Project Mini Cooper S | Magazine Series Part 10: Assembling Our Freshly Painted Mini Cooper S

Photography by Tim Suddard

Assembling an old car is a lot like building a puzzle. You lay out your pieces, group them according to their eventual destinations, and then snap everything together until–hopefully–nothing is left on the table. Now that our Mini Cooper S shell sported a coat of beautiful Tartan Red paint, we could finally begin piecing together this three-dimensional jigsaw. 

Car assembly needs to happen in a certain order–you’re basically trying to mimic the steps taken by the factory. Due to the Mini Cooper’s ground-breakingly space-efficient design, this order is even more critical than usual. We had our subframe assemblies restored and ready to go, but certain components needed to be replaced beforehand. 

We pored over the manual and our many photos of the disassembly for guidance. (Always take more photos than you think you’ll ever need.) Mini Mania supplied the remaining parts. Time to turn these components into a car. 

Step 1:

One of the first things to install during any restoration reassembly is the wiring harness. Our original harness was in terrible condition from past owners butchering in all sorts of aftermarket lights, switches, sound equipment and auxiliary gauges. We decided to start fresh, and British Wiring had a new, period-correct wiring harness right in stock. 

We’ve used their harnesses before, and they’ve always fit correctly, looked appropriate and worked well. Figure that a full new Mini harness will set you back about $300 to $400, depending on the year of manufacture. Compare that price against the aggravation of dealing with an old, cut-up harness. 

Step 2:

Next up: Installing the brake and clutch master cylinders, along with their respective lines. On a Mini, these components must go on before the subframes, since some of the lines pass between the body and the subframes. And as we learned the hard way, the main positive battery cable should also be installed before the subframes go back in. 

Step 3:

The steering rack mounts between the body and the front subframe, so its installation needs to be appropriately timed. Afterward, we could install the steering column and wheel. 

Step 4:

When we disassembled our Mini, the subframes sported two manufacturing stamps: “MOWOG,” the internal name for the conglomerate that built the car, and a star with a circle. 

Our Mini experts weren’t familiar with these markings, but rather than ignore them, we spent $20 to recreate them. We simply turned photos of the markings into line art, then had a stamp company transform it into a stamp. Finally, we applied the markings with the correct bluish-gray paint. When you’re trying make a car concours-correct, these are the details that matter.

We also found welting between the subframes and the body–a peculiarity that also seemed to stump at least one of our Mini experts. We have to assume it was used to silence squeaks and rattles. 

We found some similar material–welting intended for early Ford bodies–at a swap meet. For another $20, our car remained period-appropriate.

Step 5:

We had already completely restored and rebuilt our front and rear subframe assemblies. In fact, we even ran our engine on its subframe to check for leaks and other problems. 

To install the front subframe assembly, we simply placed it on a wheeled cart and then dropped the body onto it. Everything lined up as intended, and we easily bolted the subframe in place. We used the same process for the rear subframe. Then we hooked up the brake lines.       

Step 6:

Next, we started attaching our electrical items: headlights, taillights, parking lights, wiper motor and so on.

Step 7:

The Mini’s brake-light switch can be a trouble spot. It’s located along the front subframe, and once the car is assembled it can be tough to reach. And of course, without fully functioning brakes, the switch is difficult to test. But there is one simple way to test the circuit to the switch.

Simply build a short jumper wire that bypasses the switch, and then ask a helper to see if the brake lights turn on. Our brake lights lit up, so we moved on to the next step. 

Step 8:

Before going much further, we wanted to test our entire electrical system. Once the gas tanks are installed, for example, accessing the back of the taillights becomes very difficult; if there’s a wiring problem, the tanks have to come back out. 

Aside from one bad ground and a blown bulb, our entire electrical system operated as intended.

Step 9:

Time to work on the interior. We installed our gauge cluster and switch panel, then rewrapped the dashboard with fresh vinyl. The headliner could go in at any time since it simply snapped into place.

We put off installing the glass, however, and made sure to attach the A- and C-pillar trim and add the defroster vents first. 

Step 10:

Our car came with gauges for oil pressure and coolant temperature next to a large, center-mounted, 120-mph speedometer that was unique to the Cooper S. Inside this speedometer sat a fuel gauge.

Nisonger Instruments specializes in lovingly restoring, calibrating and testing these old Smiths gauges, so we entrusted them with ours. 

Our Mini didn’t come with a tachometer, but many owners added one. Although we’ve kept this car very, very close to stock, we decided a tachometer would be an appropriate period-correct modification that would also allow us to enjoy the car to its fullest. 

The Nisonger crew supplied the rare, period-correct Smiths tachometer that our car needed. Heritage Garage supplied the mounting pod. The pod attaches to the package tray–the same way it typically did back in the ’60s and ’70s.

Step 11:

Sound and heat insulation products have come a long way, and Quiet Ride offers solutions for many cars, including our Mini. Their kit uses both damper pads and pre-cut heat barrier material. 

They offer these pieces both individually and as part of a complete kit. Budget less than $700 for the entire setup. 

We found their Mini kit to be well cut and smartly designed. We didn’t use all of it, though, as a few parts would have detracted from our desired original appearance.

Step 12:

Our last job before reinstalling the glass: replacing the vinyl trim surrounding the front and rear windows as well as the dash area itself. 

Installing glass can be very difficult for novices and is best left to the experts. That said, with a few simple glassworking tools, a lot of patience and a little luck, you can do this job yourself.

Mk1 Minis like ours have a slightly smaller rear window than the later cars, and the correct gasket is no longer available. Solution: Cut down a later-style rear gasket and glue it together with 3M black urethane glass sealer. Then, place the gasket on the glass and move the pane into position. Slowly–and carefully–pull the gasket into the body with glass tools. Then, gently press the chrome bead into the center of the gasket. 

Step 13:

As we completed systems, we made them operational. First we bled the clutch, which proved to be easy since we’d rebuilt both our master and slave cylinders. Then we bled the brakes, hooked up the throttle, and made our starting system functional. The Mini’s cooling system is self-contained in the front subframe, and we verified it when testing the engine.

Step 14:

An original exhaust is no longer available for the 1275cc Cooper S, but the closest readily available replacement is probably Mini Mania’s RC-40 system.

Though perhaps a bit louder than a stock system, it was one we were willing to live with. We did deal with some complications during the mounting process, though: Our car didn’t come with the original pressed-steel, three-branch 1275 Cooper S header, just an aftermarket one.

Fortunately, we’d found one of these relatively rare headers on eBay. Sadly, the bottom few inches were missing, so we had to fabricate a fix. We mounted both the exhaust system and the header so we could then tack weld some missing pipe into position. Then we removed the header and seam-welded the repair. 

Someone would really have to know what to look for to spot this fix–even with the car on a lift–because this part of the header will eventually be hidden by the subframe and transaxle. 

Step 15:

Now that the car was coming together, we could reinstall the shift lever and parking brake components. The shift lever housing was easy to bolt into place once the transmission was in neutral. 

The parking brake hardware was also very straightforward. The biggest challenge–and it was fairly easy–was duplicating the tar-coated, felt-type material bolted underneath the cable bracket. This shield, which keeps moisture out of the cockpit, needed to be duplicated and reinstalled.

Step 16:

At this point, our Mini was largely assembled. With some gas in the tank, wheels and tires installed, and our Hydrolastic suspension pumped up, we could actually drive our car.

In our next installment, we’ll finish off our interior; assemble and install the doors, hood and deck lid; and begin the sorting process. 

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