choice. Make sure they are equidistant from the central line of the car, and that you have room for the number plate. Fit number plate light. N.B. All unearthed electrical componnents such as rear lights, number plate lights (and separate side lights if fitted) require a separate earth, as there is no earth return through the body. The rear lights may be earthed by running a wire from their retaining screw to the earth side of the battery.

Battery and starter cables

The battery is mounted behing the nearside wheel arch. Bolt a piece of Dexion across the end of the raised moulding over the fuel tank. Push the battery up against this and secure by normal bar and clamps. You will need two long lengths of starter cable. Both run from the battery and down the nearside box section and out of the hole at the floor level adjacent to the front wheel arch. One then runs across the floor to one of the nearside rear mountings of the front subframe (this earths the front subframe). The other runs up the front floorpan, through a hole in the front bulkhead, and along to the starter solenoid. The front loom is now earthed by bolting the earth tag you will find near the bulkhead to the metal insert near the shock absorber mounting. The rear loom is earthed direct to the battery by a similar tag near the battery. Your body/chassis unit is now ready to accept the mechanical units.


This bolts straight on to the predrilled holes. Bolt it up loosely and mount the steering column. Carefully rotate the rack in its mounts unitl the column clears the bottom of the dash. (You may need to enlarge the hole in the floor for the steering column slightly) Tighten the rack clamps. Slide the top mounting up the column and bolt through underside of the dash, using large penny washers on the other side.


The shock absorber top mounting brackets are secured to the steel plate bonded into the inner wing. There are two holes immediately above the box section and two immediately below. Use a light to help find them, and clear them out with a " drill. Mount the brackets.


Drill out the top of the rear turrets to accept the rubber bushes, and mount the rear shock absorbers in the usual way.



Although we strongly recommend that you do not lower your Mini Marcos, the low weight of the body means that the rear aluminium suspension trumpets must be shortened by 3/16 in. at the narrow end in order to bring the car level. Remember there is a 5:1 leverage ratio on the rear suspension, so the car is lowered by five times the amount you take off, so remove metal with care. (See workshop manual regarding removal of suspension trumpets). Offer the subframe up to the body/chassis unit, and secure with 8 bolts through the predrilled holes; use penny washers on the inside of the car. Connect the brake line to the pressure relief valve, and the fuel and electric feeds to the electric pump, if fittes. Temporarily fit the rear wheels.


Drilling of mounting holes

Although the main bulkhead holes are drilled, the mounting holes in the floorpan and forward bulkhead have not been drilled, due to large tolerances on Mini subframes. Mount the subframe using the four main mounting bolts, and where the other mounting holes meet the body, drill six 5/16" diameter holes.

N.B. Note there are metal inserts where you are drilling. Remove subframe and fit engine/gearbox assembly (It is possible to do the above drilling with the engine in place, but it is more difficult).


Remove the cowl from the radiator and drill the six holes in the cowl 1" lower than standard. The corner of the cowl must be removed to aloow the radiator top hose to be fitted. Refit cowl to radiator, and assembly to subframe.


Use Austin A60 cable and fit gearbox end before fitting subframe to car.


This job is possible with two people, but easier with three.

With the front subframe assembly complete with engine/gearbox, radiator and front suspension, fit the front wheels. Place blocks under gearbox and front of subframe, making sure the unit is as secure as possible.

With one person lifting under each front wheel arch, roll the body forward on the rear wheels, lift over the engine and lower. DO NOT FORGET the packing pieces that fit between the subframe and the body. Secure all mounting bolts. Connect steering rack to stub axles. Fit front dampers. Fit brake pipe from bulkhead T piece to brake light switch. Fit carburetter and exhaust pipe (Use exhaust pipe from Minivan).


Clutch pipe runs from the master cylinder to the junction with the flexible pipe in the bracket on the beam, in the usual manner. Bolt slave cylinder to clutch housing and engage pushrod.


Mounts on the nearside of the engine compartment on the raised moulding using standard Mini strap and rubber block arrangement. The rack runs through a hole in the bulkhead and through both webs under the dashboard. Cut 2" diameter holes in these webs to allow passage of the wheel boxes. Check spacing of wheel boxes before drilling holes scribed in the body, as the racks vary. Connect wiper motor to the loom.


The reservoir is mounted adjacent to the windscreen wiper motor, and the push button on the dashboard where it is convenient.



These should be mounted close together in the centre of the car and 3" back from the bottom of the screen, due to the angle of the screen. Both the heater connections from these ducts should be in the central 'box' under the dashboard.


The heater is mounted centrally as high as possible under the dash. If a Clubman heater assembly is used, fit the heater so that its control panel is just below and flush with, the dashboard.

Fresh Air Heater

The fresh air ducting goes over the top of the pedals, through the wheel arch and along the underside of the offside wing, as in the Mini installation.

Your Mini Marcos is now basically complete, but it is worthwhile to take care over the finishing touches and we suggest that you check the following:

  1. Are all the bolts holding the major components to the car fully tight?
  2. Are all the brake and fuel lines secure, and not fouling the subframe or moving parts. HAVE YOU BLED THE BRAKES?
  3. Is the steering rack and column secure. Are the wheel nuts tight?
  4. Have you checked all the electrics for correct functioning? Is everything correctly fused?
  5. Does the engine run properly? Are there any fuel leaks?

N.B. This is not a comprehensive check list but merely an indication of some of the things that should be double checked before using the car on the road.


These are easily removed by rubbing down with a wooden block about 1" square using wet and dry paper. Start with 240 grade (no coarser) and work through to 360 to 500 grade or finer. Once you have removed the excess with 240 grade move to the finer grades to avoid scratches. When you have a smooth surface, bring back the shine by using 'T' cut.

N.B. Remember you are removing excess material, until you come down to the level of the adjoining surface YOU MUST THEN BE VERY CAREFUL NOT TO RUB THROUGH THE GEL COAT (smooth surface material) which is 1/16" to 1/8" thick.


This varies from country to country, and we suggest you contact your local vehicle licensing authority about 4-6 weeks before you want to use the car. They will advise you on the current procedure. Basically you can keep your original registration if you use all the parts from the same car, or alternatively you may have a current registration, but then become liable for Car Tax (about 100)


If you have any problems during the assembly of your Mini Marcos do not hesitate to phone the factory on Saddleworth 3813. Don't try this now - the factory is long gone!

Should you have the misfortune to damage your car on the road, a comprehensive set of panels is available from stock, and any body part can be made to order.

May we take this opportunity to wishing you a successful assembly, and may miles of carefree motoring.

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Last updated 31st January, 2012